Patent Publication Number: US-2006008819-A1

Title: Novel 38594, 57312, 53659, 57250, 63760, 49938, 32146, 57259, 67118, 67067, 62092, FBH58295FL, 57255, and 57255alt molecules and uses therefor

Description:
RELATED APPLICATIONS  
      This application is a divisional of U.S. patent application Ser. No. 10/154,419, filed May 22, 2002 (pending), published as U.S. patent application Publication No. 2003-0143675 A1 on Jul. 31, 2003, which is: 
          a continuation-in-part of U.S. patent application Ser. No. 09/858,194, filed May 14, 2001, published as U.S. patent application Publication No. 2002-0061590 A1 (abandoned), which claims the benefit of U.S. Provisional Application Ser. No. 60/204,211, filed May 12, 2000;     also a continuation-in-part of U.S. patent application Ser. No. 09/895,811, filed Jun. 29, 2001 (abandoned), which claims the benefit of U.S. Provisional Application Ser. No. 60/215,376, filed Jun. 29, 2000;     also a continuation-in-part of U.S. patent application Ser. No. 09/919,781, filed Jul. 31, 2001, published as U.S. patent application Publication No. 2002-0123094 A1 (abandoned), which claims the benefit of U.S. Provisional Application Ser. No. 60/221,769, filed Jul. 31, 2000;     also a continuation-in-part of U.S. patent application Ser. No. 09/957,664, filed Sep. 19, 2001, published as U.S. patent application Publication No. 2002-0123097 A1 (abandoned), which claims the benefit of U.S. Provisional Application Ser. No. 60/233,790, filed Sep. 19, 2000;     also a continuation-in-part of U.S. patent application Ser. No. 09/964,295, filed Sep. 25, 2001, published as U.S. patent application Publication No. 2003-0050441 A1 (abandoned), which claims the benefit of U.S. Provisional Application Ser. No. 60/235,107, filed Sep. 25, 2000;     also a continuation-in-part of U.S. patent application Ser. No. 09/972,724, filed Oct. 5, 2001, published as U.S. patent application Publication No. 2002-0103351 A1 (pending), which claims the benefit of U.S. Provisional Application Ser. No. 60/238,336, filed Oct. 5, 2000;     also a continuation-in-part of U.S. patent application Ser. No. 10/002,769, filed Nov. 14, 2001, published as U.S. patent application Publication No. 2002-0132298 A1 (abandoned), which claims the benefit of U.S. Provisional Application Ser. No. 60/248,364, filed Nov. 14, 2000, and U.S. Provisional Application Ser. No. 60/248,878, filed Nov. 15, 2000;     also a continuation-in-part of U.S. patent application Ser. No. 10/024,623, filed Dec. 17, 2001, published as U.S. patent application Publication No. 2002-0187524 A1 (pending), which claims the benefit of U.S. Provisional Application Ser. No. 60/256,240, filed Dec. 15, 2000, U.S. Provisional Application Ser. No. 60/256,588, filed Dec. 18, 2000, and U.S. Provisional Application Ser. No. 60/258,028, filed Dec. 21, 2000;     also a continuation-in-part of U.S. patent application Ser. No. 10/055,025, filed Jan. 22, 2002, published as U.S. patent application Publication No. 2002-0177148 A1 (abandoned), which claims the benefit of U.S. Provisional Application Ser. No. 60/263,169, filed Jan. 22, 2001; and     also claims the benefit of U.S. Provisional Application Ser. No. 60/324,016, filed Sep. 20, 2001 (abandoned).        

      The entire contents of each of the above-referenced patent applications are incorporated herein by this reference. 
    
    
     BACKGROUND OF THE INVENTION  
      Transport of larger molecules takes place by the action of ‘permeases’ and ‘transporters’, two other classes of membrane-localized proteins which serve to move charged molecules from one side of a cellular membrane to the other. Unlike channel molecules, which permit diffusion-limited solute movement of a particular solute, these proteins require an energetic input, either in the form of a diffusion gradient (permeases) or through coupling to hydrolysis of an energetic molecule (e.g., ATP or GTP) (transporters). The permeases, integral membrane proteins often having between 6-14 membrane-spanning α-helices) enable the facilitated diffusion of molecules such as glucose or other sugars into the cell when the concentration of these molecules on one side of the membrane is greater than that on the other. Permeases do not form open channels through the membrane, but rather bind to the target molecule at the surface of the membrane and then undergo a conformational shift such that the target molecule is released on the opposite side of the membrane.  
      Transport molecules are specific for a particular target solute or class of solutes, and are also present in one or more specific membranes. Transport molecules localized to the plasma membrane permit an exchange of solutes with the surrounding environment, while transport molecules localized to intracellular membranes (e.g., membranes of the mitochondrion, peroxisome, lysosome, endoplasmic reticulum, nucleus, or vacuole) permit import and export of molecules from organelle to organelle or to the cytoplasm. For example, in the case of the mitochondrion, transporters in the inner and outer mitochondrial membranes permit the import of sugar molecules, calcium ions, and water (among other molecules) into the organelle and the export of newly synthesized ATP to the cytosol.  
      Membrane transport molecules (e.g., channels/pores, permeases, and transporters) play important roles in the ability of the cell to regulate homeostasis, to grow and divide, and to communicate with other cells, e.g., to secrete and receive signaling molecules, such as hormones, reactive oxygen species, ions, neurotransmitters, and cytokines. A wide variety of human diseases and disorders are associated with defects in transporter or other membrane transport molecules, including certain types of liver disorders (e.g., due to defects in transport of long-chain fatty acids (Al Odaib et al. (1998)  New Eng. J. Med.  339: 1752-1757)), hyperlysinemia (due to a transport defect of lysine into mitochondria (Oyanagi et al. (1986)  Inherit. Metab. Dis.  9: 313-316), and cataract (Wintour (1997)  Clin. Exp. Pharmacol. Physiol  24(1):1-9).  
      Organic anion transporters are a particular subclass of transporters which are specific for the transport of organic anions, which include a wide variety of drugs and xenobiotics, many of which are harmful to the body. In addition, organic ion transporters are responsible for the transport of the metabolites of most lipophilic compounds, e.g., sulfate and glucuronide conjugates (Moller, J. V. and Sheikh, M. I. (1982)  Pharmacol. Rev.  34:315-358; Pritchard, J. B. and Miller, D. S. (1993)  Physiol. Rev.  73:765-796; Ullrich, K. J. (1997)  J. Membr. Biol.  158:95-107; Ullrich, K. J. and Rumrich, G. (1993)  Clin. Investig.  71:843-848; Petzinger, E. (1994)  Rev. Physiol. Biochem. Pharmacol.  123:47-211).  
      Sugar transporters are members of the major facilitator superfamily of transporters. These transporters are passive in the sense that they are driven by the substrate concentration gradient and they exhibit distinct kinetics as well as sugar substrate specificity. Members of this family share several characteristics: (1) they contain twelve transmembrane domains separated by hydrophilic loops; (2) they have intracellular N- and C-termini; and (3) they are thought to function as oscillating pores. The transport mechanism occurs via sugar binding to the exofacial binding site of the transporter, which is thought to trigger a conformational change causing the sugar binding site to re-orient to the endofacial conformation, allowing the release of substrate. These transporters are specific for various sugars and are found in both prokaryotes and eukaryotes. In mammals, sugar transporters transport various monosaccharides across the cell membrane (Walmsley et al. (1998)  Trends in Biochem. Sci.  23:476-481; Barrett et al. (1999)  Curr. Op. Cell Biol.  11:496-502).  
      At least nine mammalian glucose transporters have been identified, GLUT1-GLUT9, which are expressed in a tissue-specific manner (e.g., in brain, erythrocyte, kidney, muscle, and adipose tissues) (Shepherd et al. (1999)  N. Engl. J. Med.  341:248-257; Doege et al. (2000)  Biochem. J.  350:771-776). Some GLUT proteins have been shown to be present in low amounts at the plasma membrane during the basal state, at which time large amounts are sequestered in intracellular vesicle stores. Stimulatory molecules specific for each GLUT (such as insulin) regulate the translocation of the GLUT-containing vesicles to the plasma membrane. The vesicles fuse at the membrane and subsequently expose the GLUT protein to the extracellular milieu to allow glucose (and other monosaccharide) transport into the cell (Walmsley et al. (1998)  Trends in Biochem. Sci.  23:476-481; Barrett et al. (1999)  Curr. Op. Cell Biol.  11:496-502). Other GLUT transporters play a role in constitutive sugar transport.  
      The E1-E2 ATPase family is a large superfamily of transport enzymes that contains at least 80 members found in diverse organisms such as bacteria, archaea, and eukaryotes (Palmgren, M. G. and Axelsen, K. B. (1998)  Biochim. Biophys. Acta.  1365:37-45). These enzymes are involved in ATP hydrolysis-dependent transmembrane movement of a variety of inorganic cations (e.g., H + , Na + , K + , Ca 2+ , Cu 2+ , Cd + , and Mg 2+  ions) across a concentration gradient, whereby the enzyme converts the free energy of ATP hydrolysis into electrochemical ion gradients. E1-E2 ATPases are also known as “P-type” ATPases, referring to the existence of a covalent high-energy phosphoryl-enzyme intermediate in the chemical reaction pathway of these transporters. Until recently, the superfamily contained four major groups: Ca 2+  transporting ATPases; Na + /K + — and gastric H + /K +  transporting ATPases; plasma membrane H +  transporting ATPases of plants, fungi, and lower eukaryotes; and all bacterial P-type ATPases (Kuhlbrandt et al. (1998)  Curr. Opin. Struct. Biol.  8:510-516).  
      E1-E2 ATPases are phosphorylated at a highly conserved DKTG sequence. Phosphorylation at this site is thought to control the enzyme&#39;s substrate affinity. Most E1-E2 ATPases contain ten alpha-helical transmembrane domains, although additional domains may be present. A majority of known gated-pore translocators contain twelve alpha-helices, including Na + /H +  antiporters (West (1997)  Biochim. Biophys. Acta  1331:213-234).  
      Members of the E1-E2 ATPase superfamily are able to generate electrochemical ion gradients which enable a variety of processes in the cell such as absorption, secretion, transmembrane signaling, nerve impulse transmission, excitation/contraction coupling, and growth and differentiation (Scarborough (1999)  Curr. Opin. Cell Biol.  11:517-522). These molecules are thus critical to normal cell function and well-being of the organism.  
      Recently, a new class of E1-E2 ATPases was identified, the aminophospholipid transporters or translocators. These transporters transport not cations, but phospholipids (Tang, X. et al. (1996)  Science  272:1495-1497; Bull, L. N. et al. (1998)  Nat. Genet.  18:219-224; Mauro, I. et al. (1999)  Biochem. Biophys. Res. Commun.  257:333-339). These transporters are involved in cellular functions including bile acid secretion and maintenance of the asymmetrical integrity of the plasma membrane.  
      The histidine triad (HIT) family of proteins are a superfamily of nucleotide-binding proteins which were first identified based on sequence similarity. Specifically, HIT proteins all have the histidine triad-containing sequence motif His-φ-His-φ-His-φ-φ, where φ represents a hydrophobic amino acid residue (Seraphin, B. (1992)  DNA Sequence  3:177-179). The histidine triad motif is responsible for the nucleotide binding properties of the HIT proteins (Brenner, C. et al. (1999)  J. Cell. Physiol.  181:19-187).  
      The HIT family can be divided into two branches, the Fhit branch and the Hint branch. Fhit proteins are found only in animals and fungi, while Hint proteins are found in all forms of cellular life (Brenner et al. (1999) supra). Hint proteins, first purified from rabbit heart cytosol (Gilmour et al. (1997)), are intracellular receptors for purine mononucleotides.  
      Fhit proteins bind and cleave diadenosine polyphosphates (Ap n A) such as ApppA and AppppA (Brenner et al. (1999) supra). Human Fhit is a tumor suppressor protein frequently mutated in cancers of the gastrointestinal tract (Ohta, M. et al. (1996)  Cell  84:587-597), lung (Sozzi, G. et al. (1996)  Cell  85:17-26), and other tissues.  
      Under the current model, cellular stress signals cause tRNA synthetases to produce Ap n A rather than deliver amino acids to tRNAs (Brenner et al. (1999) supra). Fhit acts as a sensor for Ap n A, and Fhit-Ap n A complexes stimulate the pro-apoptotic activity of nitrilases, enzymes which convert nitriles (such as indoleacetonitrile) to the corresponding acids (such as indoleacetic acid) plus ammonia by addition of two water molecules. When Fhit is mutated cells cannot sense Ap n A stress signals, which can result in uncontrolled growth.  
      Given the important biological and physiological roles played by the E1-E2 ATPase family of proteins and the HIT family of proteins, there exists a need to identify novel E1-E2 ATPase and HMT family members for use in a variety of diagnostic/prognostic as well as therapeutic applications.  
      The uptake of amino acids in mammalian cells is mediated by energy-dependent and passive amino acid transporters with different but overlapping specificities. Different cells contain a distinct set of transport systems in their plasma membranes. Most energy-dependent transporters are coupled to the countertransport of K +  or to the cotransport of Na +  or Cl − . Passive transporters are either facilitated transporters or channels. The transport of amino acids is important in such functions as protein synthesis, hormone metabolism, nerve transmission, cellular activation, regulation of cell growth, production of metabolic energy, synthesis of purines and pyrimidines, nitrogen metabolism, and/or biosynthesis of urea. Catagna, et al. (1997)  The Journal of Experimental Biology  200:269-286. Examples of important amino acid transport systems and their physiological roles follow.  
      L-glutamate is the major mediator of excitatory neurotransmission in the mammalian central nervous system. At least four different glutamate transporters have been cloned, EAAC1, GLT-1, GLAST, and EAAT4. Catagna, et al. (1997)  The Journal of Experimental Biology  200:269-286. L-glutamate is stored in synaptic vesicles at presynaptic terminals and released into the synaptic cleft to act on glutamate receptors. Glutamate is involved in most aspects of brain function including cognition, memory, and learning. The role of amino acid transporters in keeping the extracellular concentration of glutamate low is important for the following reasons: (1) to ensure a high signal-to-noise ratio during neurotransmission; and (2) to prevent neuronal cell death resulting from excessive activation of glutamate receptors. Glutamate transporters play a role in stroke, central nervous system ischemia, seizures, and neurodegenerative diseases such as Alzheimer&#39;s disease and amyotrophic lateral sclerosis (ALS). Seal (1999)  Annu. Rev. Pharmacol. Toxicol.  39:431-56.  
      A defect in cystine transport during renal cystine reabsorption results in cystinuria, an autosomal recessive disorder and a common hereditary cause of nephrolithiasis. The low solubility of cystine in urine favors formation of cystine-containing kidney stones. At least 2 separate amino acid transporters are involved in cystine transport: one located in the proximal tubule S1 segment and the other located in the proximal tubule S3 segment. It is believed that the D2/NBAT amino acid transport system transports cystine at the proximal tubule S3 segment.  
      Cationic amino acid (CAT) transporters are needed for protein synthesis, urea synthesis (arginine), and as precursors of bioactive molecules. Palacin, et al.  Physiological Reviews  78(4):969-1054. Arginine is the immediate precursor for the synthesis of nitric oxide. Nitric oxide acts as a vasodilator where it plays an important role in the regulation of blood flow and blood pressure. Nitric oxide is also important in neurotransmission. Arginine is also a precursor for the synthesis of creatine, which is a high energy phosphate source for muscle contraction. Ornithine is required for the synthesis of polyamines, which are important in cell and tissue growth.  
      Growth factors, cytokines, and hormones modulate amino acid transport. Kilberg, et al. (1993)  Annu. Rev. Nutr.  13:137-65. For example, epidermal growth factor stimulates amino acid transport Systems A and L in rat kidney cells. Glucagon and glucocorticoid hormones are known to stimulate Systems A and N. Both TNF and IL-1 stimulate System ASC-mediated glutamine uptake by cultured porcine endothelial cells. Further, TGF-β stimulates both Systems A and L in rat kidney cells.  
      Given the important role of amino acid transporters in regulating a wide variety of cellular processes, there exists a need for the identification of novel amino acid transporters as well as modulators of such transporters for use in a variety of pharmaceutical and therapeutic applications.  
                              INDEX                         Chapter   Page   Title                                 I.   7   38594, A NOVEL HUMAN TRANSPORTER AND               USES THEREOF; BRIEF DESCRIPTION OF               DRAWINGS       II.   17   57312 AND 53659, NOVEL HUMAN ORGANIC               ANION TRANSPORTER MOLECULES AND USES               THEREOF       III.   25   57250, A NOVEL HUMAN SUGAR TRANSPORTER               FAMILY MEMBER AND USES THEREOF       IV.   31   63760, A NOVEL HUMAN TRANSPORTER AND               USES THEREOF       V.   39   49938, A NOVEL HUMAN PHOSPHOLIPID               TRANSPORTER AND USES THEREFOR       VI.   49   32146 AND 57259, NOVEL HUMAN               TRANSPORTERS AND USES               THEREOF       VII.   58   67118, 67067, AND 62092, HUMAN PROTEINS AND               METHODS OF USE THEREOF       VIII.   70   FBH58295FL, A NOVEL HUMAN AMINO ACID               TRANSPORTER AND USES THEREOF       IX.   77   57255 and 57255alt, NOVEL HUMAN SUGAR               TRANSPORTERS AND USES THEREFOR       X   83   FURTHER EMBODIMENTS OF 38594, 57312, 53659,               57250, 63760, 49938, 32146, 57239, 67118, 67067,               62092, FPH58295FL, 57255 AND 57255alt                 Chapter I. 38594, A NOVEL HUMAN TRANSPORTER AND USES THEREOF             
 
     SUMMARY OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel members of the family of transporter molecules, referred to herein as MTP-1 nucleic acid and protein molecules. The present invention is also based, at least in part, on the realization that MTP-1 molecules are related to ABC transporter molecules, which function in cellular transmembrane lipid transport, and that MTP-1 molecules are preferentially expressed in myelo-lymphatic tissue. As such, the functioning of MTP-1 molecules may be causatively linked to hematopoietic and immunological diseases, or diseases related to lipid metabolism, e.g., atherosclerosis. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding MTP-1 proteins or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of MTP-1-encoding nucleic acids.  
      In one embodiment, an MTP-1 nucleic acid molecule of the invention is at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to the nucleotide sequence (e.g., to the entire length of the nucleotide sequence) shown in SEQ ID NO: 1 or 3, or a complement thereof.  
      In a preferred embodiment, the isolated nucleic acid molecule includes the nucleotide sequence shown in SEQ ID NO:1 or 3, or a complement thereof. In another embodiment, the nucleic acid molecule includes SEQ ID NO:3 and nucleotides 1-107 of SEQ ID NO:1. In yet a further embodiment, the nucleic acid molecule includes SEQ ID NO:3 and nucleotides 1494-1929 of SEQ ID NO:1. In another preferred embodiment, the nucleic acid molecule consists of the nucleotide sequence shown in SEQ ID NO:1 or 3.  
      In another embodiment, an MTP-1 nucleic acid molecule includes a nucleotide sequence encoding a protein having an amino acid sequence sufficiently identical to the amino acid sequence of SEQ ID NO:2. In a preferred embodiment, an MTP-1 nucleic acid molecule includes a nucleotide sequence encoding a protein having an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to the entire length of the amino acid sequence of SEQ ID NO:2.  
      In another preferred embodiment, an isolated nucleic acid molecule encodes the amino acid sequence of human MTP-1. In yet another preferred embodiment, the nucleic acid molecule includes a nucleotide sequence encoding a protein having the amino acid sequence of SEQ ID NO:2. In yet another preferred embodiment, the nucleic acid molecule is at least 50-100, 100-500, 500-1000, 1000-1500, 1500-2000, 2000-2500, 2500-3000, 3000-3500, 3500-4000, 4000-4500, 4500-5000, 5000-5500, 5500-6000, 6000-6500, 6500-6700, or more nucleotides in length. In a further preferred embodiment, the nucleic acid molecule is at least 50-100, 100-500, 500-1000, 1000-1500, 1500-2000, 2000-2500, 2500-3000, 3000-3500, 3500-4000, 4000-4500, 4500-5000, 5000-5500, 5500-6000, 6000-6500, 6500-6700, or more nucleotides in length and encodes a protein having an MTP-1 activity (as described herein).  
      Another embodiment of the invention features nucleic acid molecules, preferably MTP-1 nucleic acid molecules, which specifically detect MTP-1 nucleic acid molecules relative to nucleic acid molecules encoding non-MTP-1 proteins. For example, in one embodiment, such a nucleic acid molecule is at least 50-100, 100-500, 500-1000, 1000-1500, 1500-2000, 2000-2500, 2500-3000, 3000-3500, 3500-4000, 4000-4500, 4500-5000, 5000-5500, 5500-6000, 6000-6500, 6500-6700, or more nucleotides in length and hybridizes under stringent conditions to a nucleic acid molecule comprising the nucleotide sequence shown in SEQ ID NO: 1, or a complement thereof.  
      In preferred embodiments, the nucleic acid molecules are at least 15 (e.g., 15 contiguous) nucleotides in length and hybridize under stringent conditions to the nucleotide molecules set forth in SEQ ID NO: 1.  
      In other preferred embodiments, the nucleic acid molecule encodes a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO:2, wherein the nucleic acid molecule hybridizes to a nucleic acid molecule comprising SEQ ID NO:1 or 3, respectively, under stringent conditions.  
      Another embodiment of the invention provides an isolated nucleic acid molecule which is antisense to an MTP-1 nucleic acid molecule, e.g., the coding strand of an MTP-1 nucleic acid molecule.  
      Another aspect of the invention provides a vector comprising an MTP-1 nucleic acid molecule. In certain embodiments, the vector is a recombinant expression vector. In another embodiment, the invention provides a host cell containing a vector of the invention. In yet another embodiment, the invention provides a host cell containing a nucleic acid molecule of the invention. The invention also provides a method for producing a protein, preferably an MTP-1 protein, by culturing in a suitable medium, a host cell, e.g., a mammalian host cell such as a non-human mammalian cell, of the invention containing a recombinant expression vector, such that the protein is produced.  
      Another aspect of this invention features isolated or recombinant MTP-1 proteins and polypeptides. In one embodiment, an isolated MTP-1 protein includes at least one or more of the following domains: a transmembrane domain, and/or an ABC transporter domain.  
      In a preferred embodiment, an MTP-1 protein includes at least one or more of the following domains: a transmembrane domain, an ABC transporter domain, and has an amino acid sequence at least about 50%, 55%, 60%, 65%, 67%, 68%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to the amino acid sequence of SEQ ID NO:2. In another preferred embodiment, an MTP-1 protein includes at least one or more of the following domains: a transmembrane domain, an ABC transporter domain and has an MTP-1 activity (as described herein).  
      In yet another preferred embodiment, an MTP-1 protein includes at least one or more of the following domains: a transmembrane domain, an ABC transporter domain, and is encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 1 or 3.  
      In another embodiment, the invention features fragments of the protein having the amino acid sequence of SEQ ID NO:2, wherein the fragment comprises at least 15 amino acids (e.g., contiguous amino acids) of the amino acid sequence of SEQ ID NO:2. In another embodiment, an MTP-1 protein has the amino acid sequence of SEQ ID NO:2.  
      In another embodiment, the invention features an MTP-1 protein which is encoded by a nucleic acid molecule consisting of a nucleotide sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to a nucleotide sequence of SEQ ID NO: 1 or 3, or a complement thereof. This invention further features an MTP-1 protein which is encoded by a nucleic acid molecule consisting of a nucleotide sequence which hybridizes under stringent hybridization conditions to a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 1 or 3, or a complement thereof.  
      The proteins of the present invention or portions thereof, e.g., biologically active portions thereof, can be operatively linked to a non-MTP-1 polypeptide (e.g., heterologous amino acid sequences) to form fusion proteins. The invention further features antibodies, such as monoclonal or polyclonal antibodies, that specifically bind proteins of the invention, preferably MTP-1 proteins. In addition, the MTP-1 proteins or biologically active portions thereof can be incorporated into pharmaceutical compositions, which optionally include pharmaceutically acceptable carriers.  
      In another aspect, the present invention provides a method for detecting the presence of an MTP-1 nucleic acid molecule, protein, or polypeptide in a biological sample by contacting the biological sample with an agent capable of detecting an MTP-1 nucleic acid molecule, protein, or polypeptide such that the presence of an MTP-1 nucleic acid molecule, protein or polypeptide is detected in the biological sample.  
      In another aspect, the present invention provides a method for detecting the presence of MTP-1 activity in a biological sample by contacting the biological sample with an agent capable of detecting an indicator of MTP-1 activity such that the presence of MTP-1 activity is detected in the biological sample.  
      In another aspect, the invention provides a method for modulating MTP-1 activity comprising contacting a cell capable of expressing MTP-1 with an agent that modulates MTP-1 activity such that MTP-1 activity in the cell is modulated. In one embodiment, the agent inhibits MTP-1 activity. In another embodiment, the agent stimulates MTP-1 activity. In one embodiment, the agent is an antibody that specifically binds to an MTP-1 protein. In another embodiment, the agent modulates expression of MTP-1 by modulating transcription of an MTP-1 gene or translation of an MTP-1 mRNA. In yet another embodiment, the agent is a nucleic acid molecule having a nucleotide sequence that is antisense to the coding strand of an MTP-1 mRNA or an MTP-1 gene.  
      In one embodiment, the methods of the present invention are used to treat a subject having a disorder characterized by aberrant or unwanted MTP-1 protein or nucleic acid expression or activity by administering an agent which is an MTP-1 modulator to the subject. In one embodiment, the MTP-1 modulator is an MTP-1 protein. In another embodiment the MTP-1 modulator is an MTP-1 nucleic acid molecule. In yet another embodiment, the MTP-1 modulator is a peptide, peptidomimetic, or other small molecule. In a preferred embodiment, the disorder characterized by aberrant or unwanted MTP-1 protein or nucleic acid expression is a transporter-associated disorder.  
      The present invention also provides diagnostic assays for identifying the presence or absence of a genetic alteration characterized by at least one of (i) aberrant modification or mutation of a gene encoding an MTP-1 protein; (ii) mis-regulation of the gene; and (iii) aberrant post-translational modification of an MTP-1 protein, wherein a wild-type form of the gene encodes a protein with an MTP-1 activity.  
      In another aspect the invention provides methods for identifying a compound that binds to or modulates the activity of an MTP-1 protein, by providing an indicator composition comprising an MTP-1 protein having MTP-1 activity, contacting the indicator composition with a test compound, and determining the effect of the test compound on MTP-1 activity in the indicator composition to identify a compound that modulates the activity of an MTP-1 protein.  
      Other features and advantages of the invention will be apparent from the following detailed description and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  depicts the results of a search which was performed against the MEMSAT database and which resulted in the identification of twelve “transmembrane domains” in the full length human MTP-1 protein (SEQ ID NO:2).  
      FIGS.  2 A-C depict the results of a TaqMan analysis of the relative expression of MTP-1 mRNA in a variety of tissues.  
       FIG. 3  depicts an alignment of the human OAT5 gene with the human OATPe gene (GenBank Accession No. AB031051; SEQ ID NO:10). Identical amino acid residues are indicated by stars.  
       FIG. 4  depicts a structural, hydrophobicity, and antigenicity analysis of the human OAT4 protein. The locations of the 12 transmembrane domains are indicated (TM 1, 2, 3, etc.).  
       FIG. 5  depicts a structural, hydrophobicity, and antigenicity analysis of the human OAT5 protein. The locations of the 12 transmembrane domains are indicated (TM 1, 2, 3, etc.).  
       FIG. 6  depicts the expression levels of human OAT5 mRNA in various human cell types and tissues, as determined by Taqman analysis. Samples: (1) normal artery; (2) diseased aorta; (3) normal vein; (4) coronary smooth muscle cells; (5) human umbilical vein endothelial cells (HUVECs); (6) hemangioma; (7) normal heart; (8) heart—congestive heart failure (CHF); (9) kidney; (10) skeletal muscle; (11) normal adipose tissue; (12) pancreas; (13) primary osteoblasts; (14) differentiated osteoclasts; (15) normal skin; (16) normal spinal cord; (17) normal brain cortex; (18) brain—hypothalamus; (19) nerve; (20) dorsal root ganglion (DRG); (21) normal breast; (22) breast tumor; (23) normal ovary; (24) ovary tumor; (25) normal prostate; (26) prostate tumor; (27) salivary gland; (28) normal colon; (29) colon tumor; (30) normal lung; (31) lung tumor; (32) lung—chronic obstructive pulmonary disease (COPD); (33) colon—inflammatory bowel disease (IBD); (34) normal liver; (35) liver—fibrosis; (36) normal spleen; (37) normal tonsil; (38) normal lymph node; (39) normal small intestine; (40) macrophages; (41) synovium; (42) bone marrow mononuclear cells (BM-MNC); (43) activated peripheral blood mononuclear cells (PBMCs); (44) neutrophils; (45) megakaryocytes; (46) erythroid cells; (47) positive control.  
       FIG. 7  depicts a structural, hydrophobicity, and antigenicity analysis of the human HST-1 polypeptide.  
       FIG. 8  depicts the results of a search which was performed against the MEMSAT database and which resulted in the identification of twelve “transmembrane domains” in the human HST-1 polypeptide (SEQ ID NO:13).  
       FIG. 9  depicts an alignment of the human HST-1 amino acid sequence (SEQ ID NO: 13) with the amino acid sequence of a human potent brain type organic ion transporter (Accession No. AB040056) using the CLUSTAL W (1.74) alignment program.  
       FIG. 10  is a graph depicting the expression of human HST-1 cDNA (SEQ ID NO:13) in various human tissues as determined by Taqman analysis.  
       FIG. 11  depicts a structural, hydrophobicity, and antigenicity analysis of the human TP-2 polypeptide.  
       FIG. 12  depicts the results of a search which was performed against the MEMSAT database and which resulted in the identification of twelve “transmembrane domains” in the human TP-2 polypeptide (SEQ ID NO: 16).  
       FIG. 13  depicts an alignment of the human TP-2 amino acid sequence (SEQ ID NO: 16) with the amino acid sequences of the  Salmonella typhi  tetracycline-6-hydroxylase/oxygenase homolog gene (SEQ ID NO: 18) using the CLUSTAL W™ (1.74) alignment program.  
      FIGS.  14 A-B depict a Clustal W (1.74) alignment of the human PLTR-1 amino acid sequence (“Fbh49938pat”; SEQ ID NO:20) with the amino acid sequence of human FIC1 (“hFIC1_AT1C_”; SEQ ID NO:22). The transmembrane domains (“TM1”, “TM2”, etc.), E1-E2 ATPases phosphorylation site (“phosphorylation site”), and phospholipid transporter specific amino acid residues (“phospholipid transport”) are boxed.  
       FIG. 15  depicts a structural, hydrophobicity, and antigenicity analysis of the human PLTR-1 polypeptide. The locations of the 12 transmembrane domains, as well as the E1-E2 ATPase domain, are indicated.  
       FIG. 16  depicts a structural, hydrophobicity, and antigenicity analysis of the human TFM-2 polypeptide.  
       FIG. 17  depicts the results of a search which was performed against the MEMSAT database and which resulted in the identification of ten “transmembrane domains” in the human TFM-2 polypeptide (SEQ ID NO:28).  
       FIG. 18  depicts a structural, hydrophobicity, and antigenicity analysis of the human TFM-3 polypeptide.  
       FIG. 19  depicts the results of a search which was performed against the MEMSAT database and which resulted in the identification of nine “transmembrane domains” in the human TFM-3 polypeptide (SEQ ID NO:31).  
       FIG. 20  depicts a structural, hydrophobicity, and antigenicity analysis of the human 67118 polypeptide.  
      FIGS.  21 A-B depict a Clustal W (1.74) alignment of the human 67118 amino acid sequence (“Fbh67118pat”; SEQ ID NO:34) with the amino acid sequence of mouse Potential Phospholipid-Transporting ATPase IH (mouseAT1H) (GenBank Accession No. P98197; SEQ ID NO:46). The transmembrane domains (“TM1”, “TM2”, etc.), E1-E2 ATPases phosphorylation site (“phosphorylation site”), and phospholipid transporter specific amino acid residues (“phospholipid transport”) are boxed.  
       FIG. 22  depicts a structural, hydrophobicity, and antigenicity analysis of the human 67067 polypeptide.  
      FIGS.  23 A-B depict a Clustal W (1.74) alignment of the human 67067 amino acid sequence (“Fbh67067b”; SEQ ID NO:34) with the amino acid sequence of mouse Potential Phospholipid-Transporting ATPase VA (mouseAT5A) (GenBank Accession No O54827; SEQ ID NO:47). The transmembrane domains (“TM1”, “TM2”, etc.), E1-E2 ATPases phosphorylation site (“phosphorylation site”), and phospholipid transporter specific amino acid residues (“phospholipid transport”) are boxed.  
       FIG. 24  depicts a structural, hydrophobicity, and antigenicity analysis of the human 62092 polypeptide.  
       FIG. 25  depicts a multiple sequence alignment (MSA) of the amino acid sequences of the human 62092 protein (SEQ ID NO:40), human HINT (GenBank Accession No. NP — 005331; SEQ ID NO:48), and human FHIT (GenBank Accession No. NP — 002003; SEQ ID NO:49). The HIT family signature motifs are underlined and italicized. The location of the three histidine residues of the histidine triad in human 62092 and human HINT are indicated by stars. The alignment was performed using the Clustal algorithm which is part of the MegAlign™ program (e.g., version 3.1.7), which is part of the DNAStar™ sequence analysis software package. The pairwise alignment parameters are as follows: K-tuple=1; Gap Penalty=3; Window=5; Diagonals saved=5. The multiple alignment parameters are as follows: Gap Penalty=10; and Gap length penalty=10.  
       FIG. 26  depicts a structural, hydrophobicity, and antigenicity analysis of the HAAT polypeptide.  
       FIG. 27  depicts a Clustal W (1.74) alignment of the HAAT amino acid sequence (“Fbh58295FL”; SEQ ID NO:52) with the amino acid sequence of rat amino acid system A transporter (ratATA2). The transmembrane domains (“TM1”, “TM2”, etc.) are boxed.  
       FIG. 28  depicts the results of a search which was performed against the MEMSAT database and which resulted in the identification of ten “transmembrane domains” in the HAAT amino acid sequence (SEQ ID NO:52). An additional predicted transmembrane domain (i.e., TM1) is also shown.  
       FIG. 29  depicts a structural, hydrophobicity, and antigenicity analysis of the human HST-4 polypeptide (SEQ ID NO:55).  
       FIG. 30  depicts a structural, hydrophobicity, and antigenicity analysis of the human HST-5 polypeptide (SEQ ID NO:58). 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel molecules, referred to herein as “membrane transporter protein-1” or “MTP-1” nucleic acid and protein molecules, which are novel members of a family of proteins possessing the ability to shuttle molecules across a lipid bilayer (e.g. to sequester, export or expel a plurality of substances, for example, cytotoxic substances, metabolites, ions, and/or peptides, from the intracellular milieu). These novel molecules are capable of transporting molecules (e.g., ions, proteins, and/or small molecules) across biological membranes and, thus, play a role in or function in a variety of cellular processes, e.g., maintenance of cellular homeostasis.  
      As used herein, the term “transporter” includes a protein or molecule (e.g., a membrane-spanning protein or molecule) which is involved in the movement of a biochemical molecule from one side of a lipid bilayer to the other, for example, against a preexisting concentration gradient.  
      Exemplary transporters, for example MTP-1 transporters, include at least one, preferably two or three, more preferably four, five, six, seven, eight, nine, ten, eleven, more preferably about twelve “transmembrane domains” or more. As used herein, the term “transmembrane domain” includes an amino acid sequence of about 15 amino acid residues in length which spans the plasma membrane. More preferably, a transmembrane domain includes about at least 20, 25, 30, 35, 40, or 45 amino acid residues and spans the plasma membrane. Transmembrane domains are rich in hydrophobic residues, and typically have an alpha-helical structure. In a preferred embodiment, at least 50%, 60%, 70%, 80%, 90%, 95% or more of the amino acids of a transmembrane domain are hydrophobic, e.g., leucines, isoleucines, tyrosines, or tryptophans. Transmembrane domains are described in, for example, Zagotta W. N. et al., (1996)  Annual Rev. Neurosci.  19: 235-263, the contents of which are incorporated herein by reference. Amino acid residues 23-40, 548-564, 588-612, 624-646, 653-675, 1006-1023, 1236-1258, 1534-1556, 1587-1603, 1645-1667, 1732-1749, 1931-1947 of the native MTP-1 protein are predicted to comprise a transmembrane domain (see  FIG. 1 ). Accordingly, MTP-1 proteins having at least one transmembrane domain, preferably two or three, more preferably four, five, six, seven, eight, nine, ten, eleven or twelve transmembrane domains selected from the group consisting of amino acids 23-40, 548-564, 588-612, 624-646, 653-675, 1006-1023, 1236-1258, 1534-1556, 1587-1603, 1645-1667, 1732-1749, 1931-1947 are within the scope of the invention. Also included within the scope of the invention are MTP proteins having at least 50-60% homology, preferably about 60-70%, more preferably about 70-80%, or about 80-90% homology with a transmembrane domain of human MTP-1 are within the scope of the invention.  
      Preferably such MTP proteins comprise a family of MTP molecules. The term “family” when referring to the protein and nucleic acid molecules of the invention is intended to mean two or more proteins or nucleic acid molecules having a common structural domain or motif and having sufficient amino acid or nucleotide sequence homology as defined herein. Such family members can be naturally or non-naturally occurring and can be from either the same or different species. For example, a family can contain a first protein of human origin, as well as other, distinct proteins of human origin or alternatively, can contain homologues of non-human origin, e.g., monkey proteins. Members of a family may also have common functional characteristics.  
      In another embodiment, an MTP-1 molecule of the present invention is identified based on the presence of at least one “ABC transporter domain” in the protein or corresponding nucleic acid molecule. As used herein, the term “ABC transporter domain” includes a protein domain having an amino acid sequence of about 131-232 amino acid residues and a bit score of at least 80 when compared against an ABC transporter Hidden Markov Model (HMM), e.g., PFAM accession number PF00005. In a preferred embodiment, an ABC transporter domain includes a protein domain having an amino acid sequence of about 141-222 amino acid residues and a bit score of at least 100. In another preferred embodiment, an ABC transporter domain includes a protein domain having an amino acid sequence of about 151-212 amino acid residues and a bit score of at least 120. Preferably, an ABC transporter domain includes a protein domain having an amino acid sequence of about 171-192 amino acid residues and a bit score of at least 140 (e.g., 144.2, 150, 160, 170, 180, 190, 200, 206, 210 or more). To identify the presence of an ABC transporter domain in an MTP-1 protein, the amino acid sequence of the protein is used to search a database of known Hidden Markov Models (HMMs e.g., the PFAM HMM database). The ABC transporter HMM has been assigned the PFAM Accession PF00005 (http://pfam.wustl.edu), InterPro accession number IPR0001617 (http://www.ebi.ac.uk/interpro), and Prosite accession number PS00211 (http://www.expasy.ch/prosite). For example, a search was performed against the HMM database using the amino acid sequence (SEQ ID NO:2) of human MTP-1 resulting in the identification of a first ABC transporter domain in the amino acid sequence of human MTP-1 (SEQ ID NO: 2) at about residues 832-1012 having a score of 206.0, and a second ABC transporter domain in the amino acid sequence of human MTP-1 (SEQ ID NO: 2) at about residues 1818-1999 having a score of 144.2.  
      In a preferred embodiment, an ABC transporter domain as described herein is characterized by the presence of an “ATP/AGP binding motif” and/or an “ABC transporter signature motif.” As used herein, the term “ATP/AGP binding motif” includes a motif having the consensus sequence [AG]-X(4)-G-K-[ST] and is described under Prosite entry number PS00017 (http://www.expasy.ch/prosite). ATP/AGP binding motifs can be found, for example, within the first ABC transporter domains of the MTP-1 protein of SEQ ID NO:2 at about residues 839-846 and within the second ABC transporter domain of the MTP-1 protein of SEQ ID NO:2 at about residues 1825-1832. As used herein, the term “ABC transporter signature motif” includes a protein motif having the consensus sequence [LIVMFYC]-[SA]-[SAPGLVFYKQH]-G-[DENQMW]-[KRQASPCLIMFW]-[KRNQSTAVM]-[KRACLVM]-[LIVMFYPAN]-{PHY}-[LIVMFW]-[SAGCLIVP]-{FYWHP}-{KRHP}-[LIVMFYWSTA] and is described under Prosite entry number PS00211 (http://www.expasy.ch/prosite). An ABC transporter signature motif can be found within the first ABC transporter domain of the MTP-1 protein or SEQ ID NO:2 at about residues 938-952. The consensus sequences described herein are described according to standard Prosite Signature designation (e.g., all amino acids are indicated according to their universal single letter designation; X designates any amino acid; X(n) designates any n amino acids, e.g., X (2) designates any 2 amino acids; [LIVM] indicates any one of the amino acids appearing within the brackets, e.g., any one of L, I, V, or M, in the alternative, any one of Leu, Ile, Val, or Met.); and {LIVM} indicates any amino acid EXCEPT the amino acids appearing within the brackets, e.g., not L, not I, not V, and not M.  
      Isolated proteins of the present invention, for example MTP-1 proteins, preferably have an amino acid sequence sufficiently identical to the amino acid sequence of SEQ ID NO:2, or are encoded by a nucleotide sequence sufficiently identical to SEQ ID NO: 1 or 3. As used herein, the term “sufficiently identical” refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains have at least 30%, 40%, or 50% homology, preferably 60% homology, more preferably 70%-80%, and even more preferably 90-95% homology across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently identical. Furthermore, amino acid or nucleotide sequences which share at least 30%, 40%, or 50%, preferably 60%, more preferably 70-80%, or 90-95% homology and share a common functional activity are defined herein as sufficiently identical.  
      As used interchangeably herein, an “MTP-1 activity”, “biological activity of MTP-1” or “functional activity of MTP-1”, refers to an activity exhibited by an MTP-1 protein, polypeptide or nucleic acid molecule (e.g., in an MTP-1 expressing cell or tissue), on an MTP-1 substrate, as determined in vivo, or in vitro, according to standard techniques. In one embodiment, an MTP-1 activity is a direct activity, such as transport of an MTP-1-substrate. As used herein, a “MTP-1 substrate” is a molecule which is transported from one side of a biological membrane to the other. Exemplary substrates include, but are not limited to, cytotoxic substances, ions, peptides (e.g., antigenic peptides, hormones, cytokines, neurotransmitters and the like), and metabolites. Examples of MTP-1 substrates also include non-transported molecules that are essential for MTP-1 function, e.g., ATP or GTP. Alternatively, an MTP-1 activity is an indirect activity, such as a cellular signaling activity mediated by the transport of an MTP-1 substrate by MTP-1. In a preferred embodiment, the MTP-1 proteins of the present invention have one or more of the following activities: 1) modulate the import and/or export of MTP-1 substrates into or from cells, e.g., peptides, ions, and/or metabolites, 2) modulate intra- or intercellular signaling, 3) removal of potentially harmful compounds (e.g., cytotoxic substances) from the cell, or facilitate the compartmentalization of these molecules into a sequestered intracellular space (e.g., the peroxisome), and 4) transport of biological molecules across membranes, e.g., the plasma membrane, or the membrane of the mitochondrion, the peroxisome, the lysosome, the endoplasmic reticulum, the nucleus, or the vacuole.  
      Accordingly, another embodiment of the invention features isolated MTP-1 proteins and polypeptides having an MTP-1 activity. Other preferred proteins are MTP-1 proteins having one or more of the following domains: a transmembrane domain, an ABC transporter domain and, preferably, an MTP-1 activity.  
      Additional preferred proteins have at least one transmembrane domain, one ABC transporter domain, and are, preferably, encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 1 or 3.  
      The nucleotide sequence of the isolated human MTP-1 cDNA and the predicted amino acid sequence of the human MTP-1 polypeptide are shown in SEQ ID NOs:1 and 2, respectively.  
      The human MTP-1 gene, which is approximately 6768 nucleotides in length, encodes a protein having a molecular weight of approximately 235.8 kD and which is approximately 2144 amino acid residues in length.  
      Various aspects of the invention are described in further detail in later subsections.  
      Chapter II. 57312 and 53659, Novel Human Organic Anion Transporter Molecules and Uses Thereof  
     SUMMARY OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel organic anion transporter family members, referred to herein as “Organic Anion Transporter” or “OAT” nucleic acid and protein molecules (e.g., OAT4 and OAT5). The OAT nucleic acid and protein molecules of the present invention are useful as modulating agents in regulating a variety of cellular processes, e.g., protection of cells and/or tissues from organic anions, organic anion transport, inter- or intra-cellular signaling, and/or hormonal responses. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding OAT proteins or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of OAT-encoding nucleic acids.  
      In one embodiment, the invention features an isolated nucleic acid molecule that includes the nucleotide sequence set forth in SEQ ID NO:4, 6, 7, or 9. In another embodiment, the invention features an isolated nucleic acid molecule that encodes a polypeptide including the amino acid sequence set forth in SEQ ID NO:5 or 8.  
      In still other embodiments, the invention features isolated nucleic acid molecules including nucleotide sequences that are substantially identical (e.g., 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1% 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical) to the nucleotide sequence set forth as SEQ ID NO:4, 6, 7, or 9. The invention further features isolated nucleic acid molecules including at least 30 contiguous nucleotides of the nucleotide sequence set forth as SEQ ID NO:4, 6, 7, or 9. In another embodiment, the invention features isolated nucleic acid molecules which encode a polypeptide including an amino acid sequence that is substantially identical (e.g., 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical) to the amino acid sequence set forth as SEQ ID NO:5 or 8. Also featured are nucleic acid molecules which encode allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:5 or 8. In addition to isolated nucleic acid molecules encoding full-length polypeptides, the present invention also features nucleic acid molecules which encode fragments, for example, biologically active or antigenic fragments, of the full-length polypeptides of the present invention (e.g., fragments including at least 10 contiguous amino acid residues of the amino acid sequence of SEQ ID NO:5 or 8). In still other embodiments, the invention features nucleic acid molecules that are complementary to, antisense to, or hybridize under stringent conditions to the isolated nucleic acid molecules described herein.  
      In a related aspect, the invention provides vectors including the isolated nucleic acid molecules described herein (e.g., OAT-encoding nucleic acid molecules). Such vectors can optionally include nucleotide sequences encoding heterologous polypeptides. Also featured are host cells including such vectors (e.g., host cells including vectors suitable for producing OAT nucleic acid molecules and polypeptides).  
      In another aspect, the invention features isolated OAT polypeptides and/or biologically active or antigenic fragments thereof. Exemplary embodiments feature a polypeptide including the amino acid sequence set forth as SEQ ID NO:5 or 8, a polypeptide including an amino acid sequence at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical to the amino acid sequence set forth as SEQ ID NO:5 or 8, a polypeptide encoded by a nucleic acid molecule including a nucleotide sequence at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical to the nucleotide sequence set forth as SEQ ID NO:4, 6, 7, or 9. Also featured are fragments of the full-length polypeptides described herein (e.g., fragments including at least 10, 15, 20, 25, 30, 35, 40, 45, or 50 contiguous amino acid residues of the sequence set forth as SEQ ID NO:5 or 8) as well as allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:5 or 8.  
      The OAT polypeptides and/or biologically active or antigenic fragments thereof, are useful, for example, as reagents or targets in assays applicable to treatment and/or diagnosis of OAT associated disorders. In one embodiment, an OAT polypeptide or fragment thereof has an OAT activity. In another embodiment, an OAT polypeptide or fragment thereof has at least one of the following domains: a transmembrane domain, a sugar (and other) transporter domain, and/or an ATP/GTP-binding site motif A (P-loop) domain, and optionally, has an OAT activity. In a related aspect, the invention features antibodies (e.g., antibodies which specifically bind to any one of the polypeptides, as described herein) as well as fusion polypeptides including all or a fragment of a polypeptide described herein.  
      The present invention further features methods for detecting OAT polypeptides and/or OAT nucleic acid molecules, such methods featuring, for example, a probe, primer or antibody described herein. Also featured are kits for the detection of OAT polypeptides and/or OAT nucleic acid molecules. In a related aspect, the invention features methods for identifying compounds which bind to and/or modulate the activity of an OAT polypeptide or OAT nucleic acid molecule described herein. Also featured are methods for modulating an OAT activity.  
      Other features and advantages of the invention will be apparent from the following detailed description and claims.  
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel organic anion transporter family members, referred to herein as “Organic anion transporter” or “OAT” nucleic acid and protein molecules, e.g., OAT4 and OAT5. These novel molecules are capable of transporting organic anions (e.g., drugs, xenobiotics, and/or metabolites of lipophilic compounds such as sulfate and glucuronide conjugates) across cellular membranes and, thus, play a role in or function in a variety of cellular processes, e.g., protection of cells and/or tissues from organic anions, organic anion transport, inter- or intra-cellular signaling, and/or hormonal responses. Thus, the OAT molecules of the present invention provide novel diagnostic targets and therapeutic agents to control organic anion transporter-associated disorders.  
      As used herein, an “organic anion transporter-associated disorder” or an “OAT-associated disorder” includes a disorder, disease or condition which is caused or characterized by a misregulation (e.g., downregulation or upregulation) of organic anion transporter activity. Organic anion transporter-associated disorders can detrimentally affect cellular functions such as cellular proliferation, growth, differentiation, or migration, inter- or intra-cellular communication; tissue function, such as cardiac function or musculoskeletal function; systemic responses in an organism, such as nervous system responses, hormonal responses (e.g., insulin response); immune responses; and protection of cells from toxic compounds (e.g., carcinogens, toxins, or mutagens).  
      Examples of organic anion transporter-associated disorders include CNS disorders such as cognitive and neurodegenerative disorders, examples of which include, but are not limited to, Alzheimer&#39;s disease, dementias related to Alzheimer&#39;s disease (such as Pick&#39;s disease), Parkinson&#39;s and other Lewy diffuse body diseases, senile dementia, Huntington&#39;s disease, Gilles de la Tourette&#39;s syndrome, multiple sclerosis, amyotrophic lateral sclerosis, progressive supranuclear palsy, epilepsy, and Jakob-Creutzfieldt disease; autonomic function disorders such as hypertension and sleep disorders, and neuropsychiatric disorders, such as depression, schizophrenia, schizoaffective disorder, korsakoff&#39;s psychosis, mania, anxiety disorders, or phobic disorders; learning or memory disorders, e.g., amnesia or age-related memory loss, attention deficit disorder, dysthymic disorder, major depressive disorder, mania, obsessive-compulsive disorder, psychoactive substance use disorders, anxiety, phobias, panic disorder, as well as bipolar affective disorder, e.g., severe bipolar affective (mood) disorder (BP-1), and bipolar affective neurological disorders, e.g., migraine and obesity. Further CNS-related disorders include, for example, those listed in the American Psychiatric Association&#39;s Diagnostic and Statistical manual of Mental Disorders (DSM), the most current version of which is incorporated herein by reference in its entirety.  
      Further examples of organic anion transporter-associated disorders include cardiac-related disorders. Cardiovascular system disorders in which the OAT molecules of the invention may be directly or indirectly involved include arteriosclerosis, ischemia reperfusion injury, restenosis, arterial inflammation, vascular wall remodeling, ventricular remodeling, rapid ventricular pacing, coronary microembolism, tachycardia, bradycardia, pressure overload, aortic bending, coronary artery ligation, vascular heart disease, atrial fibrilation, Jervell syndrome, Lange-Nielsen syndrome, long-QT syndrome, congestive heart failure, sinus node dysfunction, angina, heart failure, hypertension, atrial fibrillation, atrial flutter, dilated cardiomyopathy, idiopathic cardiomyopathy, myocardial infarction, coronary artery disease, coronary artery spasm, and arrhythmia. OAT-mediated or related disorders also include disorders of the musculoskeletal system such as paralysis and muscle weakness, e.g., ataxia, myotonia, and myokymia.  
      Organic anion transporter disorders also include cellular proliferation, growth, differentiation, or migration disorders. Cellular proliferation, growth, differentiation, or migration disorders include those disorders that affect cell proliferation, growth, differentiation, or migration processes. As used herein, a “cellular proliferation, growth, differentiation, or migration process” is a process by which a cell increases in number, size or content, by which a cell develops a specialized set of characteristics which differ from that of other cells, or by which a cell moves closer to or further from a particular location or stimulus. The OAT molecules of the present invention are involved in signal transduction mechanisms, which are known to be involved in cellular growth, differentiation, and migration processes. Thus, the OAT molecules may modulate cellular growth, differentiation, or migration, and may play a role in disorders characterized by aberrantly regulated growth, differentiation, or migration. Such disorders include cancer, e.g., carcinoma, sarcoma, or leukemia; tumor angiogenesis and metastasis; skeletal dysplasia; hepatic disorders; and hematopoietic and/or myeloproliferative disorders.  
      OAT-associated or related disorders also include hormonal disorders, such as conditions or diseases in which the production and/or regulation of hormones in an organism is aberrant. Examples of such disorders and diseases include type I and type II diabetes mellitus, pituitary disorders (e.g., growth disorders), thyroid disorders (e.g., hypothyroidism or hyperthyroidism), and reproductive or fertility disorders (e.g., disorders which affect the organs of the reproductive system, e.g., the prostate gland, the uterus, or the vagina; disorders which involve an imbalance in the levels of a reproductive hormone in a subject; disorders affecting the ability of a subject to reproduce; and disorders affecting secondary sex characteristic development, e.g., adrenal hyperplasia).  
      Further examples of OAT-associated or related disorders also include immune disorders, such as autoimmune disorders or immune deficiency disorders, e.g., allergies, transplant rejection, responses to pathogenic infection (e.g., bacterial, viral, or parasitic infection), lupus, multiple sclerosis, congenital X-linked infantile hypogammaglobulinemia, transient hypogammaglobulinemia, common variable immunodeficiency, selective IgA deficiency, chronic mucocutaneous candidiasis, or severe combined immunodeficiency.  
      DHDR-associated or related disorders also include viral disorders, i.e., disorders affected or caused by infection by a virus, e.g., hepatitis, AIDS, certain cancers, influenza, and common colds.  
      OAT-associated or related disorders also include disorders affecting tissues in which OAT protein is expressed, e.g., the kidney, osteoblasts, brain cortex, lung, liver, bone marrow mononuclear cells (BM-MNC), and neutrophils.  
      The term “family” when referring to the protein and nucleic acid molecules of the invention is intended to mean two or more proteins or nucleic acid molecules having a common structural domain or motif and having sufficient amino acid or nucleotide sequence homology as defined herein. Such family members can be naturally or non-naturally occurring and can be from either the same or different species. For example, a family can contain a first protein of human origin as well as other distinct proteins of human origin or alternatively, can contain homologues of non-human origin, e.g., rat or mouse proteins. Members of a family can also have common functional characteristics.  
      For example, the family of OAT proteins of the present invention comprises at least one “transmembrane domain”. As used herein, the term “transmembrane domain” includes an amino acid sequence of about 15 amino acid residues in length which spans the plasma membrane. More preferably, a transmembrane domain includes about at least 20, 25, 30, 35, 40, or 45 amino acid residues and spans the plasma membrane. Transmembrane domains are rich in hydrophobic residues, and typically have an alpha-helical structure. In a preferred embodiment, at least 50%, 60%, 70%, 80%, 90%, 95% or more of the amino acids of a transmembrane domain are hydrophobic, e.g., leucines, isoleucines, tyrosines, or tryptophans. Transmembrane domains are described in, for example, Zagotta, W. N. et al. (1996)  Annu. Rev. Neurosci.  19:235-263, the contents of which are incorporated herein by reference. Amino acid residues 10-31,148-165, 172-195, 202-219, 228-252, 26-276, 347-365, 375-399, 406-422, 431-451, 466-484, and 495-512 of the human OAT4 protein are predicted to comprise transmembrane domains (see  FIG. 4 ). Amino acid residues 106-130, 143-166, 174-191, 230-254, 265-284, 314-335, 382-405, 419-443, 456-473, 579-603, 613-636, and 667-690 of the human OAT5 protein are predicted to comprise transmembrane domains (see  FIG. 3 ). Accordingly, OAT proteins having at least 50-60% homology, preferably about 60-70%, more preferably about 70-80%, or about 80-90% homology with a transmembrane domain of human OAT are within the scope of the invention.  
      In another embodiment, members of the OAT family of proteins, include at least one “sugar (and other) transporter domain” in the protein or corresponding nucleic acid molecule. As used herein, the term “sugar (and other) transporter domain” includes a protein domain having at least about 335-505 amino acid residues. Preferably, a sugar (and other) transporter domain includes a protein domain having an amino acid sequence of about 355-485, 375-465, 395-445, or more preferably about 415-425 amino acid residues, and a bit score of at least 10, 20, 30, or more preferably, 34.7. To identify the presence of a sugar (and other) transporter domain in an OAT protein, and make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein is searched against a database of known protein domains (e.g., the HMM database). The sugar (and other) transporter domain (HMM) has been assigned the PFAM Accession number PF00083 (see the PFAM website, available online through Washington University in St. Louis). A search was performed against the HMM database resulting in the identification of a sugar (and other) transporter domain in the amino acid sequence of human OAT4 at about residues 103-527 of SEQ ID NO:5. Another search was performed against the HMM database, further resulting in the identification of a sugar (and other) transporter domain in the amino acid sequence of human OAT5 at about residues 141-555 of SEQ ID NO:8.  
      A description of the Pfam database can be found in Sonhammer et al. (1997)  Proteins  28:405-420, and a detailed description of HMMs can be found, for example, in Gribskov et al. (1990)  Meth. Enzymol.  183:146-159; Gribskov et al. (1987)  Proc. Natl. Acad. Sci. USA  84:4355-4358; Krogh et al. (1994)  J. Mol. Biol.  235:1501-1531; and Stultz et al. (1993)  Protein Sci.  2:305-314, the contents of which are incorporated herein by reference.  
      In another embodiment, an OAT protein of the present invention includes at least one “ATP/GTP-binding site motif A (P-loop) domain”. As used herein, the term “ATP/GTP-binding site motif A (P-loop) domain” includes an amino acid sequence having the consensus sequence [AG]-X(4)-G-K-[ST] (SEQ ID NO: 11). ATP/GTP-binding site motif A (P-loop) domains are described under Prosite entry PS00017 (see the Prosite website, available online through the Swiss Institute for Bioinformatics). The consensus sequence described herein is described according to the standard Prosite signature designation (e.g., all amino acids are indicated according to their universal single letter designation; X designates any amino acid; X(n) designates any n amino acids, e.g., X(4) designates any 4 amino acids; [AG] indicates any one of the amino acids appearing within the brackets, e.g., any one of A or G). Searches were performed against the Prosite database resulting in the identification of two ATP/GTP-binding site motif A (P-loop) domains in the amino acid sequence of OAT5 at about residues 343-350 and 360-367 of SEQ ID NO:8.  
      Isolated proteins of the present invention, preferably OAT proteins, have an amino acid sequence sufficiently homologous to the amino acid sequence of SEQ ID NO:5 or 8, or are encoded by a nucleotide sequence sufficiently homologous to SEQ ID NO:4, 6, 7, or 9. As used herein, the term “sufficiently homologous” refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more homology or identity across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently homologous. Furthermore, amino acid or nucleotide sequences which share at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more homology or identity and share a common functional activity are defined herein as sufficiently homologous.  
      In a preferred embodiment, an OAT protein includes at least one of the following domains: a transmembrane domain, a sugar (and other) transporter domain, and/or an ATP/GTP-binding site motif A (P-loop) domain, and has an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more homologous or identical to the amino acid sequence of SEQ ID NO:5 or 8. In yet another preferred embodiment, an OAT protein includes at least one of the following domains: a transmembrane domain, a sugar (and other) transporter domain, and/or an ATP/GTP-binding site motif A (P-loop) domain, and is encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:4, 6, 7, or 9. In another preferred embodiment, an OAT protein includes at least one of the following domains: a transmembrane domain, a sugar (and other) transporter domain, and/or an ATP/GTP-binding site motif A (P-loop) domain, and has an OAT activity.  
      As used interchangeably herein, an “OAT activity”, “biological activity of OAT” or “functional activity of OAT”, refers to an activity exhibited by an OAT protein, polypeptide or nucleic acid molecule (e.g., in an OAT expressing cell or tissue) on an OAT responsive cell or an OAT substrate, as determined in vivo or in vitro, according to standard techniques. In one embodiment, an OAT activity is a direct activity, such as transport of an OAT substrate, e.g., a metabolite of a lipophilic compound such as a sulfate or glucuronide conjugate. As used herein, an “OAT substrate” is a molecule which is transported from one side of a membrane to the other. Exemplary OAT substrates include, but are not limited to, organic anions such as drugs, xenobiotics, and metabolites of lipophilic compounds such as sulfate and glucuronide conjugates. Examples of OAT substrates also include non-transported molecules that are essential for OAT function, such as ATP or GTP. An OAT activity can also be a direct activity such as an association with an OAT target molecule. An OAT target molecule can be a non-OAT molecule or an OAT protein or polypeptide of the present invention. In an exemplary embodiment, an OAT target molecule is an intracellular signaling protein that mediates an OAT-modulated signal transduction pathway. An OAT activity can also be an indirect activity, such as a cellular signaling activity mediated by transport of an OAT substrate or by interaction of the OAT protein with an OAT substrate or target molecule.  
      In a preferred embodiment, an OAT activity is at least one of the following activities: (i) interaction with an OAT substrate or target molecule; (ii) transport of an OAT substrate across a membrane; (iii) interaction with and/or modulation of a second non-OAT protein; (iv) modulation of cellular signaling and/or gene transcription (e.g., either directly or indirectly); (v) protection of cells and/or tissues from organic anions; and/or (vi) modulation of hormonal responses.  
      The nucleotide sequence of the isolated human OAT4 cDNA and the predicted amino acid sequence encoded by the OAT4 cDNA are shown in SEQ ID NO:4 and 5, respectively.  
      The nucleotide sequence of the isolated human OAT5 cDNA and the predicted amino acid sequence encoded by the OAT5 cDNA are shown in SEQ ID NO:7 and 8, respectively.  
      The human OAT4 gene, which is approximately 2206 nucleotides in length, encodes a protein having a molecular weight of approximately 60.5 kD and which is approximately 550 amino acid residues in length. The human OAT5 gene, which is approximately 2634 nucleotides in length, encodes a protein having a molecular weight of approximately 79.6 kD and which is approximately 724 amino acid residues in length.  
      Various aspects of the invention are described in further detail in later subsections.  
      Chapter III. 57250, A Novel Human Sugar Transporter Family Member and Uses Thereof  
     SUMMARY OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel human sugar transporter family members, referred to herein as “human sugar transporter-1” or “HST-1” nucleic acid and polypeptide molecules. The HST-1 nucleic acid and polypeptide molecules of the present invention are useful as modulating agents in regulating a variety of cellular processes, e.g., sugar homeostasis. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding HST-1 polypeptides or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of HST-1-encoding nucleic acids.  
      In one embodiment, the invention features an isolated nucleic acid molecule that includes the nucleotide sequence set forth in SEQ ID NO: 12 or 14. In another embodiment, the invention features an isolated nucleic acid molecule that encodes a polypeptide including the amino acid sequence set forth in SEQ ID NO: 13.  
      In still other embodiments, the invention features isolated nucleic acid molecules including nucleotide sequences that are substantially identical (e.g., 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical) to the nucleotide sequence set forth as SEQ ID NO: 12 or 14. The invention further features isolated nucleic acid molecules including at least 50, 57, 63, 72, 100, 124, 150, 172, 175, 200, 250, 268, 300, 305, 328, 350, 400, 431, 450, 495, 500, 550, 600, 650, 700, 750, 800, 804, 850, 900, 950, 1000, 1050, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900 or more contiguous nucleotides of the nucleotide sequence set forth as SEQ ID NO: 12 or 14. In another embodiment, the invention features isolated nucleic acid molecules which encode a polypeptide including an amino acid sequence that is substantially identical (e.g., 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical) to the amino acid sequence set forth as SEQ ID NO:13. The present invention also features nucleic acid molecules which encode allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:13. In addition to isolated nucleic acid molecules encoding full-length polypeptides, the present invention also features nucleic acid molecules which encode fragments, for example, biologically active or antigenic fragments, of the full-length polypeptides of the present invention (e.g., fragments including at least 10, 20, 50, 100, 150, 155, 200, 250, 300, 350, 350, 400, 450, 500 or more contiguous amino acid residues of the amino acid sequence of SEQ ID NO:13). In still other embodiments, the invention features nucleic acid molecules that are complementary to, antisense to, or hybridize under stringent conditions to the isolated nucleic acid molecules described herein.  
      In another aspect, the invention provides vectors including the isolated nucleic acid molecules described herein (e.g., HST-1-encoding nucleic acid molecules). Such vectors can optionally include nucleotide sequences encoding heterologous polypeptides. Also featured are host cells including such vectors (e.g., host cells including vectors suitable for producing HST-1 nucleic acid molecules and polypeptides).  
      In another aspect, the invention features isolated HST-1 polypeptides and/or biologically active or antigenic fragments thereof. Exemplary embodiments feature a polypeptide including the amino acid sequence set forth as SEQ ID NO: 13, a polypeptide including an amino acid sequence at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical to the amino acid sequence set forth as SEQ ID NO: 13, a polypeptide encoded by a nucleic acid molecule including a nucleotide sequence at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical to the nucleotide sequence set forth as SEQ ID NO: 12 or 14. Also featured are fragments of the full-length polypeptides described herein (e.g., fragments including at least 10, 20, 50, 100, 150, 155, 200, 250, 300, 350, 350, 400, 450, 500 or more contiguous amino acid residues of the sequence set forth as SEQ ID NO: 13) as well as allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO: 13.  
      The HST-1 polypeptides and/or biologically active or antigenic fragments thereof, are useful, for example, as reagents or targets in assays applicable to treatment and/or diagnosis of HST-1 mediated or related disorders. In one embodiment, an HST-1 polypeptide or fragment thereof, has an HST-1 activity. In another embodiment, an HST-1 polypeptide or fragment thereof, has a transmembrane domain and/or a sugar transporter family domain, and optionally, has an HST-1 activity. In a related aspect, the invention features antibodies (e.g., antibodies which specifically bind to any one of the polypeptides described herein) as well as fusion polypeptides including all or a fragment of a polypeptide described herein.  
      The present invention further features methods for detecting HST-1 polypeptides and/or HST-1 nucleic acid molecules, such methods featuring, for example, a probe, primer or antibody described herein. Also featured are kits e.g., kits for the detection of HST-1 polypeptides and/or HST-1 nucleic acid molecules. In a related aspect, the invention features methods for identifying compounds which bind to and/or modulate the activity of an HST-1 polypeptide or HST-1 nucleic acid molecule described herein. Further featured are methods for modulating an HST-1 activity.  
      Other features and advantages of the invention will be apparent from the following detailed description and claims.  
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel molecules, referred to herein as “human sugar transporter-1” or “HST-1” nucleic acid and polypeptide molecules, which are novel members of the sugar transporter family. These novel molecules are capable of, for example, modulating a transporter mediated activity (e.g., a sugar transporter mediated activity) in a cell, e.g., a liver cell, fat cell, muscle cell, or blood cell, such as an erythrocyte. These novel molecules are capable of transporting molecules, e.g., monosaccharides such as D-glucose, D-fructose or D-galactose, across biological membranes and, thus, play a role in or function in a variety of cellular processes, e.g., maintenance of sugar homeostasis.  
      As used herein, a “sugar transporter” includes a protein or polypeptide which is involved in transporting a molecule, e.g., a monosaccharide such as D-glucose, D-fructose or D-galactose, across the plasma membrane of a cell, e.g., a liver cell, fat cell, muscle cell, or blood cell, such as an erythrocyte. Sugar transporters regulate sugar homeostasis in a cell and, typically, have sugar substrate specificity. Examples of sugar transporters include glucose transporters, fructose transporters, and galactose transporters.  
      As used herein, a “sugar transporter mediated activity” includes an activity which involves a sugar transporter, e.g., a sugar transporter in a liver cell, fat cell, muscle cell, or blood cell, such as an erythrocyte. Sugar transporter mediated activities include the transport of sugars, e.g., D-glucose, D-fructose or D-galactose, into and out of cells; the stimulation of molecules that regulate glucose homeostasis (e.g., insulin and glucagon), in cells, e.g., pancreatic cells; and the participation in signal transduction pathways associated with sugar metabolism.  
      As the HST-1 molecules of the present invention are sugar transporters, they may be useful for developing novel diagnostic and therapeutic agents for sugar transporter associated disorders. As used herein, the term “sugar transporter associated disorder” includes a disorder, disease, or condition which is characterized by an aberrant, e.g., upregulated or downregulated, sugar transporter mediated activity. Sugar transporter associated disorders typically result in, for example, upregulated or downregulated, sugar levels in a cell. Examples of sugar transporter associated disorders include disorders associated with sugar homeostasis, such as obesity, anorexia, type-1 diabetes, type-2 diabetes, hypoglycemia, glycogen storage disease (Von Gierke disease), type I glycogenosis, bipolar disorder, seasonal affective disorder, and cluster B personality disorders. HST-1-associated disorders may also include cellular growth or proliferation disorders. Further examples of sugar transporter associated disorders include cellular growth or proliferation disorders, such as cancer, e.g., carcinoma, sarcoma, or leukemia, examples of which include, but are not limited to, colon, ovarian, lung, breast, endometrial, uterine, hepatic, gastrointestinal, prostate, and brain cancer; tumorigenesis and metastasis; skeletal dysplasia; and hematopoietic and/or myeloproliferative disorders.  
      The term “family” when referring to the polypeptide and nucleic acid molecules of the invention is intended to mean two or more polypeptides or nucleic acid molecules having a common structural domain or motif and having sufficient amino acid or nucleotide sequence homology as defined herein. Such family members can be naturally or non-naturally occurring and can be from either the same or different species. For example, a family can contain a first polypeptide of human origin, as well as other, distinct polypeptides of human origin or alternatively, can contain homologues of non-human origin, e.g., mouse or monkey polypeptides. Members of a family may also have common functional characteristics.  
      For example, the family of HST-1 polypeptides comprise at least one “transmembrane domain” and preferably twelve transmembrane domains. As used herein, the term “transmembrane domain” includes an amino acid sequence of about 20-45 amino acid residues in length which spans the plasma membrane. More preferably, a transmembrane domain includes about at least 20, 25, 30, or 35 amino acid residues and spans the plasma membrane. Transmembrane domains are rich in hydrophobic residues, and typically have an alpha-helical structure. In a preferred embodiment, at least 50%, 60%, 70%, 80%, 90%, 95% or more of the amino acids of a transmembrane domain are hydrophobic, e.g., leucines, isoleucines, alanines, valines, phenylalanines, prolines or methionines. Transmembrane domains are described in, for example, Zagotta W. N. et al, (1996)  Annual Rev. Neurosci.  19: 235-263, the contents of which are incorporated herein by reference. A MEMSAT analysis resulted in the identification of twelve transmembrane domains in the amino acid sequence of human HST-1 (SEQ ID NO:13) at about residues 20-36, 150-167, 174-196, 204-220, 231-255, 263-282, 355-372, 387-405, 413-431, 438-462, 469-485, and 505-521 as set forth in  FIG. 8 .  
      Accordingly, HST-1 polypeptides having at least 50-60% homology, preferably about 60-70%, more preferably about 70-80%, or about 80-90% homology with a transmembrane domain of human HST-1 are within the scope of the invention.  
      In another embodiment, an HST-1 molecule of the present invention is identified based on the presence of at least one “sugar transporter family domain.” As used herein, the term “sugar transporter family domain” includes a protein domain having at least about 350-500 amino acid residues and a sugar transporter mediated activity. Preferably, a sugar transporter family domain includes a polypeptide having an amino acid sequence of about 350-450, 400-450, or more preferably, about 419 amino acid residues and a sugar transporter mediated activity. To identify the presence of a sugar transporter family domain in an HST-1 protein, and make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein may be searched against a database of known protein domains (e.g., the PFAM HMM database). A PFAM sugar transporter family domain has been assigned the PFAM Accession PF00083. A search was performed against the PFAM HMM database resulting in the identification of a sugar transporter family domain in the amino acid sequence of human HST-1 (SEQ ID NO: 13) at about residues 117-536 of SEQ ID NO: 13.  
      Preferably a “sugar transporter family domain” has a “sugar transporter mediated activity” as described herein. For example, a sugar transporter family domain may have the ability to bind a monosaccharide, such as D-glucose, D-fructose, and/or D-galactose; the ability to transport a monosaccharide such as D-glucose, D-fructose, and/or D-galactose, across a cell membrane (e.g., a liver cell membrane, fat cell membrane, muscle cell membrane, and/or blood cell membrane, such as an erythrocyte membrane); and the ability to modulate sugar homeostasis in a cell. Accordingly, identifying the presence of a “sugar transporter family domain” can include isolating a fragment of an HST-1 molecule (e.g., an HST-1 polypeptide) and assaying for the ability of the fragment to exhibit one of the aforementioned sugar transporter mediated activities.  
      A description of the Pfam database can be found in Sonhammer et al. (1997)  Proteins  28:405-420 and a detailed description of HMMs can be found, for example, in Gribskov et al. (1990)  Meth. Enzymol.  183:146-159; Gribskov et al. (1987)  Proc. Natl. Acad. Sci. USA  84:4355-4358;. Krogh et al. (1994)  J. Mol. Biol.  235:1501-1531; and Stultz et al. (1993)  Protein Sci.  2:305-314, the contents of which are incorporated herein by reference.  
      In a preferred embodiment, the NPM-1 molecules of the invention include at least one, preferably two, even more preferably twelve transmembrane domain(s) and/or at least one sugar transporter family domain.  
      Isolated polypeptides of the present invention, preferably HST-1 polypeptides, have an amino acid sequence sufficiently identical to the amino acid sequence of SEQ ID NO: 13 or are encoded by a nucleotide sequence sufficiently identical to SEQ ID NO: 12 or 14. As used herein, the term “sufficiently identical” refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more homology or identity across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently identical. Furthermore, amino acid or nucleotide sequences which share at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more homology or identity and share a common functional activity are defined herein as sufficiently identical.  
      In a preferred embodiment, an HST-1 polypeptide includes at least one or more of the following domains: a transmembrane domain and/or a sugar transporter family domain, and has an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more homologous or identical to the amino acid sequence of SEQ ID NO: 13. In yet another preferred embodiment, an HST-1 polypeptide includes at least one or more of the following domains: a transmembrane domain and/or a sugar transporter family domain, and is encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 12 or 14. In another preferred embodiment, an HST-1 polypeptide includes at least one or more of the following domains: a transmembrane domain and/or a sugar transporter family domain, and has an HST-1 activity.  
      As used interchangeably herein, an “HST-1 activity”, “biological activity of HST-1” or “functional activity of HST-1,” refers to an activity exerted by an HST-1 polypeptide or nucleic acid molecule on an HST-1 responsive cell or tissue, or on an HST-1 polypeptide substrate, as determined in vivo, or in vitro, according to standard techniques. In one embodiment, an HST-1 activity is a direct activity, such as an association with an HST-1-target molecule. As used herein, a “substrate,” “target molecule,” or “binding partner” is a molecule with which an HST-1 polypeptide binds or interacts in nature, such that HST-1-mediated function is achieved. An HST-1 target molecule can be a non-HST-1 molecule or an HST-1 polypeptide or polypeptide of the present invention. In an exemplary embodiment, an HST-1 target molecule is an HST-1 ligand, e.g., a sugar transporter ligand such as D-glucose, D-fructose, and/or D-galactose. Alternatively, an HST-1 activity is an indirect activity, such as a cellular signaling activity mediated by interaction of the HST-1 polypeptide with an HST-1 ligand. The biological activities of HST-1 are described herein. For example, the HST-1 polypeptides of the present invention can have one or more of the following activities: (1) maintain sugar homeostasis in a cell, (2) influence insulin and/or glucagon secretion, (3) bind a monosaccharide, e.g., D-glucose, D-fructose, and/or D-galactose, and/or (4) transport monosaccharides across a cell membrane.  
      The nucleotide sequence of the isolated human HST-1 cDNA and the predicted amino acid sequence of the human HST-1 polypeptide are shown in SEQ ID NOs:12 and 14, respectively.  
      The human HST-1 gene, which is approximately 1917 nucleotides in length, encodes a polypeptide which is approximately 572 amino acid residues in length.  
      Various aspects of the invention are described in further detail in later subsections.  
      Chapter IV. 63760, A Novel Human Transporter and Uses Thereof  
     SUMMARY OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel human transporter family members, referred to herein as “transporter-2” or “TP-2” nucleic acid and polypeptide molecules. The TP-2 nucleic acid and polypeptide molecules of the present invention are useful as modulating agents in regulating a variety of cellular processes, e.g., cellular growth, migration, or proliferation. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding TP-2 polypeptides or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of TP-2-encoding nucleic acids.  
      In one embodiment, the invention features an isolated nucleic acid molecule that includes the nucleotide sequence set forth in SEQ ID NO:15 or 17. In another embodiment, the invention features an isolated nucleic acid molecule that encodes a polypeptide including the amino acid sequence set forth in SEQ ID NO: 16.  
      In still other embodiments, the invention features isolated nucleic acid molecules including nucleotide sequences that are substantially identical (e.g., 60% identical) to the nucleotide sequence set forth as SEQ ID NO:15 or 17. The invention further features isolated nucleic acid molecules including at least 50 contiguous nucleotides of the nucleotide sequence set forth as SEQ ID NO:15 or 17. In another embodiment, the invention features isolated nucleic acid molecules which encode a polypeptide including an amino acid sequence that is substantially identical (e.g., 60% identical) to the amino acid sequence set forth as SEQ ID NO: 16. The present invention also features nucleic acid molecules which encode allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO: 16. In addition to isolated nucleic acid molecules encoding full-length polypeptides, the present invention also features nucleic acid molecules which encode fragments, for example, biologically active or antigenic fragments, of the full-length polypeptides of the present invention (e.g., fragments including at least 10 contiguous amino acid residues of the amino acid sequence of SEQ ID NO: 16). In still other embodiments, the invention features nucleic acid molecules that are complementary to, antisense to, or hybridize under stringent conditions to the isolated nucleic acid molecules described herein.  
      In another aspect, the invention provides vectors including the isolated nucleic acid molecules described herein (e.g., TP-2-encoding nucleic acid molecules). Such vectors can optionally include nucleotide sequences encoding heterologous polypeptides. Also featured are host cells including such vectors (e.g., host cells including vectors suitable for producing TP-2 nucleic acid molecules and polypeptides).  
      In another aspect, the invention features isolated TP-2 polypeptides and/or biologically active or antigenic fragments thereof. Exemplary embodiments feature a polypeptide including the amino acid sequence set forth as SEQ ID NO: 16, a polypeptide including an amino acid sequence at least 60% identical to the amino acid sequence set forth as SEQ ID NO:16, a polypeptide encoded by a nucleic acid molecule including a nucleotide sequence at least 60% identical to the nucleotide sequence set forth as SEQ ID NO: 15 or 17. Also featured are fragments of the full-length polypeptides described herein (e.g., fragments including at least 10 contiguous amino acid residues of the sequence set forth as SEQ ID NO: 16) as well as allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:16.  
      The TP-2 polypeptides and/or biologically active or antigenic fragments thereof, are useful, for example, as reagents or targets in assays applicable to treatment and/or diagnosis of TP-2 mediated or related disorders. In one embodiment, a TP-2 polypeptide or fragment thereof, has a TP-2 activity. In another embodiment, a TP-2 polypeptide or fragment thereof, includes at least one of the following domains: a transmembrane domain, a sugar transporter domain, a LacY proton/sugar symporter domain, and optionally, has a TP-2 activity. In a related aspect, the invention features antibodies (e.g., antibodies which specifically bind to any one of the polypeptides described herein) as well as fusion polypeptides including all or a fragment of a polypeptide described herein.  
      The present invention further features methods for detecting TP-2 polypeptides and/or TP-2 nucleic acid molecules, such methods featuring, for example, a probe, primer or antibody described herein. Also featured are kits e.g., kits for the detection of TP-2 polypeptides and/or TP-2 nucleic acid molecules. In a related aspect, the invention features methods for identifying compounds which bind to and/or modulate the activity of a TP-2 polypeptide or TP-2 nucleic acid molecule described herein. Further featured are methods for modulating a TP-2 activity.  
      Other features and advantages of the invention will be apparent from the following detailed description and claims.  
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel molecules, referred to herein as “transporter-2” or “TP-2” nucleic acid and polypeptide molecules, which are novel members of the transporter family. These novel molecules are capable of, for example, transporting ions, proteins, sugars, and small molecules across biological membranes both within a cell and between the cell and the environment and, thus, play a role in or function in a variety of cellular processes, e.g., proliferation, growth, differentiation, migration, immune responses, hormonal responses, and inter- or intra-cellular communication.  
      As used herein, the term “transporter” includes a molecule which is involved in the movement of a biochemical molecule from one side of a lipid bilayer to the other, for example, against a pre-existing concentration gradient. Transporters are usually involved in the movement of biochemical compounds which would normally not be able to cross a membrane (e.g., a protein; an ion; a sugar; or other small molecule, such as ATP; signaling molecules; vitamins; and cofactors). Transporter molecules are involved in the growth, development, and differentiation of cells, in the regulation of cellular homeostasis, in the metabolism and catabolism of biochemical molecules necessary for energy production or storage, in intra- or inter-cellular signaling, in metabolism or catabolism of metabolically important biomolecules, and in the removal of potentially harmful compounds from the interior of the cell. Examples of transporters include GSH transporters, ATP transporters, sugar transporters, and fatty acid transporters. As transporters, the TP-2 molecules of the present invention provide novel diagnostic targets and therapeutic agents to control transporter-associated disorders.  
      As used herein, a “transporter-associated disorder” includes a disorder, disease or condition which is caused or characterized by a misregulation (e.g., downregulation or upregulation) of a transporter-mediated activity. Transporter-associated disorders can detrimentally affect cellular functions such as cellular proliferation, growth, differentiation, or migration, cellular regulation of homeostasis, inter- or intra-cellular communication; tissue function, such as cardiac function or musculoskeletal function; systemic responses in an organism, such as nervous system responses, hormonal responses (e.g., insulin response), or immune responses; and protection of cells from toxic compounds (e.g., carcinogens, toxins, mutagens, and toxic byproducts of metabolic activity (e.g., reactive oxygen species)). Examples of transporter-associated disorders include CNS disorders such as cognitive and neurodegenerative disorders, examples of which include, but are not limited to, Alzheimer&#39;s disease, dementias related to Alzheimer&#39;s disease (such as Pick&#39;s disease), Parkinson&#39;s and other Lewy diffuse body diseases, senile dementia, Huntington&#39;s disease, Gilles de la Tourette&#39;s syndrome, multiple sclerosis, amyotrophic lateral sclerosis, progressive supranuclear palsy, epilepsy, and Jakob-Creutzfieldt disease; autonomic function disorders such as hypertension and sleep disorders, and neuropsychiatric disorders, such as depression, schizophrenia, schizoaffective disorder, korsakoff&#39;s psychosis, mania, anxiety disorders, or phobic disorders; learning or memory disorders, e.g., amnesia or age-related memory loss, attention deficit disorder, dysthymic disorder, major depressive disorder, mania, obsessive-compulsive disorder, psychoactive substance use disorders, anxiety, phobias, panic disorder, as well as bipolar affective disorder, e.g., severe bipolar affective (mood) disorder (BP-1), and bipolar affective neurological disorders, e.g., migraine and obesity. Further CNS-related disorders include, for example, those listed in the American Psychiatric Association&#39;s Diagnostic and Statistical manual of Mental Disorders (DSM), the most current version of which is incorporated herein by reference in its entirety.  
      Further examples of transporter-associated disorders include cardiac-related disorders. Cardiovascular system disorders in which the TP-2 molecules of the invention may be directly or indirectly involved include arteriosclerosis, ischemia reperfusion injury, restenosis, arterial inflammation, vascular wall remodeling, ventricular remodeling, rapid ventricular pacing, coronary microembolism, tachycardia, bradycardia, pressure overload, aortic bending, coronary artery ligation, vascular heart disease, atrial fibrilation, Jervell syndrome, Lange-Nielsen syndrome, long-QT syndrome, congestive heart failure, sinus node dysfunction, angina, heart failure, hypertension, atrial fibrillation, atrial flutter, dilated cardiomyopathy, idiopathic cardiomyopathy, myocardial infarction, coronary artery disease, coronary artery spasm, and arrhythmia. TP-2-mediated or related disorders also include disorders of the musculoskeletal system such as paralysis and muscle weakness, e.g., ataxia, myotonia, and myokymia.  
      Transporter-associated disorders also include cellular proliferation, growth, differentiation, or migration disorders. Cellular proliferation, growth, differentiation, or migration disorders include those disorders that affect cell proliferation, growth, differentiation, or migration processes. As used herein, a “cellular proliferation, growth, differentiation, or migration process” is a process by which a cell increases in number, size or content, by which a cell develops a specialized set of characteristics which differ from that of other cells, or by which a cell moves closer to or further from a particular location or stimulus. The TP-2 molecules of the present invention are involved in signal transduction mechanisms, which are known to be involved in cellular growth, differentiation, and migration processes. Thus, the TP-2 molecules may modulate cellular growth, differentiation, or migration, and may play a role in disorders characterized by aberrantly regulated growth, differentiation, or migration. Such disorders include cancer, e.g., carcinoma, sarcoma, or leukemia; tumor angiogenesis and metastasis; skeletal dysplasia; hepatic disorders; and hematopoietic and/or myeloproliferative disorders.  
      TP-2-associated disorders also include hormonal disorders, such as conditions or diseases in which the production and/or regulation of hormones in an organism is aberrant. Examples of such disorders and diseases include type I and type II diabetes mellitus, pituitary disorders (e.g., growth disorders), thyroid disorders (e.g., hypothyroidism or hyperthyroidism), and reproductive or fertility disorders (e.g., disorders which affect the organs of the reproductive system, e.g., the prostate gland, the uterus, or the vagina; disorders which involve an imbalance in the levels of a reproductive hormone in a subject; disorders affecting the ability of a subject to reproduce; and disorders affecting secondary sex characteristic development, e.g., adrenal hyperplasia).  
      TP-2-associated disorders also include immune disorders, such as autoimmune disorders or immune deficiency disorders, e.g., congenital X-linked infantile hypogammaglobulinemia, transient hypogammaglobulinemia, common variable immunodeficiency, selective IgA deficiency, chronic mucocutaneous candidiasis, or severe combined immunodeficiency.  
      TP-2-associated disorders also include disorders associated with sugar homeostasis, such as obesity, anorexia, hypoglycemia, glycogen storage disease (Von Gierke disease), type I glycogenosis, seasonal affective disorder, and cluster B personality disorders.  
      TP-2-associated disorders also include disorders affecting tissues in which TP-2 protein is expressed.  
      As used herein, a “transporter-mediated activity” includes an activity which involves the facilitated movement of one or more molecules from one side of a biological membrane to the other. Transporter-mediated activities include the import or export across internal or external cellular membranes of biochemical molecules necessary for energy production or storage, intra- or inter-cellular signaling, metabolism or catabolism of metabolically important biomolecules, and removal of potentially harmful compounds from the cell.  
      The term “family” when referring to the polypeptide and nucleic acid molecules of the invention is intended to mean two or more polypeptides or nucleic acid molecules having a common structural domain or motif and having sufficient amino acid or nucleotide sequence homology as defined herein. Such family members can be naturally or non-naturally occurring and can be from either the same or different species. For example, a family can contain a first polypeptide of human origin, as well as other, distinct polypeptides of human origin or alternatively, can contain homologues of non-human origin, e.g., mouse or monkey polypeptides. Members of a family may also have common functional characteristics.  
      For example, the family of TP-2 polypeptides comprise at least one “transmembrane domain” and preferably twelve transmembrane domains. As used herein, the term “transmembrane domain” includes an amino acid sequence of about 15-45 amino acid residues in length which spans the plasma membrane. More preferably, a transmembrane domain includes about at least 15, 20, 25, 30, 35, 40, or 45 amino acid residues and spans the plasma membrane. Transmembrane domains are rich in hydrophobic residues, and typically have an alpha-helical structure. In a preferred embodiment, at least 50%, 60%, 70%, 80%, 90%, 95% or more of the amino acids of a transmembrane domain are hydrophobic, e.g., leucines, isoleucines, alanines, valines, phenylalanines, prolines or methionines. Transmembrane domains are described in, for example, Zagotta W. N. et al, (1996)  Annual Rev. Neurosci.  19: 235-263, the contents of which are incorporated herein by reference. A MEMSAT analysis and a structural, hydrophobicity, and antigenicity analysis resulted in the identification of twelve transmembrane domains in the amino acid sequence of human TP-2 (SEQ ID NO: 16) at about residues 45-69, 80-102, 112-126, 133-156, 167-190, 197-218, 288-310, 323-343, 352-368, 375-391, 409-433, and 442-458 as set forth in  FIGS. 11 and 12 .  
      Accordingly, TP-2 polypeptides having at least 50-60% homology, preferably about 60-70%, more preferably about 70-80%, or about 80-90% homology with a transmembrane domain of human TP-2 are within the scope of the invention.  
      For example, in one embodiment, members of the TP-2 family of proteins include at least one “sugar transporter domain” in the protein or corresponding nucleic acid molecule. As used herein, the term “sugar transporter domain” includes a protein domain having at least about 350-500 amino acid residues and a sugar transporter mediated activity. Preferably, a sugar transporter domain includes a polypeptide having an amino acid sequence of about 350-450, 400-450, or more preferably about 417 amino acid residues, and a sugar transporter mediated activity. To identify the presence of a sugar transporter domain in a TP-2 protein, and make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein may be searched against a database of known protein domains (e.g., the PFAM HMM database). A PFAM sugar transporter domain has been assigned the PFAM Accession PF00083. A search was performed against the PFAM HMM database resulting in the identification of a sugar transporter domain in the amino acid sequence of human TP-2 (SEQ ID NO:16) at about residues 37-454 of SEQ ID NO:16.  
      As used herein, a “sugar transporter mediated activity” includes the ability to bind a monosaccharide, such as D-glucose, D-fructose, and/or D-galactose; the ability to transport a monosaccharide such as D-glucose, D-fructose, and/or D-galactose, across a cell membrane (e.g., a liver cell membrane, fat cell membrane, muscle cell membrane, and/or blood cell membrane, such as an erythrocyte membrane); and the ability to modulate sugar homeostasis in a cell. Accordingly, identifying the presence of a “sugar transporter domain” can include isolating a fragment of a TP-2 molecule (e.g., a TP-2 polypeptide) and assaying for the ability of the fragment to exhibit one of the aforementioned sugar transporter mediated activities.  
      In another embodiment, a TP-2 molecule of the present invention is identified based on the presence of at least one “LacY proton/sugar symporter domain.” As used herein, the term “LacY proton/sugar symporter domain” includes a protein domain having at least about 350-500 amino acid residues and a LacY proton/sugar symporter mediated activity. Preferably, a LacY proton/sugar symporter domain includes a protein domain having an amino acid sequence of about 300-400, 300-350, or more preferably, about 344 amino acid residues and a LacY proton/sugar symporter mediated activity. To identify the presence of a LacY proton/sugar symporter domain in a TP-2 protein, and make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein may be searched against a database of known protein domains (e.g., the PFAM HMM database). A PFAM LacY proton/sugar symporter domain has been assigned the PFAM Accession PF01306. A search was performed against the PFAM HMM database resulting in the identification of a LacY proton/sugar symporter domain in the amino acid sequence of human TP-2 (SEQ ID NO:16) at about residues 39-383 of SEQ ID NO:16.  
      As used herein, a “LacY proton/sugar symporter mediated activity” includes the ability to mediate the transport of a variety of sugars (e.g., D-glucose, D-fructose, and/or D-galactose) with the concomitant transport of hydrogen ions across a biological membrane. Accordingly, identifying the presence of a “LacY proton/sugar symporter domain” can include isolating a fragment of a TP-2 molecule (e.g., a TP-2 polypeptide) and assaying for the ability of the fragment to exhibit one of the aforementioned LacY proton/sugar symporter mediated activities.  
      A description of the Pfam database can be found in Sonhammer et al. (1997)  Proteins  28:405-420 and a detailed description of HMMs can be found, for example, in Gribskov et al. (1990)  Meth. Enzymol.  183:146-159; Gribskov et al. (1987)  Proc. Natl. Acad. Sci. USA  84:4355-4358; Krogh et al. (1994)  J. Mol. Biol.  235:1501-1531; and Stultz et al. (1993)  Protein Sci.  2:305-314, the contents of which are incorporated herein by reference.  
      In a preferred embodiment, the TP-2 molecules of the invention include at least one, preferably two, even more preferably twelve transmembrane domain(s), and/or at least one sugar transporter domain, and/or at least one LacY proton/sugar symporter domain.  
      Isolated polypeptides of the present invention, preferably TP-2 polypeptides, have an amino acid sequence sufficiently identical to the amino acid sequence of SEQ ID NO:16 or are encoded by a nucleotide sequence sufficiently identical to SEQ ID NO: 15 or 17. As used herein, the term “sufficiently identical” refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or more homology or identity across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently identical. Furthermore, amino acid or nucleotide sequences which share at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homology or identity and share a common functional activity are defined herein as sufficiently identical.  
      In a preferred embodiment, a TP-2 polypeptide includes at least one or more of the following domains: a transmembrane domain, and/or a sugar transporter domain, and/or a LacY proton/sugar symporter domain, and has an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or more homologous or identical to the amino acid sequence of SEQ ID NO: 16. In yet another preferred embodiment, a TP-2 polypeptide includes at least one or more of the following domains: a transmembrane domain, and/or a sugar transporter domain, and/or a LacY proton/sugar symporter domain, and is encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:15 or 17. In another preferred embodiment, a TP-2 polypeptide includes at least one or more of the following domains: a transmembrane domain, and/or a sugar transporter domain, and/or a LacY proton/sugar symporter domain, and has a TP-2 activity.  
      As used interchangeably herein, a “TP-2 activity”, “biological activity of TP-2” or “functional activity of TP-2”, refers to an activity exerted by a TP-2 protein, polypeptide or nucleic acid molecule on a TP-2 responsive cell or tissue, or on a TP-2 protein substrate, as determined in vivo, or in vitro, according to standard techniques. In one embodiment, a TP-2 activity is a direct activity, such as an association with a TP-2-target molecule. As used herein, a “target molecule” or “binding partner” is a molecule with which a TP-2 protein binds or interacts in nature, such that TP-2-mediated function is achieved. A TP-2 target molecule can be a non-TP-2 molecule or a TP-2 protein or polypeptide of the present invention (e.g., a molecule to be transported, e.g., a monosaccharide). In an exemplary embodiment, a TP-2 target molecule is a TP-2 ligand (e.g., an energy molecule, a metabolite, a monosaccharide or an ion). Alternatively, a TP-2 activity is an indirect activity, such as a cellular signaling activity mediated by interaction of the TP-2 protein with a TP-2 ligand. The biological activities of TP-2 are described herein. For example, the TP-2 proteins of the present invention can have one or more of the following activities: 1) modulate the import and export of molecules, e.g., hormones, ions, cytokines, neurotransmitters, monosaccharides, and metabolites, from cells, 2) modulate intra- or inter-cellular signaling, 3) modulate removal of potentially harmful compounds from the cell, or facilitate the compartmentalization of these molecules into a sequestered intra-cellular space (e.g., the peroxisome), and 4) modulate transport of biological molecules across membranes, e.g., the plasma membrane, or the membrane of the mitochondrion, the peroxisome, the lysosome, the endoplasmic reticulum, the nucleus, or the vacuole.  
      The nucleotide sequence of the isolated human TP-2 cDNA and the predicted amino acid sequence of the human TP-2 polypeptide are shown in SEQ ID NOs:15 and 16, respectively.  
      The human TP-2 gene, which is approximately 1963 nucleotides in length, encodes a polypeptide which is approximately 474 amino acid residues in length.  
      Various aspects of the invention are described in further detail in later subsections.  
      Chapter V. 49938, A Novel Human Phospholipid Transporter and Uses Therefor  
     SUMMARY OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel phospholipid transporter family members, referred to herein as “Phospholipid Transporter-1” or “PLTR-1” nucleic acid and protein molecules. The PLTR-1 nucleic acid and protein molecules of the present invention are useful as modulating agents in regulating a variety of cellular processes, e.g., phospholipid transport (e.g., aminophospholipid transport), absorption, secretion, gene expression, intra- or intercellular signaling, blood coagulation, and/or cellular proliferation, growth, apoptosis, and/or differentiation. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding PLTR-1 proteins or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of PLTR-1-encoding nucleic acids.  
      In one embodiment, the invention features an isolated nucleic acid molecule that includes the nucleotide sequence set forth in SEQ ID NO: 19 or 21. In another embodiment, the invention features an isolated nucleic acid molecule that encodes a polypeptide including the amino acid sequence set forth in SEQ ID NO:20.  
      In still other embodiments, the invention features isolated nucleic acid molecules including nucleotide sequences that are substantially identical (e.g., 75%, 79%, 80%, 81%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical) to the nucleotide sequence set forth as SEQ ID NO: 19 or 21. The invention further features isolated nucleic acid molecules including at least 30, 35, 40, 45, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 676, 677, 689, 690, 691, 692, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1562, 1600, 1610, 1660, 1700, 1750, 1800, 1850, 1900, 1950, 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2373, 2374, 2375, 2400, 2450, 2500, 2550, 2600, 2650, 2700, 2750, 2800, 2850, 2900, 2950, 3000, 3050, 3063, 3064, 3100, 3150, 3200, 3250, 3300, 3350, 3400, 3450, 3500, 3550, 3600, 3650, 3700, 3750, 3753, 3754, 3800, 3850, 3900, 3950, 4000, 4050, 4100, 4150, 4200, 4250, 4300, 4350, 4400, 4450, 4500, 4550, 4600, 4650 contiguous nucleotides of the nucleotide sequence set forth as SEQ ID NO:19 or 21. In another embodiment, the invention features isolated nucleic acid molecules which encode a polypeptide including an amino acid sequence that is substantially identical (e.g., 75%, 79%, 80%, 81%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical) to the amino acid sequence set forth as SEQ ID NO:20. Also featured are nucleic acid molecules which encode allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:20. In addition to isolated nucleic acid molecules encoding full-length polypeptides, the present invention also features nucleic acid molecules which encode fragments, for example, biologically active or antigenic fragments, of the full-length polypeptides of the present invention (e.g., fragments including at least 10, 15, 20, 25, 30, 25, 40, 45, 50, 75, 100, 125, 150, 175, 200, 250, 300, 328, 350, 375, 400, 450, 465, 500, 520, 550, 600, 650, 700, 703, 750, 800, 850, 900, 932, 950, 1000, 1050, 1100, or 1150 contiguous amino acid residues of the amino acid sequence of SEQ ID NO:20). In still other embodiments, the invention features nucleic acid molecules that are complementary to, antisense to, or hybridize under stringent conditions to the isolated nucleic acid molecules described herein.  
      In a related aspect, the invention provides vectors including the isolated nucleic acid molecules described herein (e.g., PLTR-1-encoding-nucleic acid molecules). Such vectors can optionally include nucleotide sequences encoding heterologous polypeptides. Also featured are host cells including such vectors (e.g., host cells including vectors suitable for producing PLTR-1 nucleic acid molecules and polypeptides).  
      In another aspect, the invention features isolated PLTR-1 polypeptides and/or biologically active or antigenic fragments thereof. Exemplary embodiments feature a polypeptide including the amino acid sequence set forth as SEQ ID NO:20, a polypeptide including an amino acid sequence at least 75%, 79%, 80%, 81%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical to the amino acid sequence set forth as SEQ ID NO:20, a polypeptide encoded by a nucleic acid molecule including a nucleotide sequence at least 75%, 79%, 80%, 81%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1% 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical to the nucleotide sequence set forth as SEQ ID NO: 19 or 21. Also featured are fragments of the full-length polypeptides described herein (e.g., fragments including at least 10, 15, 20, 25, 30, 25, 40, 45, 50, 75, 100, 125, 150, 175, 200, 250, 300, 328, 350, 375, 400, 450, 465, 500, 520, 550, 600, 650, 700, 703, 750, 800, 850, 900, 932, 950, 1000, 1050, 1100, or 1150 contiguous amino acid residues of the sequence set forth as SEQ ID NO:20) as well as allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:20.  
      The PLTR-1 polypeptides and/or biologically active or antigenic fragments thereof, are useful, for example, as reagents or targets in assays applicable to treatment and/or diagnosis of PLTR-1 associated or related disorders. In one embodiment, a PLTR-1 polypeptide or fragment thereof has a PLTR-1 activity. In another embodiment, a PLTR-1 polypeptide or fragment thereof has at least one or more of the following domains, sites, or motifs: a transmembrane domain, an N-terminal large extramembrane domain, a C-terminal large extramembrane domain, an E1-E2 ATPases phosphorylation site, a P-type ATPase sequence 1 motif, a P-type ATPase sequence 2 motif, a P-type ATPase sequence 3 motif, and/or one or more phospholipid transporter specific amino acid resides, and optionally, has a PLTR-1 activity. In a related aspect, the invention features antibodies (e.g., antibodies which specifically bind to any one of the polypeptides, as described herein) as well as fusion polypeptides including all or a fragment of a polypeptide described herein.  
      The present invention further features methods for detecting PLTR-1 polypeptides and/or PLTR-1 nucleic acid molecules, such methods featuring, for example, a probe, primer or antibody described herein. Also featured are kits for the detection of PLTR-1 polypeptides and/or PLTR-1 nucleic acid molecules. In a related aspect, the invention features methods for identifying compounds which bind to and/or modulate the activity of a PLTR-1 polypeptide or PLTR-1 nucleic acid molecule described herein. Also featured are methods for modulating a PLTR-1 activity.  
      Other features and advantages of the invention will be apparent from the following detailed description and claims.  
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel phospholipid transporter family members, referred to herein as “Phospholipid Transporter-1” or “PLTR-1” nucleic acid and protein molecules. These novel molecules are capable of transporting phospholipids (e.g., aminophospholipids such as phosphatidylserine and phosphatidylethanolamine, choline phospholipids such as phosphatidylcholine and sphingomyelin, and bile acids) across cellular membranes and, thus, play a role in or function in a variety of cellular processes, e.g., phospholipid transport, absorption, secretion, gene expression, intra- or intercellular signaling, and/or cellular proliferation, growth, and/or differentiation. Thus, the PLTR-1 molecules of the present invention provide novel diagnostic targets and therapeutic agents to control PLTR-1-associated disorders, as defined herein.  
      The term “family” when referring to the protein and nucleic acid molecules of the invention is intended to mean two or more proteins or nucleic acid molecules having a common structural domain or motif and having sufficient amino acid or nucleotide sequence homology as defined herein. Such family members can be naturally or non-naturally occurring and can be from either the same or different species. For example, a family can contain a first protein of human origin as well as other distinct proteins of human origin or alternatively, can contain homologues of non-human origin, e.g., rat or mouse proteins. Members of a family can also have common functional characteristics.  
      For example, the family of PLTR-1 proteins of the present invention comprises at least one “transmembrane domain,” preferably at least 2, 3, or 4 transmembrane domains, more preferably 5, 6, or 7 transmembrane domains, even more preferably 8 or 9 transmembrane domains, and most preferably, 10 transmembrane domains. As used herein, the term “transmembrane domain” includes an amino acid sequence of about 15 amino acid residues in length which spans the plasma membrane. More preferably, a transmembrane domain includes about at least 20, 25, 30, 35, 40, or 45 amino acid residues and spans the plasma membrane. Transmembrane domains are rich in hydrophobic residues, and typically have an alpha-helical structure. In a preferred embodiment, at least 50%, 60%, 70%, 80%, 90%, 95% or more of the amino acids of a transmembrane domain are hydrophobic, e.g., leucines, isoleucines, tyrosines, or tryptophans. Transmembrane domains are described in, for example, Zagotta, W. N. et al. (1996)  Annu. Rev. Neurosci.  19:235-263, the contents of which are incorporated herein by reference. Amino acid residues 55-71, 78-94, 276-298, 320-344, 880-897, 904-924, 954-977, 993-1011, 1022-1038, 1066, 1084 of the human PLTR-1 protein (SEQ ID NO:20) are predicted to comprise transmembrane domains (see FIGS.  14 A-B and  15 ).  
      The family of PLTR-1 proteins of the present invention also comprises at least one “large extramembrane domain” in the protein or corresponding nucleic acid molecule. As used herein, a “large extramembrane domain” includes a domain having greater than 20 amino acid residues that is found between transmembrane domains, preferably on the cytoplasmic side of the plasma membrane, and does not span or traverse the plasma membrane. A large extramembrane domain preferably includes at least one, two, three, four or more motifs or consensus sequences characteristic of P-type ATPases, i.e., includes one, two, three, four, or more “P-type ATPase consensus sequences or motifs”. As used herein, the phrase “P-type ATPase consensus sequences or motifs” includes any consensus sequence or motif known in the art to be characteristic of P-type ATPases, including, but not limited to, the P-type ATPase sequence 1 motif (as defined herein), the P-type ATPase sequence 2 motif (as defined herein), the P-type ATPase sequence 3 motif (as defined herein), and the E1-E2 ATPases phosphorylation site (as defined herein).  
      In one embodiment, the family of PLTR-1 proteins of the present invention comprises at least one “N-terminal” large extramembrane domain in the protein or corresponding nucleic acid molecule. As used herein, an “N-terminal” large extramembrane domain is found in the N-terminal ⅓ rd  of the protein, preferably between the second and third transmembrane domains of a PLTR-1 protein and includes about 60-300, 80-280, 100-260, 120-240, 140-220, 160-200, or preferably, 181 amino acid residues. In a preferred embodiment, an N-terminal large extramembrane domain includes at least one P-type ATPase sequence 1 motif (as described herein). An N-terminal large extramembrane domain was identified in the amino acid sequence of human PLTR-1 at about residues 95-275 of SEQ ID NO:20.  
      The family of PLTR-1 proteins of the present invention also comprises at least one “C-terminal” large extramembrane domain in the protein or corresponding nucleic acid molecule. As used herein, a “C-terminal” large extramembrane domain is found in the C-terminal ⅔ rds  of the protein, preferably between the fourth and fifth transmembrane domains of a PLTR-1 protein and includes about 430-650, 450-630, 470-610, 490-590, 510-570, 530-550, or preferably, 535 amino acid residues. In a preferred embodiment, a C-terminal large extramembrane domain includes at least one or more of the following motifs: a P-type ATPase sequence 2 motif (as described herein), a P-type ATPase sequence 3 motif (as defined herein), and/or an E1-E2 ATPases phosphorylation site (as defined herein). A C-terminal large extramembrane domain was identified in the amino acid sequence of human PLTR-1 at about residues 345-879 of SEQ ID NO:20.  
      In another preferred embodiment, a C-terminal large extramembrane domain includes at least one or more of the following domains: one, two, or three hydrolase domains and/or an Adeno_EIB — 19K domain. To identify the presence of a hydrolase domain or an Adeno_E1B — 19K domain in a PLTR-1 family member and make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein is searched against a database of HMMs (e.g., the Pfam database, release 2.1) using the default parameters (available online at the PFAM website, available through Washington University in St. Louis). For example, the hmmsf program, which is available as part of the HMMER package of search programs, is a family specific default program with a score of 15 as the default threshold score for determining a hit. Alternatively, the threshold score for determining a hit can be lowered (e.g., to 8 bits). A description of the Pfam database can be found in Sonhammer et al. (1997)  Proteins  28(3)405-420 and a detailed description of HMMs can be found, for example, in Gribskov et al. (1990)  Meth. Enzymol.  183:146-159; Gribskov et al. (1987)  Proc. Natl. Acad. Sci. USA  84:4355-4358; Krogh et al. (1994)  J. Mol. Biol.  235:1501-1531; and Stultz et al. (1993)  Protein Sci.  2:305-314, the contents of which are incorporated herein by reference. A search was performed against the HMM database resulting in the identification of 3 hydrolase domains and 1 Adeno_E1B — 19K domain in the amino acid sequence of SEQ ID NO:20. The results of the search are set forth below.  
                                      Scores for sequence family classification           (score includes all domains):                                 Model   Description   Score   E-value   N               Hydrolase   haloacid dehalogenase-like hydrolase   20.9   6.5e-05   3       Adeno_E1B_19K   Adenovirus E1B 19K protein / small t-an    9.1   1                         Parsed for domains:                                                     Model   Domain   seq-f   seq-t       hmm-f   hmm-t       score   E-value                                                             Hydrolase   1/3   386   399   ..    1    14   [.   3.5   7.4       Adeno_E1B_19K   1/1   462   482   ..   56    76   ..   9.1   0.28       Hydrolase   2/3   603   682   ..   34   104   ..   4.2   4.7       Hydrolase   3/3   762   835   ..   106    184   .]   12.9    0.013                                        Alignments of top-scoring domains:           Hydrolase: domain 1 of 3, from 386 to 399: score 3.5, E = 7.4                          *−&gt;ikavvFDkDGTLtd&lt;−*                             +  ++ Dk+GTLt+                    49938  386   VEYIFSDKTGTLTQ   399               Adeno_E1B_19K: domain 1 or 1, from 462 to 482: score 9.1, E = 0.28                          *−&gt;pecpglfasLnlGytlvFqe&gt;−*                             p+++++f++L l++t+ ++ek            49938  462   PHTHEFFRLLSLCHTVMSEEK    482               Hydrolase: domain 2 of 3, from 603 to 682: score 4.2, E = 4.7                          *−&gt;apleevekllgrgl.gerilleggltaell......ld.evlglial                             +++e++e +++r l++   ++++++ 30  +   ++ +++  +lg+ a            49938  603   LDEEYYEEWARERRLqA-SLAQDSREDRLASiyeeveNNmMLLGATAI 648                              .dklypgarealkaLkerGikvailTngdr.nae&lt;−*                      +dkl  g++e+++ L  ++ik+++lT++ +++a+            49938  649 eDKLQQGVPETIALLTLANIKIWVLTGDKQeTAV   682               Hydrolase: domain 3 of 3, from 762 to 835: score 12.9, E = 0.013                         *−&gt;llealgla.lfdaivdsdevggcgpvvvgKPkpeifllalerlgvkp                            l+ al+++ +++++++++ ++  +v++ +  p  + +++e  ++            49938  762    LAHALEADmELEFLETACACK---AVICCRVTPLQKAQVVELVKKYK 805                              eevgpkvlmGDginDapalaaAGvgvamgngg&lt;−*                      ++v  +l++GDg nD+ +++ A++gv +            49938  806   KAV---TLAIGDGANDVSMIKTAHIGVGISGQE   835                  
 
      In another embodiment, a PLTR-1 protein includes at least one “P-type ATPase sequence 1 motif” in the protein or corresponding nucleic acid molecule. As used herein, a “P-type ATPase sequence 1 motif” is a conserved sequence motif diagnostic for P-type ATPases (Tang, X. et al. (1996)  Science  272:1495-1497; Fagan, M. J. and Saier, M. H. (1994)  J. Mol. Evol.  38:57). A P-type ATPase sequence 1 motif is involved in the coupling of ATP hydrolysis with transport (e.g., transport of phospholipids). The consensus sequence for a P-type ATPase sequence 1 motif is [DNS]-[QENR]-[SA]-[LIVSAN]-[LIV]-[TSN]-G-E-[SN] (SEQ ID NO:23). The use of amino acids in brackets indicates that the amino acid at the indicated position may be any one of the amino acids within the brackets, e.g., [SA] indicates any of one of either S (serine) or A (alanine). In a preferred embodiment, a P-type ATPase sequence 1 motif is contained within an N-terminal large extramembrane domain. In another preferred embodiment, a P-type ATPase sequence 1 motif in the PLTR-1 proteins of the present invention has at least 1, 2, 3, or preferably 4 amino acid resides which match the consensus sequence for a P-type ATPase sequence 1 motif. A P-type ATPase sequence 1 motif was identified in the amino acid sequence of human PLTR-1 at about residues 164-172 of SEQ ID NO:20.  
      In another embodiment, a PLTR-1 protein includes at least one “P-type ATPase sequence 2 motif” in the protein or corresponding nucleic acid molecule. As used herein, a “P-type ATPase sequence 2 motif” is a conserved sequence motif diagnostic for P-type ATPases (Tang, X. et al. (1996)  Science  272:1495-1497; Fagan, M. J. and Saier, M. H. (1994)  J. Mol. Evol.  38:57). Preferably, a P-type ATPase sequence 2 motif overlaps with and/or includes an E1-E2 ATPases phosphorylation site (as defined herein). The consensus sequence for a P-type ATPase sequence 2 motif is [LIV]-[CAML]-[STFL]-D-K-T-G-T-[LI]-T (SEQ ID NO:24). The use of amino acids in brackets indicates that the amino acid at the indicated position may be any one of the amino acids within the brackets, e.g., [LI] indicates any of one of either L (leucine) or I (isoleucine). In a preferred embodiment, a P-type ATPase sequence 2 motif is contained within a C-terminal large extramembrane domain. In another preferred embodiment, a P-type ATPase sequence 2 motif in the PLTR-1 proteins of the present invention has at least 1, 2, 3, 4, 5, 6, 7, 8, or more preferably 9 amino acid resides which match the consensus sequence for a P-type ATPase sequence 2 motif. A P-type ATPase sequence 2 motif was identified in the amino acid sequence of human PLTR-1 at about residues 389-398 of SEQ ID NO:20.  
      In yet another embodiment, a PLTR-l protein includes at least one “P-type ATPase sequence 3 motif” in the protein or corresponding nucleic acid molecule. As used herein, a “P-type ATPase sequence 3 motif” is a conserved sequence motif diagnostic for P-type ATPases (Tang, X. et al. (1996) Science 272:1495-1497; Fagan, M. J. and Saier, M. H. (1994) J. Mol. Evol. 38:57). A P-type ATPase sequence 3 motif is involved in ATP binding. The consensus sequence for a P-type ATPase sequence 3 motif is [TIV]-G-D-G-X-N-D-[ASG]-P-[ASV]-L (SEQ ID NO:25). X indicates that the amino acid at the indicated position may be any amino acid (i.e., is not conserved). The use of amino acids in brackets indicates that the amino acid at the indicated position may be any one of the amino acids within the brackets, e.g., [TIV] indicates any of one of either T (threonine), I (isoleucine), or V (valine). In a preferred embodiment, a P-type ATPase sequence 3 motif is contained within a C-terminal large extramembrane domain. In another preferred embodiment, a P-type ATPase sequence 3 motif in the PLTR-1 proteins of the present invention has at least 1, 2, 3, 4, 5, 6, or more preferably 7 amino acid resides (including the amino acid at the position indicated by “X”) which match the consensus sequence for a P-type ATPase sequence 3 motif. A P-type ATPase sequence 3 motif was identified in the amino acid sequence of human PLTR-1 at about residues 812-822 of SEQ ID NO:20.  
      In another embodiment, a PLTR-1 protein of the present invention is identified based on the presence of an “E1-E2 ATPases phosphorylation site” (alternatively referred to simply as a “phosphorylation site”) in the protein or corresponding nucleic acid molecule. An E1-E2 ATPases phosphorylation site functions in accepting a phosphate moiety and has the following consensus sequence: D-K-T-G-T-[LIVM]-[TI] (SEQ ID NO:26), wherein D is phosphorylated. The use of amino acids in brackets indicates that the amino acid at the indicated position may be any one of the amino acids within the brackets, e.g., [TI] indicates any of one of either T (threonine) or I (isoleucine). The E1-E2 ATPases phosphorylation site has been assigned ProSite Accession Number PS00154. To identify the presence of an E1-E2 ATPases phosphorylation site in a PLTR-1 protein, and to make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein may be searched against a database of known protein domains (e.g., the ProSite database) using the default parameters (available online through the Swiss Institute for Bioinformatics). A search was performed against the ProSite database resulting in the identification of an E1-E2 ATPases phosphorylation site in the amino acid sequence of human PLTR-1 (SEQ ID NO:20) at about residues 392-398 (see FIGS.  14 A-B).  
      Preferably an E1-E2 ATPases phosphorylation site has a “phosphorylation site activity,” for example, the ability to be phosphorylated; to be dephosphorylated; to regulate the E1-E2 conformational change of the phospholipid transporter in which it is contained; to regulate transport of phospholipids (e.g., aminophospholipids such as phosphatidylserine and phosphatidylethanolamine, choline phospholipids such as phosphatidylcholine and sphingomyelin, and bile acids) across a cellular membrane by the PLTR-1 protein in which it is contained; and/or to regulate the activity (as defined herein) of the PLTR-1 protein in which it is contained. Accordingly, identifying the presence of an “E1-E2 ATPases phosphorylation site” can include isolating a fragment of a PLTR-1 molecule (e.g., a PLTR-1 polypeptide) and assaying for the ability of the fragment to exhibit one of the aforementioned phosphorylation site activities.  
      In another embodiment, a PLTR-1 protein of the present invention may also be identified based on its ability to adopt an E1 conformation or an E2 conformation. As used herein, an “E1 conformation” of a PLTR-1 protein includes a 3-dimensional conformation of a PLTR-1 protein which does not exhibit PLTR-1 activity (e.g., the ability to transport phospholipids), as defined herein. An E1 conformation of a PLTR-1 protein usually occurs when the PLTR-1 protein is unphosphorylated. As used herein, an “E2 conformation” of a PLTR-1 protein includes a 3-dimensional conformation of a PLTR-1 protein which exhibits PLTR-1 activity (e.g., the ability to transport phospholipids), as defined herein. An E2 conformation of a PLTR-1 protein usually occurs when the PLTR-1 protein is phosphorylated.  
      In still another embodiment, a PLTR-1 protein of the present invention is identified based on the presence of “phospholipid transporter specific” amino acid residues. As used herein, “phospholipid transporter specific” amino acid residues are amino acid residues specific to the class of phospholipid transporting P-type ATPases (as defined in Tang, X. et al. (1996)  Science  272:1495-1497). Phospholipid transporter specific amino acid residues are not found in P-type ATPases which transport molecules which are not phospholipids (e.g., cations). For example, phospholipid transporter specific amino acid residues are found at the first, second, and fifth positions of the P-type ATPase sequence 1 motif. In phospholipid transporting P-type ATPases, the first position of the P-type ATPase sequence 1 motif is preferably E (glutamic acid), the second position is preferably T (threonine), and the fifth position is preferably L (leucine). A phospholipid transporter specific amino acid residue is further found at the second position of the P-type ATPase sequence 2 motif. In phospholipid transporting P-type ATPases, the second position of the P-type ATPase sequence 2 motif is preferably F (phenylalanine). Phospholipid transporter specific amino acid residues are still further found at the first, tenth, and eleventh positions of the P-type ATPase sequence 3 motif. In phospholipid transporting P-type ATPases, the first position of the P-type ATPase sequence 3 motif is preferably I (isoleucine), the tenth position is preferably M (methionine), and the eleventh position is preferably I (isoleucine). Phospholipid transporter specific amino acid residues were identified in the amino acid sequence of human PLTR-1 (SEQ ID NO:20) at about residues 164, 165, and 168 (within the P-type ATPase sequence 1 motif; see FIGS.  14 A-B), at about residue 390 (within the P-type ATPase sequence 2 motif; see FIGS.  14 -B), and at about residues 812, 821, and 822 (within the P-type ATPase sequence 3 motif; see FIGS.  14 -B).  
      Isolated proteins of the present invention, preferably PLTR-1 proteins, have an amino acid sequence sufficiently homologous to the amino acid sequence of SEQ ID NO:20, or are encoded by a nucleotide sequence sufficiently homologous to SEQ ID NO:19 or 21. As used herein, the term “sufficiently homologous” refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains having at least 75%, 79%, 80%, 81%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more homology or identity across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently homologous. Furthermore, amino acid or nucleotide sequences which share at least 75%, 79%, 80%, 81%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more homology or identity and share a common functional activity are defined herein as sufficiently homologous. In a preferred embodiment, amino acid or nucleotide sequences share percent identity across the full or entire length of the amino acid or nucleotide sequence being aligned, for example, when the sequences are globally aligned (e.g., as determined by the ALIGN algorithm as defined herein).  
      In a preferred embodiment, a PLTR-1 protein includes at least one or more of the following domains, sites, or motifs: a transmembrane domain, an N-terminal large extramembrane domain, a C-terminal large extramembrane domain, an E1-E2 ATPases phosphorylation site, a P-type ATPase sequence 1 motif, a P-type ATPase sequence 2 motif, a P-type ATPase sequence 3 motif, and/or one or more phospholipid transporter specific amino acid resides and has an amino acid sequence at least about 75%, 79%, 80%, 81%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more homologous or identical to the amino acid sequence of SEQ ID NO:20. In yet another preferred embodiment, a PLTR-1 protein includes at least one or more of the following domains, sites, or motifs: a transmembrane domain, an N-terminal large extramembrane domain, a C-terminal large extramembrane domain, an E1-E2 ATPases phosphorylation site, a P-type ATPase sequence 1 motif, a P-type ATPase sequence 2 motif, a P-type ATPase sequence 3 motif, and/or one or more phospholipid transporter specific amino acid resides, and is encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:19 or 21. In another preferred embodiment, a PLTR-1 protein includes at least one or more of the following domains, sites, or motifs: a transmembrane domain, an N-terminal large extramembrane domain, a C-terminal large extramembrane domain, an E1-E2 ATPases phosphorylation site, a P-type ATPase sequence 1 motif, a P-type ATPase sequence 2 motif, a P-type ATPase sequence 3 motif, and/or one or more phospholipid transporter specific amino acid resides, and has a PLTR-1 activity.  
      As used interchangeably herein, a “PLTR-1 activity”, “phospholipid transporter activity”, “biological activity of PLTR-1”, or “functional activity of PLTR-1”, includes an activity exerted or mediated by a PLTR-1 protein, polypeptide or nucleic acid molecule on a PLTR-1 responsive cell or on a PLTR-1 substrate, as determined in vivo or in vitro, according to standard techniques. In one embodiment, a PLTR-1 activity is a direct activity, such as an association with a PLTR-1 target molecule. As used herein, a “target molecule” or “binding partner” is a molecule with which a PLTR-1 protein binds or interacts in nature, such that PLTR-1-mediated function is achieved. A PLTR-1 target molecule can be a non-PLTR-1 molecule or a PLTR-1 protein or polypeptide of the present invention. In an exemplary embodiment, a PLTR-1 target molecule is a PLTR-1 substrate (e.g., a phospholipid, ATP, or a non-PLTR-1 protein). A PLTR-1 activity can also be an indirect activity, such as a cellular signaling activity mediated by interaction of the PLTR-1 protein with a PLTR-1 substrate.  
      In a preferred embodiment, a PLTR-1 activity is at least one of the following activities: (i) interaction with a PLTR-1 substrate or target molecule (e.g., a phospholipid, ATP, or a non-PLTR-1 protein); (ii) transport of a PLTR-1 substrate or target molecule (e.g., an aminophospholipid such as phosphatidylserine or phosphatidylethanolamine) from one side of a cellular membrane to the other; (iii) the ability to be phosphorylated or dephosphorylated; (iv) adoption of an E1 conformation or an E2 conformation; (v) conversion of a PLTR-1 substrate or target molecule to a product (e.g., hydrolysis of ATP); (vi) interaction with a second non-PLTR-1 protein; (vii) modulation of substrate or target molecule location (e.g., modulation of phospholipid location within a cell and/or location with respect to a cellular membrane); (viii) maintenance of aminophospholipid gradients; (ix) modulation of blood coagulation; (x) modulation of intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (xi) modulation of cellular proliferation, growth, differentiation, apoptosis, absorption, or secretion.  
      The nucleotide sequence of the isolated human PLTR-1 cDNA and the predicted amino acid sequence encoded by the PLTR-1 cDNA are shown in SEQ ID NOs:19 and 20, respectively.  
      The human PLTR-1 gene, which is approximately 4693 nucleotides in length, encodes a protein having a molecular weight of approximately 130.9 kD and which is approximately 1190 amino acid residues in length.  
      Various aspects of the invention are described in further detail in later subsections.  
      Chapter VI. 32146 and 57259, Novel Human Transporters and Uses Thereof  
     SUMMARY OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel human transporter family members, referred to herein as “transporter family members” or “TFM,” e.g., “TFM-2” and “TFM-3,” nucleic acid and polypeptide molecules. The TFM-2 and TFM-3 nucleic acid and polypeptide molecules of the present invention are useful as modulating agents in regulating a variety of cellular processes, e.g., cellular growth, migration, or proliferation. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding TFM-2 and TFM-3 polypeptides or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of TFM-2 and TFM-3-encoding nucleic acids.  
      In one embodiment, the invention features an isolated nucleic acid molecule that includes the nucleotide sequence set forth in SEQ ID NO:27, 29, 30, or 32. In another embodiment, the invention features an isolated nucleic acid molecule that encodes a polypeptide including the amino acid sequence set forth in SEQ ID NO:28 or 31.  
      In still other embodiments, the invention features isolated nucleic acid molecules including nucleotide sequences that are substantially identical (e.g., 66.6%, 66.7%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% identical) to the nucleotide sequence set forth as SEQ ID NO:27, 29, 30, or 32. The invention further features isolated nucleic acid molecules including at least 589, 590, 600, 650, 700, 750, 1000, 1250, 1500, 1750, or 1855 contiguous nucleotides of the nucleotide sequence set forth as SEQ ID NO:27, 29, 30, or 32. In another embodiment, the invention features isolated nucleic acid molecules which encode a polypeptide including an amino acid sequence that is substantially identical (e.g., 52%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% identical) to the amino acid sequence set forth as SEQ ID NO:28 or 31. The present invention also features nucleic acid molecules which encode allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:28 or 31. In addition to isolated nucleic acid molecules encoding full-length polypeptides, the present invention also features nucleic acid molecules which encode fragments, for example, biologically active or antigenic fragments, of the full-length polypeptides of the present invention (e.g., fragments including at least 157, 200, 250, 300, 350, 400 or 404 contiguous amino acid residues of the amino acid sequence of SEQ ID NO:28 or 31). In still other embodiments, the invention features nucleic acid molecules that are complementary to, antisense to, or hybridize under stringent conditions to the isolated nucleic acid molecules described herein.  
      In another aspect, the invention provides vectors including the isolated nucleic acid molecules described herein (e.g., TFM-2 and/or TFM-3-encoding nucleic acid molecules). Such vectors can optionally include nucleotide sequences encoding heterologous polypeptides. Also featured are host cells including such vectors (e.g., host cells including vectors suitable for producing TFM-2 and/or TFM-3 nucleic acid molecules and polypeptides).  
      In another aspect, the invention features isolated TFM-2 and TFM-3 polypeptides and/or biologically active or antigenic fragments thereof. Exemplary embodiments feature a polypeptide including the amino acid sequence set forth as SEQ ID NO:28 or 31, a polypeptide including an amino acid sequence at least 52%, 55%, 60%, 65%, 70%, 75%, 80%, 85%90, 95%, 98%, or 99% identical to the amino acid sequence set forth as SEQ ID NO:28 or 31, a polypeptide encoded by a nucleic acid molecule including a nucleotide sequence at least 66.6%, 66.7%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% identical to the nucleotide sequence set forth as SEQ ID NO:27, 29, 30, or 32. Also featured are fragments of the full-length polypeptides described herein (e.g., fragments including at least 157, 200, 250, 300, 350, 400 or 404 contiguous amino acid residues of the sequence set forth as SEQ ID NO:28 or 31) as well as allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:28 or 31.  
      The TFM-2 and TFM-3 polypeptides and/or biologically active or antigenic fragments thereof, are useful, for example, as reagents or targets in assays applicable to treatment and/or diagnosis of TFM-2 and TFM-3 mediated or related disorders. In one embodiment, a TFM-2 and/or TFM-3 polypeptide or fragment thereof, has a TFM-2 and/or TFM-3 activity. In another embodiment, a TFM-2 and/or TFM-3 polypeptide or fragment thereof, includes at least one of the following domains: a transmembrane domain, a sugar transporter domain, and/or a monocarboxylate transporter domain, and optionally, has a TFM-2 and/or a TFM-3 activity. In a related aspect, the invention features antibodies (e.g., antibodies which specifically bind to any one of the polypeptides described herein) as well as fusion polypeptides including all or a fragment of a polypeptide described herein.  
      The present invention further features methods for detecting TFM-2 and TFM-3 polypeptides and/or TFM-2 and TFM-3 nucleic acid molecules, such methods featuring, for example, a probe, primer or antibody described herein. Also featured are kits e.g., kits for the detection of TFM-2 and/or TFM-3 polypeptides and/or TFM-2 and/or TFM-3 nucleic acid molecules. In a related aspect, the invention features methods for identifying compounds which bind to and/or modulate the activity of a TFM-2 and/or TFM-3 polypeptide or TFM-2 and/or TFM-3 nucleic acid molecule described herein. Further featured are methods for modulating a TFM-2 and/or TFM-3 activity.  
      Other features and advantages of the invention will be apparent from the following detailed description and claims.  
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel molecules, referred to herein as “transporter family members” or “TFM,” e.g., “TFM-2” and. “TFM-3,” nucleic acid and polypeptide molecules, which are novel members of the transporter family. These novel molecules are capable of, for example, transporting lactate, pyruvate, branched chain oxoacids, ketone bodies, ions, proteins, sugars, and small molecules across biological membranes both within a cell and between the cell and the environment and, thus, play a role in or function in a variety of cellular processes, e.g., proliferation, growth, differentiation, migration, immune responses, hormonal responses, and inter- or intra-cellular communication.  
      As used herein, the term “transporter” includes a molecule which is involved in the movement of a biochemical molecule from one side of a lipid bilayer to the other, for example, against a pre-existing concentration gradient. Transporters are usually involved in the movement of biochemical compounds which would normally not be able to cross a membrane (e.g., a protein; an ion; a monocarboxylate; a sugar; or other small molecule, such as ATP; signaling molecules; vitamins; and cofactors). Transporter molecules are involved in the growth, development, and differentiation of cells, in the regulation of cellular homeostasis, in the metabolism and catabolism of biochemical molecules necessary for energy production or storage, in intra- or inter-cellular signaling, in metabolism or catabolism of metabolically important biomolecules, and in the removal of potentially harmful compounds from the interior of the cell. Examples of transporters include monocarboxylate transporters, sugar transporters, GSH transporters, ATP transporters, and fatty acid transporters. As transporters, the TFM-2 and TFM-3 molecules of the present invention provide novel diagnostic targets and therapeutic agents to control transporter-associated disorders.  
      As used herein, a “transporter-associated disorder” includes a disorder, disease or condition which is caused or characterized by a misregulation (e.g., downregulation or upregulation) of a transporter-mediated activity. Transporter-associated disorders can detrimentally affect cellular functions such as cellular proliferation, growth, differentiation, or migration, cellular regulation of homeostasis, inter- or intra-cellular communication; tissue function, such as cardiac function or musculoskeletal function; systemic responses in an organism, such as nervous system responses, hormonal responses (e.g., insulin response), or immune responses; and protection of cells from toxic compounds (e.g., carcinogens, toxins, mutagens, and toxic byproducts of metabolic activity (e.g., reactive oxygen species)). Examples of transporter-associated disorders include CNS disorders such as cognitive and neurodegenerative disorders, examples of which include, but are not limited to, Alzheimer&#39;s disease, dementias related to Alzheimer&#39;s disease (such as Pick&#39;s disease), Parkinson&#39;s and other Lewy diffuse body diseases, senile dementia, Huntington&#39;s disease, Gilles de la Tourette&#39;s syndrome, multiple sclerosis, amyotrophic lateral sclerosis, progressive supranuclear palsy, epilepsy, and Creutzfeldt-Jakob disease; autonomic function disorders such as hypertension and sleep disorders, and neuropsychiatric disorders, such as depression, schizophrenia, schizoaffective disorder, korsakoff&#39;s psychosis, mania, anxiety disorders, or phobic disorders; learning or memory disorders, e.g., amnesia or age-related memory loss, attention deficit disorder, dysthymic disorder, major depressive disorder, mania, obsessive-compulsive disorder, psychoactive substance use disorders, anxiety, phobias, panic disorder, as well as bipolar affective disorder, e.g., severe bipolar affective (mood) disorder (BP-1), and bipolar affective neurological disorders, e.g., migraine and obesity. Further CNS-related disorders include, for example, those listed in the American Psychiatric Association&#39;s Diagnostic and Statistical manual of Mental Disorders (DSM), the most current version of which is incorporated herein by reference in its entirety.  
      Further examples of transporter-associated disorders include cardiac-related disorders. Cardiovascular system disorders in which the TFM-2 and TFM-3 molecules of the invention may be directly or indirectly involved include arteriosclerosis, ischemia reperfusion injury, restenosis, arterial inflammation, vascular wall remodeling, ventricular remodeling, rapid ventricular pacing, coronary microembolism, tachycardia, bradycardia, pressure overload, aortic bending, coronary artery ligation, vascular heart disease, atrial fibrilation, Jervell syndrome, Lange-Nielsen syndrome, long-QT syndrome, congestive heart failure, sinus node dysfunction, angina, heart failure, hypertension, atrial fibrillation, atrial flutter, dilated cardiomyopathy, idiopathic cardiomyopathy, myocardial infarction, coronary artery disease, coronary artery spasm, and arrhythmia. TFM-2 and TFM-3-mediated or related disorders also include disorders of the musculoskeletal system such as paralysis and muscle weakness, e.g., ataxia, myotonia, and myokymia.  
      Transporter-associated disorders also include cellular proliferation, growth, differentiation, or migration disorders. Cellular proliferation, growth, differentiation, or migration disorders include those disorders that affect cell proliferation, growth, differentiation, or migration processes. As used herein, a “cellular proliferation, growth, differentiation, or migration process” is a process by which a cell increases in number, size or content, by which a cell develops a specialized set of characteristics which differ from that of other cells, or by which a cell moves closer to or further from a particular location or stimulus. The TFM-2 and TFM-3 molecules of the present invention are involved in signal transduction mechanisms, which are known to be involved in cellular growth, differentiation, and migration processes. Thus, the TFM-2 and TFM-3 molecules may modulate cellular growth, differentiation, or migration, and may play a role in disorders characterized by aberrantly regulated growth, differentiation, or migration. Such disorders include cancer, e.g., carcinoma, sarcoma, or leukemia; tumor angiogenesis and metastasis; skeletal dysplasia; hepatic disorders; and hematopoietic and/or myeloproliferative disorders.  
      Transporter-associated disorders also include hormonal disorders, such as conditions or diseases in which the production and/or regulation of hormones in an organism is aberrant. Examples of such disorders and diseases include type I and type II diabetes mellitus, pituitary disorders (e.g., growth disorders), thyroid disorders (e.g., hypothyroidism or hyperthyroidism), and reproductive or fertility disorders (e.g., disorders which affect the organs of the reproductive system, e.g., the prostate gland, the uterus, or the vagina; disorders which involve an imbalance in the levels of a reproductive hormone in a subject; disorders affecting the ability of a subject to reproduce; and disorders affecting secondary sex characteristic development, e.g., adrenal hyperplasia).  
      Transporter-associated disorders also include immune disorders, such as autoimmune disorders or immune deficiency disorders, e.g., congenital X-linked infantile hypogammaglobulinemia, transient hypogammaglobulinemia, common variable immunodeficiency, selective IgA deficiency, chronic mucocutaneous candidiasis, or severe combined immunodeficiency.  
      Transporter-associated disorders also include disorders associated with sugar homeostasis, such as obesity, anorexia, hypoglycemia, glycogen storage disease (Von Gierke disease), type I glycogenosis, seasonal affective disorder, and cluster B personality disorders.  
      Transporter-associated disorders also include disorders affecting tissues in which TFM-2 and TFM-3 protein is expressed.  
      As used herein, a “transporter-mediated activity” includes an activity of a transporter which involves the facilitated movement of one or more molecules, e.g., biological molecules, from one side of a biological membrane to the other. Transporter-mediated activities include the import or export across internal or external cellular membranes of biochemical molecules necessary for energy production or storage; intra- or inter-cellular signaling; metabolism or catabolism of metabolically important biomolecules; and removal of potentially harmful compounds from the cell.  
      The term “family” when referring to the polypeptide and nucleic acid molecules of the invention is intended to mean two or more polypeptides or nucleic acid molecules having a common structural domain or motif and having sufficient amino acid or nucleotide sequence homology as defined herein. Such family members can be naturally or non-naturally occurring and can be from either the same or different species. For example, a family can contain a first polypeptide of human origin, as well as other, distinct polypeptides of human origin or alternatively, can contain homologues of non-human origin, e.g., mouse or monkey polypeptides. Members of a family may also have common functional characteristics.  
      For example, the family of TFM-2 and TFM-3 polypeptides comprise at least one “transmembrane domain” and preferably eight, nine, or ten transmembrane domains. As used herein, the term “transmembrane domain” includes an amino acid sequence of about 15-45 amino acid residues in length which spans the plasma membrane. More preferably, a transmembrane domain includes about at least 15, 20, 25, 30, 35, 40, or 45 amino acid residues and spans the plasma membrane. Transmembrane domains are rich in hydrophobic residues, and typically have an alpha-helical structure. In a preferred embodiment, at least 50%, 60%, 70%, 80%, 90%, 95% or more of the amino acids of a transmembrane domain are hydrophobic, e.g., leucines, isoleucines, alanines, valines, phenylalanines, prolines or methionines. Transmembrane domains are described in, for example, Zagotta W. N. et al, (1996)  Annual Rev. Neurosci.  19: 235-263, the contents of which are incorporated herein by reference. A MEMSAT analysis and a structural, hydrophobicity, and antigenicity analysis also resulted in the identification of ten transmembrane domains in the amino acid sequence of human TFM-2 (SEQ ID NO:28) at about residues 22-42, 49-69, 76-98, 105-128, 167-186, 207-223, 236-253, 261-285, 296-318, and 327-349 as set forth in  FIGS. 16 and 17 . A MEMSAT analysis and a structural, hydrophobicity, and antigenicity analysis resulted in the identification of nine transmembrane domains in the amino acid sequence of human TFM-3 (SEQ ID NO:31) at about residues 7-23, 34-57, 66-82, 150-168, 188-206, 213-237, 255-279, 288-308, and 321-337 as set forth in  FIGS. 18 and 19 .  
      Accordingly, TFM-2 and/or TFM-3 polypeptides having at least 50-60% homology, preferably about 60-70%, more preferably about 70-80%, or about 80-90% homology with a transmembrane domain of human TFM-2 and/or TFM-3 are within the scope of the invention.  
      In one embodiment, a TFM molecule of the present invention, e.g., TFM-2, is identified based on the presence within the molecule of at least one “monocarboxylate transporter domain.” As used herein, the term “monocarboxylate transporter domain” includes a protein domain having at least about 250-500 amino acid residues, a bit score of at least 20 when compared against a monocarboxylate transporter domain Hidden Markov Model, and a monocarboxylate transporter mediated activity. Preferably, a monocarboxylate transporter domain includes a protein domain having an amino acid sequence of about 300-400, 300-350, or more preferably, about 330 amino acid residues, a bit score of at least 35, and a monocarboxylate transporter mediated activity. To identify the presence of a monocarboxylate transporter domain in a TFM-2 protein, and make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein may be searched against a database of known protein domains (e.g., the PFAM HMM database). A PFAM monocarboxylate transporter domain has been assigned the PFAM Accession PF01587. A search was performed against the PFAM HMM database resulting in the identification of a monocarboxylate transporter domain in the amino acid sequence of human TFM-2 (SEQ ID NO:28) at about residues 1-332 of SEQ ID NO:28.  
      As used herein, a “monocarboxylate transporter mediated activity” includes the ability to mediate the transport of a variety of monocarboxylates (e.g., lactate, pyruvate, branched chain oxoacids, and/or ketone bodies) across a biological membrane (e.g., a red blood cell membrane, a heart cell membrane, a brain cell membrane, a skeletal muscle cell membrane, a liver cell membrane, a kidney cell membrane, and/or a tumor cell membrane. Accordingly, identifying the presence of a “monocarboxylate transporter domain” can include isolating a fragment of a TFM-2 molecule (e.g., a TFM-2 polypeptide) and assaying for the ability of the fragment to exhibit one of the aforementioned monocarboxylate transporter mediated activities.  
      In another embodiment, members of the TFM family of proteins, e.g., TFM-3, include at least one “sugar transporter domain” in the protein or corresponding nucleic acid molecule. As used herein, the term “sugar transporter domain” includes a protein domain having at least about 250-500 amino acid residues and a sugar transporter mediated activity. Preferably, a sugar transporter domain includes a polypeptide having an amino acid sequence of about 300-400, 300-350, or more preferably, about 353 amino acid residues, and a sugar transporter mediated activity. To identify the presence of a sugar transporter domain in a TFM-3 protein, and make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein may be searched against a database of known protein domains (e.g., the PFAM HMM database). A PFAM sugar transporter domain has been assigned the PFAM Accession PF00083. A search was performed against the PFAM HMM database resulting in the identification of a sugar transporter domain in the amino acid sequence of human TFM-3 (SEQ ID NO:31) at about residues 1-353 of SEQ ID NO:31.  
      As used herein, a “sugar transporter mediated activity” includes the ability to bind a monosaccharide, such as D-glucose, D-fructose, and/or D-galactose; the ability to transport a monosaccharide such as D-glucose, D-fructose, and/or D-galactose, across a cell membrane (e.g., a liver cell membrane, fat cell membrane, muscle cell membrane, and/or blood cell membrane, such as an erythrocyte membrane); and the ability to modulate sugar homeostasis in a cell. Accordingly, identifying the presence of a “sugar transporter domain” can include isolating a fragment of a TFM-3 molecule (e.g., a TFM-3 polypeptide) and assaying for the ability of the fragment to exhibit one of the aforementioned sugar transporter mediated activities.  
      A description of the Pfam database can be found in Sonhammer et al. (1997)  Proteins  28:405-420 and a detailed description of HMMs can be found, for example, in Gribskov et al. (1990)  Meth. Enzymol.  183:146-159; Gribskov et al. (1987)  Proc. Natl. Acad. Sci. USA  84:4355-4358; Krogh et al. (1994)  J. Mol. Biol.  235:1501-1531; and Stultz et al. (1993)  Protein Sci.  2:305-314, the contents of which are incorporated herein by reference.  
      In a preferred embodiment, the TFM-2 and TFM-3 molecules of the invention include at least one, preferably two, even more preferably eight, nine or ten transmembrane domain(s), and/or at least one monocarboxylate transporter domain, and/or at least one sugar transporter domain.  
      Isolated polypeptides of the present invention, preferably TFM-2 and/or TFM-3 polypeptides, have an amino acid sequence sufficiently identical to the amino acid sequence of SEQ ID NO:28 or 31 or are encoded by a nucleotide sequence sufficiently identical to SEQ ID NO:27, 29, 30, or 32. As used herein, the term “sufficiently identical” refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homology or identity across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently identical. Furthermore, amino acid or nucleotide sequences which share at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homology or identity and share a common functional activity are defined herein as sufficiently identical.  
      In a preferred embodiment, a TFM-2 and/or a TFM-3 polypeptide includes at least one or more of the following domains: a transmembrane domain, and/or a monocarboxylate transporter domain, and/or a sugar transporter domain, and has an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homologous or identical to the amino acid sequence of SEQ ID NO:28 or 31. In yet another preferred embodiment, a TFM-2 and/or a TFM-3 polypeptide includes at least one or more of the following domains: a transmembrane domain, and/or a monocarboxylate transporter domain, and/or a sugar transporter domain, and is encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:27, 29, 30, or 32. In another preferred embodiment, a TFM-2 and/or a TFM-3 polypeptide includes at least one or more of the following domains: a transmembrane domain, and/or a monocarboxylate transporter domain, and/or a sugar transporter domain, and has a TFM-2 and/or TFM-3 activity.  
      As used interchangeably herein, a “TFM-2 activity,” “TFM-3 activity,” “biological activity of TFM-2,” “biological activity of TFM-3,” “functional activity of TFM-2,” or “functional activity of TFM-3” refers to an activity exerted by a TFM-2 and/or a TFM-3 protein, polypeptide or nucleic acid molecule on a TFM-2 and/or a TFM-3 responsive cell or tissue, or on a TFM-2 and/or a TFM-3 protein substrate, as determined in vivo, or in vitro, according to standard techniques. In one embodiment, a TFM-2 and/or a TFM-3 activity is a direct activity, such as an association with a TFM-2 and/or a TFM-3-target molecule. As used herein, a “target molecule” or “binding partner” is a molecule with which a TFM-2 and/or a TFM-3 protein binds or interacts in nature, such that TFM-2 and/or TFM-3-mediated function is achieved. A TFM-2 and/or a TFM-3 target molecule can be a non-TFM-2 and/or a non-TFM-3 molecule or a TFM-2 and/or a TFM-3 protein or polypeptide of the present invention (e.g., a molecule to be transported, e.g., a monocarboxylate and/or a monosaccharide). In an exemplary embodiment, a TFM-2 and/or a TFM-3 target molecule is a TFM-2 and/or a TFM-3 ligand (e.g., a proton, an energy molecule, a metabolite, a monocarboxylate, a monosaccharide or an ion). Alternatively, a TFM-2 and/or a TFM-3 activity is an indirect activity, such as a cellular signaling activity mediated by interaction of the TFM-2 and/or a TFM-3 protein with a TFM-2 and/or a TFM-3 ligand. The biological activities of TFM-2 and TFM-3 are described herein. For example, the TFM-2 and/or TFM-3 proteins of the present invention can have one or more of the following activities: 1) modulate the import and export of molecules, e.g., hormones, ions, cytokines, neurotransmitters, monocarboxylates, monosaccharides, and metabolites, from cells, 2) modulate intra- or inter-cellular signaling, 3) modulate removal of potentially harmful compounds from the cell, or facilitate the compartmentalization of these molecules into a sequestered intra-cellular space (e.g., the peroxisome), and 4) modulate transport of biological molecules across membranes, e.g., the plasma membrane, or the membrane of the mitochondrion, the peroxisome, the lysosome, the endoplasmic reticulum, the nucleus, or the vacuole.  
      The nucleotide sequence of the isolated human TFM-2 and TFM-3 cDNA and the predicted amino acid sequence of the human TFM-2 and TFM-3 polypeptides are shown in SEQ ID NOs:27, 28 and 30, 31, respectively.  
      The human TFM-2 gene, which is approximately 3524 nucleotides in length, encodes a polypeptide which is approximately 392 amino acid residues in length. The human TFM-3 gene, which is approximately 1855 nucleotides in length, encodes a polypeptide which is approximately 405 amino acid residues in length.  
      Various aspects of the invention are described in further detail in the following subsections:  
      Chapter VII. 67118, 67067, and 62092, Human Proteins and Methods of Use Thereof  
     SUMMARY OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel human phospholipid transporter family members, referred to herein as “67118 and 67067” nucleic acid and polypeptide molecules. The 67118 and 67067 nucleic acid and polypeptide molecules of the present invention are useful as modulating agents in regulating a variety of cellular processes, e.g., phospholipid transport (e.g., aminophospholipid transport), absorption, secretion, gene expression, intra- or inter-cellular signaling, and/or cellular proliferation, growth, apoptosis, and/or differentiation. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding 67118 and 67067 polypeptides or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of 67118 and 67067-encoding nucleic acids.  
      The present invention is also based, at least in part, on the discovery of novel histidine triad family members, referred to herein as “62092” nucleic acid and protein molecules. The 62092 nucleic acid and protein molecules of the present invention are useful as modulating agents in regulating a variety of cellular processes, e.g., gene expression, intra- or intercellular signaling, cellular proliferation, growth, differentiation, and/or apoptosis, and/or sensing of cellular stress signals. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding 62092 proteins or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of 62092-encoding nucleic acids.  
      In one embodiment, the invention features an isolated nucleic acid molecule that includes the nucleotide sequence set forth in SEQ ID NO:33, 35, 36, 38, 39, or 41. In another embodiment, the invention features an isolated nucleic acid molecule that encodes a polypeptide including the amino acid sequence set forth in SEQ ID NO:34, 37, or 40.  
      In still other embodiments, the invention features isolated nucleic acid molecules including nucleotide sequences that are substantially identical (e.g., 60% identical) to the nucleotide sequence set forth as SEQ ID NO:33, 35, 36, 38, 39, or 41. The invention further features isolated nucleic acid molecules including at least 50 contiguous nucleotides of the nucleotide sequence set forth as SEQ ID NO:33, 35, 36, 38, 39, or 41. In another embodiment, the invention features isolated nucleic acid molecules which encode a polypeptide including an amino acid sequence that is substantially identical (e.g., 60% identical) to the amino acid sequence set forth as SEQ ID NO:34, 37, or 40. The present invention also features nucleic acid molecules which encode allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:34, 37, or 40. In addition to isolated nucleic acid molecules encoding full-length polypeptides, the present invention also features nucleic acid molecules which encode fragments, for example, biologically active or antigenic fragments, of the full-length polypeptides of the present invention (e.g., fragments including at least 10 contiguous amino acid residues of the amino acid sequence of SEQ ID NO:34, 37, or 40). In still other embodiments, the invention features nucleic acid molecules that are complementary to, antisense to, or hybridize under stringent conditions to the isolated nucleic acid molecules described herein.  
      In another aspect, the invention provides vectors including the isolated nucleic acid molecules described herein (e.g., 67118, 67067, and/or 62092-encoding nucleic acid molecules). Such vectors can optionally include nucleotide sequences encoding heterologous polypeptides. Also featured are host cells including such vectors (e.g., host cells including vectors suitable for producing 67118, 67067, and/or 62092 nucleic acid molecules and polypeptides).  
      In another aspect, the invention features isolated 67118, 67067, and/or 62092 polypeptides and/or biologically active or antigenic fragments thereof. Exemplary embodiments feature a polypeptide including the amino acid sequence set forth as SEQ ID NO:34, 37, or 40, a polypeptide including an amino acid sequence at least 60% identical to the amino acid sequence set forth as SEQ ID NO:34, 37, or 40, a polypeptide encoded by a nucleic acid molecule including a nucleotide sequence at least 60% identical to the nucleotide sequence set forth as SEQ ID NO:33, 35, 36, 38, 39, or 41. Also featured are fragments of the full-length polypeptides described herein (e.g., fragments including at least 10 contiguous amino acid residues of the sequence set forth as SEQ ID NO:34, 37, or 40) as well as allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:34, 37, or 40.  
      The 67118, 67067, and/or 62092 polypeptides and/or biologically active or antigenic fragments thereof, are useful, for example, as reagents or targets in assays applicable to treatment and/or diagnosis of 67118, 67067, and/or 62092 associated or related disorders. In one embodiment, a 67118, 67067, and/or 62092 polypeptide or fragment thereof, has a 67118, 67067, and/or 62092 activity.  
      In another embodiment, a 67118 or 67067 polypeptide or fragment thereof includes at least one of the following domains, sites, or motifs: a transmembrane domain, an N-terminal large extramembrane domain, a C-terminal large extramembrane domain, an E1-E2 ATPases phosphorylation site, a P-type ATPase sequence 1 motif, a P-type ATPase sequence 2 motif, a P-type ATPase sequence 3 motif, and/or one or more phospholipid transporter specific amino acid resides, and optionally, has a 67118 and/or a 67067 activity. In yet another embodiment, a 62092 polypeptide or fragment thereof has at least one or more of the following domains or motifs: a signal peptide, a HIT family domain, and/or a HIT family signature motif, and optionally, has a 62092 activity.  
      In a related aspect, the invention features antibodies (e.g., antibodies which specifically bind to any one of the polypeptides described herein) as well as fusion polypeptides including all or a fragment of a polypeptide described herein.  
      The present invention further features methods for detecting 67118, 67067, and/or 62092 polypeptides and/or 67118, 67067, and/or 62092 nucleic acid molecules, such methods featuring, for example, a probe, primer or antibody described herein. Also featured are kits, e.g., kits for the detection of 67118, 67067, and/or 62092 polypeptides and/or 67118, 67067, and/or 62092 nucleic acid molecules. In a related aspect, the invention features methods for identifying compounds which bind to and/or modulate the activity of a 67118, 67067, and/or 62092 polypeptide or 67118, 67067, and/or 62092 nucleic acid molecule described herein. Further featured are methods for modulating a 67118, 67067, and/or 62092 activity.  
      Other features and advantages of the invention will be apparent from the following detailed description and claims.  
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel molecules, referred to herein as “67118” and “67067” nucleic acid and polypeptide molecules, which are novel members of the phospholipid transporter family. These novel molecules are capable of, for example, transporting phospholipids (e.g., aminophospholipids such as phosphatidylserine and phosphatidylethanolamine, choline phospholipids such as phosphatidylcholine and sphingomyelin, and bile acids) across cellular membranes and, thus, play a role in or function in a variety of cellular processes, e.g., phospholipid transport, absorption, secretion, gene expression, intra- or inter-cellular signaling, and/or cellular proliferation, growth, and/or differentiation.  
      The present invention is also based, at least in part, on the discovery of novel histidine triad family members, referred to herein as “62092” nucleic acid and protein molecules. These novel molecules are capable of binding nucleotides (e.g., purine mononucleotides and/or dinucleoside polyphosphates) and, thus, play a role in or function in a variety of cellular processes, e.g., gene expression, intra- or intercellular signaling, cellular proliferation, growth, differentiation, and/or apoptosis, and/or sensing of cellular stress signals. Thus, the 62092 molecules of the present invention provide novel diagnostic targets and therapeutic agents to control 62092-associated disorders, as defined herein.  
      The term “family” when referring to the protein and nucleic acid molecules of the invention is intended to mean two or more proteins or nucleic acid molecules having a common structural domain or motif and having sufficient amino acid or nucleotide sequence homology as defined herein. Such family members can be naturally or non-naturally occurring and can be from either the same or different species. For example, a family can contain a first protein of human origin as well as other distinct proteins of human origin or alternatively, can contain homologues of non-human origin, e.g., rat or mouse proteins. Members of a family can also have common functional characteristics.  
      For example, the family of 67118 and 67067 polypeptides comprise at least one “transmembrane domain” and preferably eight, nine, or ten transmembrane domains. As used herein, the term “transmembrane domain” includes an amino acid sequence of about 15-45 amino acid residues in length which spans the plasma membrane. More preferably, a transmembrane domain includes about at least 15, 20, 25, 30, 35, 40, or 45 amino acid residues and spans the plasma membrane. Transmembrane domains are rich in hydrophobic residues, and typically have an alpha-helical structure. In a preferred embodiment, at least 50%, 60%, 70%, 80%, 90%, 95% or more of the amino acids of a transmembrane domain are hydrophobic, e.g., leucines, isoleucines, alanines, valines, phenylalanines, prolines or methionines. Transmembrane domains are described in, for example, Zagotta W. N. et al, (1996)  Annual Rev. Neurosci.  19: 235-263, the contents of which are incorporated herein by reference. A MEMSAT analysis and a structural, hydrophobicity, and antigenicity analysis also resulted in the identification of ten transmembrane domains in the amino acid sequence of human 67118 (SEQ ID NO:34) at about residues 71-87, 94-110, 295-314, 349-368, 891-907, 915-935, 964-987, 1002-1018, 1033-1057, and 1064-1088 as set forth in  FIG. 20 . A MEMSAT analysis and a structural, hydrophobicity, and antigenicity analysis resulted in the identification of ten transmembrane domains in the amino acid sequence of human 67067 (SEQ ID NO:37) at about residues 65-82, 89-105, 287-304, 366-388, 1239-1259, 1322-1343, 1274-1292, 1351-1368, 1377-1399, 1425-1446 as set forth in  FIG. 22 .  
      The family of 67118 and/or 67067 proteins of the present invention also comprise at least one “extramembrane domain” in the protein or corresponding nucleic acid molecule. As used herein, an “extramembrane domain” includes a domain having greater than 20 amino acid residues that is found between transmembrane domains, preferably on the cytoplasmic side of the plasma membrane, and does not span or traverse the plasma membrane. An extramembrane domain preferably includes at least one, two, three, four or more motifs or consensus sequences characteristic of P-type ATPases, i.e., includes one, two, three, four, or more “P-type ATPase consensus sequences or motifs”. As used herein, the phrase “P-type ATPase consensus sequences or motifs” includes any consensus sequence or motif known in the art to be characteristic of P-type ATPases, including, but not limited to, the P-type ATPase sequence 1 motif (as defined herein), the P-type ATPase sequence 2 motif (as defined herein), the P-type ATPase sequence 3 motif (as defined herein), and the E1-E2 ATPases phosphorylation site (as defined herein).  
      In one embodiment, the family of 67118 and 67067 proteins of the present invention comprises at least one “N-terminal” large extramembrane domain in the protein or corresponding nucleic acid molecule. As used herein, an “N-terminal” large extramembrane domain is found in the N-terminal ⅓ rd  of the protein, preferably between the second and third transmembrane domains of a 67118 or 67067 protein and includes about 60-300, 80-280, 100-260, 120-240, 140-220, 160-200, or preferably,181 or 183 amino acid residues. In a preferred embodiment, an N-terminal large extramembrane domain includes at least one P-type ATPase sequence 1 motif (as described herein). An N-terminal large extramembrane domain was identified in the amino acid sequence of human 67118 at about residues 111-294 of SEQ ID NO:34. An N-terminal large extramembrane domain was identified in the amino acid sequence of human 67067 at about residues 105-286 of SEQ ID NO:37.  
      The family of 67118 and 67067 proteins of the present invention also comprises at least one “C-terminal” large extramembrane domain in the protein or corresponding nucleic acid molecule. As used herein, a “C-terminal” large extramembrane domain is found in the C-terminal ⅔ rds  of the protein, preferably between the fourth and fifth transmembrane domains of a PLTR protein and includes about 370-850, 400-820, 430-790, 460-760, 430-730, 460-700, 430-670, 460-640, 430-610, 490-580, 510-550, or preferably, 521 or 849 amino acid residues. In a preferred embodiment, a C-terminal large extramembrane domain includes at least one or more of the following motifs: a P-type ATPase sequence 2 motif (as described herein), a P-type ATPase sequence 3 motif (as defined herein), and/or an E1-E2 ATPases phosphorylation site (as defined herein). A C-terminal large extramembrane domain was identified in the amino acid sequence of human 67118 at about residues 369-890 of SEQ ID NO:34. A C-terminal large extramembrane domain was identified in the amino acid sequence of human 67067 at about residues 389-1238 of SEQ ID NO:37.  
      In another embodiment, a 67118 or 67067 protein extramembrane domain is characterized by at least one “P-type ATPase sequence 1 motif” in the protein or corresponding nucleic acid sequence. As used herein, a “P-type ATPase sequence 1 motif” is a conserved sequence motif diagnostic for P-type ATPases (Tang, X. et al. (1996) Science 272:1495-1497; Fagan, M. J. and Saier, M. H. (1994)  J. Mol. Evol.  38:57). Amino acid residues of the P-type ATPase sequence 1 motif are involved in the coupling of ATP hydrolysis with transport (e.g., transport of phospholipids). The consensus sequence for a P-type ATPase sequence 1 motif is [DNS]-[QENR]-[SA]-[LIVSAN]-[LIV]-[TSN]-G-E-[SN] (SEQ ID NO:42). The use of amino acids in brackets indicates that the amino acid at the indicated position may be any one of the amino acids within the brackets, e.g., [SA] indicates any of one of either S (serine) or A (alanine). In a preferred embodiment, a P-type ATPase sequence 1 motif is contained within an N-terminal large extramembrane domain. In another preferred embodiment, a P-type ATPase sequence I motif in the 67118, 67067, and/or 62092 proteins of the present invention has at least 1, 2, 3, or preferably 4 amino acid resides which match the consensus sequence for a P-type ATPase sequence 1 motif. A P-type ATPase sequence 1. motif was identified in the amino acid sequence of human 67118 at about residues 179-187 of SEQ ID NO:34. A P-type ATPase sequence 1 motif was identified in the amino acid sequence of human 67067 at about residues 175-183 of SEQ ID NO:37.  
      In another embodiment, a 67118 or 67067 protein extramembrane domain is characterized by at least one “P-type ATPase sequence 2 motif” in the protein or corresponding nucleic acid sequence. As used herein, a “P-type ATPase sequence 2 motif” is a conserved sequence motif diagnostic for P-type ATPases (Tang, X. et al. (1996) Science 272:1495-1497; Fagan, M. J. and Saier, M. H. (1994)  J. Mol. Evol.  38:57). Preferably, a P-type ATPase sequence 2 motif overlaps with and/or includes an E1-E2 ATPases phosphorylation site (as defined herein). The consensus sequence for a P-type ATPase sequence 2 motif is [LIV]-[CAML]-[STFL]-D-K-T-G-T-[LI]-T (SEQ ID NO:43). The use of amino acids in brackets indicates that the amino acid at the indicated position may be any one of the amino acids within the brackets, e.g., [LI] indicates any of one of either L (leucine) or I (isoleucine). In a preferred embodiment, a P-type ATPase sequence 2 motif is contained within a C-terminal large extramembrane domain. In another preferred embodiment, a P-type ATPase sequence 2 motif in the PLTR proteins of the present invention has at least 1, 2, 3, 4, 5, 6, 7, 8, or more preferably 9 amino acid resides which match the consensus sequence for a P-type ATPase sequence 2 motif. A P-type ATPase sequence 2 motif was identified in the amino acid sequence of human 67118 at about residues 411-420 of SEQ ID NO:34. A P-type ATPase sequence 2 motif was identified in the amino acid sequence of human 67067 at about residues 431-440 of SEQ ID NO:37.  
      In yet another embodiment, a 67118 or 67067 protein extramembrane domain is characterized by at least one “P-type ATPase sequence 3 motif” in the protein or corresponding nucleic acid sequence. As used herein, a “P-type ATPase sequence 3 motif” is a conserved sequence motif diagnostic for P-type ATPases (Tang, X. et al. (1996) Science 272:1495-1497; Fagan, M. J. and Saier, M. H. (1994)  J. Mol. Evol.  38:57). Amino acid residues of the P-type ATPase sequence 3 motif are involved in ATP binding. The consensus sequence for a P-type ATPase sequence 3 motif is [TIV]-G-D-G-X-N-D-[ASG]-P-[ASV]-L (SEQ ID NO:44). X indicates that the amino acid at the indicated position may be any amino acid (i.e., is not conserved). The use of amino acids in brackets indicates that the amino acid at the indicated position may be any one of the amino acids within the brackets, e.g., [TIV] indicates any of one of either T (threonine), I (isoleucine), or V (valine). In a preferred embodiment, a P-type ATPase sequence 3 motif is contained within a C-terminal large extramembrane domain. In another preferred embodiment, a P-type ATPase sequence 3 motif in the 67118 or 67067 proteins of the present invention has at least 1, 2, 3, 4, 5, 6, or more preferably 7 amino acid resides (including the amino acid at the position indicated by “X”) which match the consensus sequence for a P-type ATPase sequence 3 motif. A P-type ATPase sequence 3 motif was identified in the amino acid sequence of human 67118 at about residues 823-833 of SEQ ID NO:34. A P-type ATPase sequence 3 motif was identified in the amino acid sequence of human 67067 at about residues 1180-1190 of SEQ ID NO:37.  
      In another embodiment, a 67118 or 67067 protein of the present invention is identified based on the presence of an “E1-E2 ATPases phosphorylation site” (alternatively referred to simply as a “phosphorylation site”) in the protein or corresponding nucleic acid molecule. An E1-E2 ATPases phosphorylation site functions in accepting a phosphate moiety and has the amino acid sequence DKTGT (amino acid residues 1-5 of SEQ ID NO:45), and can be included within the E1-E2 ATPase phosphorylation site consensus sequence: D-K-T-G-T-[LIVM]-[TI] (SEQ ID NO:45), wherein D is phosphorylated. The use of amino acids in brackets indicates that the amino acid at the indicated position may be any one of the amino acids within the brackets, e.g., [TI] indicates any of one of either T (threonine) or I (isoleucine). The E1-E2 ATPases phosphorylation site consensus sequence has been assigned ProSite Accession Number PS00154. To identify the presence of an E1-E2 ATPases phosphorylation site consensus sequence in a 67118 or 67067 protein, and to make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein may be searched against a database of known protein motifs (e.g., the ProSite database) using the default parameters (available on the Internet at the Prosite website). A search was performed against the ProSite database resulting in the identification of an E1-E2 ATPases phosphorylation site consensus sequence in the amino acid sequence of human 67118 (SEQ ID NO:34) at about residues 414-420 (see FIGS.  21 A-B). A search was performed against the ProSite database resulting in the identification of an E1-E2 ATPases phosphorylation site consensus sequence in the amino acid sequence of human 67067 (SEQ ID NO:37) at about residues 434-440 (see FIGS.  23 A-B).  
      Preferably an E1-E2 ATPases phosphorylation site has a “phosphorylation site activity,” for example, the ability to be phosphorylated; to be dephosphorylated; to regulate the E1-E2 conformational change of the phospholipid transporter in which it is contained; to regulate transport of phospholipids (e.g., aminophospholipids such as phosphatidylserine and phosphatidylethanolamine, choline phospholipids such as phosphatidylcholine and sphingomyelin, and bile acids) across a cellular membrane by the 67118 or 67067 protein in which it is contained; and/or to regulate the activity (as defined herein) of the 67118 or 67067 protein in which it is contained. Accordingly, identifying the presence of an “E1-E2 ATPases phosphorylation site” can include isolating a fragment of a 67118 or 67067 molecule (e.g., a 67118 or 67067 polypeptide) and assaying for the ability of the fragment to exhibit one of the aforementioned phosphorylation site activities.  
      In another embodiment, a 67118 or 67067 protein of the present invention may also be identified based on its ability to adopt an E1 conformation or an E2 conformation. As used herein, an “E1 conformation” of a 67118 or 67067 protein includes a 3-dimensional conformation of a 67118 or 67067 protein which does not exhibit 67118 or 67067 activity (e.g., the ability to transport phospholipids), as defined herein. An E1 conformation of a 67118 or 67067 protein usually occurs when the 67118 or 67067 protein is unphosphorylated. As used herein, an “E2 conformation” of a 67118 or 67067 protein includes a 3-dimensional conformation of a 67118 or 67067 protein which exhibits 67118 or 67067 activity (e.g., the ability to transport phospholipids), as defined herein. An E2 conformation of a 67118 or 67067 protein usually occurs when the 67118 or 67067 protein is phosphorylated.  
      In still another embodiment, a 67118 or 67067 protein of the present invention is identified based on the presence of “phospholipid transporter specific” amino acid residues. As used herein, “phospholipid transporter specific” amino acid residues are amino acid residues specific to the class of phospholipid transporting P-type ATPases (as defined in Tang, X. et al. (1996)  Science  272:1495-1497). Phospholipid transporter specific amino acid residues are not found in those P-type ATPases which transport molecules which are not phospholipids (e.g., cations). For example, phospholipid transporter specific amino acid residues are found at the first, second, and fifth positions of the P-type ATPase sequence 1 motif. In phospholipid transporting P-type ATPases, the first position of the P-type ATPase sequence 1 motif is preferably E (glutamic acid), the second position is preferably T (threonine), and the fifth position is preferably L (leucine). A phospholipid transporter specific amino acid residue is further found at the second position of the P-type ATPase sequence 2 motif. In phospholipid transporting P-type ATPases, the second position of the P-type ATPase sequence 2 motif is preferably F (phenylalanine). Phospholipid transporter specific amino acid residues are still further found at the first, tenth, and eleventh positions of the P-type ATPase sequence 3 motif. In phospholipid transporting P-type ATPases, the first position of the P-type ATPase sequence 3 motif is preferably I (isoleucine), the tenth position is preferably M (methionine), and the eleventh position is preferably I (isoleucine). Phospholipid transporter specific amino acid residues were identified in the amino acid sequence of human 67118 (SEQ ID NO:34) at about residues 179 and 183 (within the P-type ATPase sequence 1 motif; see FIGS.  21 A-B), at about residue 442 (within the P-type ATPase sequence 2 motif; see FIGS.  21 A-B), and at about residues 823, 832 and 833 (within the P-type ATPase sequence 3 motif; see FIGS.  21 A-B). Phospholipid transporter specific amino acid residues were identified in the amino acid sequence of human 67067 (SEQ ID NO:37) at about residues 175, 176, and 179 (within the P-type ATPase sequence 1 motif; see FIGS.  23 A-B), at about residue 432 (within the P-type ATPase sequence 2 motif; see FIGS.  23 A-B), and at about residues 1180, 1189, and 1190 (within the P-type ATPase sequence 3 motif; see FIGS.  23 A-B).  
      Isolated polypeptides of the present invention, preferably 67118 and/or 67067 polypeptides, have an amino acid sequence sufficiently identical to the amino acid sequence of SEQ ID NO:34 or 37 or are encoded by a nucleotide sequence sufficiently identical to SEQ ID NO:33, 35, 36, or 38. As used herein, the term “sufficiently identical” refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homology or identity across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently identical. Furthermore, amino acid or nucleotide sequences which share at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homology or identity and share a common functional activity are defined herein as sufficiently identical.  
      In a preferred embodiment, a 67118 or 67067 protein includes at least one or more of the following domains, sites, or motifs: a transmembrane domain, an N-terminal large extramembrane domain, a C-terminal large extramembrane domain, an E1-E2 ATPases phosphorylation site, a P-type ATPase sequence 1 motif, a P-type ATPase sequence 2 motif, a P-type ATPase sequence 3 motif, and/or one or more phospholipid transporter specific amino acid resides, and has an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homologous or identical to the amino acid sequence of SEQ ID NO:34 or 37. In yet another preferred embodiment, a 67118 or 67067 protein includes at least one or more of the following domains, sites, or motifs: a transmembrane domain, an N-terminal large extramembrane domain, a C-terminal large extramembrane domain, an E1-E2 ATPases phosphorylation site, a P-type ATPase sequence 1 motif, a P-type ATPase sequence 2 motif, a P-type ATPase sequence 3 motif, and/or one or more phospholipid transporter specific amino acid resides, and is encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 1, 3, 4, or 6. In another preferred embodiment, a 67118 or 67067 protein includes at least one or more of the following domains, sites, or motifs: a transmembrane domain, an N-terminal large extramembrane domain, a C-terminal large extramembrane domain, an E1-E2 ATPases phosphorylation site, a P-type ATPase sequence 1 motif, a P-type ATPase sequence 2 motif, a P-type ATPase sequence 3 motif, and/or one or more phospholipid transporter specific amino acid resides, and has a 67118 or 67067 activity.  
      As used interchangeably herein, a “phospholipid transporter activity” or a “67118 or 67067 activity” includes an activity exerted or mediated by a 67118 or 67067 protein, polypeptide or nucleic acid molecule on a 67118 or 67067 responsive cell or on a 67118 or 67067 substrate, as determined in vivo or in vitro, according to standard techniques. In one embodiment, a phospholipid transporter activity is a direct activity, such as an association with a 67118 or 67067 target molecule. As used herein, a “target molecule” or “binding partner” is a molecule with which a 67118 or 67067 protein binds or interacts in nature, such that 67118 or 67067-mediated function is achieved. In an exemplary embodiment, a 67118 or 67067 target molecule is a 67118 or 67067 substrate (e.g., a phospholipid, ATP, or a non-67118 or 67067 protein). A phospholipid transporter activity can also be an indirect activity, such as a cellular signaling activity mediated by interaction of the 67118 or 67067 protein with a 67118 or 67067 substrate.  
      In a preferred embodiment, a phospholipid transporter activity is at least one of the following activities: (i) interaction with a 67118 or 67067 substrate or target molecule (e.g., a phospholipid, ATP, or a non-67118 or non-67067 protein); (ii) transport of a 67118 or 67067 substrate or target molecule (e.g., an aminophospholipid such as phosphatidylserine or phosphatidylethanolamine) from one side of a cellular membrane to the other; (iii) the ability to be phosphorylated or dephosphorylated; (iv) adoption of an E1 conformation or an E2 conformation; (v) conversion of a 67118 or 67067 substrate or target molecule to a product (e.g., hydrolysis of ATP); (vi) interaction with a second non-67118 or non-67067 protein; (vii) modulation of substrate or target molecule location (e.g., modulation of phospholipid location within a cell and/or location with respect to a cellular membrane); (viii) maintenance of aminophospholipid gradients; (ix) modulation of intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (x) modulation of cellular proliferation, growth, differentiation, apoptosis, absorption, or secretion.  
      The nucleotide sequence of the isolated human 67118 and 67067 cDNA and the predicted amino acid sequence of the human 67118 and 67067 polypeptides are shown in SEQ ID NOs:33, 34 and 36, 37, respectively.  
      The human 67118 gene, which is approximately 7745 nucleotides in length, encodes a polypeptide which is approximately 1134 amino acid residues in length. The human 67067 gene, which is approximately 7205 nucleotides in length, encodes a polypeptide which is approximately 1588 amino acid residues in length.  
      62092 family members likewise share structural and functional characteristics and can be identified by said characteristics, as follows. In another embodiment, a 62092 protein of the present invention is identified based on the presence of a signal peptide. The prediction of such a signal peptide can be made, for example, by using the computer algorithm SignalP (Henrik et al. (1997) Protein Eng. 10: 1-6). As used herein, a “signal sequence” or “signal peptide” includes a peptide containing about 15 or more amino acids which occurs at the N-terminus of secretory and/or membrane bound proteins and which contains a large number of hydrophobic amino acid residues. For example, a signal sequence contains at least about 10-30 amino acid residues, preferably about 15-25 amino acid residues, more preferably about 18-20 amino acid residues, and more preferably about 19 amino acid residues, and has at least about 35-65%, preferably about 38-50%, and more preferably about 40-45% hydrophobic amino acid residues (e.g., Valine, Leucine, Isoleucine or Phenylalanine). Such a “signal sequence”, also referred to in the art as a “signal peptide”, serves to direct a protein containing such a sequence to a lipid bilayer, and is cleaved in secreted and membrane bound proteins. A possible signal sequence was identified in the amino acid sequence of human 62092 at about amino acids 1-19 of SEQ ID NO:40.  
      In still another embodiment, members of the 62092 family of proteins include at least one “HIT family domain” in the protein or corresponding nucleic acid molecule. As used interchangeably herein, the term “HIT family domain” includes a protein domain having at least about 30-170 amino acid residues and a bit score of at least 60.0 when compared against a HIT family domain Hidden Markov Model (HMM), e.g., Accession Number PF01230. Preferably, a HIT family domain includes a protein domain having an amino acid sequence of about 50-150, 70-130, 90-110, or more preferably about 102 amino acid residues, and a bit score of at least 80, 100, 120, 140, 160, or more preferably, 180.3. To identify the presence of a HIT family domain in a 62092 protein, and make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein is searched against a database of known protein motifs and/or domains (e.g., the HMM database). The HIT family domain (HMM) has been assigned the PFAM Accession number PF01230. A search was performed against the HMM database resulting in the identification of a HIT family domain in the amino acid sequence of human 62092 at about residues 54-155 of SEQ ID NO:40.  
      A description of the Pfam database can be found in Sonhammer et al. (1997)  Proteins  28:405-420, and a detailed description of HMMs can be found, for example, in Gribskov et al. (1990)  Meth. Enzymol.  183:146-159; Gribskov et al. (1987)  Proc. Natl. Acad. Sci. USA  84:4355-4358; Krogh et al. (1994)  J. Mol. Biol.  235:1501-1531; and Stultz et al. (1993)  Protein Sci.  2:305-314, the contents of which are incorporated herein by reference.  
      Preferably a HIT family domain is at least about 80-120 amino acid residues and comprises core amino acid residues sufficient to carry out a 62092 activity, as described herein. In a preferred embodiment, a “HIT family domain” includes at least about 90-110 amino acid residues, for example, about 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, or 110 amino acid residues, preferably, about 102 residues, and is capable of carrying out a 62092 biological activity. Accordingly, identifying the presence of a “HIT family domain” can include isolating a fragment of a 62092 molecule (e.g., a 62092 polypeptide) and assaying for the ability of the fragment to exhibit one of the aforementioned HIT family domain activities.  
      In another embodiment, a 62092 protein of the present invention is identified based on the presence of an “HIT family signature motif” in the protein or corresponding nucleic acid molecule. The consensus for a HIT family signature motif is a protein motif and has the consensus sequence [NGA]-X(4)-[GSAV]-X-[QF]-X-[LIVM]-X-H-[LIVMFYST]-H-[LIVMFT]-H-[LIVMF](2)-[PSGA] (SEQ ID NO:50). The HIT family signature motif functions in nucleotide binding and has been assigned Prosite™ Accession Number PS00892. To identify the presence of an HIT family signature motif in a 62092 protein, and to make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein may be searched against a database of known protein domains or motifs (e.g., the Prosite™ database) using the default parameters (available at the ProSite internet website). A search was performed against the ProSite database resulting in the identification of a HIT family signature motif in the amino acid sequence of human 62092 (SEQ ID NO:40) at about residues 136-151.  
      Isolated proteins of the present invention, preferably 62092 proteins, have an amino acid sequence sufficiently homologous to the amino acid sequence of SEQ ID NO:40, or are encoded by a nucleotide sequence sufficiently homologous to SEQ ID NO:39 or 41. As used herein, the term “sufficiently homologous” refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homology or identity across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently homologous. Furthermore, amino acid or nucleotide sequences which share at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homology or identity and share a common functional activity are defined herein as sufficiently homologous.  
      In a preferred embodiment, a 62092 protein includes at least one or more of the following domains or motifs: a signal peptide, a HIT family domain, and/or a HIT family signature motif, and has an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homologous or identical to the amino acid sequence of SEQ ID NO:40. In yet another preferred embodiment, a 62092 protein includes at least one or more of the following domains or motifs: a signal peptide, a HIT family domain, and/or a HIT family signature motif, and is encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:39 or 41. In another preferred embodiment, a 62092 protein includes at least one or more of the following domains or motifs: a signal peptide, a HIT family domain, and/or a HIT family signature motif, and has a 62092 activity.  
      As used interchangeably herein, a “62092 activity”, “biological activity of 62092” or “functional activity of 62092”, includes an activity exerted or mediated by a 62092 protein, polypeptide or nucleic acid molecule on a 62092 responsive cell or on a 62092 substrate, as determined in vivo or in vitro, according to standard techniques. In one embodiment, a 62092 activity is a direct activity, such as an association with a 62092 target molecule. As used herein, a “target molecule” or “binding partner” is a molecule with which a 62092 protein binds or interacts in nature, such that 62092-mediated function is achieved. In an exemplary embodiment, a 62092 target molecule is a 62092 substrate (e.g., a nucleotide such as a purine mononucleotide (e.g., adenosine, AMP, GMP, or 8Br-AMP) or an dinucleoside polyphosphate (e.g., ApppA, AppppA, or AppppG)). A 62092 activity can also be an indirect activity, such as a cellular signaling activity mediated by interaction of the 62092 protein with a 62092 substrate. For example, a 62092 protein:substrate complex can interact with a downstream signaling molecule or target in order to indirectly effect a 62092 biological activity.  
      In a preferred embodiment, a 62092 activity is at least one of the following activities: (i) interaction with a 62092 substrate or target molecule (e.g., a nucleotide such as a purine mononucleotide or a nucleoside polyphosphate), or a non-62092 protein); (ii) conversion of a 62092 substrate or target molecule to a product (e.g., cleavage of a dinucleoside polyphosphate); (iii) interaction with a second non-62092 protein; (iv) sensation of cellular stress signals; (v) regulation of substrate or target molecule availability or activity; (vi) modulation of intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (vii) modulation of cellular proliferation, growth, differentiation, and/or apoptosis.  
      The nucleotide sequence of the isolated human 62092 cDNA and the predicted amino acid sequence encoded by the 62092 cDNA are shown in SEQ ID NOs:39 and 40, respectively.  
      The human 62092 gene, which is approximately 978 nucleotides in length, encodes a protein having a molecular weight of approximately 6.9 kD and which is approximately 163 amino acid residues in length.  
      Various aspects of the invention are described in further detail in later subsections.  
      Chapter VIII.FBH58295FL, A Novel Human Amino Acid Transporter and Uses Thereof  
     SUMMARY OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel amino acid transporter family members, referred to herein as “Human Amino Acid Transporter” or “HAAT” nucleic acid and protein molecules. The HAAT nucleic acid and protein molecules of the present invention are useful as modulating agents in regulating a variety of cellular processes, e.g., protein synthesis, hormone metabolism, nerve transmission, cellular activation, regulation of cell growth, production of metabolic energy, synthesis of purines and pyrimidines, nitrogen metabolism, and/or biosynthesis of urea. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding HAAT proteins or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of HAAT-encoding nucleic acids.  
      In one embodiment, the invention features an isolated nucleic acid molecule that includes the nucleotide sequence set forth in SEQ ID NO:51 or 53. In another embodiment, the invention features an isolated nucleic acid molecule that encodes a polypeptide including the amino acid sequence set forth in SEQ ID NO:52.  
      In still other embodiments, the invention features isolated nucleic acid molecules including nucleotide sequences that are substantially identical (e.g., 80% identical) to the nucleotide sequence set forth as SEQ ID NO:51 or 53. The invention further features isolated nucleic acid molecules including at least 30 contiguous nucleotides of the nucleotide sequence set forth as SEQ ID NO: 51 or 53. In another embodiment, the invention features isolated nucleic acid molecules which encode a polypeptide including an amino acid sequence that is substantially identical (e.g., 80% identical) to the amino acid sequence set forth as SEQ ID NO:52. Also featured are nucleic acid molecules which encode allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:52. In addition to isolated nucleic acid molecules encoding full-length polypeptides, the present invention also features nucleic acid molecules which encode fragments, for example, biologically active or antigenic fragments, of the full-length polypeptides of the present invention (e.g., fragments including at least 10 contiguous amino acid residues of the amino acid sequence of SEQ ID NO:52). In still other embodiments, the invention features nucleic acid molecules that are complementary to, antisense to, or hybridize under stringent conditions to the isolated nucleic acid molecules described herein.  
      In a related aspect, the invention provides vectors including the isolated nucleic acid molecules described herein (e.g., HAAT-encoding nucleic acid molecules). Such vectors can optionally include nucleotide sequences encoding heterologous polypeptides. Also featured are host cells including such vectors (e.g., host cells including vectors suitable for producing HAAT nucleic acid molecules and polypeptides).  
      In another aspect, the invention features isolated HAAT polypeptides and/or biologically active or antigenic fragments thereof. Exemplary embodiments feature a polypeptide including the amino acid sequence set forth as SEQ ID NO:52, a polypeptide including an amino acid sequence at least 80% identical to the amino acid sequence set forth as SEQ ID NO:52, a polypeptide encoded by a nucleic acid molecule including a nucleotide sequence at least 80% identical to the nucleotide sequence set forth as SEQ ID NO:51 or 53. Also featured are fragments of the full-length polypeptides described herein (e.g., fragments including at least 10 contiguous amino acid residues of the sequence set forth as SEQ ID NO:52) as well as allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:52.  
      The HAAT polypeptides and/or biologically active or antigenic fragments thereof, are useful, for example, as reagents or targets in assays applicable to treatment and/or diagnosis of HAAT associated or related disorders. In one embodiment, a HAAT polypeptide or fragment thereof has a HAAT activity. In another embodiment, a HAAT polypeptide or fragment thereof has at least one or more of the following domains, sites, or motifs: a transmembrane domain, a transmembrane amino acid transporter domain, and optionally, has a HAAT activity. In a related aspect, the invention features antibodies (e.g., antibodies which specifically bind to any one of the polypeptides, as described herein) as well as fusion polypeptides including all or a fragment of a polypeptide described herein.  
      The present invention further features methods for detecting HAAT polypeptides and/or HAAT nucleic acid molecules, such methods featuring, for example, a probe, primer or antibody described herein. Also featured are kits for the detection of HAAT polypeptides and/or HAAT nucleic acid molecules. In a related aspect, the invention features methods for identifying compounds which bind to and/or modulate the activity of a HAAT polypeptide or HAAT nucleic acid molecule described herein. Also featured are methods for modulating a HAAT activity.  
      Other features and advantages of the invention will be apparent from the following detailed description and claims.  
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel amino acid transporter family members, referred to herein as “Human Amino Acid Transporter” or “HAAT” nucleic acid and protein molecules, also referred to interchangeably herein as “FBH5829FL” nucleic acid and protein molecules. These novel molecules are capable of transporting alanine, serine, proline, glutamine, and N-methyl amino acids across cellular membranes and, thus, play a role in or function in a variety of cellular processes, e.g., protein synthesis, hormone metabolism, nerve transmission, cellular activation, regulation of cell growth, production of metabolic energy, synthesis of purines and pyrimidines, nitrogen metabolism, and/or biosynthesis of urea. Thus, the HAAT molecules of the present invention provide novel diagnostic targets and therapeutic agents to control HAAT-associated disorders, as defined herein.  
      The term “treatment” as used herein, is defined as the application or administration of a therapeutic agent to a patient, or application or administration of a therapeutic agent to an isolated tissue or cell line from a patient, who has a disease, a symptom of disease or a predisposition toward a disease, with the purpose to cure, heal, alleviate, relieve, alter, remedy, ameliorate, improve or affect the disease, the symptoms of disease or the predisposition toward disease. A therapeutic agent includes, but is not limited to, small molecules, peptides, antibodies, ribozymes and antisense oligonucleotides.  
      The term “family” when referring to the protein and nucleic acid molecules of the invention is intended to mean two or more proteins or nucleic acid molecules having a common structural domain or motif and having sufficient amino acid or nucleotide sequence homology as defined herein. Such family members can be naturally or non-naturally occurring and can be from either the same or different species. For example, a family can contain a first protein of human origin as well as other distinct proteins of human origin or alternatively, can contain homologues of non-human origin, e.g., rat or mouse proteins. Members of a family can also have common functional characteristics.  
      For example, the family of HAAT polypeptides comprise at least one “transmembrane domain” and preferably at least two, three, four, five, fix, seven, eight, nine, ten, or eleven transmembrane domains. As used herein, the term “transmembrane domain” includes an amino acid sequence of about 15-45 amino acid residues in length which spans the plasma membrane. More preferably, a transmembrane domain includes about at least 15, 20, 25, 30, 35, 40, or 45 amino acid residues and spans the plasma membrane. Transmembrane domains are rich in hydrophobic residues, and typically have an alpha-helical structure. In a preferred embodiment, at least 50%, 60%, 70%, 80%, 90%, 95% or more of the amino acids of a transmembrane domain are hydrophobic, e.g., leucines, isoleucines, alanines, valines, phenylalanines, prolines or methionines. Transmembrane domains are described in, for example, Zagotta W. N. et al, (1996)  Annual Rev. Neurosci.  19: 235-263, the contents of which are incorporated herein by reference. A MEMSAT analysis and a structural, hydrophobicity, and antigenicity analysis resulted in the identification of ten transmembrane domains in the amino acid sequence of HAAT (SEQ ID NO:52) at about residues 68-92, 135-156, 190-207, 214-232, 256-274, 287-308, 334-356, 373-390, 397-421, and 435-453 as set forth in  FIGS. 26 and 28 . Manual analysis of the amino acid sequence of human HAAT resulted in the identification of an additional transmembrane domain at amino acids 42-65 of SEQ ID NO:52.  
      The family of HAAT polypeptides also comprises at least one “transmembrane amino acid transporter protein domain.” As used herein, the term “transmembrane amino acid transporter protein domain” includes transmembrane domains found in amino acid sequences that are involved in the transport of amino acids across a membrane. There are a wide range of amino acid transporter proteins that may be classified into a multitude of different amino acid transporter systems. A listing of some of the different amino acid transporter systems follows.  
      System A  
      System A transports small aliphatic amino acids including alanine, serine, proline, glutamine and is wide expressed in mammalian cells including myocytes and hepatocytes. In the intestine, system A is localized to basolateral membranes where it absorbs amino acids from the blood for the metabolic requirement of enterocytes. (Stevens, et al. (1984)  A. Rev. Physiol.  46:417-433). System A is Na + -coupled, tolerates Li +  and is pH sensitive. (Christensen, et al. (1965)  J. Biol. Chem.  240:3609-3616). System A recognize N-methyl amino acids, and (N-methylamino)-α-isobutyric acid (MeAIB) is a characteristic substrate. System A is regulated by amino acid deprivation, hormones, growth factors and hyperosmotic stress. For example, insulin stimulates system A activity in both liver and skeletal muscle, and glucagon also stimulates it synergistically in hepatocytes. (Le Cam, et al. (1978)  Diabetologia  15:1835-1853).  
      System ASC  
      System ASC provides cell with the amino acids alanine, threonine, serine, cysteine. System ASC is distinguishable from system A because (1) it does not recognize (N-methylamino)-α-isobutyric acid (MeAIB), and (2) neutral amino acid uptake is relatively pH-insensitive.  
      Systems B, B 0 , and B 0+   
      Systems B, B 0 , and B 0+  mediate the absorption of aliphate, branched-chain and aromatic amino acids. B 0+  also accepts dibasic amino acids. (Van Winkle, et al. (1988)  Biochim. Biophys. Acta  947:173-208.) Systems B, B 0 , and B 0+  are Na + -dependent. Systems B and B 0  have a broader specificity for neutral amino acids than systems A and ASC. Systems B and B 0  are present in intestinal and renal epithelial brush-border membranes. (Stevens, et al. (1984)  A. Rev. Physiol.  46:417-433). System B 0+  is both Na +  and Cl − -coupled. (Van Winkle (1985)  J. Biol. Chem.  260:12118-12123.)  
      System b 0+   
      The mouse blastocyst transport system b 0+  mediates Na +  independent, high affinity transport of neutral and dibasic amino acids. It is expressed in kidney and intestinal epithelia.  
      System N  
      System N is Na +  coupled and specific for neutral amino acids. It has a more restricted tissue distribution than systems A, ASC, B, B 0 , and B 0+ . It is expressed in liver and muscle. In liver, system N is involved in the transport of glutamine, asparagine and histidine and it plays an important role in glutamine metabolism. Kilberg, et al. (1980)  J. Biol. Chem.  255:4011-4019.  
      System GLY  
      System GLY is specific for glycine and sarcosine and is found in liver, erythrocytes, and brain.  
      System β 
      System β is specific for β-amino acids and taurine. Given its high abundance in the brain, it is thought to play a role in neurotransmission.  
      The Imino System  
      The iminio system is specific for proline and was described in brush border membranes of intestinal enterocytes. The iminio system accounts for 60% of the Na + -dependent uptake of proline in brush-border membranes and is specific for imino acids and MeAIB.  
      System L  
      System L transport branched-chain and aromatic amino acids. System L is Na + -independent. In the brain, system L is the major transport system of the blood-brain barrier and of glial cells. The bicyclic amino acid 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH) is a characteristic substrate of system L.  
      System X −   AG    
      System X −   AG  is an electrogenic Na + -dependent acidic amino acid transport system that has been found in both epithelial cells and neurons. In the central nervous system, glutamate plays an important role as excitatory neurotransmitter. To terminate signal transmission, glutamate is removed from the extracellular fluid in the synaptic cleft surrounding the receptors by specialized uptake systems in neurons and glial cells because there are no enzymatic pathways for transmitter inactivation.  
      System y +   
      System y +  takes up cationic acid. System y +  also takes up some neutral amino acids in the presence of Na + , resulting in electrogenic transport.  
      System x −   c    
      System x −   c  is a Na + -independent, Cl −  dependent, cystine/glutamate exchange. System x −   c  has been found in fibroblasts, macrophages, endothelial cells, glial cells, and hepatocytes.  
      Isolated proteins of the present invention, preferably HAAT proteins, have an amino acid sequence sufficiently homologous to the amino acid sequence of SEQ ID NO:52, or are encoded by a nucleotide sequence sufficiently homologous to SEQ ID NO:51 or 53. As used herein, the term “sufficiently homologous” refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains having at least 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homology or identity across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently homologous. Furthermore, amino acid or nucleotide sequences which share at least 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homology or identity and share a common functional activity are defined herein as sufficiently homologous. In a preferred embodiment, amino acid or nucleotide sequences share percent identity across the full or entire length of the amino acid or nucleotide sequence being aligned, for example, when the sequences are globally aligned (e.g., as determined by the ALIGN algorithm as defined herein).  
      In a preferred embodiment, a HAAT protein includes at least one or more of the following domains, sites, or motifs: a transmembrane domain, a transmembrane amino acid transporter domain and has an amino acid sequence at least about 75%, 80%, 85%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more homologous or identical to the amino acid sequence of SEQ ID NO:52.  
      As used interchangeably herein, a “HAAT activity”, “amino acid transporter activity”, “biological activity of HAAT”, or “functional activity of HAAT”, includes an activity exerted or mediated by a HAAT protein, polypeptide or nucleic acid molecule on a HAAT responsive cell or on a HAAT substrate, as determined in vivo or in vitro, according to standard techniques. In one embodiment, a HAAT activity is a direct activity, such as an association with a HAAT target molecule. As used herein, a “target molecule” or “binding partner” is a molecule with which a HAAT protein binds or interacts in nature, such that HAAT-mediated function is achieved. A HAAT target molecule can be a non-HAAT molecule or a HAAT protein or polypeptide of the present invention. In an exemplary embodiment, a HAAT target molecule is a HAAT substrate (e.g., an amino acid). A HAAT activity can also be an indirect activity, such as a protein synthesis activity mediated by interaction of the HAAT protein with a HAAT substrate.  
      In a preferred embodiment, a HAAT activity is at least one of the following activities: (i) interaction with a HAAT substrate or target molecule (e.g., an amino acid); (ii) transport of a HAAT substrate or target molecule (e.g., an amino acid) from one side of a cellular membrane to the other; (iii) conversion of a HAAT substrate or target molecule to a product (e.g., glucose production); (iv) interaction with a second non-HAAT protein; (v) modulation of substrate or target molecule location (e.g., modulation of amino acid location within a cell and/or location with respect to a cellular membrane); (vi) maintenance of amino acid gradients; (vii) modulation of hormone metabolism and/or nerve transmission (e.g., either directly or indirectly); (viii) modulation of cellular proliferation, growth, differentiation, and production of metabolic energy; and/or (ix) modulation of amino acid homeostasis.  
      The nucleotide sequence of the isolated human HAAT cDNA and the predicted amino acid sequence encoded by the HAAT cDNA are shown in SEQ ID NO:51 and 52, respectively.  
      The human HAAT gene, which is approximately 2397 nucleotides in length, encodes a protein which is approximately 485 amino acid residues in length.  
      Various aspects of the invention are described in further detail in later subsections.  
      Chapter IX. 57255 and 57255alt, Novel Human Sugar Transporters and Uses Therefor  
     SUMMARY OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel human sugar transporter family members, referred to herein as “human sugar transporters,” e.g., “human sugar transporter-4” and “human sugar transporter-5” or “HST-4” and “HST-5,” nucleic acid and polypeptide molecules. The HST-4 and HST-5 nucleic acid and polypeptide molecules of the present invention are useful as modulating agents in regulating a variety of cellular processes, e.g., sugar homeostasis. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding HST-4 and HST-5 polypeptides or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of HST-4- and HST-5-encoding nucleic acids.  
      In one embodiment, the invention features an isolated nucleic acid molecule that includes the nucleotide sequence set forth in SEQ ID NO:54, 56, 57, or 59. In another embodiment, the invention features an isolated nucleic acid molecule that encodes a polypeptide including the amino acid sequence set forth in SEQ ID NO:55 or 58.  
      In still other embodiments, the invention features isolated nucleic acid molecules including nucleotide sequences that are substantially identical (e.g., 60% identical) to the nucleotide sequence set forth as SEQ ID NO: 54, 56, 57, or 59. The invention further features isolated nucleic acid molecules including at least 50 contiguous nucleotides of the nucleotide sequence set forth as SEQ ID NO: 54, 56, 57, or 59. In another embodiment, the invention features isolated nucleic acid molecules which encode a polypeptide including an amino acid sequence that is substantially identical (e.g., 60% identical) to the amino acid sequence set forth as SEQ ID NO:55 or 58. The present invention also features nucleic acid molecules which encode allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:55 or 58. In addition to isolated nucleic acid molecules encoding full-length polypeptides, the present invention also features nucleic acid molecules which encode fragments, for example, biologically active or antigenic fragments, of the full-length polypeptides of the present invention (e.g., fragments including at least 10 contiguous amino acid residues of the amino acid sequence of SEQ ID NO:55 or 58). In still other embodiments, the invention features nucleic acid molecules that are complementary to, antisense to, or hybridize under stringent conditions to the isolated nucleic acid molecules described herein.  
      In another aspect, the invention provides vectors including the isolated nucleic acid molecules described herein (e.g., HST-4- and HST-5-encoding nucleic acid molecules). Such vectors can optionally include nucleotide sequences encoding heterologous polypeptides. Also featured are host cells including such vectors (e.g., host cells including vectors suitable for producing HST-4 and HST-5 nucleic acid molecules and polypeptides).  
      In another aspect, the invention features isolated HST-4 and HST-5 polypeptides and/or biologically active or antigenic fragments thereof. Exemplary embodiments feature a polypeptide including the amino acid sequence set forth as SEQ ID NO:55 or 58, a polypeptide including an amino acid sequence at least 60% identical to the amino acid sequence set forth as SEQ ID NO:55 or 58, a polypeptide encoded by a nucleic acid molecule including a nucleotide sequence at least 60% identical to the nucleotide sequence set forth as SEQ ID NO: 54, 56, 57, or 59. Also featured are fragments of the full-length polypeptides described herein (e.g., fragments including at least 10 contiguous amino acid residues of the sequence set forth as SEQ ID NO:55 or 58) as well as allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:55 or 58.  
      The HST-4 and HST-5 polypeptides and/or biologically active or antigenic fragments thereof, are useful, for example, as reagents or targets in assays applicable to treatment and/or diagnosis of HST-4 and HST-5 mediated or related disorders. In one embodiment, HST-4 and/or HST-5 polypeptides or fragments thereof, have an HST-4 and/or HST-5 activity. In another embodiment, HST-4 and/or HST-5 polypeptides or fragments thereof, have at least one, preferably two, three, four, five, six, seven, eight, nine, ten, or eleven transmembrane domains and/or a sugar transporter family domain, and optionally, have an HST-4 and/or HST-5 activity. In a related aspect, the invention features antibodies (e.g., antibodies which specifically bind to any one of the polypeptides described herein) as well as fusion polypeptides including all or a fragment of a polypeptide described herein.  
      The present invention further features methods for detecting HST-4 and/or HST-5 polypeptides and/or HST-4 and/or HST-5 nucleic acid molecules, such methods featuring, for example, a probe, primer or antibody described herein. Also featured are kits e.g., kits for the detection of HST-4 and/or HST-5 polypeptides and/or HST-4 and/or HST-5 nucleic acid molecules. In a related aspect, the invention features methods for identifying compounds which bind to and/or modulate the activity of an HST-4 and/or an HST-5 polypeptide or HST-4 and/or HST-5 nucleic acid molecule described herein. Further featured are methods for modulating an HST-4 and/or an HST-5 activity.  
      Other features and advantages of the invention will be apparent from the following detailed description and claims.  
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is based, at least in part, on the discovery of novel molecules, referred to herein as “human sugar transporter-4” and “human sugar transporter-5” or “HST-4” and “HST-5” nucleic acid and polypeptide molecules, which are novel members of the sugar transporter family. These novel molecules are splice variants which have resulted from alternative splicing of the same gene. These novel molecules are capable of, for example, modulating a transporter mediated activity (e.g., a sugar transporter mediated activity) in a cell, e.g., a liver cell, fat cell, muscle cell, or blood cell, such as an erythrocyte. These novel molecules are capable of transporting molecules, e.g., hexoses such as D-glucose, D-fructose, D-galactose or mannose across biological membranes and, thus, play a role in or function in a variety of cellular processes, e.g., maintenance of sugar homeostasis. As used herein, a “sugar transporter” includes a protein or polypeptide which is involved in transporting a molecule, e.g., a monosaccharide such as D-glucose, D-fructose, D-galactose or mannose, across the plasma membrane of a cell, e.g., a liver cell, fat cell, muscle cell, or blood cell, such as an erythrocyte. Sugar transporters regulate sugar homeostasis in a cell and, typically, have sugar substrate specificity. Examples of sugar transporters include glucose transporters, fructose transporters, and galactose transporters.  
      As used herein, a “sugar transporter mediated activity” includes an activity which involves a sugar transporter, e.g., a sugar transporter in a liver cell, fat cell, muscle cell, or blood cell, such as an erythrocyte. Sugar transporter mediated activities include the transport of sugars, e.g., D-glucose, D-fructose, D-galactose or mannose, into and out of cells; the stimulation of molecules that regulate glucose homeostasis (e.g., insulin and glucagon), from cells, e.g., pancreatic cells; and the participation in signal transduction pathways associated with sugar metabolism.  
      As the HST-4 and HST-5 molecules of the present invention are sugar transporters, they may be useful for developing novel diagnostic and therapeutic agents for sugar transporter associated disorders. As used herein, the term “sugar transporter associated disorder” includes a disorder, disease, or condition which is characterized by an aberrant, e.g., upregulated or downregulated, sugar transporter mediated activity. Sugar transporter associated disorders typically result in, e.g., upregulated or downregulated, sugar levels in a cell. Examples of sugar transporter associated disorders include disorders associated with sugar homeostasis, such as obesity, anorexia, type-1 diabetes, type-2 diabetes, hypoglycemia, glycogen storage disease (Von Gierke disease), type I glycogenosis, bipolar disorder, seasonal affective disorder, and cluster B personality disorders.  
      The term “family” when referring to the polypeptide and nucleic acid molecules of the invention is intended to mean two or more polypeptides or nucleic acid molecules having a common structural domain or motif and having sufficient amino acid or nucleotide sequence homology as defined herein. Such family members can be naturally or non-naturally occurring and can be from either the same or different species. For example, a family can contain a first polypeptide of human origin, as well as other, distinct polypeptides of human origin or alternatively, can contain homologues of non-human origin, e.g., mouse or monkey polypeptides. Members of a family may also have common functional characteristics.  
      For example, the family of HST-4 and HST-5 polypeptides comprise at least one “transmembrane domain” and at least one, preferably two, three, four, five, six, seven, eight, nine, ten, or eleven transmembrane domains. As used herein, the term “transmembrane domain” includes an amino acid sequence of about 20-45 amino acid residues in length which spans the plasma membrane. More preferably, a transmembrane domain includes about at least 20, 25, 30, 35, 40, or 45 amino acid residues and spans the plasma membrane. Transmembrane domains are rich in hydrophobic residues, and typically have an alpha-helical structure. In a preferred embodiment, at least 50%, 60%, 70%, 80%, 90%, 95% or more of the amino acids of a transmembrane domain are hydrophobic, e.g., leucines, isoleucines, alanines, valines, phenylalanines, prolines or methionines. Transmembrane domains are described in, for example, Zagotta W. N. et al, (1996)  Annual Rev. Neurosci.  19: 235-263, the contents of which are incorporated herein by reference. A MEMSAT and additional analyses resulted in the identification of ten transmembrane domains in the amino acid sequence of human HST-4 (SEQ ID NO:55) at about residues 25-49, 62-80, 92-113, 126-143, 154-178, 186-202, 278-298, 318-337, 372-395, and 402-423. A MEMSAT and additional analyses resulted in the identification of eleven transmembrane domains in the amino acid sequence of human HST-5 (SEQ ID NO:58) at about residues 30-51, 62-84, 92-111, 126-143, 154-178, 186-202, 240-260, 276-296, 316-335, 370-393, and 400-421.  
      Accordingly, HST-4 and HST-5 polypeptides having at least 50-60% homology, preferably about 60-70%, more preferably about 70-80%, or about 80-90% homology with at least one, preferably at least two, three, four, five, six, seven, eight, nine, ten, or eleven transmembrane domains of human HST-4 and HST-5, respectively are within the scope of the invention.  
      In another embodiment, an HST-4 and/or HST-5 molecule of the present invention is identified based on the presence of at least one “sugar transporter family domain.” As used herein, the term “sugar transporter family domain” includes a protein domain having at least about 300-600 amino acid residues and a sugar transporter mediated activity. Preferably, a sugar transporter family domain includes a polypeptide having an amino acid sequence of about 350-550, 400-550, or more preferably, about 408 or 406 amino acid residues and a sugar transporter mediated activity. To identify the presence of a sugar transporter family domain in an HST-4 and/or an HST-5 protein, and make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein may be searched against a database of known protein domains (e.g., the PFAM HMM database). A PFAM sugar transporter family domain has been assigned the PFAM Accession PF00083. A search was performed against the PFAM HMM database resulting in the identification of a sugar transporter family domain in the amino acid sequence of human HST-4 at about residues 23-431 of SEQ ID NO:55 and in the amino acid sequence of human HST-5 at about residues 23-429 of SEQ ID NO:58.  
      Preferably a “sugar transporter family domain” has a “sugar transporter mediated activity” as described herein. For example, a sugar transporter family domain may have the ability to bind a monosaccharide (e.g., D-glucose, D-fructose, D-galactose and/or mannose); the ability to transport a monosaccharide (e.g., D-glucose, D-fructose, D-galactose and/or mannose) in a constitutive manner or in response to stimuli (e.g., insulin) across a cell membrane (e.g., a liver cell membrane, fat cell membrane, muscle cell membrane, and/or blood cell membrane, such as an erythrocyte membrane); the ability to mediate trans-epithelial movement; and/or the ability to modulate sugar homeostasis in a cell. Accordingly, identifying the presence of a “sugar transporter family domain” can include isolating a fragment of an HST-4 and/or an HST-5 molecule (e.g., an HST-4 and/or an HST-5 polypeptide) and assaying for the ability of the fragment to exhibit one of the aforementioned sugar transporter mediated activities.  
      A description of the PFAM database can be found in Sonhammer et al. (1997)  Proteins  28:405-420 and a detailed description of HMMs can be found, for example, in Gribskov et al. (1990)  Meth. Enzymol.  183:146-159; Gribskov et al. (1987)  Proc. Natl. Acad. Sci. USA  84:4355-4358; Krogh et al. (1994)  J. Mol. Biol.  235:1501-1531; and Stultz et al. (1993)  Protein Sci.  2:305-314, the contents of which are incorporated herein by reference.  
      In a preferred embodiment, the HST-4 and/or HST-5 molecules of the invention include at least one, preferably two, even more preferably at least three, four, five, six, seven, eight, nine, ten, or eleven transmembrane domain(s) and/or at least one sugar transporter family domain.  
      Isolated polypeptides of the present invention, preferably HST-4 or HST-5 polypeptides, have an amino acid sequence sufficiently identical to the amino acid sequence of SEQ ID NO:55 or 58 or are encoded by a nucleotide sequence sufficiently identical to SEQ ID NO: 54, 56, 57, or 59. As used herein, the term “sufficiently identical” refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more homology or identity across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently identical. Furthermore, amino acid or nucleotide sequences which share at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more homology or identity and share a common functional activity are defined herein as sufficiently identical.  
      In a preferred embodiment, an HST-4 and/or HST-5 polypeptide includes at least one or more of the following domains: a transmembrane domain and/or a sugar transporter family domain, and has an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more homologous or identical to the amino acid sequence of SEQ ID NO:55 or 58. In yet another preferred embodiment, an HST-4 and/or an HST-5 polypeptide includes at least one or more of the following domains: a transmembrane domain and/or a sugar transporter family domain, and is encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 54, 56, 57, or 59. In another preferred embodiment, an HST-4 and/or an HST-5 polypeptide includes at least one or more of the following domains: a transmembrane domain and/or a sugar transporter family domain, and has an HST-4 and/or an HST-5 activity.  
      As used interchangeably herein, an “HST-4 activity”, “HST-5 activity”, “biological activity of HST-4”, “biological activity of HST-5”, “functional activity of HST-4” or “functional activity of HST-5” refers to an activity exerted by an HST-4 and/or HST-5 polypeptide or nucleic acid molecule on an HST-4 and/or HST-5 responsive cell or tissue, or on an HST-4 and/or HST-5 polypeptide substrate, as determined in vivo, or in vitro, according to standard techniques. In one embodiment, an HST-4 and/or HST-5 activity is a direct activity, such as an association with an HST-4- and/or HST-5-target molecule. As used herein, a “substrate,” “target molecule,” or “binding partner” is a molecule with which an HST-4 and/or HST-5 polypeptide binds or interacts in nature, such that HST-4- and/or HST-5-mediated function is achieved. An HST-4 and/or HST-5 target molecule can be a non-HST-4 and/or a non-HST-5 molecule or an HST-4 and/or HST-5 polypeptide or polypeptide of the present invention. In an exemplary embodiment, an HST-4 and/or HST-5 target molecule is an HST-4 and/or HST-5 ligand, e.g., a sugar transporter ligand such D-glucose, D-fructose, D-galactose, and/or mannose. Alternatively, an HST-4 and/or HST-5 activity is an indirect activity, such as a cellular signaling activity mediated by interaction of the HST-4 and/or HST-5 polypeptide with an HST-4 and/or HST-5 ligand. The biological activities of HST-4 and/or HST-5 are described herein. For example, the HST-4 and/or HST-5 polypeptides of the present invention can have one or more of the following activities: (1) bind a monosaccharide, e.g., D-glucose, D-fructose, D-galactose, and/or mannose; (2) transport monosaccharides across a cell membrane; (3) influence insulin and/or glucagon secretion; (4) maintain sugar homeostasis in a cell; and (5) mediate trans-epithelial movement in a cell. Moreover, in a preferred embodiment, HST-4 and/or HST-5 molecules of the present invention, HST-4 and/or HST-5 antibodies, HST-4 and/or HST-5 modulators are useful in at least one of the following: (1) modulation of insulin sensitivity; (2) modulation of blood sugar levels; (3) treatment of blood sugar level disorders (e.g., diabetes); and/or (4) modulation of insulin resistance.  
      The nucleotide sequence of the isolated human HST-4 and HST-5 cDNAs and the predicted amino acid sequences of the human HST-4 and HST-5 polypeptides are shown in SEQ ID NOs:54 and 55, and SEQ ID NOs:57 and 58, respectively.  
      The human HST-4 gene, which is approximately 2565 nucleotides in length, encodes a polypeptide which is approximately 438 amino acid residues in length. The human HST-5 gene, which is approximately 2558 nucleotides in length, encodes a polypeptide which is approximately 436 amino acid residues in length.  
      Various aspects of the invention are described in further detail in the following subsections:  
      Chapter X. Further Embodiments of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and HST-5  
      I. Isolated Nucleic Acid Molecules  
      One aspect of the invention pertains to isolated nucleic acid molecules that encode MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides or biologically active portions thereof, as well as nucleic acid fragments sufficient for use as hybridization probes to identify MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4- and/or HST-5-encoding nucleic acid molecules (e.g., MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA) and fragments for use as PCR primers for the amplification or mutation of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acid molecules. As used herein, the term “nucleic acid molecule” is intended to include DNA molecules (e.g., cDNA or genomic DNA) and RNA molecules (e.g., mRNA) and analogs of the DNA or RNA generated using nucleotide analogs. The nucleic acid molecule can be single-stranded or double-stranded, but preferably is double-stranded DNA.  
      The term “isolated nucleic acid molecule” includes nucleic acid molecules which are separated from other nucleic acid molecules which are present in the natural source of the nucleic acid. For example, with regards to genomic DNA, the term “isolated” includes nucleic acid molecules which are separated from the chromosome with which the genomic DNA is naturally associated. Preferably, an “isolated” nucleic acid is free of sequences which naturally flank the nucleic acid (i.e., sequences located at the 5′ and 3′ ends of the nucleic acid) in the genomic DNA of the organism from which the nucleic acid is derived. For example, in various embodiments, the isolated MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acid molecule can contain less than about 5 kb, 4 kb, 3 kb, 2 kb, 1 kb, 0.5 kb or 0.1 kb of nucleotide sequences which naturally flank the nucleic acid molecule in genomic DNA of the cell from which the nucleic acid is derived. Moreover, an “isolated” nucleic acid molecule, such as a cDNA molecule, can be substantially free of other cellular material, or culture medium when produced by recombinant techniques, or substantially free of chemical precursors or other chemicals when chemically synthesized.  
      A nucleic acid molecule of the present invention, e.g., a nucleic acid molecule having the nucleotide sequence of SEQ ID NO:1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57, or 59, or a portion thereof, can be isolated using standard molecular biology techniques and the sequence information provided herein. Using all or a portion of the nucleic acid sequence of SEQ ID NO:1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57,or 59, as a hybridization probe, MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acid molecules can be isolated using standard hybridization and cloning techniques (e.g., as described in Sambrook, J., Fritsh, E. F., and Maniatis, T.  Molecular Cloning: A Laboratory Manual.  2 nd, ed., Cold Spring Harbor Laboratory,  Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989).  
      Moreover, a nucleic acid molecule encompassing all or a portion of SEQ ID NO: 1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57, or 59, can be isolated by the polymerase chain reaction (PCR) using synthetic oligonucleotide primers designed based upon the sequence of SEQ ID NO:1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57,or 59.  
      A nucleic acid of the invention can be amplified using cDNA, mRNA or alternatively, genomic DNA, as a template and appropriate oligonucleotide primers according to standard PCR amplification techniques. The nucleic acid so amplified can be cloned into an appropriate vector and characterized by DNA sequence analysis. Furthermore, oligonucleotides corresponding to MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleotide sequences can be prepared by standard synthetic techniques, e.g., using an automated DNA synthesizer.  
      In a preferred embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO: 1 or 3. This cDNA may comprise sequences encoding the human MTP-1 protein (i.e., “the coding region”, from nucleotides 165-6599), as well as 5′ untranslated sequences (nucleotides 1-164) and 3′ untranslated sequences (nucleotides 6600-6768) of SEQ ID NO: 1. Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO: 1 (e.g., nucleotides 165-6599, corresponding to SEQ ID NO:3).  
      In another preferred embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule which is a complement of the nucleotide sequence shown in SEQ ID NO: 1 or 3, or a portion of any of these nucleotide sequences. A nucleic acid molecule which is complementary to the nucleotide sequence shown in SEQ ID NO: 1 or 3, is one which is sufficiently complementary to the nucleotide sequence shown in SEQ ID NO:1 or 3, such that it can hybridize to the nucleotide sequence shown in SEQ ID NO: 1 or 3, respectively, thereby forming a stable duplex.  
      In still another preferred embodiment, an isolated nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to the entire length of the nucleotide sequence shown in SEQ ID NO: 1 or 3, or a portion of any of these nucleotide sequences.  
      Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NO: 1 or 3, for example, a fragment which can be used as a probe or primer or a fragment encoding a portion of an MTP-1 protein, e.g., a biologically active portion of an MTP-1 protein. The nucleotide sequence determined from the cloning of the MTP-1 gene allows for the generation of probes and primers designed for use in identifying and/or cloning other MTP-1 family members, as well as MTP-1 homologues from other species. The probe/primer typically comprises substantially purified oligonucleotide. The oligonucleotide typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12 or 15, preferably about 20 or 25, more preferably about 30, 35, 40, 45, 50, 55, 60, 65, or 75 consecutive nucleotides of a sense sequence of SEQ ID NO: 1 or 3, of an anti-sense sequence of SEQ ID NO: 1 or 3, or of a naturally occurring allelic variant or mutant of SEQ ID NO:1 or 3. In one embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is greater than 50-100, 100-500, 500-1000, 1000-1500, 1500-2000, 2000-2500, 2500-3000, 3000-3500, 3500-4000, 4000-4500, 4500-5000, 5000-5500, 5500-6000, 6000-6500, 6500-6700, or more nucleotides in length and hybridizes under stringent hybridization conditions to a nucleic acid molecule of SEQ ID NO: 1 or 3.  
      Probes based on the MTP-1 nucleotide sequences can be used to detect transcripts or genomic sequences encoding the same or homologous proteins. In preferred embodiments, the probe further comprises a label group attached thereto, e.g., the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor. Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress an MTP-1 protein, such as by measuring a level of an MTP-1-encoding nucleic acid in a sample of cells from a subject e.g., detecting MTP-1 mRNA levels or determining whether a genomic MTP-1 gene has been mutated or deleted.  
      A nucleic acid fragment encoding a “biologically active portion of an MTP-1 protein” can be prepared by isolating a portion of the nucleotide sequence of SEQ ID NO: 1 or 3, which encodes a polypeptide having an MTP-1 biological activity (the biological activities of the MTP-1 proteins are described herein), expressing the encoded portion of the MTP-1 protein (e.g., by recombinant expression in vitro) and assessing the activity of the encoded portion of the MTP-1 protein.  
      The invention further encompasses nucleic acid molecules that differ from the nucleotide sequence shown in SEQ ID NO: 1 or 3, due to degeneracy of the genetic code and thus encode the same MTP-1 proteins as those encoded by the nucleotide sequence shown in SEQ ID NO: 1 or 3. In another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a protein having an amino acid sequence shown in SEQ ID NO:2.  
      In addition to the MTP-1 nucleotide sequences shown in SEQ ID NO: 1 or 3, it will be appreciated by those skilled in the art that DNA sequence polymorphisms that lead to changes in the amino acid sequences of the MTP-1 proteins may exist within a population (e.g., the human population). Such genetic polymorphism in the MTP-1 genes may exist among individuals within a population due to natural allelic variation. As used herein, the terms “gene” and “recombinant gene” refer to nucleic acid molecules which include an open reading frame encoding an MTP-1 protein, preferably a mammalian MTP-1 protein, and can further include non-coding regulatory sequences, and introns.  
      Allelic variants of human MTP-1 include both functional and non-functional MTP-1 proteins. Functional allelic variants are naturally occurring amino acid sequence variants of the human MTP-1 protein that maintain the ability to transport an MTP-1 substrate and/or modulate cellular homeostasis. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO:2, or substitution, deletion or insertion of non-critical residues in non-critical regions of the protein.  
      Non-functional allelic variants are naturally occurring amino acid sequence variants of the human MTP-1 protein that do not have the ability to bind or transport an MTP-1 substrate and/or carry out any of the MTP-1 activities described herein. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion or premature truncation of the amino acid sequence of SEQ ID NO:2, or a substitution, insertion or deletion in critical residues or critical regions of the protein.  
      The present invention further provides non-human orthologues of the human MTP-1 protein. Orthologues of the human MTP-1 protein are proteins that are isolated from non-human organisms and possess the same MTP-1 substrate binding and/or modulation of membrane excitability activities of the human MTP-1 protein. Orthologues of the human MTP-1 protein can readily be identified as comprising an amino acid sequence that is substantially identical to SEQ ID NO:2.  
      Moreover, nucleic acid molecules encoding other MTP-1 family members and, thus, which have a nucleotide sequence which differs from the MTP-1 sequences of SEQ ID NO: 1 or 3, are intended to be within the scope of the invention. For example, another MTP-1 cDNA can be identified based on the nucleotide sequence of human MTP-1. Moreover, nucleic acid molecules encoding MTP-1 proteins from different species, and which, thus, have a nucleotide sequence which differs from the MTP-1 sequences of SEQ ID NO:1 or 3, are intended to be within the scope of the invention. For example, a mouse MTP-1 cDNA can be identified based on the nucleotide sequence of a human MTP-1.  
      Nucleic acid molecules corresponding to natural allelic variants and homologues of the MTP-1 cDNAs of the invention can be isolated based on their homology to the MTP-1 nucleic acids disclosed herein using the cDNAs disclosed herein, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions. Nucleic acid molecules corresponding to natural allelic variants and homologues of the MTP-1 cDNAs of the invention can further be isolated by mapping to the same chromosome or locus as the MTP-1 gene.  
      Accordingly, in another embodiment, an isolated nucleic acid molecule of the invention is at least 15, 20, 25, 30 or more nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:1 or 3. In other embodiment, the nucleic acid is at least 50-100, 100-500, 500-1000, 1000-1500, 1500-2000, 2000-2500, 2500-3000, 3000-3500, 3500-4000, 4000-4500, 4500-5000, 5000-5500, 5500-6000, 6000-6500, 6500-6700, or more nucleotides in length.  
      In one embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:4 or 6. This cDNA may comprise sequences encoding the human OAT4 protein (e.g., the “coding region”, from nucleotides 372-2021), as well as 5′ untranslated sequence (nucleotides 1-371) and 3′ untranslated sequences (nucleotides 2022-2206) of SEQ ID NO:4. Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:4 (e.g., nucleotides 372-2021, corresponding to SEQ ID NO:6). Accordingly, in another embodiment, an isolated nucleic acid molecule of the invention comprises SEQ ID NO:6 and nucleotides 1-371 of SEQ ID NO:4. In yet another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:6 and nucleotides 2022-2206 of SEQ ID NO:4. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:4 or SEQ ID NO:6. In still another embodiment, the nucleic acid molecule can comprise the coding region of SEQ ID NO:4 (e.g., nucleotides 372-2021, corresponding to SEQ ID NO:6), as well as a stop codon (e.g., nucleotides 2022-2024 of SEQ ID NO:4). In another embodiment, the nucleic acid molecule comprises nucleotides 1-25 of SEQ ID NO:4 or nucleotides 2186-2206 of SEQ ID NO:4.  
      In another embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:7 or 9. This cDNA may comprise sequences encoding the human OAT4 protein (e.g., the “coding region”, from nucleotides 104-2275), as well as 5′ untranslated sequence (nucleotides 1-103) and 3′ untranslated sequences (nucleotides 2276-2634) of SEQ ID NO:7. Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:7 (e.g., nucleotides 104-2275, corresponding to SEQ ID NO:9). Accordingly, in another embodiment, an isolated nucleic acid molecule of the invention comprises SEQ ID NO:9 and nucleotides 1-103 of SEQ ID NO:7. In yet another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:9 and nucleotides 2276-2634 of SEQ ID NO:7. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:7 or SEQ ID NO:9. In still another embodiment, the nucleic acid molecule can comprise the coding region of SEQ ID NO:7 (e.g., nucleotides 104-2275, corresponding to SEQ ID NO:9), as well as a stop codon (e.g., nucleotides 2276-2278 of SEQ ID NO:7). In another embodiment, the nucleic acid molecule comprises nucleotides 1-1305, nucleotides 1622-2634, nucleotides 104-1305, or nucleotides 1622-2275 of SEQ ID NO:7.  
      In still another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule which is a complement of the nucleotide sequence shown in SEQ ID NO:4, 6, 7, or 9, or a portion of any of these nucleotide sequences. A nucleic acid molecule which is complementary to the nucleotide sequence shown in SEQ ID NO:4, 6, 7, or 9, is one which is sufficiently complementary to the nucleotide sequence shown in SEQ ID NO:4, 6, 7, or 9, such that it can hybridize to the nucleotide sequence shown in SEQ ID NO:4, 6, 7, or 9, thereby forming a stable duplex.  
      In still another embodiment, an isolated nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least about 50%, 55%, 60%, 65%, 70%,75%, 80%, 85%,90%, 91%, 92%, 93%, 94%, 95%, 96%,97%, 98%, 99%, 99.1% 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to the nucleotide sequence shown in SEQ ID NO:4, 6, 7, or 9 (e.g., to the entire length of the nucleotide sequence), or a portion or complement of any of these nucleotide sequences. In one embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least (or no greater than) 50, 100, 150, 200, 250, 300, 317, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1769, 1800, 1850, 1869, 1900, 1950, 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2400, 2450, 2500, 2550, 2600 or more nucleotides in length and hybridizes under stringent hybridization conditions to a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:4, 6, 7, or 9.  
      Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NO:4, 6, 7, or 9, for example, a fragment which can be used as a probe or primer or a fragment encoding a portion of an OAT protein, e.g., a biologically active portion of an OAT protein. The nucleotide sequence determined from the cloning of the OAT gene allows for the generation of probes and primers designed for use in identifying and/or cloning other OAT family members, as well as OAT homologues from other species. The probe/primer (e.g., oligonucleotide) typically comprises substantially purified oligonucleotide. The oligonucleotide typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12 or 15, preferably about 20 or 25, more preferably about 30, 35, 40, 45, 50, 55, 60, 65, or 75 consecutive nucleotides of a sense sequence of SEQ ID NO:4, 6, 7, or 9, of an anti-sense sequence of SEQ ID NO:4, 6, 7, or 9, or of a naturally occurring allelic variant or mutant of SEQ ID NO:4, 6, 7, or 9.  
      Exemplary probes or primers are at least (or no greater than) 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or more nucleotides in length and/or comprise consecutive nucleotides of an isolated nucleic acid molecule described herein. Also included within the scope of the present invention are probes or primers comprising contiguous or consecutive nucleotides of an isolated nucleic acid molecule described herein, but for the difference of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 bases within the probe or primer sequence. Probes based on the OAT nucleotide sequences can be used to detect (e.g., specifically detect) transcripts or genomic sequences encoding the same or homologous proteins. In preferred embodiments, the probe further comprises a label group attached thereto, e.g., the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor. In another embodiment a set of primers is provided, e.g., primers suitable for use in a PCR, which can be used to amplify a selected region of an OAT sequence, e.g., a domain, region, site or other sequence described herein. The primers should be at least 5, 10, or 50 base pairs in length and less than 100, or less than 200, base pairs in length. The primers should be identical, or differ by no greater than 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 bases when compared to a sequence disclosed herein or to the sequence of a naturally occurring variant. Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress an OAT protein, such as by measuring a level of an OAT-encoding nucleic acid in a sample of cells from a subject, e.g., detecting OAT mRNA levels or determining whether a genomic OAT gene has been mutated or deleted.  
      A nucleic acid fragment encoding a “biologically active portion of an OAT protein” can be prepared by isolating a portion of the nucleotide sequence of SEQ ID NO:4, 6, 7, or 9, which encodes a polypeptide having an OAT biological activity (the biological activities of the OAT proteins are described herein), expressing the encoded portion of the OAT protein (e.g., by recombinant expression in vitro) and assessing the activity of the encoded portion of the OAT protein. In an exemplary embodiment, the nucleic acid molecule is at least 50, 100, 150, 200, 250, 300, 317, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1769, 1800, 1850, 1869, 1900, 1950, 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2400, 2450, 2500, 2550, 2600 or more nucleotides in length and encodes a protein having an OAT activity (as described herein).  
      The invention further encompasses nucleic acid molecules that differ from the nucleotide sequence shown in SEQ ID NO:4, 6, 7, or 9, due to degeneracy of the genetic code and thus encode the same OAT proteins as those encoded by the nucleotide sequence shown in SEQ ID NO:4, 6, 7, or 9. In another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a protein having an amino acid sequence which differs by at least 1, but no greater than 5, 10, 20, 50 or 100 amino acid residues from the amino acid sequence shown in SEQ ID NO:5 or 8. In yet another embodiment, the nucleic acid molecule encodes the amino acid sequence of human OAT4 or OAT5. If an alignment is needed for this comparison, the sequences should be aligned for maximum homology.  
      Nucleic acid variants can be naturally occurring, such as allelic variants (same locus), homologues (different locus), and orthologues (different organism) or can be non naturally occurring. Non-naturally occurring variants can be made by mutagenesis techniques, including those applied to polynucleotides, cells, or organisms. The variants can contain nucleotide substitutions, deletions, inversions and insertions. Variation can occur in either or both the coding and non-coding regions. The variations can produce both conservative and non-conservative amino acid substitutions (as compared in the encoded product).  
      Allelic variants result, for example, from DNA sequence polymorphisms within a population (e.g., the human population) that lead to changes in the amino acid sequences of the OAT proteins. Such genetic polymorphism in the OAT genes may exist among individuals within a population due to natural allelic variation. As used herein, the terms “gene” and “recombinant gene” refer to nucleic acid molecules which include an open reading frame encoding an OAT protein, preferably a mammalian OAT protein, and can further include non-coding regulatory sequences, and introns.  
      Accordingly, in one embodiment, the invention features isolated nucleic acid molecules which encode a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO:5 or 8, wherein the nucleic acid molecule hybridizes to a complement of a nucleic acid molecule comprising SEQ ID NO:4, 6, 7, or 9, for example, under stringent hybridization conditions.  
      Allelic variants of human OAT include both functional and non-functional OAT proteins. Functional allelic variants are naturally occurring amino acid sequence variants of the OAT protein that maintain the ability to bind an OAT substrate or target molecule, transport an OAT substrate across a membrane, protect cells and/or tissues from organic anions, modulate inter- or intra-cellular signaling, and/or modulate hormone responses. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO:5 or 8, or substitution, deletion or insertion of non-critical residues in non-critical regions of the protein.  
      Non-functional allelic variants are naturally occurring amino acid sequence variants of the OAT proteins that, for example, do not have the ability to bind an OAT substrate or target molecule, transport an OAT substrate, protect cells and/or tissues from organic anions, modulate inter- or intra-cellular signaling, and/or modulate hormone responses. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion, or premature truncation of the amino acid sequence of SEQ ID NO:5 or 8, or a substitution, insertion, or deletion in critical residues or critical regions of the protein.  
      The present invention further provides non-human orthologues (e.g., non-human orthologues of the human OAT4 or OAT5 proteins). Orthologues of the human OAT proteins are proteins that are isolated from non-human organisms and possess the same OAT substrate-transporting mechanisms, substrate or target molecule binding mechanisms, mechanisms of protecting cells and/or tissues from organic anions, and/or inter- or intra-cellular signaling or hormonal modulating mechanisms of the human OAT proteins. Orthologues of the human OAT proteins can readily be identified as comprising an amino acid sequence that is substantially homologous to SEQ ID NO:5 or 8.  
      Moreover, nucleic acid molecules encoding other OAT family members and, thus, which have a nucleotide sequence which differs from the OAT sequences of SEQ ID NO:4, 6, 7, or 9, are intended to be within the scope of the invention. For example, another OAT cDNA can be identified based on the nucleotide sequence of human OAT4 or OAT5. Moreover, nucleic acid molecules encoding OAT proteins from different species, and which, thus, have a nucleotide sequence which differs from the OAT sequences of SEQ ID NO:4, 6, 7, or 9, are intended to be within the scope of the invention. For example, a mouse or monkey OAT cDNA can be identified based on the nucleotide sequence of human OAT, e.g., OAT4 or OAT5.  
      Nucleic acid molecules corresponding to natural allelic variants and homologues of the OAT cDNAs of the invention can be isolated based on their homology to the OAT nucleic acids disclosed herein using the cDNAs disclosed herein, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions. Nucleic acid molecules corresponding to natural allelic variants and homologues of the OAT cDNAs of the invention can further be isolated by mapping to the same chromosome or locus as the OAT gene.  
      Orthologues, homologues and allelic variants can be identified using methods known in the art (e.g., by hybridization to an isolated nucleic acid molecule of the present invention, for example, under stringent hybridization conditions). In one embodiment, an isolated nucleic acid molecule of the invention is at least 15, 20, 25, 30 or more nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:4, 6, 7, or 9. In other embodiment, the nucleic acid is at least 50, 100, 150, 200, 250, 300, 317, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1769, 1800, 1850, 1869, 1900, 1950, 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2400, 2450, 2500, 2550, 2600 or more nucleotides in length.  
      In one embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO: 12. The sequence of SEQ ID NO: 12 corresponds to the human HST-1 cDNA. This cDNA comprises sequences encoding the human HST-1 polypeptide (i.e., “the coding region”, from nucleotides 13-1732) as well as 5′ untranslated sequences (nucleotides 1-12) and 3′ untranslated sequences (nucleotides 1733-1917). Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:12 (e.g., nucleotides 13-1732, corresponding to SEQ ID NO: 14). Accordingly, in another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO: 14 and nucleotides 1-12 and 1733-1917 of SEQ ID NO:12. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:12 or 14.  
      In still another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule which is a complement of the nucleotide sequence shown in SEQ ID NO:12 or 14, or a portion of any of these nucleotide sequences. A nucleic acid molecule which is complementary to the nucleotide sequence shown in SEQ ID NO:12 or 14, is one which is sufficiently complementary to the nucleotide sequence shown in SEQ ID NO:12 or 14, such that it can hybridize to the nucleotide sequence shown in SEQ ID NO:12 or 14, thereby forming a stable duplex.  
      In still another preferred embodiment, an isolated nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical to the nucleotide sequence shown in SEQ ID NO:12 or 14 (e.g., to the entire length of the nucleotide sequence), or a portion of any of these nucleotide sequences. In one embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least (or no greater than) 50, 57, 63, 72, 100, 124, 150, 172, 175, 200, 250, 268, 300, 305, 328, 350, 400, 431, 450, 495, 500, 550, 600, 650, 700, 750, 800, 804, 850, 900, 950, 1000, 1050, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900 or more nucleotides in length and hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule of SEQ ID NO: 12 or 14.  
      Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NO: 12 or 14, for example, a fragment which can be used as a probe or primer or a fragment encoding a portion of an HST-1 polypeptide, e.g., a biologically active portion of an HST-1 polypeptide. The nucleotide sequence determined from the cloning of the HST-1 gene allows for the generation of probes and primers designed for use in identifying and/or cloning other HST-1 family members, as well as HST-1 homologues from other species. The probe/primer typically comprises substantially purified oligonucleotide. The probe/primer (e.g., oligonucleotide) typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12 or 15, preferably about 20 or 25, more preferably about 30, 35, 40, 45, 50, 55, 60, 65, 75, 80, 85, 90, 95, or 100 or more consecutive nucleotides of a sense sequence of SEQ ID NO: 12 or 14, of an anti-sense sequence of SEQ ID NO: 12 or 14, or of a naturally occurring allelic variant or mutant of SEQ ID NO:12 or 14.  
      Exemplary probes or primers are at least 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or more nucleotides in length and/or comprise consecutive nucleotides of an isolated nucleic acid molecule described herein. Probes based on the HST-1 nucleotide sequences can be used to detect (e.g., specifically detect) transcripts or genomic sequences encoding the same or homologous polypeptides. In preferred embodiments, the probe further comprises a label group attached thereto, e.g., the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor. In another embodiment a set of primers is provided, e.g., primers suitable for use in a PCR, which can be used to amplify a selected region of an HST-1 sequence, e.g., a domain, region, site or other sequence described herein. The primers should be at least 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more nucleotides in length. Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress an HST-1 polypeptide, such as by measuring a level of an HST-1-encoding nucleic acid in a sample of cells from a subject e.g., detecting HST-1 mRNA levels or determining whether a genomic HST-1 gene has been mutated or deleted.  
      A nucleic acid fragment encoding a “biologically active portion of an HST-1 polypeptide” can be prepared by isolating a portion of the nucleotide sequence of SEQ ID NO:12 or 14, which encodes a polypeptide having an HST-1 biological activity (the biological activities of the HST-1 polypeptides are described herein), expressing the encoded portion of the HST-1 polypeptide (e.g., by recombinant expression in vitro) and assessing the activity of the encoded portion of the HST-1 polypeptide. In an exemplary embodiment, the nucleic acid molecule is at least 50, 57, 63, 72, 100, 124, 150, 172, 175, 200, 250, 268, 300, 305, 328, 350, 400, 431, 450, 495, 500, 550, 600, 650, 700, 750, 800, 804, 850, 900, 950, 1000, 1050, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900 or more nucleotides in length and encodes a polypeptide having an HST-1 activity (as described herein).  
      The invention further encompasses nucleic acid molecules that differ from the nucleotide sequence shown in SEQ ID NO:12 or 14. Such differences can be due to due to degeneracy of the genetic code, thus resulting in a nucleic acid which encodes the same HST-1 polypeptides as those encoded by the nucleotide sequence shown in SEQ ID NO:12 or 14. In another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a polypeptide having an amino acid sequence which differs by at least 1, but no greater than 5, 10, 20, 50, 100, 150, 155, 200, 250, 300, 350, 350, 400, 450, or 500 amino acid residues from the amino acid sequence shown in SEQ ID NO: 13. In yet another embodiment, the nucleic acid molecule encodes the amino acid sequence of human HST-1. If an alignment is needed for this comparison, the sequences should be aligned for maximum homology.  
      Nucleic acid variants can be naturally occurring, such as allelic variants (same locus), homologues (different locus), and orthologues (different organism) or can be non naturally occurring. Non-naturally occurring variants can be made by mutagenesis techniques, including those applied to polynucleotides, cells, or organisms. The variants can contain nucleotide substitutions, deletions, inversions and insertions. Variation can occur in either or both the coding and non-coding regions. The variations can produce both conservative and non-conservative amino acid substitutions (as compared in the encoded product).  
      Allelic variants result, for example, from DNA sequence polymorphisms within a population (e.g., the human population) that lead to changes in the amino acid sequences of the HST-1 polypeptides. Such genetic polymorphism in the HST-1 genes may exist among individuals within a population due to natural allelic variation. As used herein, the terms “gene” and “recombinant gene” refer to nucleic acid molecules which include an open reading frame encoding an HST-1 polypeptide, preferably a mammalian HST-1 polypeptide, and can further include non-coding regulatory sequences, and introns.  
      Accordingly, in one embodiment, the invention features isolated nucleic acid molecules which encode a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO: 13, wherein the nucleic acid molecule hybridizes to a complement of a nucleic acid molecule comprising SEQ ID NO:12 or 14, for example, under stringent hybridization conditions.  
      Allelic variants of human HST-1 include both functional and non-functional HST-1 polypeptides. Functional allelic variants are naturally occurring amino acid sequence variants of the human HST-1 polypeptide that have an HST-1 activity, e.g., maintain the ability to bind an HST-1 ligand or substrate and/or modulate sugar transport, or sugar homeostasis. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO: 13, or substitution, deletion or insertion of non-critical residues in non-critical regions of the polypeptide.  
      Non-functional allelic variants are naturally occurring amino acid sequence variants of the human HST-1 polypeptide that do not have an HST-1 activity, e.g., they do not have the ability to transport sugars into and out of cells or to modulate sugar homeostasis. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion or premature truncation of the amino acid sequence of SEQ ID NO: 13, or a substitution, insertion or deletion in critical residues or critical regions.  
      The present invention further provides non-human orthologues of the human HST-1 polypeptide. Orthologues of human HST-1 polypeptides are polypeptides that are isolated from non-human organisms and possess the same HST-1 activity, e.g., ligand binding and/or modulation of sugar transport mechanisms, as the human HST-1 polypeptide. Orthologues of the human HST-1 polypeptide can readily be identified as comprising an amino acid sequence that is substantially identical to SEQ ID NO:13.  
      Moreover, nucleic acid molecules encoding other HST-1 family members and, thus, which have a nucleotide sequence which differs from the HST-1 sequences of SEQ ID NO:12 or 14, are intended to be within the scope of the invention. For example, another HST-1 cDNA can be identified based on the nucleotide sequence of human HST-1. Moreover, nucleic acid molecules encoding HST-1 polypeptides from different species, and which, thus, have a nucleotide sequence which differs from the HST-1 sequences of SEQ ID NO:12 or 14, are intended to be within the scope of the invention. For example, a mouse HST-1 cDNA can be identified based on the nucleotide sequence of a human HST-1.  
      Nucleic acid molecules corresponding to natural allelic variants and homologues of the HST-1 cDNAs of the invention can be isolated based on their homology to the HST-1 nucleic acids disclosed herein using the cDNAs disclosed herein, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions. Nucleic acid molecules corresponding to natural allelic variants and homologues of the HST-1 cDNAs of the invention can further be isolated by mapping to the same chromosome or locus as the HST-1 gene.  
      Orthologues, homologues and allelic variants can be identified using methods known in the art (e.g., by hybridization to an isolated nucleic acid molecule of the present invention, for example, under stringent hybridization conditions). In one embodiment, an isolated nucleic acid molecule of the invention is at least 15, 20, 25, 30 or more nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 12 or 14. In other embodiment, the nucleic acid is at least 50, 57, 63, 72, 100, 124, 150, 172, 175, 200, 250, 268, 300, 305, 328, 350, 400, 431, 450, 495, 500, 550, 600, 650, 700, 750, 800, 804, 850, 900, 950, 1000, 1050, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900 or more nucleotides in length.  
      In one embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:15. The sequence of SEQ ID NO:15 corresponds to the human TP-2 cDNA. This cDNA comprises sequences encoding the human TP-2 polypeptide (i.e., “the coding region”, from nucleotides 67-1491) as well as 5′ untranslated sequences (nucleotides 1-66) and 3′ untranslated sequences (nucleotides 1492-1963). Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:15 (e.g., nucleotides 67-1491, corresponding to SEQ ID NO:17). Accordingly, in another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO: 17 and nucleotides 1-66 and 1492-1963 of SEQ ID NO: 15. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO: 15 or 17.  
      In still another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule which is a complement of the nucleotide sequence shown in SEQ ID NO: 15 or 17, or a portion of any of these nucleotide sequences. A nucleic acid molecule which is complementary to the nucleotide sequence shown in SEQ ID NO:15 or 17, is one which is sufficiently complementary to the nucleotide sequence shown in SEQ ID NO:15 or 17, such that it can hybridize to the nucleotide sequence shown in SEQ ID NO:15 or 17, thereby forming a stable duplex.  
      In still another preferred embodiment, an isolated nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to the nucleotide sequence shown in SEQ ID NO:15 or 17 (e.g., to the entire length of the nucleotide sequence), or a portion of any of these nucleotide sequences. In one embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least (or no greater than) 50, 100, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 1950 or more nucleotides in length and hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule of SEQ ID NO: 15 or 17.  
      Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NO: 15 or 17, for example, a fragment which can be used as a probe or primer or a fragment encoding a portion of a TP-2 polypeptide, e.g., a biologically active portion of a TP-2 polypeptide. The nucleotide sequence determined from the cloning of the TP-2 gene allows for the generation of probes and primers designed for use in identifying and/or cloning other TP-2 family members, as well as TP-2 homologues from other species. The probe/primer typically comprises substantially purified oligonucleotide. The probe/primer (e.g., oligonucleotide) typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12 or 15, preferably about 20 or 25, more preferably about 30, 35, 40, 45, 50, 55, 60, 65, 75, 80, 85, 90, 95, or 100 or more consecutive nucleotides of a sense sequence of SEQ ID NO: 15 or 17, of an anti-sense sequence of SEQ ID NO: 15 or 17, or of a naturally occurring allelic variant or mutant of SEQ ID NO: 15 or 17.  
      Exemplary probes or primers are at least 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or more nucleotides in length and/or comprise consecutive nucleotides of an isolated nucleic acid molecule described herein. Probes based on the TP-2 nucleotide sequences can be used to detect (e.g., specifically detect) transcripts or genomic sequences encoding the same or homologous polypeptides. In preferred embodiments, the probe further comprises a label group attached thereto, e.g., the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor. In another embodiment a set of primers is provided, e.g., primers suitable for use in a PCR, which can be used to amplify a selected region of a TP-2 sequence, e.g., a domain, region, site or other sequence described herein. The primers should be at least 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more nucleotides in length. Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress a TP-2 polypeptide, such as by measuring a level of a TP-2-encoding nucleic acid in a sample of cells from a subject e.g., detecting TP-2 mRNA levels or determining whether a genomic TP-2 gene has been mutated or deleted.  
      A nucleic acid fragment encoding a “biologically active portion of a TP-2 polypeptide” can be prepared by isolating a portion of the nucleotide sequence of SEQ ID NO:15 or 17, which encodes a polypeptide having a TP-2 biological activity (the biological activities of the TP-2 polypeptides are described herein), expressing the encoded portion of the TP-2 polypeptide (e.g., by recombinant expression in vitro) and assessing the activity of the encoded portion of the TP-2 polypeptide. In an exemplary embodiment, the nucleic acid molecule is at least 50, 100, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 1950 or more nucleotides in length and encodes a polypeptide having a TP-2 activity (as described herein).  
      The invention further encompasses nucleic acid molecules that differ from the nucleotide sequence shown in SEQ ID NO:15 or 17. Such differences can be due to due to degeneracy of the genetic code, thus resulting in a nucleic acid which encodes the same TP-2 polypeptides as those encoded by the nucleotide sequence shown in SEQ ID NO:15 or 17. In another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a polypeptide having an amino acid sequence which differs by at least 1, but no greater than 5, 10, 20, 50 or 100 amino acid residues from the amino acid sequence shown in SEQ ID NO: 16. In yet another embodiment, the nucleic acid molecule encodes the amino acid sequence of human TP-2. If an alignment is needed for this comparison, the sequences should be aligned for maximum homology.  
      Nucleic acid variants can be naturally occurring, such as allelic variants (same locus), homologues (different locus), and orthologues (different organism) or can be non naturally occurring. Non-naturally occurring variants can be made by mutagenesis techniques, including those applied to polynucleotides, cells, or organisms. The variants can contain nucleotide substitutions, deletions, inversions and insertions. Variation can occur in either or both the coding and non-coding regions. The variations can produce both conservative and non-conservative amino acid substitutions (as compared in the encoded product).  
      Allelic variants result, for example, from DNA sequence polymorphisms within a population (e.g., the human population) that lead to changes in the amino acid sequences of the TP-2 polypeptides. Such genetic polymorphism in the TP-2 genes may exist among individuals within a population due to natural allelic variation. As used herein, the terms “gene” and “recombinant gene” refer to nucleic acid molecules which include an open reading frame encoding a TP-2 polypeptide, preferably a mammalian TP-2 polypeptide, and can further include non-coding regulatory sequences, and introns.  
      Accordingly, in one embodiment, the invention features isolated nucleic acid molecules which encode a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO:16, wherein the nucleic acid molecule hybridizes to a complement of a nucleic acid molecule comprising SEQ ID NO:15 or 17, for example, under stringent hybridization conditions.  
      Allelic variants of human TP-2 include both functional and non-functional TP-2 polypeptides. Functional allelic variants are naturally occurring amino acid sequence variants of the human TP-2 polypeptide that have a TP-2 activity, e.g., maintain the ability to bind a TP-2 ligand or substrate and/or modulate the import and export of molecules from cells or across membranes, e.g., monosaccharides. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO: 16, or substitution, deletion or insertion of non-critical residues in non-critical regions of the polypeptide.  
      Non-functional allelic variants are naturally occurring amino acid sequence variants of the human TP-2 polypeptide that do not have a TP-2 activity, e.g., they do not have the ability to transport molecules into and out of cells or across membranes. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion or premature truncation of the amino acid sequence of SEQ ID NO: 16, or a substitution, insertion or deletion in critical residues or critical regions.  
      The present invention further provides non-human orthologues of the human TP-2 polypeptide. Orthologues of human TP-2 polypeptides are polypeptides that are isolated from non-human organisms and possess the same TP-2 activity, e.g., ligand binding and/or modulation of import and export of molecules from cells or across membranes, e.g., monosaccharides, as the human TP-2 polypeptide. Orthologues of the human TP-2 polypeptide can readily be identified as comprising an amino acid sequence that is substantially identical to SEQ ID NO:16.  
      Moreover, nucleic acid molecules encoding other TP-2 family members and, thus, which have a nucleotide sequence which differs from the TP-2 sequences of SEQ ID NO:15 or 17, are intended to be within the scope of the invention. For example, another TP-2 cDNA can be identified based on the nucleotide sequence of human TP-2. Moreover, nucleic acid molecules encoding TP-2 polypeptides from different species, and which, thus, have a nucleotide sequence which differs from the TP-2 sequences of SEQ ID NO: 15 or 17, are intended to be within the scope of the invention. For example, a mouse TP-2 cDNA can be identified based on the nucleotide sequence of a human TP-2.  
      Nucleic acid molecules corresponding to natural allelic variants and homologues of the TP-2 cDNAs of the invention can be isolated based on their homology to the TP-2 nucleic acids disclosed herein using the cDNAs disclosed herein, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions. Nucleic acid molecules corresponding to natural allelic variants and homologues of the TP-2 cDNAs of the invention can further be isolated by mapping to the same chromosome or locus as the TP-2 gene.  
      Orthologues, homologues and allelic variants can be identified using methods known in the art (e.g., by hybridization to an isolated nucleic acid molecule of the present invention, for example, under stringent hybridization conditions). In one embodiment, an isolated nucleic acid molecule of the invention is at least 15, 20, 25, 30 or more nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 15 or 17. In other embodiment, the nucleic acid is at least 50, 100, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 1950 or more nucleotides in length.  
      In one embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:19 or 21. This cDNA may comprise sequences encoding the human PLTR-1 protein (e.g., the “coding region”, from nucleotides 171-3740), as well as 5′ untranslated sequence (nucleotides 1-170) and 3′ untranslated sequences (nucleotides 3741-4693) of SEQ ID NO:19. Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:19 (e.g., nucleotides 171-3740, corresponding to SEQ ID NO:21). Accordingly, in another embodiment, an isolated nucleic acid molecule of the invention comprises SEQ ID NO:21 and nucleotides 1-170 of SEQ ID NO:19. In yet another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:21 and nucleotides 3741-4693 of SEQ ID NO: 19. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:19 or 21. In another embodiment, the nucleic acid molecule can comprise the coding region of SEQ ID NO:19 (e.g., nucleotides 171-3740, corresponding to SEQ ID NO:21), as well as a stop codon (e.g., nucleotides 3741-3743 of SEQ ID NO: 19). In other embodiments, the nucleic acid molecule can comprise nucleotides 1-743 of SEQ ID NO: 19.  
      In still another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule which is a complement of the nucleotide sequence shown in SEQ ID NO: 19 or 21, or a portion of any of these nucleotide sequences. A nucleic acid molecule which is complementary to the nucleotide sequence shown in SEQ ID NO: 19 or 21, is one which is sufficiently complementary to the nucleotide sequence shown in SEQ ID NO:19 or 21, such that it can hybridize to the nucleotide sequence shown in SEQ ID NO:19 or 21, thereby forming a stable duplex.  
      In still another embodiment, an isolated nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least about 75%, 79%, 80%, 81%, 85%, 90%, 91%,92%,93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to the nucleotide sequence shown in SEQ ID NO: 19 or 21 (e.g., to the entire length of the nucleotide sequence), or a portion or complement of any of these nucleotide sequences. In one embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least (or no greater than) 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 676, 677, 689, 690, 691, 692, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1562, 1600, 1610, 1660, 1700, 1750, 1800, 1850, 1900, 1950, 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2373, 2374, 2375, 2400, 2450, 2500, 2550, 2600, 2650, 2700, 2750, 2800, 2850, 2900, 2950, 3000, 3050, 3063, 3064, 3100, 3150, 3200, 3250, 3300, 3350, 3400, 3450, 3500, 3550, 3600, 3650, 3700, 3750, 3753, 3754, 3800, 3850, 3900, 3950, 4000, 4050, 4100, 4150, 4200, 4250, 4300, 4350, 4400, 4450, 4500, 4550, 4600, 4650 or more nucleotides in length and hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule of SEQ ID NO:19 or 21.  
      Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NO: 19 or 21, for example, a fragment which can be used as a probe or primer or a fragment encoding a portion of a PLTR-1 protein, e.g., a biologically active portion of a PLTR-1 protein. The nucleotide sequence determined from the cloning of the PLTR-1 gene allows for the generation of probes and primers designed for use in identifying and/or cloning other PLTR-1 family members, as well as PLTR-1 homologues from other species. The probe/primer (e.g., oligonucleotide) typically comprises substantially purified oligonucleotide. The oligonucleotide typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12 or 15, preferably about 20 or 25, more preferably about 30, 35, 40, 45, 50, 55, 60, 65, or 75 consecutive nucleotides of a sense sequence of SEQ ID NO: 19 or 21, of an anti-sense sequence of SEQ ID NO:19 or 21, or of a naturally occurring allelic variant or mutant of SEQ ID NO:19 or 21.  
      Exemplary probes or primers are at least (or no greater than) 12 or 15, 20 or 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or more nucleotides in length and/or comprise consecutive nucleotides of an isolated nucleic acid molecule described herein. Also included within the scope of the present invention are probes or primers comprising contiguous or consecutive nucleotides of an isolated nucleic acid molecule described herein, but for the difference of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 bases within the probe or primer sequence. Probes based on the PLTR-1 nucleotide sequences can be used to detect (e.g., specifically detect) transcripts or genomic sequences encoding the same or homologous proteins. In preferred embodiments, the probe further comprises a label group attached thereto, e.g., the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor. In another embodiment a set of primers is provided, e.g., primers suitable for use in a PCR, which can be used to amplify a selected region of a PLTR-1 sequence, e.g., a domain, region, site or other sequence described herein. The primers should be at least 5, 10, or 50 base pairs in length and less than 100, or less than 200, base pairs in length. The primers should be identical, or differ by no greater than 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 bases when compared to a sequence disclosed herein or to the sequence of a naturally occurring variant. Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress a PLTR-1 protein, such as by measuring a level of a PLTR-1-encoding nucleic acid in a sample of cells from a subject, e.g., detecting PLTR-1 mRNA levels or determining whether a genomic PLTR-1 gene has been mutated or deleted.  
      A nucleic acid fragment encoding a “biologically active portion of a PLTR-1 protein” can be prepared by isolating a portion of the nucleotide sequence of SEQ ID NO:19 or 21, which encodes a polypeptide having a PLTR-1 biological activity (the biological activities of the PLTR-1 proteins are described herein), expressing the encoded portion of the PLTR-1 protein (e.g., by recombinant expression in vitro) and assessing the activity of the encoded portion of the PLTR-1 protein. In an exemplary embodiment, the nucleic acid molecule is at least 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 676, 677, 689, 690, 691, 692, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1562, 1600, 1610, 1660, 1700, 1750, 1800, 1850, 1900, 1950, 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2373, 2374, 2375, 2400, 2450, 2500, 2550, 2600, 2650, 2700, 2750, 2800, 2850, 2900, 2950, 3000, 3050, 3063, 3064, 3100, 3150, 3200, 3250, 3300, 3350, 3400, 3450, 3500, 3550, 3600, 3650, 3700, 3750, 3753, 3754, 3800, 3850, 3900, 3950, 4000, 4050, 4100, 4150, 4200, 4250, 4300, 4350, 4400, 4450, 4500, 4550, 4600, 4650 or more nucleotides in length and encodes a protein having a PLTR-1 activity (as described herein).  
      The invention further encompasses nucleic acid molecules that differ from the nucleotide sequence shown in SEQ ID NO: 19 or 21, due to degeneracy of the genetic code and thus encode the same PLTR-1 proteins as those encoded by the nucleotide sequence shown in SEQ ID NO: 19 or 21. In another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a protein having an amino acid sequence which differs by at least 1, but no greater than 5, 10, 20, 50 or 100 amino acid residues from the amino acid sequence shown in SEQ ID NO:20. In yet another embodiment, the nucleic acid molecule encodes the amino acid sequence of human PLTR-1. If an alignment is needed for this comparison, the sequences should be aligned for maximum homology.  
      Nucleic acid variants can be naturally occurring, such as allelic variants (same locus), homologues (different locus), and orthologues (different organism) or can be non naturally occurring. Non-naturally occurring variants can be made by mutagenesis techniques, including those applied to polynucleotides, cells, or organisms. The variants can contain nucleotide substitutions, deletions, inversions and insertions. Variation can occur in either or both the coding and non-coding regions. The variations can produce both conservative and non-conservative amino acid substitutions (as compared in the encoded product).  
      Allelic variants result, for example, from DNA sequence polymorphisms within a population (e.g., the human population) that lead to changes in the amino acid sequences of the PLTR-1 proteins. Such genetic polymorphism in the PLTR-1 genes may exist among individuals within a population due to natural allelic variation. As used herein, the terms “gene” and “recombinant gene” refer to nucleic acid molecules which include an open reading frame encoding a PLTR-1 protein, preferably a mammalian PLTR-1 protein, and can further include non-coding regulatory sequences, and introns.  
      Accordingly, in one embodiment, the invention features isolated nucleic acid molecules which encode a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO:20, wherein the nucleic acid molecule hybridizes to a complement of a nucleic acid molecule comprising SEQ ID NO: 19 or 21, for example, under stringent hybridization conditions.  
      Allelic variants of PLTR-1, e.g., human PLTR-1, include both functional and non-functional PLTR-1 proteins. Functional allelic variants are naturally occurring amino acid sequence variants of the PLTR-1 protein that maintain the ability to, e.g., bind or interact with a PLTR-1 substrate or target molecule, transport a PLTR-1 substrate or target molecule (e.g., a phospholipid) across a cellular membrane, hydrolyze ATP, be phosphorylated or dephosphorylated, adopt an E1 conformation or an E2 conformation, and/or modulate cellular signaling, growth, proliferation, differentiation, absorption, or secretion. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO:20, or substitution, deletion or insertion of non-critical residues in non-critical regions of the protein.  
      Non-functional allelic variants are naturally occurring amino acid sequence variants of the PLTR-1 protein, e.g., human PLTR-1, that do not have the ability to, e.g., bind or interact with a PLTR-1 substrate or target molecule, transport a PLTR-1 substrate or target molecule (e.g., a phospholipid) across a cellular membrane, hydrolyze ATP, be phosphorylated or dephosphorylated, adopt an E1 conformation or an E2 conformation, and/or modulate cellular signaling, growth, proliferation, differentiation, absorption, or secretion. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion, or premature truncation of the amino acid sequence of SEQ ID NO:20, or a substitution, insertion, or deletion in critical residues or critical regions of the protein.  
      The present invention further provides non-human orthologues (e.g., non-human orthologues of the human PLTR-1 protein). Orthologues of the human PLTR-1 protein are proteins that are isolated from non-human organisms and possess the same PLTR-1 substrate or target molecule binding mechanisms, phospholipid transporting activity, ATPase activity, and/or modulation of cellular signaling mechanisms of the human PLTR-1 proteins. Orthologues of the human PLTR-1 protein can readily be identified as comprising an amino acid sequence that is substantially homologous to SEQ ID NO:20.  
      Moreover, nucleic acid molecules encoding other PLTR-1 family members and, thus, which have a nucleotide sequence which differs from the PLTR-1 sequences of SEQ ID NO: 19 or 21, are intended to be within the scope of the invention. For example, another PLTR-1 cDNA can be identified based on the nucleotide sequence of human PLTR-1. Moreover, nucleic acid molecules encoding PLTR-1 proteins from different species, and which, thus, have a nucleotide sequence which differs from the PLTR-1 sequences of SEQ ID NO: 19 or 21, are intended to be within the scope of the invention. For example, a mouse or monkey PLTR-1 cDNA can be identified based on the nucleotide sequence of a human PLTR-1.  
      Nucleic acid molecules corresponding to natural allelic variants and homologues of the PLTR-1 cDNAs of the invention can be isolated based on their homology to the PLTR-1 nucleic acids disclosed herein using the cDNAs disclosed herein, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions. Nucleic acid molecules corresponding to natural allelic variants and homologues of the PLTR-1 cDNAs of the invention can further be isolated by mapping to the same chromosome or locus as the PLTR-1 gene.  
      Orthologues, homologues and allelic variants can be identified using methods known in the art (e.g., by hybridization to an isolated nucleic acid molecule of the present invention, for example, under stringent hybridization conditions). In one embodiment, an isolated nucleic acid molecule of the invention is at least 15, 20, 25, 30 or more nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 19 or 21. In other embodiment, the nucleic acid is at least 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 676, 677, 689, 690, 691, 692, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1562, 1600, 1610, 1660, 1700, 1750, 1800, 1850, 1900, 1950, 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2373, 2374, 2375, 2400, 2450, 2500, 2550, 2600, 2650, 2700, 2750, 2800, 2850, 2900, 2950, 3000, 3050, 3063, 3064, 3100, 3150, 3200, 3250, 3300, 3350, 3400, 3450, 3500, 3550, 3600, 3650, 3700, 3750, 3753, 3754, 3800, 3850, 3900, 3950, 4000, 4050, 4100, 4150, 4200, 4250, 4300, 4350, 4400, 4450, 4500, 4550, 4600, 4650 or more nucleotides in length.  
      In one embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:27. The sequence of SEQ ID NO:27 corresponds to the human TFM-2 cDNA. This cDNA comprises sequences encoding the human TFM-2 polypeptide (i.e., “the coding region”, from nucleotides 615-1794) as well as 5′ untranslated sequences (nucleotides 1-614) and 3′ untranslated sequences (nucleotides 1795-3524). Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:27 (e.g., nucleotides 615-1794, corresponding to SEQ ID NO:29). Accordingly, in another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:29 and nucleotides 1-614 and 1795-3524 of SEQ ID NO:27. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:27 or SEQ ID NO:29.  
      In another embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:30. The sequence of SEQ ID NO:30 corresponds to the human TFM-3 cDNA. This cDNA comprises sequences encoding the human TFM-3 polypeptide (i.e., “the coding region”, from nucleotides 384-1602) as well as 5′ untranslated sequences (nucleotides 1-383) and 3′ untranslated sequences (nucleotides 1603-1855). Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:30 (e.g., nucleotides 384-1602, corresponding to SEQ ID NO:32). Accordingly, in another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:32 and nucleotides 1-383 and 1603-1855 of SEQ ID NO:30. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:30 or SEQ ID NO:32.  
      In still another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule which is a complement of the nucleotide sequence shown in SEQ ID NO:27, 29, 30, or 32, or a portion of any of these nucleotide sequences. A nucleic acid molecule which is complementary to the nucleotide sequence shown in SEQ ID NO:27, 29, 30, or 32, is one which is sufficiently complementary to the nucleotide sequence shown in SEQ ID NO:27, 29, 30, or 32, such that it can hybridize to the nucleotide sequence shown in SEQ ID NO:27, 29, 30, or 32, thereby forming a stable duplex.  
      In still another preferred embodiment, an isolated nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to the nucleotide sequence shown in SEQ ID NO:27, 29, 30, or 32 (e.g., to the entire length of the nucleotide sequence), or a portion of any of these nucleotide sequences. In one embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least (or no greater than) 50-100, 100-250, 250-500, 500-750, 750-1000, 1000-1250, 1250-1500, 1500-1750, 1750-2000, 2000-2250, 2250-2500, 2500-2750, 2750-3000, 3000-3250, 3250-3500 or more nucleotides in length and hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule of SEQ ID NO:27 or 29. In another embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least (or no greater than) 50-100, 100-250, 250-500, 500-750, 750-1000, 1000-1250, 1250-1500, 1500-1750, 1750-1850 or more nucleotides in length and hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule of SEQ ID NO:30 or 32.  
      Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NO:27, 29, 30, or 32, for example, a fragment which can be used as a probe or primer or a fragment encoding a portion of a TFM-2 and/or TFM-3 polypeptide, e.g., a biologically active portion of a TFM-2 and/or TFM-3 polypeptide. The nucleotide sequence determined from the cloning of the TFM-2 and/or TFM-3 gene allows for the generation of probes and primers designed for use in identifying and/or cloning other TFM-2 and/or TFM-3 family members, as well as TFM-2 and/or TFM-3 homologues from other species. The probe/primer typically comprises substantially purified oligonucleotide. The probe/primer (e.g., oligonucleotide) typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12 or 15, preferably about 20 or 25, more preferably about 30, 35, 40, 45, 50, 55, 60, 65, 75, 80, 85, 90, 95, or 100 or more consecutive nucleotides of a sense sequence of SEQ ID NO:27, 29, 30, or 32, of an anti-sense sequence of SEQ ID NO:27, 29, 30, or 32, or of a naturally occurring allelic variant or mutant of SEQ ID NO:27, 29, 30, or 32.  
      Exemplary probes or primers are at least 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or more nucleotides in length and/or comprise consecutive nucleotides of an isolated nucleic acid molecule described herein. Probes based on the TFM-2 and/or TFM-3 nucleotide sequences can be used to detect (e.g., specifically detect) transcripts or genomic sequences encoding the same or homologous polypeptides. In preferred embodiments, the probe further comprises a label group attached thereto, e.g., the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor. In another embodiment a set of primers is provided, e.g., primers suitable for use in a PCR, which can be used to amplify a selected region of a TFM-2 and/or TFM-3 sequence, e.g., a domain, region, site or other sequence described herein. The primers should be at least 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more nucleotides in length. Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress a TFM-2 and/or TFM-3 polypeptide, such as by measuring a level of a TFM-2 and/or TFM-3-encoding nucleic acid in a sample of cells from a subject e.g., detecting TFM-2 and/or TFM-3 mRNA levels or determining whether a genomic TFM-2 and/or TFM-3 gene has been mutated or deleted.  
      A nucleic acid fragment encoding a “biologically active portion of a TFM-2 polypeptide” and/or a “biologically active portion of a TFM-3 polypeptide” can be prepared by isolating a portion of the nucleotide sequence of SEQ ID NO:27, 29, 30, or 32, which encodes a polypeptide having a TFM-2 and/or TFM-3 biological activity (the biological activities of the TFM-2 and/or TFM-3 polypeptides are described herein), expressing the encoded portion of the TFM-2 and/or TFM-3 polypeptide (e.g., by recombinant expression in vitro) and assessing the activity of the encoded portion of the TFM-2 and/or TFM-3 polypeptide. In an exemplary embodiment, the nucleic acid molecule is at least 50-100, 100-250, 250-500, 500-750, 750-1000, 1000-1250, 1250-1500, 1500-1750, 1750-2000, 2000-2250, 2250-2500, 2500-2750, 2750-3000, 3000-3250, 3250-3500 or more nucleotides in length and encodes a polypeptide having a TFM-2 activity (as described herein). In another exemplary embodiment, the nucleic acid molecule is at least 50-100, 100-250, 250-500, 500-750, 750-1000, 1000-1250, 1250-1500, 1500-1750, 1750-1850 or more nucleotides in length and encodes a polypeptide having a TFM-3 activity (as described herein).  
      The invention further encompasses nucleic acid molecules that differ from the nucleotide sequence shown in SEQ ID NO:27, 29, 30, or 32. Such differences can be due to due to degeneracy of the genetic code, thus resulting in a nucleic acid which encodes the same TFM-2 and/or TFM-3 polypeptides as those encoded by the nucleotide sequence shown in SEQ ID NO:27, 29, 30, or 32. In another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a polypeptide having an amino acid sequence which differs by at least 1, but no greater than 5, 10, 20, 50 or 100 amino acid residues from the amino acid sequence shown in SEQ IfD NO:28 or 31. In yet another embodiment, the nucleic acid molecule encodes the amino acid sequence of human TFM-2 and TFM-3. If an alignment is needed for this comparison, the sequences should be aligned for maximum homology.  
      Nucleic acid variants can be naturally occurring, such as allelic variants (same locus), homologues (different locus), and orthologues (different organism) or can be non naturally occurring. Non-naturally occurring variants can be made by mutagenesis techniques, including those applied to polynucleotides, cells, or organisms. The variants can contain nucleotide substitutions, deletions, inversions and insertions. Variation can occur in either or both the coding and non-coding regions. The variations can produce both conservative and non-conservative amino acid substitutions (as compared in the encoded product).  
      Allelic variants result, for example, from DNA sequence polymorphisms within a population (e.g., the human population) that lead to changes in the amino acid sequences of the TFM-2 and/or TFM-3 polypeptides. Such genetic polymorphism in the TFM-2 and/or TFM-3 genes may exist among individuals within a population due to natural allelic variation. As used herein, the terms “gene” and “recombinant gene” refer to nucleic acid molecules which include an open reading frame encoding a TFM-2 and/or TFM-3 polypeptide, preferably a mammalian TFM-2 and/or TFM-3 polypeptide, and can further include non-coding regulatory sequences, and introns.  
      Accordingly, in one embodiment, the invention features isolated nucleic acid molecules which encode a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO:28 or 31, wherein the nucleic acid molecule hybridizes to a complement of a nucleic acid molecule comprising SEQ ID NO:27, 29, 30, or 32, for example, under stringent hybridization conditions.  
      Allelic variants of human TFM-2 and/or TFM-3 include both functional and non-functional TFM-2 and/or TFM-3 polypeptides. Functional allelic variants are naturally occurring amino acid sequence variants of the human TFM-2 and/or TFM-3 polypeptide that have a TFM-2 and/or TFM-3 activity, e.g., maintain the ability to bind a TFM-2 and/or TFM-3 ligand or substrate and/or modulate the import and export of molecules from cells or across membranes, e.g., monocarboxylates and/or monosaccharides. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO:28 or 31, or substitution, deletion or insertion of non-critical residues in non-critical regions of the polypeptide.  
      Non-functional allelic variants are naturally occurring amino acid sequence variants of the human TFM-2 and/or TFM-3 polypeptide that do not have a TFM-2 and/or TFM-3 activity, e.g., they do not have the ability to transport molecules into and out of cells or across membranes. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion or premature truncation of the amino acid sequence of SEQ ID NO:28 or 31, or a substitution, insertion or deletion in critical residues or critical regions.  
      The present invention further provides non-human orthologues of the human TFM-2 and/or TFM-3 polypeptide. Orthologues of human TFM-2 and/or TFM-3 polypeptides are polypeptides that are isolated from non-human organisms and possess the same TFM-2 and/or TFM-3 activity, e.g., ligand binding and/or modulation of import and export of molecules from cells or across membranes, e.g., monocarboxylates and/or monosaccharides, as the human TFM-2 and/or TFM-3 polypeptide. Orthologues of the human TFM-2 and/or TFM-3 polypeptide can readily be identified as comprising an amino acid sequence that is substantially identical to SEQ ID NO:28 or 31.  
      Moreover, nucleic acid molecules encoding other TFM-2 and/or TFM-3 family members and, thus, which have a nucleotide sequence which differs from the TFM-2 and/or TFM-3 sequences of SEQ ID NO:27, 29, 30, or 32, are intended to be within the scope of the invention. For example, another TFM-2 and/or TFM-3 cDNA can be identified based on the nucleotide sequence of human TFM-2 and/or TFM-3. Moreover, nucleic acid molecules encoding TFM-2 and/or TFM-3 polypeptides from different species, and which, thus, have a nucleotide sequence which differs from the TFM-2 and/or TFM-3 sequences of SEQ ID NO:27, 29, 30, or 32, are intended to be within the scope of the invention. For example, a mouse TFM-2 and/or TFM-3 cDNA can be identified based on the nucleotide sequence of a human TFM-2 and/or TFM-3.  
      Nucleic acid molecules corresponding to natural allelic variants and homologues of the TFM-2 and/or TFM-3 cDNAs of the invention can be isolated based on their homology to the TFM-2 and/or TFM-3 nucleic acids disclosed herein using the cDNAs disclosed herein, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions. Nucleic acid molecules corresponding to natural allelic variants and homologues of the TFM-2 and/or TFM-3 cDNAs of the invention can further be isolated by mapping to the same chromosome or locus as the TFM-2 and/or TFM-3 gene.  
      Orthologues, homologues and allelic variants can be identified using methods known in the art (e.g., by hybridization to an isolated nucleic acid molecule of the present invention, for example, under stringent hybridization conditions). In one embodiment, an isolated nucleic acid molecule of the invention is at least 15, 20, 25, 30 or more nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:27, 29, 30, or 32. In other embodiment, the nucleic acid is at least 100-150, 150-200, 200-250, 250-300, 300-350, 350-400, 400-450, 450-500, 500-550, 550-600, 600-650, 650-700, 700-750, 750-800, 800-850, 850-900, 900-950, 950-1000, 1000-1050, 1050-1100, 1100-1150, 1150-1200, 1200-1250, 1250-1300, 1300-1350, 1350-1400, 1400-1450, 1450-1500, 1500-1550, 1550-1600, 1600-1650, 1650-1700, 1700-1750, 1750-1800, 1800-1850, 1850-1900, 1900-1950, 1950-2000, 2000-2500, 2500-3000, 3000-3500 or more nucleotides in length. In other embodiment, the nucleic acid is at least 100-150, 150-200, 200-250, 250-300, 300-350, 350-400, 400-450, 450-500, 500-550, 550-600, 600-650, 650-700, 700-750, 750-800, 800-850, 850-900, 900-950, 950-1000, 1000-1050, 1050-1100, 1100-1150, 1150-1200, 1200-1250, 1250-1300, 1300-1350, 1350-1400, 1400-1450, 1450-1500, 1500-1550, 1550-1600, 1600-1650, 1650-1700, 1700-1750, 1750-1800, 1800-1850 or more nucleotides in length.  
      In one embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:33. The sequence of SEQ ID NO:33 corresponds to the human 67118 cDNA. This cDNA comprises sequences encoding the human 67118 polypeptide (i.e., “the coding region”, from nucleotides 94-3495) as well as 5′ untranslated sequences (nucleotides 1-83) and 3′ untranslated sequences (nucleotides 3486-7745). Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:33 (e.g., nucleotides 84-3485, corresponding to SEQ ID NO:35). Accordingly, in another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:35 and nucleotides.1-84 and 3486-7745 of SEQ ID NO:33. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:33 or 35.  
      In another embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:36. The sequence of SEQ ID NO:36 corresponds to the human 67067 cDNA. This cDNA comprises sequences encoding the human 67067 polypeptide (i.e., “the coding region”, from nucleotides 157-4920) as well as 5′ untranslated sequences (nucleotides 1-156) and 3′ untranslated sequences (nucleotides 4921-7205). Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:36 (e.g., nucleotides 157-4920, corresponding to SEQ ID NO:38). Accordingly, in another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:38 and nucleotides 1-156 and 4921-7205 of SEQ ID NO:36. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:36 or 38.  
      In still another embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:39 or 41. This cDNA comprises sequences encoding the human 62092 protein (e.g., the “coding region”, from nucleotides 357-845), as well as 5′ untranslated sequence (nucleotides 1-356) and 3′ untranslated sequences (nucleotides 846-978) of SEQ ID NO:39. Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:39 (e.g., nucleotides 357-845, corresponding to SEQ ID NO:41). Accordingly, in another embodiment, an isolated nucleic acid molecule of the invention comprises SEQ ID NO:41 and nucleotides 1-356 of SEQ ID NO:39. In yet another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:41 and nucleotides 846-978 of SEQ ID NO:39. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:39 or 41.  
      In still another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule which is a complement of the nucleotide sequence shown in SEQ ID NO:33, 35, 36, 38, 39, or 41, or a portion of any of these nucleotide sequences. A nucleic acid molecule which is complementary to the nucleotide sequence shown in SEQ ID NO:33, 35, 36, 38, 39, or 41, is one which is sufficiently complementary to the nucleotide sequence shown in SEQ ID NO:33, 35, 36, 38, 39, or 41, such that it can hybridize to the nucleotide sequence shown in SEQ ID NO:33, 35, 36, 38, 39, or 41, thereby forming a stable duplex.  
      In still another preferred embodiment, an isolated nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical to the nucleotide sequence shown in SEQ ID NO:33, 35, 36, 38, 39, or 41 (e.g., to the entire length of the nucleotide sequence), or a portion of any of these nucleotide sequences. In one embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least (or no greater than) 50-100, 100-250, 250-500, 500-750, 750-1000, 1000-1250, 1250-1500, 1500-1750, 1750-2000, 2000-2250, 2250-2500, 2500-2750, 2750-3000, 3000-3250, 3250-3500, 3500-3750, 3750-4000, 4000-4250, 4250-4500, 4500-4750, 4750-5000, 5000-5250, 5250-5500, 5500-5750, 5750-6000, 6000-6250, 6250-6500, 6500-6750, 6750-7000, 7000-7250, 7250-7500 or more nucleotides in length and hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule of SEQ ID NO:33, 35, 36, 38, 39, 41.  
      Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NO:33, 35, 36, 38, 39, 41, for example, a fragment which can be used as a probe or primer or a fragment encoding a portion of a 67118, 67067, and/or 62092 polypeptide, e.g., a biologically active portion of a 67118, 67067, and/or 62092 polypeptide. The nucleotide sequence determined from the cloning of the 67118, 67067, and/or 62092 gene allows for the generation of probes and primers designed for use in identifying and/or cloning other 67118, 67067, and/or 62092 family members, as well as 67118, 67067, and/or 62092 homologues from other species. The probe/primer typically comprises substantially purified oligonucleotide. The probe/primer (e.g., oligonucleotide) typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12 or 15, preferably about 20 or 25, more preferably about 30, 35, 40, 45, 50, 55, 60, 65, 75, 80, 85, 90, 95, or 100 or more consecutive nucleotides of a sense sequence of SEQ ID NO: 33, 35, 36, 38, 39, 41, of an anti-sense sequence of SEQ ID NO:33, 35, 36, 38, 39, 41, or of a naturally occurring allelic variant or mutant of SEQ ID NO:33, 35, 36, 38, 39, 41.  
      Exemplary probes or primers are at least 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or more nucleotides in length and/or comprise consecutive nucleotides of an isolated nucleic acid molecule described herein. Probes based on the 67118, 67067, and/or 62092 nucleotide sequences can be used to detect (e.g., specifically detect) transcripts or genomic sequences encoding the same or homologous polypeptides. In preferred embodiments, the probe further comprises a label group attached thereto, e.g., the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor. In another embodiment a set of primers is provided, e.g., primers suitable for use in a PCR, which can be used to amplify a selected region of a 67118, 67067, and/or 62092 sequence, e.g., a domain, region, site or other sequence described herein. The primers should be at least 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more nucleotides in length. Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress a 67118, 67067, and/or 62092 polypeptide, such as by measuring a level of a 67118, 67067, and/or 62092-encoding nucleic acid in a sample of cells from a subject e.g., detecting 67118, 67067, and/or 62092 mRNA levels or determining whether a genomic 67118, 67067, and/or 62092 gene has been mutated or deleted.  
      A nucleic acid fragment encoding a “biologically active portion of a 67118 polypeptide,” a “biologically active portion of a 67067 polypeptide,” or a “biologically active portion of a 62092 polypeptide,” can be prepared by isolating a portion of the nucleotide sequence of SEQ ID NO:33, 35, 36, 38, 39, 41, which encodes a polypeptide having a 67118, 67067, and/or 62092 biological activity (the biological activities of the 67118, 67067, and/or 62092 polypeptides are described herein), expressing the encoded portion of the 67118, 67067, and/or 62092 polypeptide (e.g., by recombinant expression in vitro) and assessing the activity of the encoded portion of the 67118, 67067, and/or 62092 polypeptide. In an exemplary embodiment, the nucleic acid molecule is at least 50-100, 100-250, 250-500, 500-750, 750-1000, 1000-1250, 1250-1500, 1500-1750, 1750-2000, 2000-2250, 2250-2500, 2500-2750, 2750-3000, 3000-3250, 3250-3500, 3500-3750, 3750-4000, 4000-4250, 4250-4500, 4500-4750, 4750-5000, 5000-5250, 5250-5500, 5500-5750, 5750-6000, 6000-6250, 6250-6500, 6500-6750, 6750-7000, 7000-7250, 7250-7500 or more nucleotides in length and encodes a polypeptide having a 67118, 67067, and/or 62092 activity (as described herein).  
      The invention further encompasses nucleic acid molecules that differ from the nucleotide sequence shown in SEQ ID NO:33, 35, 36, 38, 39, or 41. Such differences can be due to due to degeneracy of the genetic code, thus resulting in a nucleic acid which encodes the same 67118, 67067, and/or 62092 polypeptides as those encoded by the nucleotide sequence shown in SEQ ID NO:33, 35, 36, 38, 39, or 41. In another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a polypeptide having an amino acid sequence which differs by at least 1, but no greater than 5, 10, 20, 50 or 100 amino acid residues from the amino acid sequence shown in SEQ ID NO:34, 37, or 40. In yet another embodiment, the nucleic acid molecule encodes the amino acid sequence of human 67118, 67067, and/or 62092. If an alignment is needed for this comparison, the sequences should be aligned for maximum homology.  
      Nucleic acid variants can be naturally occurring, such as allelic variants (same locus), homologues (different locus), and orthologues (different organism) or can be non naturally occurring. Non-naturally occurring variants can be made by mutagenesis techniques, including those applied to polynucleotides, cells, or organisms. The variants can contain nucleotide substitutions, deletions, inversions and insertions. Variation can occur in either or both the coding and non-coding regions. The variations can produce both conservative and non-conservative amino acid substitutions (as compared in the encoded product).  
      Allelic variants result, for example, from DNA sequence polymorphisms within a population (e.g., the human population) that lead to changes in the amino acid sequences of the 67118, 67067, and/or 62092 polypeptides. Such genetic polymorphism in the 67118, 67067, and/or 62092 genes may exist among individuals within a population due to natural allelic variation. As used herein, the terms “gene” and “recombinant gene” refer to nucleic acid molecules which include an open reading frame encoding a 67118, 67067, and/or 62092 polypeptide, preferably a mammalian 67118, 67067, and/or 62092 polypeptide, and can further include non-coding regulatory sequences, and introns.  
      Accordingly, in one embodiment, the invention features isolated nucleic acid molecules which encode a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO:34, 37, or 40, wherein the nucleic acid molecule hybridizes to a complement of a nucleic acid molecule comprising SEQ ID NO:33, 35, 36, 38, 39, or 41, for example, under stringent hybridization conditions.  
      Allelic variants of human 67118, 67067, and/or 62092 include both functional and non-functional 67118, 67067, and/or 62092 polypeptides. Functional allelic variants are naturally occurring amino acid sequence variants of the human 67118 or 67067 polypeptide that have a 67118 or 67067 activity, e.g., bind or interact with a 67118 or 67067 substrate or target molecule, transport a 67118 or 67067 substrate or target molecule (e.g., a phospholipid) across a cellular membrane, hydrolyze ATP, be phosphorylated or dephosphorylated, adopt an E1 conformation or an E2 conformation, and/or modulate cellular signaling, growth, proliferation, differentiation, absorption, or secretion. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO:34 or 37, or substitution, deletion or insertion of non-critical residues in non-critical regions of the polypeptide. Functional allelic variants are naturally occurring amino acid sequence variants of the 62092 protein that maintain the ability to, e.g., bind or interact with a 62092 substrate or target molecule and/or modulate cellular signaling and/or gene transcription. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO:40, or substitution, deletion or insertion of non-critical residues in non-critical regions of the protein.  
      Non-functional allelic variants are naturally occurring amino acid sequence variants of the human 67118 or 67067 polypeptide that do not have a 67118 or 67067 activity, e.g., that do not have the ability to, e.g., bind or interact with a 67118 or 67067 substrate or target molecule, transport a 67118 or 67067 substrate or target molecule (e.g., a phospholipid) across a cellular membrane, hydrolyze ATP, be phosphorylated or dephosphorylated, adopt an E1 conformation or an E2 conformation, and/or modulate cellular signaling, growth, proliferation, differentiation, absorption, or secretion. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion or premature truncation of the amino acid sequence of SEQ ID NO:34 or 37, or a substitution, insertion or deletion in critical residues or critical regions. Moreover, non-functional allelic variants are naturally occurring amino acid sequence variants of the 62092 protein, e.g., human 62092, that do not have the ability to, e.g., bind or interact with a 62092 substrate or target molecule and/or modulate cellular signaling and/or gene transcription. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion, or premature truncation of the amino acid sequence of SEQ ID NO:40, or a substitution, insertion, or deletion in critical residues or critical regions of the protein.  
      The present invention further provides non-human orthologues of the human 67118, 67067, and/or 62092 polypeptides. Orthologues of human 67118 or 67067 polypeptides are polypeptides that are isolated from non-human organisms and possess the same 67118 or 67067 substrate or target molecule binding mechanisms, phospholipid transporting activity, ATPase activity, and/or modulation of cellular signaling mechanisms of the human PLTR proteins as the human 67118 or 67067 polypeptides. Orthologues of the human 67118 or 67067 polypeptides can readily be identified as comprising an amino acid sequence that is substantially identical to SEQ ID NO:34 or 37. Orthologues of the human 62092 protein are proteins that are isolated from non-human organisms and possess the same 62092 substrate or target molecule binding mechanisms and/or ability to modulate cellular signaling and/or gene transcription of the human 62092 protein. Orthologues of the human 62092 protein can readily be identified as comprising an amino acid sequence that is substantially homologous to SEQ ID NO:40.  
      Moreover, nucleic acid molecules encoding other 67118, 67067, and/or 62092 family members and, thus, which have a nucleotide sequence which differs from the 67118, 67067, and/or 62092 sequences of SEQ ID NO:33, 35, 36, 38, 39, or 41, are intended to be within the scope of the invention. For example, another 67118, 67067, and/or 62092 cDNA can be identified based on the nucleotide sequence of human 67118, 67067, and/or 62092. Moreover, nucleic acid molecules encoding 67118, 67067, and/or 62092 polypeptides from different species, and which, thus, have a nucleotide sequence which differs from the 67118, 67067, and/or 62092 sequences of SEQ ID NO:33, 35, 36, 38, 39, or 41, are intended to be within the scope of the invention. For example, a mouse 67118, 67067, and/or 62092 cDNA can be identified based on the nucleotide sequence of a human 67118, 67067, and/or 62092.  
      Nucleic acid molecules corresponding to natural allelic variants and homologues of the 67118, 67067, and/or 62092 cDNAs of the invention can be isolated based on their homology to the 67118, 67067, and/or 62092 nucleic acids disclosed herein using the cDNAs disclosed herein, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions. Nucleic acid molecules corresponding to natural allelic variants and homologues of the 67118, 67067, and/or 62092 cDNAs of the invention can further be isolated by mapping to the same chromosome or locus as the 67118, 67067, and/or 62092 gene.  
      Orthologues, homologues and allelic variants can be identified using methods known in the art (e.g., by hybridization to an isolated nucleic acid molecule of the present invention, for example, under stringent hybridization conditions). In one embodiment, an isolated nucleic acid molecule of the invention is at least 15, 20, 25, 30 or more nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:33, 35, 36, 38, 39, or 41. In other embodiment, the nucleic acid is at least 50-100, 100-250, 250-500, 500-750, 750-1000, 1000-1250, 1250-1500, 1500-1750, 1750-2000, 2000-2250, 2250-2500, 2500-2750, 2750-3000, 3000-3250, 3250-3500, 3500-3750, 3750-4000, 4000-4250, 4250-4500, 4500-4750, 4750-5000, 5000-5250, 5250-5500, 5500-5750, 5750-6000, 6000-6250, 6250-6500, 6500-6750, 6750-7000, 7000-7250, 7250-7500 or more nucleotides in length.  
      In one embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:51 or 53. This cDNA may comprise sequences encoding the human HAAT protein (e.g., the “coding region”, from nucleotides 69-1526), as well as 5′ untranslated sequence (nucleotides 1-68) and 3′ untranslated sequences (nucleotides 1527-2397) of SEQ ID NO:51. Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:51 (e.g., nucleotides 69-1526, corresponding to SEQ ID NO:53). Accordingly, in another embodiment, an isolated nucleic acid molecule of the invention comprises SEQ ID NO:53 and nucleotides 1-68 of SEQ ID NO:51. In yet another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:53 and nucleotides 1527-2397 of SEQ ID NO:51. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:51 or 53.  
      In still another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule which is a complement of the nucleotide sequence shown in SEQ ID NO:51 or 53, or a portion of any of these nucleotide sequences. A nucleic acid molecule which is complementary to the nucleotide sequence shown in SEQ ID NO:51 or 53, is one which is sufficiently complementary to the nucleotide sequence shown in SEQ ID NO:51 or 53, such that it can hybridize to the nucleotide sequence shown in SEQ ID NO:51 or 53, thereby forming a stable duplex.  
      In still another embodiment, an isolated nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least about 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to the nucleotide sequence shown in SEQ ID NO:51 or 53 (e.g., to the entire length of the nucleotide sequence), or a portion or complement of any of these nucleotide sequences. In one embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least (or no greater than) 50-100, 100-250, 250-500, 500-750, 750-1000, 1000-1250, 1250-1500, 1500-1750, 1750-2000, 2000-2250, 2250-2500, 2500-2750, 2750-3000 or more nucleotides in length and hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule of SEQ ID NO:51 or 53.  
      Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NO:51 or 53, for example, a fragment which can be used as a probe or primer or a fragment encoding a portion of a HAAT protein, e.g., a biologically active portion of a HAAT protein. The nucleotide sequence determined from the cloning of the HAAT gene allows for the generation of probes and primers designed for use in identifying and/or cloning other HAAT family members, as well as HAAT homologues from other species. The probe/primer (e.g., oligonucleotide) typically comprises substantially purified oligonucleotide. The oligonucleotide typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12 or 15, preferably about 20 or 25, more preferably about 30, 35, 40, 45, 50, 55, 60, 65, or 75 consecutive nucleotides of a sense sequence of SEQ ID NO:51 or 53, of an anti-sense sequence of SEQ ID NO:51 or 53, or of a naturally occurring allelic variant or mutant of SEQ ID NO:51 or 53. In another embodiment, a fragment comprises at least 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 100, 150, 200, 250, 300, 350, 400, 450, 475, 500, 550, 575, 600, 650 or more nucleic acids (e.g., contiguous or consecutive nucleotides) of the nucleotide sequence of SEQ ID NO:51 or 53, or of a naturally occurring allelic variant or mutant of SEQ ID NO:51 or 53.  
      Exemplary probes or primers are at least (or no greater than) 12 or 15, 20 or 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or more nucleotides in length and/or comprise consecutive nucleotides of an isolated nucleic acid molecule described herein. Also included within the scope of the present invention are probes or primers comprising contiguous or consecutive nucleotides of an isolated nucleic acid molecule described herein, but for the difference of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 bases within the probe or primer sequence. Probes based on the HAAT nucleotide sequences can be used to detect (e.g., specifically detect) transcripts or genomic sequences encoding the same or homologous proteins. In preferred embodiments, the probe further comprises a label group attached thereto, e.g., the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor. In another embodiment a set of primers is provided, e.g., primers suitable for use in a PCR, which can be used to amplify a selected region of a HAAT sequence, e.g., a domain, region, site or other sequence described herein. The primers should be at least 5, 10, or 50 base pairs in length and less than 100, or less than 200, base pairs in length. The primers should be identical, or differ by no greater than 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 bases when compared to a sequence disclosed herein or to the sequence of a naturally occurring variant. Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress a HAAT protein, such as by measuring a level of a HAAT-encoding nucleic acid in a sample of cells from a subject, e.g., detecting HAAT mRNA levels or determining whether a genomic HAAT gene has been mutated or deleted.  
      A nucleic acid fragment encoding a “biologically active portion of a HAAT protein” can be prepared by isolating a portion of the nucleotide sequence of SEQ ID NO:51 or 53, which encodes a polypeptide having a HAAT biological activity (the biological activities of the HAAT proteins are described herein), expressing the encoded portion of the HAAT protein (e.g., by recombinant expression in vitro) and assessing the activity of the encoded portion of the HAAT protein. In an exemplary embodiment, the nucleic acid molecule is at least 50-100, 100-250, 250-500, 500-700, 750-1000, 1000-1250, 1250-1500, 1500-1750, 1750-2000, 2000-2250, 2250-2400 or more nucleotides in length and encodes a protein having a HAAT activity (as described herein).  
      The invention further encompasses nucleic acid molecules that differ from the nucleotide sequence shown in SEQ ID NO:51 or 53, due to degeneracy of the genetic code and thus encode the same HAAT proteins as those encoded by the nucleotide sequence shown in SEQ ID NO:51 or 53. In another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a protein having an amino acid sequence which differs by at least 1, but no greater than 5, 10, 20, 50 or 100 amino acid residues from the amino acid sequence shown in SEQ ID NO:52. In yet another embodiment, the nucleic acid molecule encodes the amino acid sequence of human HAAT. If an alignment is needed for this comparison, the sequences should be aligned for maximum homology.  
      Nucleic acid variants can be naturally occurring, such as allelic variants (same locus), homologues (different locus), and orthologues (different organism) or can be non naturally occurring. Non-naturally occurring variants can be made by mutagenesis techniques, including those applied to polynucleotides, cells, or organisms. The variants can contain nucleotide substitutions, deletions, inversions and insertions. Variation can occur in either or both the coding and non-coding regions. The variations can produce both conservative and non-conservative amino acid substitutions (as compared in the encoded product).  
      Allelic variants result, for example, from DNA sequence polymorphisms within a population (e.g., the human population) that lead to changes in the amino acid sequences of the HAAT proteins. Such genetic polymorphism in the HAAT genes may exist among individuals within a population due to natural allelic variation. As used herein, the terms “gene” and “recombinant gene” refer to nucleic acid molecules which include an open reading frame encoding a HAAT protein, preferably a mammalian HAAT protein, and can further include non-coding regulatory sequences, and introns.  
      Accordingly, in one embodiment, the invention features isolated nucleic acid molecules which encode a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO:52, wherein the nucleic acid molecule hybridizes to a complement of a nucleic acid molecule comprising SEQ ID NO:51 or 53, for example, under stringent hybridization conditions.  
      Allelic variants of HAAT, e.g., human HAAT, include both functional and non-functional HAAT proteins. Functional allelic variants are naturally occurring amino acid sequence variants of the HAAT protein that maintain the ability to, e.g., bind or interact with a HAAT substrate or target molecule, transport a HAAT substrate or target molecule (e.g., an amino acid) across a cellular membrane and/or modulate protein synthesis, hormone metabolism, nerve transmission, cellular activation, regulation of cell growth, production of metabolic energy, synthesis of purines and pyrimidines, nitrogen metabolism, and/or biosynthesis of urea. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO:52, or substitution, deletion or insertion of non-critical residues in non-critical regions of the protein.  
      Non-functional allelic variants are naturally occurring amino acid sequence variants of the HAAT protein, e.g., human HAAT, that do not have the ability to, e.g., bind or interact with a HAAT substrate or target molecule, transport a HAAT substrate or target molecule (e.g., an amino acid) across a cellular membrane and/or modulate protein synthesis, hormone metabolism, nerve transmission, cellular activation, regulation of cell growth, production of metabolic energy, synthesis of purines and pyrimidines, nitrogen metabolism, and/or biosynthesis of urea. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion, or premature truncation of the amino acid sequence of SEQ ID NO:52, or a substitution, insertion, or deletion in critical residues or critical regions of the protein.  
      The present invention further provides non-human orthologues (e.g., non-human orthologues of the human HAAT protein). Orthologues of the human HAAT protein are proteins that are isolated from non-human organisms and possess the same HAAT substrate or target molecule binding mechanisms, amino acid transporting activity and/or modulation of nitrogen metabolism mechanisms of the human HAAT proteins. Orthologues of the human HAAT protein can readily be identified as comprising an amino acid sequence that is substantially homologous to SEQ ID NO:52.  
      Moreover, nucleic acid molecules encoding other HAAT family members and, thus, which have a nucleotide sequence which differs from the HAAT sequences of SEQ ID NO:51 or 53, are intended to be within the scope of the invention. For example, another HAAT cDNA can be identified based on the nucleotide sequence of human HAAT. Moreover, nucleic acid molecules encoding HAAT proteins from different species, and which, thus, have a nucleotide sequence which differs from the HAAT sequences of SEQ ID NO:51 or 53, are intended to be within the scope of the invention. For example, a mouse or monkey HAAT cDNA can be identified based on the nucleotide sequence of a human HAAT.  
      Nucleic acid molecules corresponding to natural allelic variants and homologues of the HAAT cDNAs of the invention can be isolated based on their homology to the HAAT nucleic acids disclosed herein using the cDNAs disclosed herein, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions. Nucleic acid molecules corresponding to natural allelic variants and homologues of the HAAT cDNAs of the invention can further be isolated by mapping to the same chromosome or locus as the HAAT gene.  
      Orthologues, homologues and allelic variants can be identified using methods known in the art (e.g., by hybridization to an isolated nucleic acid molecule of the present invention, for example, under stringent hybridization conditions). In one embodiment, an isolated nucleic acid molecule of the invention is at least 15, 20, 25, 30 or more nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:51 or 53. In other embodiment, the nucleic acid is at least 50-100, 100-250, 250-500, 500-700, 750-1000, 1000-1250, 1250-1500, 1500-1750, 1750-2000, 2000-2250, 2250-2400 or more nucleotides in length (e.g., 2397 nucleotides in length).  
      In one embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:54. The sequence of SEQ ID NO:54 corresponds to the human HST-4 cDNA. This cDNA comprises sequences encoding the human HST-4 polypeptide (i.e., “the coding region”, from nucleotides 137-1450) as well as 5′ untranslated sequences (nucleotides 1-136) and 3′ untranslated sequences (nucleotides 1451-2565). Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:54 (e.g., nucleotides 137-1450, corresponding to SEQ ID NO:56). Accordingly, in another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:56 and nucleotides 1-136 and 1451-2565 of SEQ ID NO:54. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:54 or SEQ ID NO:56.  
      In another embodiment, an isolated nucleic acid molecule of the invention comprises the nucleotide sequence shown in SEQ ID NO:57. The sequence of SEQ ID NO:57 corresponds to the human HST-5 cDNA. This cDNA comprises sequences encoding the human HST-5 polypeptide (i.e., “the coding region”, from nucleotides 137-1444) as well as 5′ untranslated sequences (nucleotides 1-136) and 3′ untranslated sequences (nucleotides 1445-2558). Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NO:57 (e.g., nucleotides 137-1444, corresponding to SEQ ID NO:59). Accordingly, in another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:59 and nucleotides 1-136 and 1445-2558 of SEQ ID NO:57. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NO:57 or SEQ ID NO:59.  
      In still another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule which is a complement of the nucleotide sequence shown in SEQ ID NO:54, 56, 57, or 59, or a portion of any of these nucleotide sequences. A nucleic acid molecule which is complementary to the nucleotide sequence shown in SEQ ID NO:54, 56, 57, or 59, is one which is sufficiently complementary to the nucleotide sequence shown in SEQ ID NO:54, 56, 57, or 59, such that it can hybridize to the nucleotide sequence shown in SEQ ID NO:54, 56, 57, or 59, thereby forming a stable duplex.  
      In still another preferred embodiment, an isolated nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical to the nucleotide sequence shown in SEQ ID NO:54, 56, 57, or 59 (e.g., to the entire length of the nucleotide sequence), or a portion of any of these nucleotide sequences. In one embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least 10, 20, 30, 40, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500 or more nucleotides in length and hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule of SEQ ID NO:54, 56, 57, or 59. In another embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least 10, 20, 30, 40, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500 or more nucleotides in length and hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule of SEQ ID NO:54, 56, 57, or 59.  
      Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NO:54, 56, 57, or 59, for example, a fragment which can be used as a probe or primer or a fragment encoding a portion of an HST-4 and/or HST-5 polypeptide, e.g., a biologically active portion of an HST-4 and/or HST-5 polypeptide. The nucleotide sequence determined from the cloning of the HST-4 and/or HST-5 gene allows for the generation of probes and primers designed for use in identifying and/or cloning other HST-4 and/or HST-5 family members, as well as HST-4 and/or HST-5 homologues from other species. The probe/primer typically comprises substantially purified oligonucleotide. The probe/primer (e.g., oligonucleotide) typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12 or 15, preferably about 20 or 25, more preferably about 30, 35, 40, 45, 50, 55, 60, 65, 75, 80, 85, 90, 95, or 100 or more consecutive nucleotides of a sense sequence of SEQ ID NO:54, 56, 57, or 59, of an anti-sense sequence of SEQ ID NO:54, 56, 57, or 59, or of a naturally occurring allelic variant or mutant of SEQ ID NO:54, 56, 57, or 59.  
      Exemplary probes or primers are at least 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or more nucleotides in length and/or comprise consecutive nucleotides of an isolated nucleic acid molecule described herein. Probes based on the HST-4 and/or HST-5 nucleotide sequences can be used to detect (e.g., specifically detect) transcripts or genomic sequences encoding the same or homologous polypeptides. In preferred embodiments, the probe further comprises a label group attached thereto, e.g., the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor. In another embodiment a set of primers is provided, e.g., primers suitable for use in a PCR, which can be used to amplify a selected region of an HST-4 and/or HST-5 sequence, e.g., a domain, region, site or other sequence described herein. The primers should be at least 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more nucleotides in length. Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress an HST-4 and/or HST-5 polypeptide, such as by measuring a level of an HST-4 and/or HST-5-encoding nucleic acid in a sample of cells from a subject e.g., detecting HST-4 and/or HST-5 mRNA levels or determining whether a genomic HST-4 and/or HST-5 gene has been mutated or deleted.  
      A nucleic acid fragment encoding a “biologically active portion of an HST-4 polypeptide” or a “biologically active portion of an HST-5 polypeptide” can be prepared by isolating a portion of the nucleotide sequence of SEQ ID NO:54, 56, 57, or 59, which encodes a polypeptide having an HST-4 and/or HST-5 biological activity (the biological activities of the HST-4 and/or HST-5 polypeptides are described herein), expressing the encoded portion of the HST-4 and/or HST-5 polypeptide (e.g., by recombinant expression in vitro) and assessing the activity of the encoded portion of the HST-4 and/or HST-5 polypeptide. In an exemplary embodiment, the nucleic acid molecule is at least 10, 20, 30, 40, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500 or more nucleotides in length and encodes a polypeptide having an HST-4 activity (as described herein). In another exemplary embodiment, the nucleic acid molecule is at least 10, 20, 30, 40, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500 or more nucleotides in length and encodes a polypeptide having an HST-5 activity (as described herein).  
      The invention further encompasses nucleic acid molecules that differ from the nucleotide sequence shown in SEQ ID NO:54, 56, 57, or 59. Such differences can be due to due to degeneracy of the genetic code, thus resulting in a nucleic acid which encodes the same HST-4 and/or HST-5 polypeptides as those encoded by the nucleotide sequence shown in SEQ ID NO:54, 56, 57, or 59. In another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a polypeptide having an amino acid sequence which differs by at least 1, but no greater than 5, 10, 20, 50 or 100 amino acid residues from the amino acid sequence shown in SEQ ID NO:55 or 58. In yet another embodiment, the nucleic acid molecule encodes the amino acid sequence of human HST-4 and/or HST-5. If an alignment is needed for this comparison, the sequences should be aligned for maximum homology.  
      Nucleic acid variants can be naturally occurring, such as allelic variants (same locus), homologues (different locus), and orthologues (different organism) or can be non naturally occurring. Non-naturally occurring variants can be made by mutagenesis techniques, including those applied to polynucleotides, cells, or organisms. The variants can contain nucleotide substitutions, deletions, inversions and insertions. Variation can occur in either or both the coding and non-coding regions. The variations can produce both conservative and non-conservative amino acid substitutions (as compared in the encoded product).  
      Allelic variants result, for example, from DNA sequence polymorphisms within a population (e.g., the human population) that lead to changes in the amino acid sequences of the HST-4 and/or HST-5 polypeptides. Such genetic polymorphism in the HST-4 and/or HST-5 genes may exist among individuals within a population due to natural allelic variation. As used herein, the terms “gene” and “recombinant gene” refer to nucleic acid molecules which include an open reading frame encoding an HST-4 and/or HST-5 polypeptide, preferably a mammalian HST-4 and/or HST-5 polypeptide, and can further include non-coding regulatory sequences, and introns.  
      Accordingly, in one embodiment, the invention features isolated nucleic acid molecules which encode a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO:55 or 58, wherein the nucleic acid molecule hybridizes to a complement of a nucleic acid molecule comprising SEQ ID NO:54, 56, 57, or 59 for example, under stringent hybridization conditions.  
      Allelic variants of human HST-4 and/or HST-5 include both functional and non-functional HST-4 and/or HST-5 polypeptides. Functional allelic variants are naturally occurring amino acid sequence variants of the human HST-4 and/or HST-5 polypeptide that have an HST-4 and/or HST-5 activity, e.g., maintain the ability to bind an HST-4 and/or HST-5 ligand or substrate and/or modulate sugar transport, or sugar homeostasis. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO:55 or 58, or substitution, deletion or insertion of non-critical residues in non-critical regions of the polypeptide.  
      Non-functional allelic variants are naturally occurring amino acid sequence variants of the human HST-4 and/or HST-5 polypeptide that do not have an HST-4 and/or HST-5 activity, e.g., they do not have the ability to transport sugars into and out of cells or to modulate sugar homeostasis. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion or premature truncation of the amino acid sequence of SEQ ID NO:55 or 58, or a substitution, insertion or deletion in critical residues or critical regions.  
      The present invention further provides non-human orthologues of the human HST-4 and/or HST-5 polypeptide. Orthologues of human HST-4 and/or HST-5 polypeptides are polypeptides that are isolated from non-human organisms and possess the same HST-4 and/or HST-5 activity, e.g., ligand binding and/or modulation of sugar transport mechanisms, as the human HST-4 and/or HST-5 polypeptide. Orthologues of the human HST-4 and/or HST-5 polypeptide can readily be identified as comprising an amino acid sequence that is substantially identical to SEQ ID NO:55 or 58.  
      Moreover, nucleic acid molecules encoding other HST-4 and/or HST-5 family members and, thus, which have a nucleotide sequence which differs from the HST-4 and/or HST-5 sequences of SEQ ID NO:54, 56, 57, or 59, are intended to be within the scope of the invention. For example, another HST-4 and/or HST-5 cDNA can be identified based on the nucleotide sequence of human HST-4 and/or HST-5. Moreover, nucleic acid molecules encoding HST-4 and/or HST-5 polypeptides from different species, and which, thus, have a nucleotide sequence which differs from the HST-4 and/or HST-5 sequences of SEQ ID NO:54, 56, 57, or 59, are intended to be within the scope of the invention. For example, a mouse HST-4 and/or HST-5 cDNA can be identified based on the nucleotide sequence of a human HST-4 and/or HST-5.  
      Nucleic acid molecules corresponding to natural allelic variants and homologues of the HST-4 and/or HST-5 cDNAs of the invention can be isolated based on their homology to the HST-4 and/or HST-5 nucleic acids disclosed herein using the cDNAs disclosed herein, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions. Nucleic acid molecules corresponding to natural allelic variants and homologues of the HST-4 and/or HST-5 cDNAs of the invention can further be isolated by mapping to the same chromosome or locus as the HST-4 and/or HST-5 gene.  
      Orthologues, homologues and allelic variants can be identified using methods known in the art (e.g., by hybridization to an isolated nucleic acid molecule of the present invention, for example, under stringent hybridization conditions). In one embodiment, an isolated nucleic acid molecule of the invention is at least 15, 20, 25, 30 or more nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:54, 56, 57, or 59. In other embodiment, the nucleic acid is at least 10, 20, 30, 40, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500 or more nucleotides in length.  
      As used herein, the term “hybridizes under stringent conditions” is intended to describe conditions for hybridization and washing under which nucleotide sequences that are significantly identical or homologous to each other remain hybridized to each other. Preferably, the conditions are such that sequences at least about 70%, more preferably at least about 80%, even more preferably at least about 85% or 90% identical to each other remain hybridized to each other. Such stringent conditions are known to those skilled in the art and can be found in  Current Protocols in Molecular Biology,  Ausubel et al., eds., John Wiley &amp; Sons, Inc. (1995), sections 2, 4 and 6. Additional stringent conditions can be found in  Molecular Cloning: A Laboratory Manual, Sambrook  et al., Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1989), chapters 7, 9 and 11. A preferred, non-limiting example of stringent hybridization conditions includes hybridization in 4× sodium chloride/sodium citrate (SSC), at about 65-70° C. (or hybridization in 4×SSC plus 50% formamide at about 42-50° C.) followed by one or more washes in 1×SSC, at about 65-70° C. A preferred, non-limiting example of highly stringent hybridization conditions includes hybridization in 1×SSC, at about 65-70° C. (or hybridization in 1×SSC plus 50% formamide at about 42-50° C.) followed by one or more washes in 0.3×SSC, at about 65-70° C. A preferred, non-limiting example of reduced stringency hybridization conditions includes hybridization in 4×SSC, at about 50-60° C. (or alternatively hybridization in 6×SSC plus 50% formamide at about 40-45° C.) followed by one or more washes in 2×SSC, at about 50-60° C. Ranges intermediate to the above-recited values, e.g., at 65-70° C. or at 42-50° C. are also intended to be encompassed by the present invention. SSPE (1×SSPE is 0.15M NaCl, 10 mM NaH 2 PO 4 , and 1.25 mM EDTA, pH 7.4) can be substituted for SSC (1×SSC is 0.15M NaCl and 15 mM sodium citrate) in the hybridization and wash buffers; washes are performed for 15 minutes each after hybridization is complete. The hybridization temperature for hybrids anticipated to be less than 50 base pairs in length should be 5-10° C. less than the melting temperature (T m ) of the hybrid, where T m  is determined according to the following equations. For hybrids less than 18 base pairs in length, T m (° C.)=2(# of A+T bases)+4(# of G+C bases). For hybrids between 18 and 49 base pairs in length, T m (° C.)=81.5+16.6(log 10 [Na + ])+0.41(% G+C)−(600/N), where N is the number of bases in the hybrid, and [Na + ] is the concentration of sodium ions in the hybridization buffer ([Na + ] for 1×SSC=0.165 M). It will also be recognized by the skilled practitioner that additional reagents may be added to hybridization and/or wash buffers to decrease non-specific hybridization of nucleic acid molecules to membranes, for example, nitrocellulose or nylon membranes, including but not limited to blocking agents (e.g., BSA or salmon or herring sperm carrier DNA), detergents (e.g., SDS), chelating agents (e.g., EDTA), Ficoll, PVP and the like. When using nylon membranes, in particular, an additional preferred, non-limiting example of stringent hybridization conditions is hybridization in 0.25-0.5M NaH 2 PO 4 , 7% SDS at about 65° C., followed by one or more washes at 0.02M NaH 2 PO 4 , 1% SDS at 65° C., see e.g., Church and Gilbert (1984)  Proc. Natl. Acad. Sci. USA  81:1991-1995, (or alternatively 0.2×SSC, 1% SDS).  
      Preferably, an isolated nucleic acid molecule of the invention that hybridizes under stringent conditions to the sequence of SEQ ID NO:1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57, or 59, and corresponds to a naturally-occurring nucleic acid molecule. As used herein, a “naturally-occurring” nucleic acid molecule refers to an RNA or DNA molecule having a nucleotide sequence that occurs in nature (e.g., encodes a natural polypeptide).  
      In addition to naturally-occurring allelic variants of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 sequences that may exist in the population, the skilled artisan will further appreciate that changes can be introduced by mutation into the nucleotide sequences of SEQ ID NO:1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57, or 59, thereby leading to changes in the amino acid sequence of the encoded MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, without altering the functional ability of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptides. For example, nucleotide substitutions leading to amino acid substitutions at “non-essential” amino acid residues can be made in the sequence of SEQ ID NO:1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57, or 59. A “non-essential” amino acid residue is a residue that can be altered from the wild-type sequence of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 (e.g., the sequences of SEQ ID NO:2, 5, 8, 13, 16, 20, 28, 31, 34, 37, 40, 52, 55 and/or 58) without altering the biological activity, whereas an “essential” amino acid residue is required for biological activity. For example, amino acid residues that are conserved among the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptides of the present invention, e.g., those present in a transmembrane domain and/or a sugar transporter family domain, are predicted to be particularly unamenable to alteration. Furthermore, additional amino acid residues that are conserved between the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptides of the present invention and other members of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 family are not likely to be amenable to alteration.  
      Accordingly, another aspect of the invention pertains to nucleic acid molecules encoding OAT, HST-1, or PLTR-1, proteins that contain changes in amino acid residues that are not essential for activity. Such OAT proteins differ in amino acid sequence from SEQ ID NO:5, 8, 13, or 20, yet retain biological activity. In one embodiment, the isolated nucleic acid molecule comprises a nucleotide sequence encoding a protein, wherein the protein comprises an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to SEQ ID NO:5, 8, 13, or 20, e.g., to the entire length of SEQ ID NO:5, 8, 13, or 20.  
      Accordingly, another aspect of the invention pertains to nucleic acid molecules encoding MTP-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides that contain changes in amino acid residues that are not essential for activity. Such MTP-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides differ in amino acid sequence from SEQ ID NO:2, 16, 28, 31, 34, 37, 40, 52, 55 or 58, yet retain biological activity. In one embodiment, the isolated nucleic acid molecule comprises a nucleotide sequence encoding a polypeptide, wherein the polypeptide comprises an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical to SEQ ID NO:2, 16, 28, 31, 34, 37, 40, 52, 55 or 58 (e.g., to the entire length of SEQ ID NO:2, 16, 28, 31, 34, 37, 40, 52, 55 or 58).  
      An isolated nucleic acid molecule encoding an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide identical to the polypeptide of SEQ ID NO:2, 5, 8, 13, 16, 20, 28, 31, 34, 37, 40, 52, 55 or 58, can be created by introducing one or more nucleotide substitutions, additions or deletions into the nucleotide sequence of SEQ ID NO:1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57, or 59, such that one or more amino acid substitutions, additions or deletions are introduced into the encoded polypeptide. Mutations can be introduced into SEQ ID NO:1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57, or 59, by standard techniques, such as site-directed mutagenesis and PCR-mediated mutagenesis. Preferably, conservative amino acid substitutions are made at one or more predicted non-essential amino acid residues. A “conservative amino acid substitution” is one in which the amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine, tryptophan), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Thus, a predicted nonessential amino acid residue in an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide is preferably replaced with another amino acid residue from the same side chain family. Alternatively, in another embodiment, mutations can be introduced randomly along all or part of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 coding sequence, such as by saturation mutagenesis, and the resultant mutants can be screened for MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 biological activity to identify mutants that retain activity. Following mutagenesis of SEQ ID NO:1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57, or 59, the encoded polypeptide can be expressed recombinantly and the activity of the polypeptide can be determined.  
      In a preferred embodiment, a mutant MTP-1 protein can be assayed for the ability to metabolize or catabolize biochemical molecules necessary for energy production or storage, permit intra- or intercellular signaling, metabolize or catabolize metabolically important biomolecules, and to detoxify potentially harmful compounds, or to facilitate the compartmentalization of these molecules into a sequestered intracellular space (e.g., the peroxisome).  
      In a preferred embodiment, a mutant OAT protein can be assayed for the ability to (i) interact with an OAT substrate or target molecule; (ii) transport an OAT substrate across a membrane; (iii) interact with and/or modulation of a second non-OAT protein; (iv) modulate cellular signaling and/or gene transcription (e.g., either directly or indirectly); (v) protect cells and/or tissues from organic anions; and/or (vi) modulate hormonal responses.  
      In a preferred embodiment, a mutant HST-1 polypeptide can be assayed for the ability to (1) maintain sugar homeostasis in a cell, (2) influence insulin and/or glucagon secretion, (3) bind a monosaccharide, e.g., D-glucose, D-fructose, and/or D-galactose, and (4) transport monosaccharides across a cell membrane.  
      In a preferred embodiment, a mutant TP-2 polypeptide can be assayed for the ability to 1) modulate the import and export of molecules, e.g., hormones, ions, cytokines, neurotransmitters, monosaccharides, and metabolites, from cells, 2) modulate intra- or inter-cellular signaling, 3) modulate removal of potentially harmful compounds from the cell, or facilitate the compartmentalization of these molecules into a sequestered intra-cellular space (e.g., the peroxisome), and 4) modulate transport of biological molecules across membranes, e.g., the plasma membrane, or the membrane of the mitochondrion, the peroxisome, the lysosome, the endoplasmic reticulum, the nucleus, or the vacuole.  
      In a preferred embodiment, a mutant PLTR-1 protein can be assayed for the ability to (i) interact with a PLTR-1 substrate or target molecule (e.g., a phospholipid, ATP, or a non-PLTR-1 protein); (ii) transport a PLTR-1 substrate or target molecule (e.g., an aminophospholipid such as phosphatidylserine or phosphatidylethanolamine) from one side of a cellular membrane to the other; (iii) be phosphorylated or dephosphorylated; (iv) adopt an E1 conformation or an E2 conformation; (v) convert a PLTR-1 substrate or target molecule to a product (e.g., hydrolysis of ATP); (vi) interact with a second non-PLTR-1 protein; (vii) modulate substrate or target molecule location (e.g., modulation of phospholipid location within a cell and/or location with respect to a cellular membrane); (viii) maintain aminophospholipid gradients; (ix) modulate blood coagulation; (x) modulate intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (xi) modulate cellular proliferation, growth, differentiation, apoptosis, absorption, or secretion.  
      In a preferred embodiment, a mutant TFM-2 and/or TFM-3 polypeptide can be assayed for the ability to 1) modulate the import and export of molecules, e.g., hormones, ions, cytokines, neurotransmitters, monocarboxylates monosaccharides, and metabolites, from cells, 2) modulate intra- or inter-cellular signaling, 3) modulate removal of potentially harmful compounds from the cell, or facilitate the compartmentalization of these molecules into a sequestered intra-cellular space (e.g., the peroxisome), and 4) modulate transport of biological molecules across membranes, e.g., the plasma membrane, or the membrane of the mitochondrion, the peroxisome, the lysosome, the endoplasmic reticulum, the nucleus, or the vacuole.  
      In a preferred embodiment, a mutant 67118 or 67067 polypeptide can be assayed for the ability to (i) interact with a 67118 or 67067 substrate or target molecule (e.g., a phospholipid, ATP, or a non-67118 or -67067 protein); (ii) transport a 67118 or 67067 substrate or target molecule (e.g., an aminophospholipid such as phosphatidylserine or phosphatidylethanolamine) from one side of a cellular membrane to the other; (iii) be phosphorylated or dephosphorylated; (iv) adopt an El conformation or an E2 conformation; (v) convert a 67118 or 67067 substrate or target molecule to a product (e.g., hydrolysis of ATP); (vi) interact with a second non-67118 or -67067 protein; (vii) modulate substrate or target molecule location (e.g., modulation of phospholipid location within a cell and/or location with respect to a cellular membrane); (viii) maintain aminophospholipid gradients; (ix) modulate intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (x) modulate cellular proliferation, growth, differentiation, apoptosis, absorption, or secretion.  
      In another preferred embodiment, a mutant 62092 protein can be assayed for the ability to (i) interact with a 62092 substrate or target molecule (e.g., a nucleotide such as a purine mononucleotide or a dinucleoside polyphosphate, or a non-62092 protein); (ii) convert a 62092 substrate or target molecule to a product (e.g., cleave a dinucleoside polyphosphate); (iii) interact with a second non-62092 protein; (iv) sense of cellular stress signals; (v) regulate substrate or target molecule availability or activity; (vi) modulate intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (vii) modulate cellular proliferation, growth, differentiation, and/or apoptosis.  
      In a preferred embodiment, a mutant HAAT protein can be assayed for the ability to (i) interact with a HAAT substrate or target molecule (e.g., an amino acid); (ii) transport a HAAT substrate or target molecule (e.g., an amino acid) from one side of a cellular membrane to the other; (iii) convert a HAAT substrate or target molecule to a product (e.g., glucose production); (iv) interact with a second non-HAAT protein; (v) modulate substrate or target molecule location (e.g., modulation of amino acid location within a cell and/or location with respect to a cellular membrane); (vi) maintain amino acid gradients; (vii) modulate hormone metabolism and/or nerve transmission (e.g., either directly or indirectly); and/or (viii) modulate cellular proliferation, growth, differentiation, and production of metabolic energy.  
      In a preferred embodiment, a mutant HST-4 and/or HST-5 polypeptide can be assayed for the ability to (1) bind a monosaccharide, e.g., D-glucose, D-fructose, D-galactose, and/or mannose; (2) transport monosaccharides across a cell membrane, (3) influence insulin and/or glucagon secretion; (4) maintain sugar homeostasis in a cell; and (5) mediate trans-epithelial movement in a cell.  
      In addition to the nucleic acid molecules encoding MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides described above, another aspect of the invention pertains to isolated nucleic acid molecules which are antisense thereto. In an exemplary embodiment, the invention provides an isolated nucleic acid molecule which is antisense to an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acid molecule (e.g., is antisense to the coding strand of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acid molecule). An “antisense” nucleic acid comprises a nucleotide sequence which is complementary to a “sense” nucleic acid encoding a polypeptide, e.g., complementary to the coding strand of a double-stranded cDNA molecule or complementary to an mRNA sequence. Accordingly, an antisense nucleic acid can hydrogen bond to a sense nucleic acid. The antisense nucleic acid can be complementary to an entire MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 coding strand, or to only a portion thereof. In one embodiment, an antisense nucleic acid molecule is antisense to a “coding region” of the coding strand of a nucleotide sequence encoding MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5. The term “coding region” refers to the region of the nucleotide sequence comprising codons which are translated into amino acid residues (e.g., the coding regions of human MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and HST-5 correspond to SEQ ID NO:3, 6, 9, 14, 17, 21, 29, 32, 35, 38, 41, 53, 56, and 59, respectively). In another embodiment, the antisense nucleic acid molecule is antisense to a “noncoding region” of the coding strand of a nucleotide sequence encoding MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5. The term “noncoding region” refers to 5′ and 3′ sequences which flank the coding region that are not translated into amino acids (i.e., also referred to as 5′ and 3′ untranslated regions).  
      Given the coding strand sequences encoding MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 disclosed herein (e.g., SEQ I) NO:3, 6, 9, 14, 17, 21, 29, 32, 35, 38, 41, 53, 56, and 59, respectively), antisense nucleic acids of the invention can be designed according to the rules of Watson and Crick base pairing. The antisense nucleic acid molecule can be complementary to the entire coding region of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA, but more preferably is an oligonucleotide which is antisense to only a portion of the coding or noncoding region of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA. For example, the antisense oligonucleotide can be complementary to the region surrounding the translation start site of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA (e.g., between the −10 and +10 regions of the start site of a gene nucleotide sequence). An antisense oligonucleotide can be, for example, about 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50 nucleotides in length. An antisense nucleic acid of the invention can be constructed using chemical synthesis and enzymatic ligation reactions using procedures known in the art. For example, an antisense nucleic acid (e.g., an antisense oligonucleotide) can be chemically synthesized using naturally occurring nucleotides or variously modified nucleotides designed to increase the biological stability of the molecules or to increase the physical stability of the duplex formed between the antisense and sense nucleic acids, e.g., phosphorothioate derivatives and acridine substituted nucleotides can be used. Examples of modified nucleotides which can be used to generate the antisense nucleic acid include 5-fluorouracil, 5-bromouracil, 5-chlorouracil, 5-iodouracil, hypoxanthine, xantine, 4-acetylcytosine, 5-(carboxyhydroxylmethyl) uracil, 5-carboxymethylaminomethyl-2-thiouridine, 5-carboxymethylaminomethyluracil, dihydrouracil, beta-D-galactosylqueosine, inosine, N6-isopentenyladenine, 1-methylguanine, 1-methylinosine, 2,2-dimethylguanine, 2-methyladenine, 2-methylguanine, 3-methylcytosine, 5-methylcytosine, N6-adenine, 7-methylguanine, 5-methylaminomethyluracil, 5-methoxyaminomethyl-2-thiouracil, beta-D-mannosylqueosine, 5′-methoxycarboxymethyluracil, 5-methoxyuracil, 2-methylthio-N6-isopentenyladenine, uracil-5-oxyacetic acid (v), wybutoxosine, pseudouracil, queosine, 2-thiocytosine, 5-methyl-2-thiouracil, 2-thiouracil, 4-thiouracil, 5-methyluracil, uracil-5-oxyacetic acid methylester, uracil-5-oxyacetic acid (v), 5-methyl-2-thiouracil, 3-(3-amino-3-N-2-carboxypropyl) uracil, (acp3)w, and 2,6-diaminopurine. Alternatively, the antisense nucleic acid can be produced biologically using an expression vector into which a nucleic acid has been subcloned in an antisense orientation (i.e., RNA transcribed from the inserted nucleic acid will be of an antisense orientation to a target nucleic acid of interest, described further in the following subsection).  
      The antisense nucleic acid molecules of the invention are typically administered to a subject or generated in situ such that they hybridize with or bind to cellular mRNA and/or genomic DNA encoding an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide to thereby inhibit expression of the polypeptide, e.g., by inhibiting transcription and/or translation. The hybridization can be by conventional nucleotide complementarity to form a stable duplex, or, for example, in the case of an antisense nucleic acid molecule which binds to DNA duplexes, through specific interactions in the major groove of the double helix. An example of a route of administration of antisense nucleic acid molecules of the invention include direct injection at a tissue site. Alternatively, antisense nucleic acid molecules can be modified to target selected cells and then administered systemically. For example, for systemic administration, antisense molecules can be modified such that they specifically bind to receptors or antigens expressed on a selected cell surface, e.g., by linking the antisense nucleic acid molecules to peptides or antibodies which bind to cell surface receptors or antigens. The antisense nucleic acid molecules can also be delivered to cells using the vectors described herein. To achieve sufficient intracellular concentrations of the antisense molecules, vector constructs in which the antisense nucleic acid molecule is placed under the control of a strong pol II or pol III promoter are preferred.  
      In yet another embodiment, the antisense nucleic acid molecule of the invention is an α-anomeric nucleic acid molecule. An α-anomeric nucleic acid molecule forms specific double-stranded hybrids with complementary RNA in which, contrary to the usual β-units, the strands run parallel to each other (Gaultier et al. (1987)  Nucleic Acids. Res.  15:6625-6641). The antisense nucleic acid molecule can also comprise a 2′-o-methylribonucleotide (Inoue et al. (1987)  Nucleic Acids Res.  15:6131-6148) or a chimeric RNA-DNA analogue (Inoue et al. (1987)  FEBS Lett.  215:327-330).  
      In still another embodiment, an antisense nucleic acid of the invention is a ribozyme. Ribozymes are catalytic RNA molecules with ribonuclease activity which are capable of cleaving a single-stranded nucleic acid, such as an mRNA, to which they have a complementary region. Thus, ribozymes (e.g., hammerhead ribozymes (described in Haseloff and Gerlach (1988)  Nature  334:585-591)) can be used to catalytically cleave MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA transcripts to thereby inhibit translation of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA. A ribozyme having specificity for an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4- and/or HST-5-encoding nucleic acid can be designed based upon the nucleotide sequence of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 cDNA disclosed herein (i.e., SEQ ID NO:1, 3, 4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57, or 59). For example, a derivative of a Tetrahymena L-19 IVS RNA can be constructed in which the nucleotide sequence of the active site is complementary to the nucleotide sequence to be cleaved in an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4- and/or HST-5-encoding mRNA. See, e.g., Cech et al. U.S. Pat. No. 4,987,071; and Cech et al. U.S. Pat. No. 5,116,742. Alternatively, MTP-1, OAT, HST-1, TP-2, PLTR-.1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA can be used to select a catalytic RNA having a specific ribonuclease activity from a pool of RNA molecules. See, e.g., Bartel, D. and Szostak, J. W. (1993)  Science  261:1411-1418.  
      Alternatively, MTP-1 gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the MTP-1 (e.g., the MTP-1 promoter and/or enhancers; e.g., nucleotides 1-107 of SEQ ID NO:1) to form triple helical structures that prevent transcription of the MTP-1 gene in target cells. See generally, Helene, C. (1991)  Anticancer Drug Des.  6(6): 569-84; Helene, C. et al. (1992)  Ann. N.Y. Acad. Sci.  660:27-36; and Maher, L. J. (1992)  Bioassays  14(12):807-15.  
      Alternatively, OAT gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the OAT (e.g., the OAT promoter and/or enhancers; e.g., nucleotides 1-371 of SEQ ID NO:4) to form triple helical structures that prevent transcription of the OAT gene in target cells. See generally, Helene, C. (1991)  Anticancer Drug Des.  6(6):569-84; Helene, C. et al. (1992)  Ann. N.Y. Acad. Sci.  660:27-36; and Maher, L. J. (1992)  Bioessays  14(12):807-15.  
      Alternatively, HST-1 gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the HST-1 (e.g., the HST-1 promoter and/or enhancers) to form triple helical structures that prevent transcription of the HST-1 gene in target cells. See generally, Helene, C. (1991)  Anticancer Drug Des.  6(6):569-84; Helene, C. et al. (1992)  Ann. N.Y. Acad. Sci.  660:27-36; and Maher, L. J. (1992)  Bioassays  14(12):807-15.  
      Alternatively, TP-2 gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the TP-2 (e.g., the TP-2 promoter and/or enhancers) to form triple helical structures that prevent transcription of the TP-2 gene in target cells. See generally, Helene, C. (1991)  Anticancer Drug Des.  6(6):569-84; Helene, C. et al. (1992)  Ann. N.Y. Acad. Sci.  660:27-36; and Maher, L. J. (1992)  Bioassays  14(12):807-15.  
      Alternatively, PLTR-1 gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the PLTR-1 (e.g., the PLTR-1 promoter and/or enhancers; e.g., nucleotides 1-170 of SEQ ID NO: 19) to form triple helical structures that prevent transcription of the PLTR-1 gene in target cells. See generally, Helene, C. (1991)  Anticancer Drug Des.  6(6):569-84; Helene, C. et al. (1992)  Ann. N. Y. Acad. Sci.  660:27-36; and Maher, L. J. (1992)  Bioessays  14(12):807-15.  
      Alternatively, TFM-2 and/or TFM-3 gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the TFM-2 and/or TFM-3 (e.g., the TFM-2 and/or TFM-3 promoter and/or enhancers) to form triple helical structures that prevent transcription of the TFM-2 and/or TFM-3 gene in target cells. See generally, Helene, C. (1991)  Anticancer Drug Des.  6(6):569-84; Helene, C. et al. (1992)  Ann. N.Y. Acad. Sci.  660:27-36; and Maher, L. J. (1992)  Bioassays  14(12):807-15.  
      Alternatively, 67118, 67067, and/or 62092 gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the 67118, 67067, and/or 62092 (e.g., the 67118, 67067, and/or 62092 promoter and/or enhancers) to form triple helical structures that prevent transcription of the 67118, 67067, and/or 62092 gene in target cells. See generally, Helene, C. (1991)  Anticancer Drug Des.  6(6):569-84; Helene, C. et al. (1992)  Ann. N.Y. Acad. Sci.  660:27-36; and Maher, L. J. (1992)  Bioassays  14(12):807-15.  
      Alternatively, HAAT gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the HAAT (e.g., the HAAT promoter and/or enhancers; e.g., nucleotides 1-68 of SEQ ID NO:51) to form triple helical structures that prevent transcription of the HAAT gene in target cells. See generally, Helene, C. (1991)  Anticancer Drug Des.  6(6):569-84; Helene, C. et al. (1992)  Ann. N.Y. Acad. Sci.  660:27-36; and Maher, L. J. (1992)  Bioessays  14(12):807-15.  
      Alternatively, HST-4 and/or HST-5 gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the HST-4 and/or HST-5 (e.g., the HST-4 and/or HST-5 promoter and/or enhancers) to form triple helical structures that prevent transcription of the HST-4 and/or HST-5 gene in target cells. See generally, Helene, C. (1991)  Anticancer Drug Des.  6(6):569-84; Helene, C. et al. (1992)  Ann. N.Y. Acad. Sci.  660:27-36; and Maher, L. J. (1992)  Bioassays  14(12):807-15.  
      In yet another embodiment, the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acid molecules of the present invention can be modified at the base moiety, sugar moiety or phosphate backbone to improve, e.g., the stability, hybridization, or solubility of the molecule. For example, the deoxyribose phosphate backbone of the nucleic acid molecules can be modified to generate peptide nucleic acids (see Hyrup B. et al. (1996)  Bioorganic  &amp;  Medicinal Chemistry  4 (1): 5-23). As used herein, the terms “peptide nucleic acids” or “PNAs” refer to nucleic acid mimics, e.g., DNA mimics, in which the deoxyribose phosphate backbone is replaced by a pseudopeptide backbone and only the four natural nucleobases are retained. The neutral backbone of PNAs has been shown to allow for specific hybridization to DNA and RNA under conditions of low ionic strength. The synthesis of PNA oligomers can be performed using standard solid phase peptide synthesis protocols as described in Hyrup B. et al. (1996) supra; Perry-O&#39;Keefe et al.  Proc. Natl. Acad. Sci.  93: 14670-675.  
      PNAs of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acid molecules can be used in therapeutic and diagnostic applications. For example, PNAs can be used as antisense or antigene agents for sequence-specific modulation of gene expression by, for example, inducing transcription or translation arrest or inhibiting replication. PNAs of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acid molecules can also be used in the analysis of single base pair mutations in a gene, (e.g., by PNA-directed PCR clamping); as ‘artificial restriction enzymes’ when used in combination with other enzymes, (e.g., S1 nucleases (Hyrup B. (1996) supra)); or as probes or primers for DNA sequencing or hybridization (Hyrup B. et al. (1996) supra; Perry-O&#39;Keefe supra).  
      In another embodiment, PNAs of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 can be modified, (e.g., to enhance their stability or cellular uptake), by attaching lipophilic or other helper groups to PNA, by the formation of PNA-DNA chimeras, or by the use of liposomes or other techniques of drug delivery known in the art. For example, PNA-DNA chimeras of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acid molecules can be generated which may combine the advantageous properties of PNA and DNA. Such chimeras allow DNA recognition enzymes, (e.g., RNase H and DNA polymerases), to interact with the DNA portion while the PNA portion would provide high binding affinity and specificity. PNA-DNA chimeras can be linked using linkers of appropriate lengths selected in terms of base stacking, number of bonds between the nucleobases, and orientation (Hyrup B. (1996) supra). The synthesis of PNA-DNA chimeras can be performed as described in Hyrup B. (1996) supra and Finn P. J. et al. (1996)  Nucleic Acids Res.  24 (17): 3357-63. For example, a DNA chain can be synthesized on a solid support using standard phosphoramidite coupling chemistry and modified nucleoside analogs, e.g., 5′-(4-methoxytrityl)amino-5′-deoxy-thymidine phosphoramidite, can be used as a between the PNA and the 5′ end of DNA (Mag, M. et al. (1989)  Nucleic Acid Res.  17: 5973-88). PNA monomers are then coupled in a stepwise manner to produce a chimeric molecule with a 5′ PNA segment and a 3′ DNA segment (Finn P. J. et al. (1996) supra). Alternatively, chimeric molecules can be synthesized with a 5′ DNA segment and a 3′ PNA segment (Peterser, K. H. et al. (1975)  Bioorganic Med. Chem. Lett.  5: 1119-11124).  
      In other embodiments, the oligonucleotide may include other appended groups such as peptides (e.g., for targeting host cell receptors in vivo), or agents facilitating transport across the cell membrane (see, e.g., Letsinger et al. (1989)  Proc. Natl. Acad. Sci. USA  86:6553-6556; Lemaitre et al. (1987)  Proc. Natl. Acad. Sci. USA  84:648-652; PCT Publication No. WO88/09810) or the blood-brain barrier (see, e.g., PCT Publication No. WO89/10134). In addition, oligonucleotides can be modified with hybridization-triggered cleavage agents (See, e.g., Krol et al. (1988)  Bio - Techniques  6:958-976) or intercalating agents. (See, e.g., Zon (1988)  Pharm. Res.  5:539-549). To this end, the oligonucleotide may be conjugated to another molecule, (e.g., a peptide, hybridization triggered cross-linking agent, transport agent, or hybridization-triggered cleavage agent).  
      Alternatively, the expression characteristics of an endogenous MTP-1, HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HST-4 and/or HST-5 gene within a cell line or microorganism may be modified by inserting a heterologous DNA regulatory element into the genome of a stable cell line or cloned microorganism such that the inserted regulatory element is operatively linked with the endogenous MTP-1, HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HST-4 and/or HST-5 gene. For example, an endogenous MTP-1, HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HST-4 and/or HST-5 gene which is normally “transcriptionally silent”, i.e., an MTP-1, HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HST-4 and/or HST-5 gene which is normally not expressed, or is expressed only at very low levels in a cell line or microorganism, may be activated by inserting a regulatory element which is capable of promoting the expression of a normally expressed gene product in that cell line or microorganism. Alternatively, a transcriptionally silent, endogenous MTP-1, HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HST-4 and/or HST-5 gene may be activated by insertion of a promiscuous regulatory element that works across cell types.  
      A heterologous regulatory element may be inserted into a stable cell line or cloned microorganism, such that it is operatively linked with an endogenous MTP-1, HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HST-4 and/or HST-5 gene, using techniques, such as targeted homologous recombination, which are well known to those of skill in the art, and described, e.g., in Chappel, U.S. Pat. No. 5,272,071; PCT publication No. WO 91/06667, published May 16, 1991.  
      II. Isolated Polypeptides and Antibodies  
      One aspect of the invention pertains to isolated or recombinant MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 proteins and polypeptides, and biologically active portions thereof, as well as polypeptide fragments suitable for use as immunogens to raise anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti-HAAT, anti-HST-4 and/or anti-HST-5 antibodies. In one embodiment, native MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides can be isolated from cells or tissue sources by an appropriate purification scheme using standard protein purification techniques. In another embodiment, MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides are produced by recombinant DNA techniques. Alternative to recombinant expression, an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide or polypeptide can be synthesized chemically using standard peptide synthesis techniques.  
      An “isolated” or “purified” polypeptide or biologically active portion thereof is substantially free of cellular material or other contaminating proteins from the cell or tissue source from which the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide is derived, or substantially free from chemical precursors or other chemicals when chemically synthesized. The language “substantially free of cellular material” includes preparations of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide in which the polypeptide is separated from cellular components of the cells from which it is isolated or recombinantly produced. In one embodiment, the language “substantially free of cellular material” includes preparations of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide having less than about 30% (by dry weight) of non-MTP-1, non-OAT, non-HST-1, non-TP-2, non-PLTR-1, non-TFM-2, non-TFM-3, non-67118, non-67067, non-62092, non- HAAT, non-HST-4 and/or non-HST-5 polypeptide (also referred to herein as a “contaminating protein”), more preferably less than about 20% of non-MTP-1, non-OAT, non-HST-1, non-TP-2, non-PLTR-1, non-TFM-2, non-TFM-3, non-67118, non-67067, non-62092, non- HAAT, non-HST-4 and/or non-HST-5 polypeptide, still more preferably less than about 10% of non-MTP-1, non-OAT, non-HST-1, non-TP-2, non-PLTR-1, non-TFM-2, non-TFM-3, non-67118, non-67067, non-62092, non- HAAT, non-HST-4 and/or non-HST-5 polypeptide, and most preferably less than about 5% non-MTP-1, non-OAT, non-HST-1, non-TP-2, non-PLTR-1, non-TFM-2, non-TFM-3, non-67118, non-67067, non-62092, non- HAAT, non-HST-4 and/or non-HST-5 polypeptide. When the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide or biologically active portion thereof is recombinantly produced, it is also preferably substantially free of culture medium, i.e., culture medium represents less than about 20%, more preferably less than about 10%, and most preferably less than about 5% of the volume of the protein preparation.  
      The language “substantially free of chemical precursors or other chemicals” includes preparations of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide in which the polypeptide is separated from chemical precursors or other chemicals which are involved in the synthesis of the polypeptide. In one embodiment, the language “substantially free of chemical precursors or other chemicals” includes preparations of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide having less than about 30% (by dry weight) of chemical precursors or non-MTP-1, non-OAT, non-HST-1, non-TP-2, non-PLTR-1, non-TFM-2, non-TFM-3, non-67118, non-67067, non-62092, non-HAAT, non-HST-4 and/or non-HST-5 chemicals, more preferably less than about 20% chemical precursors or non-MTP-1, non-OAT, non-HST-1, non-TP-2, non-PLTR-1, non-TFM-2, non-TFM-3, non-67118, non-67067, non-62092, non- HAAT, non-HST-4 and/or non-HST-5 chemicals, still more preferably less than about 10% chemical precursors or non-MTP-1, non-OAT, non-HST-1, non-TP-2, non-PLTR-1, non-TFM-2, non-TFM-3, non-67118, non-67067, non-62092, non- HAAT, non-HST-4 and/or non-HST-5 chemicals, and most preferably less than about 5% chemical precursors or non-MTP-1, non-OAT, non-HST-1, non-TP-2, non-PLTR-1, non-TFM-2, non-TFM-3, non-67118, non-67067, non-62092, non-HAAT, non-HST-4 and/or non-HST-5 chemicals.  
      As used herein, a “biologically active portion” of an MTP-1 protein includes a fragment of an MTP-1 protein which participates in an interaction between an MTP-1 molecule and a non-MTP-1 molecule. Biologically active portions of an MTP-1 protein include peptides comprising amino acid sequences sufficiently identical to or derived from the amino acid sequence of the MTP-1 protein, e.g., the amino acid sequence shown in SEQ ID NO:2, which include less amino acids than the full length MTP-1 protein, and exhibit at least one activity of an MTP-1 protein. Typically, biologically active portions comprise a domain or motif with at least one activity of the MTP-1 protein, e.g., transporting a substrate molecule across a biological membrane. A biologically active portion of an MTP-1 protein can be a polypeptide which is, for example, 25, 50, 75, 100, 125, 150, 175, 200, 250, 300 or more amino acids in length. Biologically active portions of an MTP-1 protein can be used as targets for developing agents which modulate an MTP-1 mediated activity, e.g., lipid transport.  
      In one embodiment, a biologically active portion of an MTP-1 protein comprises at least one transmembrane domain. It is to be understood that a preferred biologically active portion of an MTP-1 protein of the present invention may contain at least one transmembrane domain and one or more of the following domains: a transmembrane domain, and/or an ABC transporter domain. Moreover, other biologically active portions, in which other regions of the protein are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native MTP-1 protein.  
      In a preferred embodiment, the MTP-1 protein has an amino acid sequence shown in SEQ ID NO:2. In other embodiments, the MTP-1 protein is substantially identical to SEQ ID NO:2, and retains the functional activity of the protein of SEQ ID NO:2, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail in subsection I above. Accordingly, in another embodiment, the MTP-1 protein is a protein which comprises an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to SEQ ID NO:2.  
      To determine the percent identity of two amino acid sequences or of two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-identical sequences can be disregarded for comparison purposes). In a preferred embodiment, the length of a reference sequence aligned for comparison purposes is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and even more preferably at least 70%, 80%, or 90% of the length of the reference sequence (e.g., when aligning a second sequence to the MTP-1 amino acid sequence of SEQ ID NO:2 having 400 amino acid residues, at least 50, preferably at least 100, more preferably at least 150, even more preferably at least 200, and even more preferably at least 300 or more amino acid residues are aligned). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid “identity” is equivalent to amino acid or nucleic acid “homology”). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.  
      As used herein, a “biologically active portion” of an OAT protein includes a fragment of an OAT protein which participates in an interaction between an OAT molecule and a non-OAT molecule (e.g., an OAT substrate or target molecule). Biologically active portions of an OAT protein include peptides comprising amino acid sequences sufficiently homologous to or derived from the OAT amino acid sequences, e.g., the amino acid sequences shown in SEQ ID NO:5 or 8, which include sufficient amino acid residues to exhibit at least one activity of an OAT protein. Typically, biologically active portions comprise a domain or motif with at least one activity of the OAT protein, e.g., OAT substrate transporting activity, OAT substrate or target molecule binding activity, intra- or inter-cellular signal modulating activity, gene expression modulating activity, hormonal response modulating activity, and/or the ability to protect cells and/or tissues from organic anions. A biologically active portion of an OAT protein can be a polypeptide which is, for example, 10, 25, 50, 75, 100, 125, 150, 175, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700 or more amino acids in length. Biologically active portions of an OAT protein can be used as targets for developing agents which modulate an OAT mediated activity, e.g., OAT substrate transport, OAT substrate or target molecule binding, intra- or inter-cellular signaling, cellular gene expression, hormonal responses, and/or protection of cells and/or tissues from organic anions.  
      In one embodiment, a biologically active portion of an OAT protein comprises at least one transmembrane domain. Moreover, other biologically active portions, in which other regions of the protein are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native OAT protein.  
      Another aspect of the invention features fragments of the protein having the amino acid sequence of SEQ ID NO:5 or 8, for example, for use as immunogens. In one embodiment, a fragment comprises at least 8 amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:5 or 8. In another embodiment, a fragment comprises at least 10, 15, 20, 25, 30, 35, 40, 45, 50 or more amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:5 or 8.  
      In a preferred embodiment, an OAT protein has an amino acid sequence shown in SEQ ID NO:5 or 8. In other embodiments, the OAT protein is substantially identical to SEQ ID NO:5 or 8, and retains the functional activity of the protein of SEQ ID NO:5 or 8, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail in subsection I above. In another embodiment, the OAT protein is a protein which comprises an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to SEQ ID NO:5 or 8.  
      In another embodiment, the invention features an OAT protein which is encoded by a nucleic acid molecule consisting of a nucleotide sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to a nucleotide sequence of SEQ ID NO:4, 6, 7, or 9, or a complement thereof. This invention further features an OAT protein which is encoded by a nucleic acid molecule consisting of a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:4, 6, 7, or 9, or a complement thereof.  
      To determine the percent identity of two amino acid sequences or of two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-homologous sequences can be disregarded for comparison purposes). In a preferred embodiment, the length of a reference sequence aligned for comparison purposes is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and even more preferably at least 70%, 80%, or 90% of the length of the reference sequence (e.g., when aligning a second sequence to the OAT amino acid sequence of SEQ ID NO:5 having 550 amino acid residues, at least 165, preferably at least 220, more preferably at least 275, even more preferably at least 330, and even more preferably at least 385, 440 or 495 amino acid residues are aligned; when aligning a second sequence to the OAT amino acid sequence of SEQ ID NO:8 having 724 amino acid residues, at least 217, preferably at least 290, more preferably at least 362, even more preferably at least 434, and even more preferably at least 507, 579 or 652 amino acid residues are aligned). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid “identity” is equivalent to amino acid or nucleic acid “homology”). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.  
      As used herein, a “biologically active portion” of an HST-1 polypeptide includes a fragment of an HST-1 polypeptide which participates in an interaction between an HST-1 molecule and a non-HST-1 molecule. Biologically active portions of an HST-1 polypeptide include peptides comprising amino acid sequences sufficiently identical to or derived from the amino acid sequence of the HST-1 polypeptide, e.g., the amino acid sequence shown in SEQ ID NO:13, which include less amino acids than the full length HST-1 polypeptides, and exhibit at least one activity of an HST-1 polypeptide. Typically, biologically active portions comprise a domain or motif with at least one activity of the HST-1 polypeptide, e.g., modulating sugar transport mechanisms. A biologically active portion of an HST-1 polypeptide can be a polypeptide which is, for example, 25, 30, 35, 40, 45, 50, 75, 100, 125, 150, 155, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550 or more amino acids in length. Biologically active portions of an HST-1 polypeptide can be used as targets for developing agents which modulate an HST-1 mediated activity, e.g., a sugar transport mechanism.  
      In one embodiment, a biologically active portion of an HST-1 polypeptide comprises at least one transmembrane domain. It is to be understood that a preferred biologically active portion of an HST-1 polypeptide of the present invention comprises at least one or more of the following domains: a transmembrane domain and/or a sugar transporter family domain. Moreover, other biologically active portions, in which other regions of the polypeptide are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native HST-1 polypeptide.  
      Another aspect of the invention features fragments of the polypeptide having the amino acid sequence of SEQ ID NO:13, for example, for use as immunogens. In one embodiment, a fragment comprises at least 5 amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:13. In another embodiment, a fragment comprises at least 10, 15, 20, 25, 30, 35, 40, 45, 50 or more amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:13.  
      In a preferred embodiment, an HST-1 polypeptide has an amino acid sequence shown in SEQ ID NO:13. In other embodiments, the HST-1 polypeptide is substantially identical to SEQ ID NO:13, and retains the functional activity of the polypeptide of SEQ ID NO:13, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail in subsection I above. In another embodiment, the HST-1 polypeptide is a polypeptide which comprises an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%,75%, 80%, 85%,90%,95%,96%,97%,98%,99%, 99.1%,99.2%, 99.3%,99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to SEQ ID NO:13.  
      In another embodiment, the invention features an HST-1 polypeptide which is encoded by a nucleic acid molecule consisting of a nucleotide sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to a nucleotide sequence of SEQ ID NO:12 or 14, or a complement thereof. This invention further features an HST-1 polypeptide which is encoded by a nucleic acid molecule consisting of a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:12 or 14, or a complement thereof.  
      To determine the percent identity of two amino acid sequences or of two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-identical sequences can be disregarded for comparison purposes). In a preferred embodiment, the length of a reference sequence aligned for comparison purposes is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and even more preferably at least 70%, 80%, or 90% of the length of the reference sequence (e.g., when aligning a second sequence to the HST-1 amino acid sequence of SEQ ID NO:13 having 419 amino acid residues, at least 126, preferably at least 168, more preferably at least 210, more preferably at least 251, even more preferably at least 293, and even more preferably at least 335 or 377 or more amino acid residues are aligned). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid “identity” is equivalent to amino acid or nucleic acid “homology”). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.  
      As used herein, a “biologically active portion” of a TP-2 polypeptide includes a fragment of a TP-2 polypeptide which participates in an interaction between a TP-2 molecule and a non-TP-2 molecule. Biologically active portions of a TP-2 polypeptide include peptides comprising amino acid sequences sufficiently identical to or derived from the amino acid sequence of the TP-2 polypeptide, e.g., the amino acid sequence shown in SEQ ID NO:16, which include less amino acids than the full length TP-2 polypeptides, and exhibit at least one activity of a TP-2 polypeptide. Typically, biologically active portions comprise a domain or motif with at least one activity of the TP-2 polypeptide, e.g., modulating transport mechanisms. A biologically active portion of a TP-2 polypeptide can be a polypeptide which is, for example, 25, 30, 35, 40, 45, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475 or more amino acids in length. Biologically active portions of a TP-2 polypeptide can be used as targets for developing agents which modulate a TP-2 mediated activity, e.g., modulating transport of biological molecules across membranes.  
      In one embodiment, a biologically active portion of a TP-2 polypeptide comprises at least one transmembrane domain. It is to be understood that a preferred biologically active portion of a TP-2 polypeptide of the present invention comprises at least one or more of the following domains: a transmembrane domain, and/or a sugar transporter domain, and/or a LacY proton/sugar symporter domain. Moreover, other biologically active portions, in which other regions of the polypeptide are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native TP-2 polypeptide.  
      Another aspect of the invention features fragments of the polypeptide having the amino acid sequence of SEQ ID NO:16, for example, for use as immunogens. In one embodiment, a fragment comprises at least 5 amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:16. In another embodiment, a fragment comprises at least 10, 15, 20, 25, 30, 35, 40, 45, 50 or more amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:16.  
      In a preferred embodiment, a TP-2 polypeptide has an amino acid sequence shown in SEQ ID NO:16. In other embodiments, the TP-2 polypeptide is substantially identical to SEQ ID NO:16, and retains the functional activity of the polypeptide of SEQ ID NO:16, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail in subsection I above. In another embodiment, the TP-2 polypeptide is a polypeptide which comprises an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to SEQ ID NO:16.  
      In another embodiment, the invention features a TP-2 polypeptide which is encoded by a nucleic acid molecule consisting of a nucleotide sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more indentical to a nucleotide sequence of SEQ ID NO:15 or 17, or a complement thereof. This invention further features a TP-2 polypeptide which is encoded by a nucleic acid molecule consisting of a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:15 or 17, or a complement thereof.  
      To determine the percent identity of two amino acid sequences or of two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-identical sequences can be disregarded for comparison purposes). In a preferred embodiment, the length of a reference sequence aligned for comparison purposes is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and even more preferably at least 70%, 80%, or 90% of the length of the reference sequence (e.g., when aligning a second sequence to the TP-2 amino acid sequence of SEQ ID NO:16 having 474 amino acid residues, at least 142, preferably at least 189, more preferably at least 237, more preferably at least 284, even more preferably at least 331, and even more preferably at least 379 or 426 or more amino acid residues are aligned). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid “identity” is equivalent to amino acid or nucleic acid “homology”). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.  
      As used herein, a “biologically active portion” of a PLTR-1 protein includes a fragment of a PLTR-1 protein which participates in an interaction between a PLTR-1 molecule and a non-PLTR-1 molecule (e.g., a PLTR-1 substrate such as a phospholipid or ATP). Biologically active portions of a PLTR-1 protein include peptides comprising amino acid sequences sufficiently homologous to or derived from the PLTR-1 amino acid sequences, e.g., the amino acid sequences shown in SEQ ID NO:20, which include sufficient amino acid residues to exhibit at least one activity of a PLTR-1 protein. Typically, biologically active portions comprise a domain or motif with at least one activity of the PLTR-1 protein, e.g., the ability to interact with a PLTR-1 substrate or target molecule (e.g., a phospholipid; ATP; a non-PLTR-1 protein; or another PLTR-1 protein or subunit); the ability to transport a PLTR-1 substrate or target molecule (e.g., a phospholipid) from one side of a cellular membrane to the other; the ability to be phosphorylated or dephosphorylated; the ability to adopt an E1 conformation or an E2 conformation; the ability to convert a PLTR-1 substrate or target molecule to a product (e.g., the ability to hydrolyze ATP); the ability to interact with a second non-PLTR-1 protein; the ability to modulate intra- or inter-cellular signaling and/or gene transcription (e.g., either directly or indirectly); the ability to modulate cellular growth, proliferation, differentiation, absorption, and/or secretion. A biologically active portion of a PLTR-1 protein can be a polypeptide which is, for example, 10, 15, 20, 25, 30, 25, 40, 45, 50, 75, 100, 125, 150, 175, 200, 250, 300, 328, 350, 375, 400, 450, 465, 500, 520, 550, 600, 650, 700, 703, 750, 800, 850, 900, 932, 950, 1000, 1050, 1100, 1150 or more amino acids in length. Biologically active portions of a PLTR-1 protein can be used as targets for developing agents which modulate a PLTR-1 mediated activity, e.g., any of the aforementioned PLTR-1 activities.  
      In one embodiment, a biologically active portion of a PLTR-1 protein comprises at least one at least one or more of the following domains, sites, or motifs: a transmembrane domain, an N-terminal large extramembrane domain, a C-terminal large extramembrane domain, an E1-E2 ATPases phosphorylation site, a P-type ATPase sequence 1 motif, a P-type ATPase sequence 2 motif, a P-type ATPase sequence 3 motif, and/or one or more phospholipid transporter specific amino acid resides. Moreover, other biologically active portions, in which other regions of the protein are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native PLTR-1 protein.  
      Another aspect of the invention features fragments of the protein having the amino acid sequence of SEQ ID NO:20, for example, for use as immunogens. In one embodiment, a fragment comprises at least 5 amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:20. In another embodiment, a fragment comprises at least 8, 10, 15, 20, 25, 30, 35, 40, 45, 50 or more amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:20.  
      In a preferred embodiment, a PLTR-1 protein has an amino acid sequence shown in SEQ ID NO:20. In other embodiments, the PLTR-1 protein is substantially identical to SEQ ID NO:20, and retains the functional activity of the protein of SEQ ID NO:20, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail in subsection I above. In another embodiment, the PLTR-1 protein is a protein which comprises an amino acid sequence at least about 75%, 79%, 80%, 81%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to SEQ ID NO:20.  
      In another embodiment, the invention features a PLTR-1 protein which is encoded by a nucleic acid molecule consisting of a nucleotide sequence at least about 75%, 79%, 80%, 81%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to a nucleotide sequence of SEQ ID NO:19 or 21, or a complement thereof. This invention further features a PLTR-1 protein which is encoded by a nucleic acid molecule consisting of a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:19 or 21, or a complement thereof.  
      To determine the percent identity of two amino acid sequences or of two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-homologous sequences can be disregarded for comparison purposes). In a preferred embodiment, the length of a reference sequence aligned for comparison purposes is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and even more preferably at least 70%, 80%, or 90% of the length of the reference sequence (e.g., when aligning a second sequence to the PLTR-1 amino acid sequence of SEQ ID NO:20 having 1190 amino acid residues, at least 357, preferably at least 476, more preferably at least 595, even more preferably at least 714, and even more preferably at least 833, 952 or 1071 amino acid residues are aligned). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid “identity” is equivalent to amino acid or nucleic acid “homology”). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.  
      As used herein, a “biologically active portion” of a TFM-2 and/or TFM-3 polypeptide includes a fragment of a TFM-2 and/or TFM-3 polypeptide which participates in an interaction between a TFM-2 and/or TFM-3 molecule and a non-TFM-2 and/or TFM-3 molecule. Biologically active portions of a TFM-2 and/or TFM-3 polypeptide include peptides comprising amino acid sequences sufficiently identical to or derived from the amino acid sequence of the TFM-2 and/or TFM-3 polypeptide, e.g., the amino acid sequence shown in SEQ ID NO:28 or 31, which include less amino acids than the full length TFM-2 and/or TFM-3 polypeptides, and exhibit at least one activity of a TFM-2 and/or TFM-3 polypeptide. Typically, biologically active portions comprise a domain or motif with at least one activity of the TFM-2 and/or TFM-3 polypeptide, e.g., modulating transport mechanisms. A biologically active portion of a TFM-2 and/or TFM-3 polypeptide can be a polypeptide which is, for example, 25, 30, 35, 40, 45, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375 or more amino acids in length. Biologically active portions of a TFM-2 and/or TFM-3 polypeptide can be used as targets for developing agents which modulate a TFM-2 and/or TFM-3 mediated activity, e.g., modulating transport of biological molecules across membranes.  
      In one embodiment, a biologically active portion of a TFM-2 and/or TFM-3 polypeptide comprises at least one transmembrane domain. It is to be understood that a preferred biologically active portion of a TFM-2 and/or TFM-3 polypeptide of the present invention comprises at least one or more of the following domains: a transmembrane domain, and/or a monocarboxylate domain, and/or a sugar transporter domain. Moreover, other biologically active portions, in which other regions of the polypeptide are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native TFM-2 and/or TFM-3 polypeptide.  
      Another aspect of the invention features fragments of the polypeptide having the amino acid sequence of SEQ ID NO:28 or 31, for example, for use as immunogens. In one embodiment, a fragment comprises at least 5 amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:28 or 31. In another embodiment, a fragment comprises at least 10, 15, 20, 25, 30, 35, 40, 45, 50 or more amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:28 or 31.  
      In a preferred embodiment, a TFM-2 and/or TFM-3 polypeptide has an amino acid sequence shown in SEQ ID NO:28 or 31. In other embodiments, the TFM-2 and/or TFM-3 polypeptide is substantially identical to SEQ ID NO:28 or 31, and retains the functional activity of the polypeptide of SEQ ID NO:28 or 31, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail in subsection I above. In another embodiment, the TFM-2 and/or TFM-3 polypeptide is a polypeptide which comprises an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to SEQ ID NO:28 or 31.  
      In another embodiment, the invention features a TFM-2 and/or TFM-3 polypeptide which is encoded by a nucleic acid molecule consisting of a nucleotide sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to a nucleotide sequence of SEQ ID NO:27, 29, 30, or 32, or a complement thereof. This invention further features a TFM-2 and/or TFM-3 polypeptide which is encoded by a nucleic acid molecule consisting of a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:27, 29, 30, or 32, or a complement thereof.  
      To determine the percent identity of two amino acid sequences or of two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-identical sequences can be disregarded for comparison purposes). In a preferred embodiment, the length of a reference sequence aligned for comparison purposes is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and even more preferably at least 70%, 80%, or 90% of the length of the reference sequence (e.g., when aligning a second sequence to the TFM-2 amino acid sequence of SEQ ID NO:28 having 392 amino acid residues, at least 117, preferably at least 156, more preferably at least 196, more preferably at least 235, even more preferably at least 274, and even more preferably at least 313 or 352 or more amino acid residues are aligned; when aligning a second sequence to the TFM-3 amino acid sequence of SEQ iID NO:31 having 405 amino acid residues, at least 121, preferably at least 162, more preferably at least 202, more preferably at least 243, even more preferably at least 283, and even more preferably at least 324 or 364 or more amino acid residues are aligned). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid “identity” is equivalent to amino acid or nucleic acid “homology”). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.  
      As used herein, a “biologically active portion” of a 67118, 67067, and/or 62092 polypeptide includes a fragment of a 67118, 67067, and/or 62092 polypeptide which participates in an interaction between a 67118, 67067, and/or 62092 molecule and a non-67118, 67067, and/or 62092 molecule (e.g., a 67118 or 67067 substrate such as a phospholipid or ATP, or a 62092 substrate such as a nucleotide or a non-62092 protein). Biologically active portions of a 67118, 67067, and/or 62092 polypeptide include peptides comprising amino acid sequences sufficiently identical to or derived from the amino acid sequence of the 67118, 67067, and/or 62092 polypeptide, e.g., the amino acid sequence shown in SEQ ID NO:34, 37, or 40, which include less amino acids than the full length 67118, 67067, and/or 62092 polypeptides, and exhibit at least one activity of a 67118, 67067, and/or 62092 polypeptide.  
      Typically, biologically active portions of a 67118 or 67067 polypeptide comprise a domain or motif with at least one activity of the 67118 or 67067 polypeptide, e.g., the ability to interact with a 67118 or 67067 substrate or target molecule (e.g., a phospholipid; ATP; a non-67118 or 67067 protein; or another 67118 or 67067 protein or subunit); the ability to transport a 67118 or 67067 substrate or target molecule (e.g., a phospholipid) from one side of a cellular membrane to the other; the ability to be phosphorylated or dephosphorylated; the ability to adopt an E1 conformation or an E2 conformation; the ability to convert a 67118 or 67067 substrate or target molecule to a product (e.g., the ability to hydrolyze ATP); the ability to interact with a second non-67118 or 67067 protein; the ability to modulate intra- or inter-cellular signaling and/or gene transcription (e.g., either directly or indirectly); the ability to modulate cellular growth, proliferation, differentiation, absorption, and/or secretion. A biologically active portion of a 67118 or 67067 polypeptide can be a polypeptide which is, for example, 10, 25, 50, 75, 100, 125, 150, 175, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550 or more amino acids in length. Biologically active portions of a 67118 or 67067 polypeptide can be used as targets for developing agents which modulate a 67118 or 67067 mediated activity, e.g., modulating transport of biological molecules across membranes.  
      Moreover, biologically active portions of a 62092 protein typically comprise a domain or motif with at least one activity of the 62092 protein, e.g., 62092 activity, nucleotide-binding activity, ability to modulate intra- or inter-cellular signaling and/or gene expression, and/or ability to modulate cell growth, proliferation, differentiation, and/or apoptosis mechanisms. A biologically active portion of a 62092 protein can be a polypeptide which is, for example, 10, 25, 50, 75, 100, 125, 150 or more amino acids in length. Biologically active portions of a 62092 protein can be used as targets for developing agents which modulate a 62092 mediated activity, e.g., 62092 activity, nucleotide-binding activity, ability to modulate intra- or inter-cellular signaling and/or gene expression, and/or ability to modulate cell growth, proliferation, differentiation, and/or apoptosis mechanisms.  
      In one embodiment, a biologically active portion of a 67118, or 67067 polypeptide comprises at least one at least one or more of the following domains, sites, or motifs: a transmembrane domain, an N-terminal large extramembrane domain, a C-terminal large extramembrane domain, an E1-E2 ATPases phosphorylation site, a P-type ATPase sequence 1 motif, a P-type ATPase sequence 2 motif, a P-type ATPase sequence 3 motif, and/or one or more phospholipid transporter specific amino acid resides. Moreover, other biologically active portions, in which other regions of the polypeptide are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native 67118, or 67067 polypeptide.  
      In another embodiment, a biologically active portion of a 62092 protein comprises at least a 62092 family domain and/or a 62092 family signature motif. Moreover, other biologically active portions, in which other regions of the protein are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native 62092 protein.  
      Another aspect of the invention features fragments of the polypeptide having the amino acid sequence of SEQ ID NO:34, 37, or 40, for example, for use as immunogens. In one embodiment, a fragment comprises at least 5 amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:34, 37, or 40. In another embodiment, a fragment comprises at least 10, 15, 20, 25, 30, 35, 40, 45, 50 or more amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:34, 37, or 40.  
      In a preferred embodiment, a 67118, 67067, and/or 62092 polypeptide has an amino acid sequence shown in SEQ ID NO:34, 37, or 40. In other embodiments, the 67118, 67067, and/or 62092 polypeptide is substantially identical to SEQ ID NO:34, 37, or 40, and retains the functional activity of the polypeptide of SEQ ID NO:34, 37, or 40, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail in subsection I above. In another embodiment, the 67118, 67067, and/or 62092 polypeptide is a polypeptide which comprises an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to SEQ ID NO:34, 37, or 40.  
      In another embodiment, the invention features a 67118, 67067, and/or 62092 polypeptide which is encoded by a nucleic acid molecule consisting of a nucleotide sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or more identical to a nucleotide sequence of SEQ ID NO:33, 35, 36, 38, 39, or 41, or a complement thereof. This invention further features a 67118, 67067, and/or 62092 polypeptide which is encoded by a nucleic acid molecule consisting of a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:33, 35, 36, 38, 39, or 41, or a complement thereof.  
      To determine the percent identity of two amino acid sequences or of two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-identical sequences can be disregarded for comparison purposes). In a preferred embodiment, the length of a reference sequence aligned for comparison purposes is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and even more preferably at least 70%, 80%, or 90% of the length of the reference sequence (e.g., when aligning a second sequence to the 67118 amino acid sequence of SEQ ID NO:34 having 1134 amino acid residues, at least 340, preferably at least 453, more preferably at least 567, more preferably at least 640, even more preferably at least 793, and even more preferably at least 907 or 1020 or more amino acid residues are aligned; when aligning a second sequence to the 67067 amino acid sequence of SEQ ID NO:37 having 1588 amino acid residues, at least 476, preferably at least 635, more preferably at least 794, more preferably at least 952, even more preferably at least 1111, and even more preferably at least 1270 or 1429 or more amino acid residues are aligned; when aligning a second sequence to the 62092 amino acid sequence of SEQ ID NO:40 having 163 amino acid residues, at least 48, preferably at least 65, more preferably at least 81, more preferably at least 97, even more preferably at least 114, and even more preferably at least 130 or 146 or more amino acid residues are aligned). In another preferred embodiment, the sequences being aligned for comparison purposes are globally aligned and percent identity is determined over the entire length of the sequences aligned. The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid “identity” is equivalent to amino acid or nucleic acid “homology”). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.  
      As used herein, a “biologically active portion” of a HAAT protein includes a fragment of a HAAT protein which participates in an interaction between a HAAT molecule and a non-HAAT molecule (e.g., a HAAT substrate such as an amino acid). Biologically active portions of a HAAT protein include peptides comprising amino acid sequences sufficiently homologous to or derived from the HAAT amino acid sequences, e.g., the amino acid sequences shown in SEQ ID NO:52, which include sufficient amino acid residues to exhibit at least one activity of a HAAT protein. Typically, biologically active portions comprise a domain or motif with at least one activity of the HAAT protein, e.g., (i) interaction with a HAAT substrate or target molecule (e.g., an amino acid); (ii) transport of a HAAT substrate or target molecule (e.g., an amino acid) from one side of a cellular membrane to the other; (iii) conversion of a HAAT substrate or target molecule to a product (e.g., glucose production); (iv) interaction with a second non-HAAT protein; (v) modulation of substrate or target molecule location (e.g., modulation of amino acid location within a cell and/or location with respect to a cellular membrane); (vi) maintenance of amino acid gradients; (vii) modulation of hormone metabolism and/or nerve transmission (e.g., either directly or indirectly); (viii) modulation of cellular proliferation, growth, differentiation, and production of metabolic energy; and/or (ix) modulation of amino acid homeostasis. A biologically active portion of a HAAT protein can be a polypeptide which is, for example, 10, 25, 50, 75, 100, 125, 150, 175, 200, 250, 300, 350, 400, 450, 475, or 485 or more amino acids in length. Biologically active portions of a HAAT protein can be used as targets for developing agents which modulate a HAAT mediated activity, e.g., any of the aforementioned HAAT activities.  
      In one embodiment, a biologically active portion of a HAAT protein comprises at least one at least one or more of the following domains, sites, or motifs: a transmembrane domain, a transmembrane amino acid transporter domain, and/or one or more amino acid transporter specific amino acid residues. Moreover, other biologically active portions, in which other regions of the protein are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native HAAT protein.  
      Another aspect of the invention features fragments of the protein having the amino acid sequence of SEQ ID NO:52, for example, for use as immunogens. In one embodiment, a fragment comprises at least 5 amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:52. In another embodiment, a fragment comprises at least 8, 10, 15, 20, 25, 30, 35, 40, 45, 50 or more amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:52.  
      In a preferred embodiment, a HAAT protein has an amino acid sequence shown in SEQ ID NO:52. In other embodiments, the HAAT protein is substantially identical to SEQ ID NO:52, and retains the functional activity of the protein of SEQ ID NO:52, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail in subsection I above. In another embodiment, the HAAT protein is a protein which comprises an amino acid sequence at least about 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to SEQ ID NO:52.  
      In another embodiment, the invention features a HAAT protein which is encoded by a nucleic acid molecule consisting of a nucleotide sequence at least about 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more identical to a nucleotide sequence of SEQ ID NO:51 or 53, or a complement thereof. This invention further features a HAAT protein which is encoded by a nucleic acid molecule consisting of a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ I) NO:51 or 53, or a complement thereof.  
      To determine the percent identity of two amino acid sequences or of two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-homologous sequences can be disregarded for comparison purposes). In a preferred embodiment, the length of a reference sequence aligned for comparison purposes is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and even more preferably at least 70%, 80%, or 90% of the length of the reference sequence (e.g., when aligning a second sequence to the HAAT amino acid sequence of SEQ ID NO:52 having 485 amino acid residues, at least 157, preferably at least 276, more preferably at least 395, and even more preferably at least 414 amino acid residues are aligned). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein, amino acid or nucleic acid “identity” is equivalent to amino acid or nucleic acid “homology”). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.  
      As used herein, a “biologically active portion” of an HST-4 and/or an HST-5 polypeptide includes a fragment of an HST-4 and/or an HST-5 polypeptide which participates in an interaction between an HST-4 and/or an HST-5 molecule and a non-HST-4 and/or a non-HST-5 molecule. Biologically active portions of an HST-4 and/or an HST-5 polypeptide include peptides comprising amino acid sequences sufficiently identical to or derived from the amino acid sequence of the HST-4 and/or the HST-5 polypeptide, e.g., the amino acid sequence shown in SEQ ID NO:55 or 58, which include less amino acids than the full length HST-4 and/or HST-5 polypeptides, and exhibit at least one activity of an HST-4 and/or an HST-5 polypeptide. Typically, biologically active portions comprise a domain or motif with at least one activity of the HST-4 and/or the HST-5 polypeptide, e.g., modulating sugar transport mechanisms. A biologically active portion of an HST-4 polypeptide can be a polypeptide which is, for example, 25, 30, 35, 40,-45, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425 or more amino acids in length. A biologically active portion of an HST-5 polypeptide can be a polypeptide which is, for example, 25, 30, 35, 40, 45, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425 or more amino acids in length. Biologically active portions of an HST-4 and/or an HST-5 polypeptide can be used as targets for developing agents which modulate an HST-4 and/or HST-5 mediated activity, e.g., a sugar transport mechanism.  
      In one embodiment, a biologically active portion of an HST-4 and/or an HST-5 polypeptide comprises at least one transmembrane domain. It is to be understood that a preferred biologically active portion of an HST-4 and/or an HST-5 polypeptide of the present invention comprises at least one or more of the following domains: a transmembrane domain and/or a sugar transporter family domain. Moreover, other biologically active portions, in which other regions of the polypeptide are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native HST-4 and/or HST-5 polypeptide.  
      Another aspect of the invention features fragments of the polypeptide having the amino acid sequence of SEQ ID NO:55 or 58, for example, for use as immunogens. In one embodiment, a fragment comprises at least 5 amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequences of SEQ ID NO:55 or 58. In another embodiment, a fragment comprises at least 10, 15, 20, 25, 30, 35, 40, 45, 50 or more amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:55 or 58.  
      In a preferred embodiment, an HST-4 and/or an HST-5 polypeptide has an amino acid sequence shown in SEQ ID NO:55 or 58. In other embodiments, the HST-4 and/or the HST-5 polypeptide is substantially identical to SEQ ID NO:55 or 58, and retains the functional activity of the polypeptide of SEQ ID NO:55 or 58, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail in subsection I above. In another embodiment, the HST-4 and/or the HST-5 polypeptide is a polypeptide which comprises an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical to SEQ ID NO:55 or 58.  
      In another embodiment, the invention features an HST-4 and/or an HST-5 polypeptide which is encoded by a nucleic acid molecule consisting of a nucleotide sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical to a nucleotide sequence of SEQ ID NO:54, 56, 57, or 59, or a complement thereof. This invention further features an HST-4 and/or an HST-5 polypeptide which is encoded by a nucleic acid molecule consisting of a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:54, 56, 57, or 59, or a complement thereof.  
      To determine the percent identity of two amino acid sequences or of two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-identical sequences can be disregarded for comparison purposes). In a preferred embodiment, the length of a reference sequence aligned for comparison purposes is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and even more preferably at least 70%, 80%, or 90% of the length of the reference sequence (e.g., when aligning a second sequence to the HST-4 amino acid sequence of SEQ ID NO:55 having 438 amino acid residues, at least 131, preferably at least 175, more preferably at least 219, more preferably at least 262, even more preferably at least 306, and even more preferably at least 350 or 394 or more amino acid residues are aligned; when aligning a second sequence to the HST-5 amino acid sequence of SEQ ID NO:58 having 436 amino acid residues, at least 130, preferably at least 174, more preferably at least 218, more preferably at least 261, even more preferably at least 305, and even more preferably at least 348 or 392 or more amino acid residues are aligned). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid “identity” is equivalent to amino acid or nucleic acid “homology”). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.  
      The comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm. In a preferred embodiment, the percent identity between two amino acid sequences is determined using the Needleman and Wunsch ( J. Mol. Biol.  (48):444-453 (1970)) algorithm which has been incorporated into the GAP program in the GCG software package (available at http://www.gcg.com), using either a Blosum 62 matrix or a PAM250 matrix, and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5, or 6. In yet another preferred embodiment, the percent identity between two nucleotide sequences is determined using the GAP program in the GCG software package (available at http://www.gcg.com), using a NWSgapdna.CMP matrix and a gap weight of 40, 50, 60, 70, or 80 and a length weight of 1, 2, 3, 4, 5, or 6. A preferred, non-limiting example of parameters to be used in conjunction with the GAP program include a Blosum 62 scoring matrix with a gap penalty of 12, a gap extend penalty of 4, and a frameshift gap penalty of 5.  
      In another embodiment, the percent identity between two amino acid or nucleotide sequences is determined using the algorithm of E. Meyers and W. Miller ( Comput. Appl. Biosci.,  4:11-17 (1988)) which has been incorporated into the ALIGN program (version 2.0 or version 2.0U), using a PAM120 weight residue table, a gap length penalty of 12 and a gap penalty of 4.  
      The nucleic acid and polypeptide sequences of the present invention can further be used as a “query sequence” to perform a search against public databases to, for example, identify other family members or related sequences. Such searches can be performed using the NBLAST and XBLAST programs (version 2.0) of Altschul, et al. (1990)  J. Mol. Biol.  215:403-10. BLAST nucleotide searches can be performed with the NBLAST program, score=100, wordlength=12 to obtain nucleotide sequences homologous to HST-4 and/or HST-5 nucleic acid molecules of the invention. BLAST protein searches can be performed with the XBLAST program, score=100, wordlength=3, and a Blosum62 matrix to obtain amino acid sequences homologous to HST-4 and/or HST-5 polypeptide molecules of the invention. To obtain gapped alignments for comparison purposes, Gapped BLAST can be utilized as described in Altschul et al., (1997)  Nucleic Acids Res.  25(17):3389-3402. When utilizing BLAST and Gapped BLAST programs, the default parameters of the respective programs (e.g., XBLAST and NBLAST) can be used. See the internet website for the National Center for Biotechnology Information.  
      The invention also provides MTP-1 chimeric or fusion proteins. As used herein, an MTP-1 “chimeric protein” or “fusion protein” comprises an MTP-1 polypeptide operatively linked to a non-MTP-1 polypeptide. An “MTP-1 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to an MTP-1 molecule, whereas a “non-MTP-1 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to a protein which is not substantially homologous to the MTP-1 protein, e.g., a protein which is different from the MTP-1 protein and which is derived from the same or a different organism. Within an MTP-1 fusion protein the MTP-1 polypeptide can correspond to all or a portion of an MTP-1 protein. In a preferred embodiment, an MTP-1 fusion protein comprises at least one biologically active portion of an MTP-1 protein. In another preferred embodiment, an MTP-1 fusion protein comprises at least two biologically active portions of an MTP-1 protein. Within the fusion protein, the term “operatively linked” is intended to indicate that the MTP-1 polypeptide and the non-MTP-1 polypeptide are fused in-frame to each other. The non-MTP-1 polypeptide can be fused to the N-terminus or C-terminus of the MTP-1 polypeptide.  
      For example, in one embodiment, the fusion protein is a GST-MTP-1 fusion protein in which the MTP-1 sequences are fused to the C-terminus of the GST sequences. Such fusion proteins can facilitate the purification of recombinant MTP-1.  
      In another embodiment, the fusion protein is an MTP-1 protein containing a heterologous signal sequence at its N-terminus. In certain host cells (e.g., mammalian host cells), expression and/or secretion of MTP-1 can be increased through use of a heterologous signal sequence.  
      The invention also provides OAT chimeric or fusion proteins. As used herein, an OAT “chimeric protein” or “fusion protein” comprises an OAT polypeptide operatively linked to a non-OAT polypeptide. AN “OAT polypeptide” refers to a polypeptide having an amino acid sequence corresponding to an OAT protein, whereas a “non-OAT polypeptide” refers to a polypeptide having an amino acid sequence corresponding to a protein which is not substantially homologous to the OAT protein, e.g., a protein which is different from the OAT protein and which is derived from the same or a different organism. Within an OAT fusion protein the OAT polypeptide can correspond to all or a portion of an OAT protein. In a preferred embodiment, an OAT fusion protein comprises at least one biologically active portion of an OAT protein. In another preferred embodiment, an OAT fusion protein comprises at least two biologically active portions of an OAT protein. Within the fusion protein, the term “operatively linked” is intended to indicate that the OAT polypeptide and the non-OAT polypeptide are fused in-frame to each other. The non-OAT polypeptide can be fused to the N-terminus or C-terminus of the OAT polypeptide.  
      For example, in one embodiment, the fusion protein is a GST-OAT fusion protein in which the OAT sequences are fused to the C-terminus of the GST sequences. Such fusion proteins can facilitate the purification of recombinant OAT. In another embodiment, the fusion protein is an OAT protein containing a heterologous signal sequence at its N-terminus. In certain host cells (e.g., mammalian host cells), expression and/or secretion of OAT can be increased through use of a heterologous signal sequence.  
      The invention also provides HST-1 chimeric or fusion proteins. As used herein, an HST-1 “chimeric protein” or “fusion protein” comprises an HST-1 polypeptide operatively linked to a non-HST-1 polypeptide. An “HST-1 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to HST-1, whereas a “non-HST-1 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to a polypeptide which is not substantially homologous to the HST-1 polypeptide, e.g., a polypeptide which is different from the HST-1 polypeptide and which is derived from the same or a different organism. Within an HST-1 fusion protein the HST-1 polypeptide can correspond to all or a portion of an HST-1 polypeptide. In a preferred embodiment, an HST-1 fusion protein comprises at least one biologically active portion of an HST-1 polypeptide. In another preferred embodiment, an HST-1 fusion protein comprises at least two biologically active portions of an HST-1 polypeptide. Within the fusion protein, the term “operatively linked” is intended to indicate that the HST-1 polypeptide and the non-HST-1 polypeptide are fused in-frame to each other. The non-HST-1 polypeptide can be fused to the N-terminus or C-terminus of the HST-1 polypeptide.  
      For example, in one embodiment, the fusion protein is a GST-HST-1 fusion protein in which the HST-1 sequences are fused to the C-terminus of the GST sequences. Such fusion proteins can facilitate the purification of recombinant HST-1.  
      In another embodiment, the fusion protein is an HST-1 polypeptide containing a heterologous signal sequence at its N-terminus. In certain host cells (e.g., mammalian host cells), expression and/or secretion of HST-1 can be increased through the use of a heterologous signal sequence.  
      The invention also provides TP-2 chimeric or fusion proteins. As used herein, a TP-2 “chimeric protein” or “fusion protein” comprises a TP-2 polypeptide operatively linked to a non-TP-2 polypeptide. An “TP-2 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to TP-2, whereas a “non-TP-2 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to a polypeptide which is not substantially homologous to the TP-2 polypeptide, e.g., a polypeptide which is different from the TP-2 polypeptide and which is derived from the same or a different organism. Within a TP-2 fusion protein the TP-2 polypeptide can correspond to all or a portion of a TP-2 polypeptide. In a preferred embodiment, a TP-2 fusion protein comprises at least one biologically active portion of a TP-2 polypeptide. In another preferred embodiment, a TP-2 fusion protein comprises at least two biologically active portions of a TP-2 polypeptide. Within the fusion protein, the term “operatively linked” is intended to indicate that the TP-2 polypeptide and the non-TP-2 polypeptide are fused in-frame to each other. The non-TP-2 polypeptide can be fused to the N-terminus or C-terminus of the TP-2 polypeptide.  
      For example, in one embodiment, the fusion protein is a GST-TP-2 fusion protein in which the TP-2 sequences are fused to the C-terminus of the GST sequences. Such fusion proteins can facilitate the purification of recombinant TP-2.  
      In another embodiment, the fusion protein is a TP-2 polypeptide containing a heterologous signal sequence at its N-terminus. In certain host cells (e.g., mammalian host cells), expression and/or secretion of TP-2 can be increased through the use of a heterologous signal sequence.  
      The invention also provides PLTR-1 chimeric or fusion proteins. As used herein, a PLTR-1 “chimeric protein” or “fusion protein” comprises a PLTR-1 polypeptide operatively linked to a non-PLTR-1 polypeptide. A “PLTR-1 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to PLTR-1, whereas a “non-PLTR-1 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to a protein which is not substantially homologous to the PLTR-1 protein, e.g., a protein which is different from the PLTR-1 protein and which is derived from the same or a different organism. Within a PLTR-1 fusion protein the PLTR-1 polypeptide can correspond to all or a portion of a PLTR-1 protein. In a preferred embodiment, a PLTR-1 fusion protein comprises at least one biologically active portion of a PLTR-1 protein. In another preferred embodiment, a PLTR-1 fusion protein comprises at least two biologically active portions of a PLTR-1 protein. Within the fusion protein, the term “operatively linked” is intended to indicate that the PLTR-1 polypeptide and the non-PLTR-1 polypeptide are fused in-frame to each other. The non-PLTR-1 polypeptide can be fused to the N-terminus or C-terminus of the PLTR-1 polypeptide.  
      For example, in one embodiment, the fusion protein is a GST-PLTR-1 fusion protein in which the PLTR-1 sequences are fused to the C-terminus of the GST sequences. Such fusion proteins can facilitate the purification of recombinant PLTR-1. In another embodiment, the fusion protein is a PLTR-1 protein containing a heterologous signal sequence at its N-terminus. In certain host cells (e.g., mammalian host cells), expression and/or secretion of PLTR-1 can be increased through use of a heterologous signal sequence.  
      The invention also provides TFM-2 and/or TFM-3 chimeric or fusion proteins. As used herein, a TFM-2 and/or TFM-3 “chimeric protein” or “fusion protein” comprises a TFM-2 and/or TFM-3 polypeptide operatively linked to a non-TFM-2 and/or TFM-3 polypeptide. A “TFM-2 polypeptide” and a “TFM-3 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to TFM-2 and TFM-3, respectively, whereas a “non-TFM-2 polypeptide” and a “non-TFM-3 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to a polypeptide which is not substantially homologous to the TFM-2 and TFM-3 polypeptides, respectively, e.g., a polypeptide which is different from the TFM-2 and TFM-3 polypeptide and which is derived from the same or a different organism. Within a TFM-2 and/or TFM-3 fusion protein the TFM-2 and/or TFM-3 polypeptide can correspond to all or a portion of a TFM-2 and/or TFM-3 polypeptide. In a preferred embodiment, a TFM-2 and/or TFM-3 fusion protein comprises at least one biologically active portion of a TFM-2 and/or TFM-3 polypeptide. In another preferred embodiment, a TFM-2 and/or TFM-3 fusion protein comprises at least two biologically active portions of a TFM-2 and/or TFM-3 polypeptide. Within the fusion protein, the term “operatively linked” is intended to indicate that the TFM-2 and/or TFM-3 polypeptide and the non-TFM-2 and/or TFM-3 polypeptide are fused in-frame to each other. The non-TFM-2 and/or TFM-3 polypeptide can be fused to the N-terminus or C-terminus of the TFM-2 and/or TFM-3 polypeptide.  
      For example, in one embodiment, the fusion protein is a GST-TFM-2 and/or GST-TFM-3 fusion protein in which the TFM-2 and/or TFM-3 sequences are fused to the C-terminus of the GST sequences. Such fusion proteins can facilitate the purification of recombinant TFM-2 and/or TFM-3.  
      In another embodiment, the fusion protein is a TFM-2 and/or TFM-3 polypeptide containing a heterologous signal sequence at its N-terminus. In certain host cells (e.g., mammalian host cells), expression and/or secretion of TFM-2 and/or TFM-3 can be increased through the use of a heterologous signal sequence.  
      The invention also provides 67118, 67067, and/or 62092 chimeric or fusion proteins. As used herein, a 67118, 67067, and/or 62092 “chimeric protein” or “fusion protein” comprises a 67118, 67067, and/or 62092 polypeptide operatively linked to a non-67118, a non-67067, and/or a non-62092 polypeptide. A “67118 polypeptide,” a “67067 polypeptide,” and a “62092 polypeptide” refer to a polypeptide having an amino acid sequence corresponding to 67118, 67067, and 62092, respectively, whereas a “non-67118 polypeptide,” a “non-67067 polypeptide,” and a “non-62092 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to a polypeptide which is not substantially homologous to the 67118, 67067, and 62092 polypeptides, respectively, e.g., a polypeptide which is different from the 67118, 67067, and 62092 polypeptide and which is derived from the same or a different organism. Within a 67118, 67067, and/or 62092 fusion protein the 67118, 67067, and/or 62092 polypeptide can correspond to all or a portion of a 67118, 67067, and/or 62092 polypeptide. In a preferred embodiment, a 67118, 67067, and/or 62092 fusion protein comprises at least one biologically active portion of a 67118, 67067, and/or 62092 polypeptide. In another preferred embodiment, a 67118, 67067, and/or 62092 fusion protein comprises at least two biologically active portions of a 67118, 67067, and/or 62092 polypeptide. Within the fusion protein, the term “operatively linked” is intended to indicate that the 67118, 67067, and/or 62092 polypeptide and the non-67118, 67067, and/or 62092 polypeptide are fused in-frame to each other. The non-67118, 67067, and/or 62092 polypeptide can be fused to the N-terminus or C-terminus of the 67118, 67067, and/or 62092 polypeptide.  
      For example, in one embodiment, the fusion protein is a GST-67118, GST-67067, or GST-62092 fusion protein in which the 67118, 67067, or 62092 sequences are fused to the C-terminus of the GST sequences. Such fusion proteins can facilitate the purification of recombinant 67118, 67067, or 62092.  
      In another embodiment, the fusion protein is a 67118, 67067, and/or 62092 polypeptide containing a heterologous signal sequence at its N-terminus. In certain host cells (e.g., mammalian host cells), expression and/or secretion of 67118, 67067, and/or 62092 can be increased through the use of a heterologous signal sequence.  
      The invention also provides HAAT chimeric or fusion proteins. As used herein, a HAAT “chimeric protein” or “fusion protein” comprises a HAAT polypeptide operatively linked to a non-HAAT polypeptide. A “HAAT polypeptide” refers to a polypeptide having an amino acid sequence corresponding to HAAT, whereas a “non-HAAT polypeptide” refers to a polypeptide having an amino acid sequence corresponding to a protein which is not substantially homologous to the HAAT protein, e.g., a protein which is different from the HAAT protein and which is derived from the same or a different organism. Within a HAAT fusion protein the HAAT polypeptide can correspond to all or a portion of a HAAT protein. In a preferred embodiment, a HAAT fusion protein comprises at least one biologically active portion of a HAAT protein. In another preferred embodiment, a HAAT fusion protein comprises at least two biologically active portions of a HAAT protein. Within the fusion protein, the term “operatively linked” is intended to indicate that the HAAT polypeptide and the non-HAAT polypeptide are fused in-frame to each other. The non-HAAT polypeptide can be fused to the N-terminus or C-terminus of the HAAT polypeptide.  
      For example, in one embodiment, the fusion protein is a GST-HAAT fusion protein in which the HAAT sequences are fused to the C-terminus of the GST sequences. Such fusion proteins can facilitate the purification of recombinant HAAT. In another embodiment, the fusion protein is a HAAT protein containing a heterologous signal sequence at its N-terminus. In certain host cells (e.g., mammalian host cells), expression and/or secretion of HAAT can be increased through use of a heterologous signal sequence.  
      The invention also provides HST-4 and/or HST-5 chimeric or fusion proteins. As used herein, an HST-4 and/or an HST-5 “chimeric protein” or “fusion protein” comprises an HST-4 and/or an HST-5 polypeptide operatively linked to a non-HST-4 and/or non-HST-5 polypeptide. An “HST-4 polypeptide” or an “HST-5 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to HST-4 and/or HST-5, whereas a “non- HST-4 polypeptide” or a “non- HST-5 polypeptide” refers to a polypeptide having an amino acid sequence corresponding to a polypeptide which is not substantially homologous to the HST-4 and/or the HST-5 polypeptide, e.g., a polypeptide which is different from the HST-4 and/or the HST-5 polypeptide and which is derived from the same or a different organism. Within an HST-4 and/or an HST-5 fusion protein the HST-4 and/or the HST-5 polypeptide can correspond to all or a portion of an HST-4 and/or an HST-5 polypeptide. In a preferred embodiment, an HST-4 and/or an HST-5 fusion protein comprises at least one biologically active portion of an HST-4 and/or an HST-5 polypeptide. In another preferred embodiment, an HST-4 and/or an HST-5 fusion protein comprises at least two biologically active portions of an HST-4 and/or an HST-5 polypeptide. Within the fusion protein, the term “operatively linked” is intended to indicate that the HST-4 and/or the HST-5 polypeptide and the non-HST-4 and/or non-HST-5 polypeptide are fused in-frame to each other. The non-HST-4 and/or the non-HST-5 polypeptide can be fused to the N-terminus or C-terminus of the HST-4 and/or the HST-5 polypeptide.  
      For example, in one embodiment, the fusion protein is a GST-HST-4 and/or a GST-HST-5 fusion protein in which the HST-4 and/or the HST-5 sequences are fused to the C-terminus of the GST sequences. Such fusion proteins can facilitate the purification of recombinant HST-4 and/or HST-5.  
      In another embodiment, the fusion protein is an HST-4 and/or an HST-5 polypeptide containing a heterologous signal sequence at its N-terminus. In certain host cells (e.g., mammalian host cells), expression and/or secretion of HST-4 and/or HST-5 can be increased through the use of a heterologous signal sequence.  
      The MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 fusion proteins of the invention can be incorporated into pharmaceutical compositions and administered to a subject in vivo. The MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 fusion proteins can be used to affect the bioavailability of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 substrate. Use of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 fusion proteins may be useful therapeutically for the treatment of disorders caused by, for example, (i) aberrant modification or mutation of a gene encoding an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide; (ii) mis-regulation of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 gene; and (iii) aberrant post-translational modification of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide.  
      Moreover, the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4- and/or the HST-5-fusion proteins of the invention can be used as immunogens to produce anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti- HAAT, anti-HST-4 and/or anti-HST-5 antibodies in a subject, to purify MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 ligands and in screening assays to identify molecules which inhibit the interaction of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118,67067,62092, HAAT, HST-4 and/or HST-5 with an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118,67067,62092, HAAT, HST-4 and/or an HST-5 substrate.  
      Preferably, an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3,67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 chimeric or fusion protein of the invention is produced by standard recombinant DNA techniques. For example, DNA fragments coding for the different polypeptide sequences are ligated together in-frame in accordance with conventional techniques, for example by employing blunt-ended or stagger-ended termini for ligation, restriction enzyme digestion to provide for appropriate termini, filling-in of cohesive ends as appropriate, alkaline phosphatase treatment to avoid undesirable joining, and enzymatic ligation. In another embodiment, the fusion gene can be synthesized by conventional techniques including automated DNA synthesizers. Alternatively, PCR amplification of gene fragments can be carried out using anchor primers which give rise to complementary overhangs between two consecutive gene fragments which can subsequently be annealed and reamplified to generate a chimeric gene sequence (see, for example,  Current Protocols in Molecular Biology,  eds. Ausubel et al. John Wiley &amp; Sons: 1992). Moreover, many expression vectors are commercially available that already encode a fusion moiety (e.g., a GST polypeptide). An MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3,67118, 67067, 62092, HAAT, HST-4- and/or an HST-5-encoding nucleic acid can be cloned into such an expression vector such that the fusion moiety is linked in-frame to the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptide.  
      The present invention also pertains to variants of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptides which function as either MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 agonists (mimetics) or as HST-4 and/or HST-5 antagonists. Variants of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptides can be generated by mutagenesis, e.g., discrete point mutation or truncation of an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 polypeptide. An agonist of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptides can retain substantially the same, or a subset, of the biological activities of the naturally occurring form of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide. An antagonist of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide can inhibit one or more of the activities of the naturally occurring form of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118,67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptide by, for example, competitively modulating an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4- and/or an HST-5-mediated activity of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide. Thus, specific biological effects can be elicited by treatment with a variant of limited function. In one embodiment, treatment of a subject with a variant having a subset of the biological activities of the naturally occurring form of the polypeptide has fewer side effects in a subject relative to treatment with the naturally occurring form of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptide.  
      In one embodiment, variants of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide which function as either MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 agonists (mimetics) or as MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 antagonists can be identified by screening combinatorial libraries of mutants, e.g., truncation mutants, of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide for MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide agonist or antagonist activity. In one embodiment, a variegated library of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 variants is generated by combinatorial mutagenesis at the nucleic acid level and is encoded by a variegated gene library. A variegated library of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 variants can be produced by, for example, enzymatically ligating a mixture of synthetic oligonucleotides into gene sequences such that a degenerate set of potential MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequences is expressible as individual polypeptides, or alternatively, as a set of larger fusion proteins (e.g., for phage display) containing the set of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequences therein. There are a variety of methods which can be used to produce libraries of potential MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 variants from a degenerate oligonucleotide sequence. Chemical synthesis of a degenerate gene sequence can be performed in an automatic DNA synthesizer, and the synthetic gene then ligated into an appropriate expression vector. Use of a degenerate set of genes allows for the provision, in one mixture, of all of the sequences encoding the desired set of potential MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequences. Methods for synthesizing degenerate oligonucleotides are known in the art (see, e.g., Narang, S. A. (1983)  Tetrahedron  39:3; Itakura et al. (1984)  Annu. Rev. Biochem.  53:323; Itakura et al. (1984)  Science  198:1056; Ike et al. (1983)  Nucleic Acid Res.  11:477.  
      In addition, libraries of fragments of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide coding sequence can be used to generate a variegated population of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 fragments for screening and subsequent selection of variants of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide. In one embodiment, a library of coding sequence fragments can be generated by treating a double stranded PCR fragment of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 coding sequence with a nuclease under conditions wherein nicking occurs only about once per molecule, denaturing the double stranded DNA, renaturing the DNA to form double stranded DNA which can include sense/antisense pairs from different nicked products, removing single stranded portions from reformed duplexes by treatment with S1 nuclease, and ligating the resulting fragment library into an expression vector. By this method, an expression library can be derived which encodes N-terminal, C-terminal and internal fragments of various sizes of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptide.  
      Several techniques are known in the art for screening gene products of combinatorial libraries made by point mutations or truncation, and for screening cDNA libraries for gene products having a selected property. Such techniques are adaptable for rapid screening of the gene libraries generated by the combinatorial mutagenesis of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides. The most widely used techniques, which are amenable to high through-put analysis, for screening large gene libraries typically include cloning the gene library into replicable expression vectors, transforming appropriate cells with the resulting library of vectors, and expressing the combinatorial genes under conditions in which detection of a desired activity facilitates isolation of the vector encoding the gene whose product was detected. Recursive ensemble mutagenesis (REM), a new technique which enhances the frequency of functional mutants in the libraries, can be used in combination with the screening assays to identify MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 variants (Arkin and Youvan (1992)  Proc. Natl. Acad. Sci. USA  89:7811-7815; Delagrave et al. (1993)  Protein Engineering  6(3):327-331).  
      In one embodiment, cell based assays can be exploited to analyze a variegated MTP-1 library. For example, a library of expression vectors can be transfected into a cell line, e.g., a neuronal cell line, which ordinarily responds to an MTP-1 ligand in a particular MTP-1 ligand-dependent manner. The transfected cells are then contacted with an MTP-1 ligand and the effect of expression of the mutant on, e.g., membrane excitability of MTP-1 can be detected. Plasmid DNA can then be recovered from the cells which score for inhibition, or alternatively, potentiation of signaling by the MTP-1 ligand, and the individual clones further characterized.  
      An isolated MTP-1 protein, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind MTP-1 using standard techniques for polyclonal and monoclonal antibody preparation. A full-length MTP-1 protein can be used or, alternatively, the invention provides antigenic peptide fragments of MTP-1 for use as immunogens. The antigenic peptide of MTP-1 comprises at least 8 amino acid residues of the amino acid sequence shown in SEQ ID NO:2 and encompasses an epitope of MTP-1 such that an antibody raised against the peptide forms a specific immune complex with the MTP-1 protein. Preferably, the antigenic peptide comprises at least 10 amino acid residues, more preferably at least 15 amino acid residues, even more preferably at least 20 amino acid residues, and most preferably at least 30 amino acid residues. In a preferred embodiment, portions of the extracellular domains (e.g., extracellular non-transmembrane domains) in the amino acid sequence of MTP-1 are used as immunogens (e.g., at about residues 40-548, at about residues 612-624, at about residue 675-1006, at about residue 1258-1534, at about residues 1603-1645, and at about residues 1749-1931 of SEQ ID NO:2).  
      Preferred epitopes encompassed by the antigenic peptide are regions of MTP-1 that are located on the surface of the protein, e.g., hydrophilic regions, as well as regions with high antigenicity.  
      In one embodiment, cell based assays can be exploited to analyze a variegated OAT library. For example, a library of expression vectors can be transfected into a cell line, e.g., a liver cell line, which ordinarily responds to OAT in a particular OAT substrate-dependent manner. The transfected cells are then contacted with an OAT substrate and the effect of the expression of the mutant on signaling by the OAT substrate can be detected, e.g., by measuring levels of OAT substrate transported into or out of the cells, by measuring gene transcription, by measuring cellular proliferation, and/or by measuring activity of intracellular signaling pathways. Plasmid DNA can then be recovered from the cells which score for inhibition, or alternatively, potentiation of signaling by the OAT substrate, and the individual clones further characterized.  
      An isolated OAT protein, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind OAT using standard techniques for polyclonal and monoclonal antibody preparation. A full-length OAT protein can be used or, alternatively, the invention provides antigenic peptide fragments of OAT for use as immunogens. The antigenic peptide of OAT comprises at least 8 amino acid residues of the amino acid sequence shown in SEQ ID NO:5 or 8 and encompasses an epitope of OAT such that an antibody raised against the peptide forms a specific immune complex with OAT. Preferably, the antigenic peptide comprises at least 10 amino acid residues, more preferably at least 15 amino acid residues, even more preferably at least 20 amino acid residues, and most preferably at least 30 amino acid residues.  
      Preferred epitopes encompassed by the antigenic peptide are regions of OAT that are located on the surface of the protein, e.g., hydrophilic regions, as well as regions with high antigenicity (see, for example,  FIGS. 4 and 5 ).  
      In one embodiment, cell based assays can be exploited to analyze a variegated HST-1 library. For example, a library of expression vectors can be transfected into a cell line, e.g., an endothelial cell line, which ordinarily responds to HST-1 in a particular HST-1 substrate-dependent manner. The transfected cells are then contacted with HST-1 and the effect of expression of the mutant on signaling by the HST-1 substrate can be detected, e.g., by monitoring intracellular calcium, IP3, or diacylglycerol concentration, phosphorylation profile of intracellular proteins, or the activity of an HST-1-regulated transcription factor. Plasmid DNA can then be recovered from the cells which score for inhibition, or alternatively, potentiation of signaling by the HST-1 substrate, and the individual clones further characterized.  
      An isolated HST-1 polypeptide, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind HST-1 using standard techniques for polyclonal and monoclonal antibody preparation. A full-length HST-1 polypeptide can be used or, alternatively, the invention provides antigenic peptide fragments of HST-1 for use as immunogens. The antigenic peptide of HST-1 comprises at least 8 amino acid residues of the amino acid sequence shown in SEQ ID NO:13 and encompasses an epitope of HST-1 such that an antibody raised against the peptide forms a specific immune complex with HST-1. Preferably, the antigenic peptide comprises at least 10 amino acid residues, more preferably at least 15 amino acid residues, even more preferably at least 20 amino acid residues, and most preferably at least 30 amino acid residues.  
      Preferred epitopes encompassed by the antigenic peptide are regions of HST-1 that are located on the surface of the polypeptide, e.g., hydrophilic regions, as well as regions with high antigenicity (see, for example,  FIG. 7 ).  
      In one embodiment, cell based assays can be exploited to analyze a variegated TP-2 library. For example, a library of expression vectors can be transfected into a cell line, e.g., an endothelial cell line, which ordinarily responds to TP-2 in a particular TP-2 substrate-dependent manner. The transfected cells are then contacted with TP-2 and the effect of expression of the mutant on signaling by the TP-2 substrate can be detected, e.g., by monitoring intra-cellular calcium, IP3, or diacylglycerol concentration, phosphorylation profile of intra-cellular proteins, or the activity of a TP-2-regulated transcription factor. Plasmid DNA can then be recovered from the cells which score for inhibition, or alternatively, potentiation of signaling by the TP-2 substrate, and the individual clones further characterized.  
      An isolated TP-2 polypeptide, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind TP-2 using standard techniques for polyclonal and monoclonal antibody preparation. A full-length TP-2 polypeptide can be used or, alternatively, the invention provides antigenic peptide fragments of TP-2 for use as immunogens. The antigenic peptide of TP-2 comprises at least 8 amino acid residues of the amino acid sequence shown in SEQ ID NO:16 and encompasses an epitope of TP-2 such that an antibody raised against the peptide forms a specific immune complex with TP-2. Preferably, the antigenic peptide comprises at least 10 amino acid residues, more preferably at least 15 amino acid residues, even more preferably at least 20 amino acid residues, and most preferably at least 30 amino acid residues.  
      Preferred epitopes encompassed by the antigenic peptide are regions of TP-2 that are located on the surface of the polypeptide, e.g., hydrophilic regions, as well as regions with high antigenicity (see, for example,  FIG. 11 ).  
      In one embodiment, cell based assays can be exploited to analyze a variegated PLTR-1 library. For example, a library of expression vectors can be transfected into a cell line which ordinarily responds to PLTR-1 in a particular PLTR-1 substrate-dependent manner. The transfected cells are then contacted with PLTR-1 and the effect of the expression of the mutant on signaling by the PLTR-1 substrate can be detected, e.g., phospholipid transport (e.g., by measuring phospholipid levels inside the cell or its various cellular compartments, within various cellular membranes, or in the extracellular medium), hydrolysis of ATP, phosphorylation or dephosphorylation of the HEAT protein, and/or gene transcription. Plasmid DNA can then be recovered from the cells which score for inhibition, or alternatively, potentiation of signaling by the HEAT substrate, or which score for increased or decreased levels of phospholipid transport or ATP hydrolysis, and the individual clones further characterized.  
      An isolated PLTR-1 protein, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind PLTR-1 using standard techniques for polyclonal and monoclonal antibody preparation. A full-length PLTR-1 protein can be used or, alternatively, the invention provides antigenic peptide fragments of PLTR-1 for use as immunogens. The antigenic peptide of PLTR-1 comprises at least 8 amino acid residues of the amino acid sequence shown in SEQ ID NO:20 and encompasses an epitope of PLTR-1 such that an antibody raised against the peptide forms a specific immune complex with PLTR-1. Preferably, the antigenic peptide comprises at least 10 amino acid residues, more preferably at least 15 amino acid residues, even more preferably at least 20 amino acid residues, and most preferably at least 30 amino acid residues.  
      Preferred epitopes encompassed by the antigenic peptide are regions of PLTR-1 that are located on the surface of the protein, e.g., hydrophilic regions, as well as regions with high antigenicity (see, for example,  FIG. 15 ).  
      In one embodiment, cell based assays can be exploited to analyze a variegated TFM-2 and/or TFM-3 library. For example, a library of expression vectors can be transfected into a cell line, e.g., an endothelial cell line, which ordinarily responds to TFM-2 and/or TFM-3 in a particular TFM-2 and/or TFM-3 substrate-dependent manner. The transfected cells are then contacted with TFM-2 and/or TFM-3 and the effect of expression of the mutant on signaling by the TFM-2 and/or TFM-3 substrate can be detected, e.g., by monitoring intra-cellular calcium, IP3, or diacylglycerol concentration, phosphorylation profile of intra-cellular proteins, or the activity of a TFM-2 and/or TFM-3-regulated transcription factor. Plasmid DNA can then be recovered from the cells which score for inhibition, or alternatively, potentiation of signaling by the TFM-2 and/or TFM-3 substrate, and the individual clones further characterized.  
      An isolated TFM-2 and/or TFM-3 polypeptide, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind TFM-2 and/or TFM-3 using standard techniques for polyclonal and monoclonal antibody preparation. A full-length TFM-2 and/or TFM-3 polypeptide can be used or, alternatively, the invention provides antigenic peptide fragments of TFM-2 and/or TFM-3 for use as immunogens. The antigenic peptide of TFM-2 and/or TFM-3 comprises at least 8 amino acid residues of the amino acid sequence shown in SEQ ID NO:28 or 31 and encompasses an epitope of TFM-2 and/or TFM-3 such that an antibody raised against the peptide forms a specific immune complex with TFM-2 and/or TFM-3. Preferably, the antigenic peptide comprises at least 10 amino acid residues, more preferably at least 15 amino acid residues, even more preferably at least 20 amino acid residues, and most preferably at least 30 amino acid residues.  
      Preferred epitopes encompassed by the antigenic peptide are regions of TFM-2 and/or TFM-3 that are located on the surface of the polypeptide, e.g., hydrophilic regions, as well as regions with high antigenicity (see, for example,  FIGS. 16 and 18 ).  
      In one embodiment, cell based assays can be exploited to analyze a variegated 67118 or 67067 library. For example, a library of expression vectors can be transfected into a cell line, which ordinarily responds to 67118 or 67067 in a particular 67118 or 67067 substrate-dependent manner. The transfected cells are then contacted with 67118 or 67067 and the effect of the expression of the mutant on signaling by the 67118 or 67067 substrate can be detected, e.g., the effect on phospholipid transport (e.g., by measuring phospholipid levels inside the cell or its various cellular compartments, within various cellular membranes, or in the extra-cellular medium), hydrolysis of ATP, phosphorylation or dephosphorylation of the HEAT protein, and/or gene transcription. Plasmid DNA can then be recovered from the cells which score for inhibition, or alternatively, potentiation of signaling by the HEAT substrate, or which score for increased or decreased levels of phospholipid transport or ATP hydrolysis, and the individual clones further characterized.  
      In another embodiment, cell based assays can be exploited to analyze a variegated 62092 library. For example, a library of expression vectors can be transfected into a cell line which ordinarily responds to 62092 in a particular 62092 substrate-dependent manner. The transfected cells are then contacted with 62092 and the effect of the expression of the mutant on signaling by the 62092 substrate can be detected, e.g., by measuring levels of free or 62092 bound nucleotides, cleaved nucleotides, gene transcription, and/or cell proliferation, growth, differentiation, or apoptosis. Plasmid DNA can then be recovered from the cells which score for inhibition, or alternatively, potentiation of signaling by the 62092 substrate, and the individual clones further characterized.  
      An isolated 67118, 67067, and/or 62092 polypeptide, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind 67118, 67067, and/or 62092 using standard techniques for polyclonal and monoclonal antibody preparation. A full-length 67118, 67067, and/or 62092 polypeptide can be used or, alternatively, the invention provides antigenic peptide fragments of 67118, 67067, and/or 62092 for use as immunogens. The antigenic peptide of 67118, 67067, and/or 62092 comprises at least 8 amino acid residues of the amino acid sequence shown in SEQ ID NO:34, 37, or 40 and encompasses an epitope of 67118, 67067, and/or 62092 such that an antibody raised against the peptide forms a specific immune complex with 67118, 67067, and/or 62092. Preferably, the antigenic peptide comprises at least 10 amino acid residues, more preferably at least 15 amino acid residues, even more preferably at least 20 amino acid residues, and most preferably at least 30 amino acid residues.  
      Preferred epitopes encompassed by the antigenic peptide are regions of 67118, 67067, and/or 62092 that are located on the surface of the polypeptide, e.g., hydrophilic regions, as well as regions with high antigenicity (see, for example,  FIGS. 20, 22 , and  24 , respectively).  
      In one embodiment, cell based assays can be exploited to analyze a variegated HAAT library. For example, a library of expression vectors can be transfected into a cell line which ordinarily responds to HAAT in a particular HAAT substrate-dependent manner. The transfected cells are then contacted with HAAT and the effect of the expression of the mutant on the HAAT substrate can be detected, e.g., amino acid transport (e.g., by measuring amino acid levels inside the cell or its various cellular compartments, within various cellular membranes, or in the extracellular medium), and/or gene transcription. Plasmid DNA can then be recovered from the cells which score for increased or decreased levels of amino acid transport, and the individual clones further characterized.  
      An isolated HAAT protein, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind HAAT using standard techniques for polyclonal and monoclonal antibody preparation. A full-length HAAT protein can be used or, alternatively, the invention provides antigenic peptide fragments of HAAT for use as immunogens. The antigenic peptide of HAAT comprises at least 8 amino acid residues of the amino acid sequence shown in SEQ ID NO:52 and encompasses an epitope of HAAT such that an antibody raised against the peptide forms a specific immune complex with HAAT. Preferably, the antigenic peptide comprises at least 10 amino acid residues, more preferably at least 15 amino acid residues, even more preferably at least 20 amino acid residues, and most preferably at least 30 amino acid residues.  
      Preferred epitopes encompassed by the antigenic peptide are regions of HAAT that are located on the surface of the protein, e.g., hydrophilic regions, as well as regions with high antigenicity (see, for example,  FIG. 26 ).  
      In one embodiment, cell based assays can be exploited to analyze a variegated HST-4 and/or HST-5 library. For example, a library of expression vectors can be transfected into a cell line, e.g., an endothelial cell line, which ordinarily responds to HST-4 and/or HST-5 in a particular HST-4 and/or HST-5 substrate-dependent manner. The transfected cells are then contacted with HST-4 and/or HST-5 and the effect of expression of the mutant on signaling by the HST-4 and/or the HST-5 substrate can be detected, e.g., by monitoring intracellular calcium, IP3, or diacylglycerol concentration, phosphorylation profile of intracellular proteins, or the activity of an HST-4- and/or an HST-5-regulated transcription factor. Plasmid DNA can then be recovered from the cells which score for inhibition, or alternatively, potentiation of signaling by the HST-4 and/or the HST-5 substrate, and the individual clones further characterized.  
      An isolated HST-4 and/or HST-5 polypeptide, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind HST-4 and/or HST-5 using standard techniques for polyclonal and monoclonal antibody preparation. A full-length HST-4 and/or HST-5 polypeptide can be used or, alternatively, the invention provides antigenic peptide fragments of HST-4 and/or HST-5 for use as immunogens. The antigenic peptide of HST-4 and/or HST-5 comprises at least 8 amino acid residues of the amino acid sequence shown in SEQ ID NO:55 or 58 and encompasses an epitope of HST-4 and/or HST-5 such that an antibody raised against the peptide forms a specific immune complex with HST-4 and/or HST-5. Preferably, the antigenic peptide comprises at least 10 amino acid residues, more preferably at least 15 amino acid residues, even more preferably at least 20 amino acid residues, and most preferably at least 30 amino acid residues.  
      Preferred epitopes encompassed by the antigenic peptide are regions of HST-4 and/or HST-5 that are located on the surface of the polypeptide, e.g., hydrophilic regions, as well as regions with high antigenicity (see, for example,  FIGS. 29 and 30 ).  
      An MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 immunogen typically is used to prepare antibodies by immunizing a suitable subject, (e.g., rabbit, goat, mouse or other mammal) with the immunogen. An appropriate immunogenic preparation can contain, for example, recombinantly expressed MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide or a chemically synthesized MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide. The preparation can further include an adjuvant, such as Freund&#39;s complete or incomplete adjuvant, or similar immunostimulatory agent. Immunization of a suitable subject with an immunogenic HST-4 and/or HST-5 preparation induces a polyclonal anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti- HAAT, anti-HST-4 and/or anti-HST-5 antibody response.  
      Accordingly, another aspect of the invention pertains to anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti- HAAT, anti-HST-4 and/or anti-HST-5 antibodies. The term “antibody” as used herein refers to immunoglobulin molecules and immunologically active portions of immunoglobulin molecules, i.e., molecules that contain an antigen binding site which specifically binds (immunoreacts with) an antigen, such as MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5. Examples of immunologically active portions of immunoglobulin molecules include F(ab) and F(ab′) 2  fragments which can be generated by treating the antibody with an enzyme such as pepsin. The invention provides polyclonal and monoclonal antibodies that bind MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5. The term “monoclonal antibody” or “monoclonal antibody composition”, as used herein, refers to a population of antibody molecules that contain only one species of an antigen binding site capable of immunoreacting with a particular epitope of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5. A monoclonal antibody composition thus typically displays a single binding affinity for a particular MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide with which it immunoreacts.  
      Polyclonal anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti- HAAT, anti-HST-4 and/or anti-HST-5 antibodies can be prepared as described above by immunizing a suitable subject with an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 immunogen. The anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti- HAAT, anti-HST-4 and/or anti-HST-5 antibody titer in the immunized subject can be monitored over time by standard techniques, such as with an enzyme linked immunosorbent assay (ELISA) using immobilized MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5. If desired, the antibody molecules directed against MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 can be isolated from the mammal (e.g., from the blood) and further purified by well known techniques, such as protein A chromatography to obtain the IgG fraction. At an appropriate time after immunization, e.g., when the anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti-HAAT, anti-HST-4 and/or anti-HST-5 antibody titers are highest, antibody-producing cells can be obtained from the subject and used to prepare monoclonal antibodies by standard techniques, such as the hybridoma technique originally described by Kohler and Milstein (1975)  Nature  256:495-497) (see also, Brown et al. (1981)  J. Immunol.  127:539-46; Brown et al. (1980)  J. Biol. Chem.  255:4980-83; Yeh et al. (1976)  Proc. Natl. Acad. Sci. USA  76:2927-31; and Yeh et al. (1982)  Int. J. Cancer  29:269-75), the more recent human B cell hybridoma technique (Kozbor et al. (1983)  Immunol Today  4:72), the EBV-hybridoma technique (Cole et al. (1985),  Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, Inc., pp.  77-96) or trioma techniques. The technology for producing monoclonal antibody hybridomas is well known (see generally R. H. Kenneth, in  Monoclonal Antibodies: A New Dimension In Biological Analyses,  Plenum Publishing Corp., New York, New York (1980); E. A. Lerner (1981)  Yale J. Biol. Med.,  54:387-402; M. L. Gefter et al. (1977)  Somatic Cell Genet.  3:231-36). Briefly, an immortal cell line (typically a myeloma) is fused to lymphocytes (typically splenocytes) from a mammal immunized with an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 immunogen as described above, and the culture supernatants of the resulting hybridoma cells are screened to identify a hybridoma producing a monoclonal antibody that binds MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5.  
      Any of the many well known protocols used for fusing lymphocytes and immortalized cell lines can be applied for the purpose of generating an anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti- HAAT, anti-HST-4 and/or anti-HST-5 monoclonal antibody (see, e.g., G. Galfre et al. (1977)  Nature  266:55052; Gefter et al.  Somatic Cell Genet.,  cited supra; Lerner,  Yale J. Biol. Med.,  cited supra; Kenneth,  Monoclonal Antibodies,  cited supra). Moreover, the ordinarily skilled worker will appreciate that there are many variations of such methods which also would be useful. Typically, the immortal cell line (e.g., a myeloma cell line) is derived from the same mammalian species as the lymphocytes. For example, murine hybridomas can be made by fusing lymphocytes from a mouse immunized with an immunogenic preparation of the present invention with an immortalized mouse cell line. Preferred immortal cell lines are mouse myeloma cell lines that are sensitive to culture medium containing hypoxanthine, aminopterin and thymidine (“HAT medium”). Any of a number of myeloma cell lines can be used as a fusion partner according to standard techniques, e.g., the P3-NS1/1-Ag4-1, P3-x63-Ag8.653 or Sp2/O-Ag14 myeloma lines. These myeloma lines are available from ATCC (American Type Culture Collection, Manassas, Va.). Typically, HAT-sensitive mouse myeloma cells are fused to mouse splenocytes using polyethylene glycol (“PEG”). Hybridoma cells resulting from the fusion are then selected using HAT medium, which kills unfused and unproductively fused myeloma cells (unfused splenocytes die after several days because they are not transformed). Hybridoma cells producing a monoclonal antibody of the invention are detected by screening the hybridoma culture supernatants for antibodies that bind MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5, e.g., using a standard ELISA assay.  
      Alternative to preparing monoclonal antibody-secreting hybridomas, a monoclonal anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1,anti- TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti- HAAT, anti-HST-4 and/or anti-HST-5 antibody can be identified and isolated by screening a recombinant combinatorial immunoglobulin library (e.g., an antibody phage display library) with MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 to thereby isolate immunoglobulin library members that bind MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5. Kits for generating and screening phage display libraries are commercially available (e.g., the Pharmacia  Recombinant Phage Antibody System,  Catalog No. 27-9400-01; and the Stratagene SurfZAP™ Phage Display Kit, Catalog No. 240612). Additionally, examples of methods and reagents particularly amenable for use in generating and screening antibody display library can be found in, for example, Ladner et al. U.S. Pat. No. 5,223,409; Kang et al. PCT International Publication No. WO 92/18619; Dower et al. PCT International Publication No. WO 91/17271; Winter et al. PCT International Publication WO 92/20791; Markland et al. PCT International Publication No. WO 92/15679; Breitling et al. PCT International Publication WO 93/01288; McCafferty et al. PCT International Publication No. WO 92/01047; Garrard et al. PCT International Publication No. WO 92/09690; Ladner et al. PCT International Publication No. WO 90/02809; Fuchs et al. (1991)  Bio/Technology  9:1369-1372; Hay et al. (1992)  Hum. Antibod. Hybridomas  3:81-85; Huse et al. (1989)  Science  246:1275-1281; Griffiths et al. (1993)  EMBO J  12:725-734; Hawkins et al. (1992)  J. Mol. Biol.  226:889-896; Clackson et al. (1991)  Nature  352:624-628; Gram et al. (1992)  Proc. Natl. Acad. Sci. USA  89:3576-3580; Garrard et al. (1991)  Bio/Technology  9:1373-1377; Hoogenboom et al. (1991)  Nuc. Acid Res.  19:4133-4137; Barbas et al. (1991)  Proc. Natl. Acad. Sci. USA  88:7978-7982; and McCafferty et al.  Nature ( 1990) 348:552-554.  
      Additionally, recombinant anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1,anti- TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti- HAAT, anti-HST-4 and/or anti-HST-5 antibodies, such as chimeric and humanized monoclonal antibodies, comprising both human and non-human portions, which can be made using standard recombinant DNA techniques, are within the scope of the invention. Such chimeric and humanized monoclonal antibodies can be produced by recombinant DNA techniques known in the art, for example using methods described in Robinson et al. International Application No. PCT/US86/02269; Akira, et al. European Patent Application 184,187; Taniguchi, M., European Patent Application 171,496; Morrison et al. European Patent Application 173,494; Neuberger et al. PCT International Publication No. WO 86/01533; Cabilly et al. U.S. Pat. No. 4,816,567; Cabilly et al. European Patent Application 125,023; Better et al. (1988)  Science  240:1041-1043; Liu et al. (1987)  Proc. Natl. Acad. Sci. USA  84:3439-3443; Liu et al. (1987)  J. Immunol.  139:3521-3526; Sun et al. (1987)  Proc. Natl. Acad. Sci. USA  84:214-218; Nishimura et al. (1987)  Canc. Res.  47:999-1005; Wood et al. (1985)  Nature  314:446-449; and Shaw et al. (1988)  J. Natl. Cancer Inst.  80:1553-1559); Morrison, S. L. (1985)  Science  229:1202-1207; Oi et al. (1986)  BioTechniques  4:214; Winter U.S. Pat. No. 5,225,539; Jones et al. (1986)  Nature  321:552-525; Verhoeyen et al. (1988)  Science  239:1534; and Beidler et al. (1988)  J. Immunol.  141:4053-4060.  
      An anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti- TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti- HAAT, anti-HST-4 and/or anti-HST-5 antibody (e.g., monoclonal antibody) can be used to isolate MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 by standard techniques, such as affinity chromatography or immunoprecipitation. An anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti- TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti-HAAT, anti-HST-4 and/or anti-HST-5 antibody can facilitate the purification of natural MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 from cells and of recombinantly produced MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expressed in host cells. Moreover, an anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1,anti- TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti-HAAT, anti-HST-4 and/or anti-HST-5 antibody can be used to detect MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides (e.g., in a cellular lysate or cell supernatant) in order to evaluate the abundance and pattern of expression of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides. Anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1,anti- TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti-HAAT, anti-HST-4 and/or anti-HST-5 antibodies can be used diagnostically to monitor polypeptide levels in tissue as part of a clinical testing procedure, e.g., to, for example, determine the efficacy of a given treatment regimen. Detection can be facilitated by coupling (i.e., physically linking) the antibody to a detectable substance. Examples of detectable substances include various enzymes, prosthetic groups, fluorescent materials, luminescent materials, bioluminescent materials, and radioactive materials. Examples of suitable enzymes include horseradish peroxidase, alkaline phosphatase, β-galactosidase, or acetylcholinesterase; examples of suitable prosthetic group complexes include streptavidin/biotin and avidin/biotin; examples of suitable fluorescent materials include umbelliferone, fluorescein, fluorescein isothiocyanate, rhodamine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; an example of a luminescent material includes luminol; examples of bioluminescent materials include luciferase, luciferin, and aequorin, and examples of suitable radioactive material include  125 I,  131 I,  35 S or  3 H.  
      III. Recombinant Expression Vectors and Host Cells  
      Another aspect of the invention pertains to vectors, preferably expression vectors, containing a nucleic acid encoding an MTP-1 protein (or a portion thereof). Another aspect of the invention pertains to vectors, for example recombinant expression vectors, containing an OAT nucleic acid molecule or vectors containing a nucleic acid molecule which encodes an OAT protein (or a portion thereof). Another aspect of the invention pertains to vectors, for example recombinant expression vectors, containing a nucleic acid containing an HST-1 nucleic acid molecule or vectors containing a nucleic acid molecule which encodes an HST-1 polypeptide (or a portion thereof). Another aspect of the invention pertains to vectors, for example recombinant expression vectors, containing a nucleic acid containing a TP-2 nucleic acid molecule or vectors containing a nucleic acid molecule which encodes a TP-2 polypeptide (or a portion thereof). Another aspect of the invention pertains to vectors, for example recombinant expression vectors, containing a PLTR-1 nucleic acid molecule or vectors containing a nucleic acid molecule which encodes a PLTR-1 protein (or a portion thereof). Another aspect of the invention pertains to vectors, for example recombinant expression vectors, containing a nucleic acid containing a TFM-2 and/or TFM-3 nucleic acid molecule or vectors containing a nucleic acid molecule which encodes a TFM-2 and/or TFM-3 polypeptide (or a portion thereof). Another aspect of the invention pertains to vectors, for example recombinant expression vectors, containing a nucleic acid containing a 67118, 67067, and/or 62092 nucleic acid molecule or vectors containing a nucleic acid molecule which encodes a 67118, 67067, and/or 62092 polypeptide (or a portion thereof). Another aspect of the invention pertains to vectors, for example recombinant expression vectors, containing a HAAT nucleic acid molecule or vectors containing a nucleic acid molecule which encodes a HAAT protein (or a portion thereof). Another aspect of the invention pertains to vectors, for example recombinant expression vectors, containing a nucleic acid containing an HST-4 and/or an HST-5 nucleic acid molecule or vectors containing a nucleic acid molecule which encodes an HST-4 and/or an HST-5 polypeptide (or a portion thereof). As used herein, the term “vector” refers to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. One type of vector is a “plasmid”, which refers to a circular double stranded DNA loop into which additional DNA segments can be ligated. Another type of vector is a viral vector, wherein additional DNA segments can be ligated into the viral genome. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (e.g., non-episomal mammalian vectors) are integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. Moreover, certain vectors are capable of directing the expression of genes to which they are operatively linked. Such vectors are referred to herein as “expression vectors”. In general, expression vectors of utility in recombinant DNA techniques are often in the form of plasmids. In the present specification, “plasmid” and “vector” can be used interchangeably as the plasmid is the most commonly used form of vector. However, the invention is intended to include such other forms of expression vectors, such as viral vectors (e.g., replication defective retroviruses, adenoviruses and adeno-associated viruses), which serve equivalent functions.  
      The recombinant expression vectors of the invention comprise a nucleic acid of the invention in a form suitable for expression of the nucleic acid in a host cell, which means that the recombinant expression vectors include one or more regulatory sequences, selected on the basis of the host cells to be used for expression, which is operatively linked to the nucleic acid sequence to be expressed. Within a recombinant expression vector, “operably linked” is intended to mean that the nucleotide sequence of interest is linked to the regulatory sequence(s) in a manner which allows for expression of the nucleotide sequence (e.g., in an in vitro transcription/translation system or in a host cell when the vector is introduced into the host cell). The term “regulatory sequence” is intended to include promoters, enhancers and other expression control elements (e.g., polyadenylation signals). Such regulatory sequences are described, for example, in Goeddel;  Gene Expression Technology: Methods in Enzymology  185, Academic Press, San Diego, Calif. (1990). Regulatory sequences include those which direct constitutive expression of a nucleotide sequence in many types of host cells and those which direct expression of the nucleotide sequence only in certain host cells (e.g., tissue-specific regulatory sequences). It will be appreciated by those skilled in the art that the design of the expression vector can depend on such factors as the choice of the host cell to be transformed, the level of expression of polypeptide desired, and the like. The expression vectors of the invention can be introduced into host cells to thereby produce proteins or peptides, including fusion proteins or peptides, encoded by nucleic acids as described herein (e.g., MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, mutant forms of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, fusion proteins, and the like).  
      Accordingly, an exemplary embodiment provides a method for producing a protein, preferably an OAT protein, by culturing in a suitable medium a host cell of the invention (e.g., a mammalian host cell such as a non-human mammalian cell) containing a recombinant expression vector, such that the protein is produced.  
      Accordingly, an exemplary embodiment provides a method for producing a polypeptide, preferably an HST-1 polypeptide, by culturing in a suitable medium a host cell of the invention (e.g., a mammalian host cell such as a non-human mammalian cell) containing a recombinant expression vector, such that the polypeptide is produced.  
      Accordingly, an exemplary embodiment provides a method for producing a polypeptide, preferably a TP-2 polypeptide, by culturing in a suitable medium a host cell of the invention (e.g., a mammalian host cell such as a non-human mammalian cell) containing a recombinant expression vector, such that the polypeptide is produced.  
      Accordingly, an exemplary embodiment provides a method for producing a protein, preferably a PLTR-l protein, by culturing in a suitable medium a host cell of the invention (e.g., a mammalian host cell such as a non-human mammalian cell) containing a recombinant expression vector, such that the protein is produced.  
      Accordingly, an exemplary embodiment provides a method for producing a polypeptide, preferably a TFM-2 and/or TFM-3 polypeptide, by culturing in a suitable medium a host cell of the invention (e.g., a mammalian host cell such as a non-human mammalian cell) containing a recombinant expression vector, such that the polypeptide is produced.  
      Accordingly, an exemplary embodiment provides a method for producing a polypeptide, preferably a 67118, 67067, and/or 62092 polypeptide, by culturing in a suitable medium a host cell of the invention (e.g., a mammalian host cell such as a non-human mammalian cell) containing a recombinant expression vector, such that the polypeptide is produced.  
      Accordingly, an exemplary embodiment provides a method for producing a protein, preferably a HAAT protein, by culturing in a suitable medium a host cell of the invention (e.g., a mammalian host cell such as a non-human mammalian cell) containing a recombinant expression vector, such that the protein is produced.  
      Accordingly, an exemplary embodiment provides a method for producing a polypeptide, preferably an HST-4 and/or an HST-5 polypeptide, by culturing in a suitable medium a host cell of the invention (e.g., a mammalian host cell such as a non-human mammalian cell) containing a recombinant expression vector, such that the polypeptide is produced.  
      The recombinant expression vectors of the invention can be designed for expression of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides in prokaryotic or eukaryotic cells. For example, MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides can be expressed in bacterial cells such as  E. coli,  insect cells (using baculovirus expression vectors) yeast cells or mammalian cells. Suitable host cells are discussed further in Goeddel,  Gene Expression Technology: Methods in Enzymology  185, Academic Press, San Diego, Calif. (1990). Alternatively, the recombinant expression vector can be transcribed and translated in vitro, for example using T7 promoter regulatory sequences and T7 polymerase.  
      Expression of proteins in prokaryotes is most often carried out in  E. coli  with vectors containing constitutive or inducible promoters directing the expression of either fusion or non-fusion proteins. Fusion vectors add a number of amino acids to a protein encoded therein, usually to the amino terminus of the recombinant protein. Such fusion vectors typically serve three purposes: 1) to increase expression of recombinant protein; 2) to increase the solubility of the recombinant protein; and 3) to aid in the purification of the recombinant protein by acting as a ligand in affinity purification. Often, in fusion expression vectors, a proteolytic cleavage site is introduced at the junction of the fusion moiety and the recombinant protein to enable separation of the recombinant protein from the fusion moiety subsequent to purification of the fusion protein. Such enzymes, and their cognate recognition sequences, include Factor Xa, thrombin and enterokinase. Typical fusion expression vectors include pGEX (Pharmacia Biotech Inc; Smith, D. B. and Johnson, K. S. (1988)  Gene  67:31-40), pMAL (New England Biolabs, Beverly, Mass.) and pRIT5 (Pharmacia, Piscataway, N.J.) which fuse glutathione S-transferase (GST), maltose E binding protein, or protein A, respectively, to the target recombinant protein.  
      Purified fusion proteins can be utilized in MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity assays, (e.g., direct assays or competitive assays described in detail below), or to generate antibodies specific for MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, for example. In a preferred embodiment, an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 fusion protein expressed in a retroviral expression vector of the present invention can be utilized to infect bone marrow cells which are subsequently transplanted into irradiated recipients. The pathology of the subject recipient is then examined after sufficient time has passed (e.g., six (6) weeks).  
      Examples of suitable inducible non-fusion  E. coli  expression vectors include pTrc (Amann et al., (1988)  Gene  69:301-315) and pET 11d (Studier et al.,  Gene Expression Technology: Methods in Enzymology  185, Academic Press, San Diego, Calif. (1990) 60-89). Target gene expression from the pTrc vector relies on host RNA polymerase transcription from a hybrid trp-lac fusion promoter. Target gene expression from the pET 11d vector relies on transcription from a T7 gn10-lac fusion promoter mediated by a coexpressed viral RNA polymerase (T7 gn1). This viral polymerase is supplied by host strains BL21(DE3) or HMS174(DE3) from a resident prophage harboring a T7 gn1 gene under the. transcriptional control of the lacUV 5 promoter.  
      One strategy to maximize recombinant protein expression in  E. coli  is to express the protein in a host bacteria with an impaired capacity to proteolytically cleave the recombinant protein (Gottesman, S.,  Gene Expression Technology: Methods in Enzymology  185, Academic Press, San Diego, Calif. (1990) 119-128). Another strategy is to alter the nucleic acid sequence of the nucleic acid to be inserted into an expression vector so that the individual codons for each amino acid are those preferentially utilized in  E. coli  (Wada et al., (1992)  Nucleic Acids Res.  20:2111-2118). Such alteration of nucleic acid sequences of the invention can be carried out by standard DNA synthesis techniques.  
      In another embodiment, the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 expression vector is a yeast expression vector. Examples of vectors for expression in yeast  S. cerevisiae  include pYepSec1 (Baldari, et al., (1987)  EMBO J.  6:229-234), pMFa (Kurjan and Herskowitz, (1982)  Cell  30:933-943), pJRY88 (Schultz et al., (1987)  Gene  54:113-123), pYES2 (Invitrogen Corporation, San Diego, Calif.), and picZ (Invitrogen Corporation, San Diego, Calif.).  
      Alternatively, MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides can be expressed in insect cells using baculovirus expression vectors. Baculovirus vectors available for expression of proteins in cultured insect cells (e.g., Sf 9 cells) include the pAc series (Smith et al. (1983)  Mol. Cell Biol.  3:2156-2165) and the pVL series (Lucklow and Summers (1989)  Virology  170:31-39).  
      In yet another embodiment, a nucleic acid of the invention is expressed in mammalian cells using a mammalian expression vector. Examples of mammalian expression vectors include pCDM8 (Seed, B. (1987)  Nature  329:840) and pMT2PC (Kaufman et al. (1987)  EMBO J.  6:187-195). When used in mammalian cells, the expression vector&#39;s control functions are often provided by viral regulatory elements. For example, commonly used promoters are derived from polyoma, Adenovirus 2, cytomegalovirus and Simian Virus 40. For other suitable expression systems for both prokaryotic and eukaryotic cells see chapters 16 and 17 of Sambrook, J., Fritsh, E. F., and Maniatis, T.  Molecular Cloning: A Laboratory Manual.  2nd, ed., Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989.  
      In another embodiment, the recombinant mammalian expression vector is capable of directing expression of the nucleic acid preferentially in a particular cell type (e.g., tissue-specific regulatory elements are used to express the nucleic acid). Tissue-specific regulatory elements are known in the art. Non-limiting examples of suitable tissue-specific promoters include the albumin promoter (liver-specific; Pinkert et al. (1987)  Genes Dev.  1:268-277), lymphoid-specific promoters (Calame and Eaton (1988)  Adv. Immunol.  43:235-275), in particular promoters of T cell receptors (Winoto and Baltimore (1989)  EMBO J.  8:729-733) and immunoglobulins (Banerji et al. (1983)  Cell  33:729-740; Queen and Baltimore (1983)  Cell  33:741-748), neuron-specific promoters (e.g., the neurofilament promoter; Byrne and Ruddle (1989)  Proc. Natl. Acad. Sci. USA  86:5473-5477), pancreas-specific promoters (Edlund et al. (1985)  Science  230:912-916), and mammary gland-specific promoters (e.g., milk whey promoter; U.S. Pat. No. 4,873,316 and European Application Publication No. 264,166). Developmentally-regulated promoters are also encompassed, for example the murine hox promoters (Kessel and Gruss (1990)  Science  249:374-379) and the α-fetoprotein promoter (Campes and Tilghman (1989)  Genes Dev.  3:537-546).  
      The invention further provides a recombinant expression vector comprising a DNA molecule of the invention cloned into the expression vector in an antisense orientation. That is, the DNA molecule is operatively linked to a regulatory sequence in a manner which allows for expression (by transcription of the DNA molecule) of an RNA molecule which is antisense to MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA. Regulatory sequences operatively linked to a nucleic acid cloned in the antisense orientation can be chosen which direct the continuous expression of the antisense RNA molecule in a variety of cell types, for instance viral promoters and/or enhancers, or regulatory sequences can be chosen which direct constitutive, tissue specific or cell type specific expression of antisense RNA. The antisense expression vector can be in the form of a recombinant plasmid, phagemid or attenuated virus in which antisense nucleic acids are produced under the control of a high efficiency regulatory region, the activity of which can be determined by the cell type into which the vector is introduced. For a discussion of the regulation of gene expression using antisense genes see Weintraub, H. et al., Antisense RNA as a molecular tool for genetic analysis,  Reviews—Trends in Genetics, Vol.  1(1) 1986.  
      Another aspect of the invention pertains to host cells into which an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 nucleic acid molecule of the invention is introduced, e.g., an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 nucleic acid molecule within a vector (e.g., a recombinant expression vector) or an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 nucleic acid molecule containing sequences which allow it to homologously recombine into a specific site of the host cell&#39;s genome. The terms “host cell” and “recombinant host cell” are used interchangeably herein. It is understood that such terms refer not only to the particular subject cell but to the progeny or potential progeny of such a cell. Because certain modifications may occur in succeeding generations due to either mutation or environmental influences, such progeny may not, in fact, be identical to the parent cell, but are still included within the scope of the term as used herein.  
      A host cell can be any prokaryotic or eukaryotic cell. For example, an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide can be expressed in bacterial cells such as  E. coli,  insect cells, yeast or mammalian cells (such as Chinese hamster ovary cells (CHO) or COS cells). Other suitable host cells are known to those skilled in the art.  
      Vector DNA can be introduced into prokaryotic or eukaryotic cells via conventional transformation or transfection techniques. As used herein, the terms “transformation” and “transfection” are intended to refer to a variety of art-recognized techniques for introducing foreign nucleic acid (e.g., DNA) into a host cell, including calcium phosphate or calcium chloride co-precipitation, DEAE-dextran-mediated transfection, lipofection, or electroporation. Suitable methods for transforming or transfecting host cells can be found in Sambrook, et al. ( Molecular Cloning: A Laboratory Manual.  2nd, ed., Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989), and other laboratory manuals.  
      For stable transfection of mammalian cells, it is known that, depending upon the expression vector and transfection technique used, only a small fraction of cells may integrate the foreign DNA into their genome. In order to identify and select these integrants, a gene that encodes a selectable marker (e.g., resistance to antibiotics) is generally introduced into the host cells along with the gene of interest. Preferred selectable markers include those which confer resistance to drugs, such as G418, hygromycin and methotrexate. Nucleic acid encoding a selectable marker can be introduced into a host cell on the same vector as that encoding an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 polypeptide or can be introduced on a separate vector. Cells stably transfected with the introduced nucleic acid can be identified by drug selection (e.g., cells that have incorporated the selectable marker gene will survive, while the other cells die).  
      A host cell of the invention, such as a prokaryotic or eukaryotic host cell in culture, can be used to produce (i.e., express) an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 polypeptide. Accordingly, the invention further provides methods for producing an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 polypeptide using the host cells of the invention. In one embodiment, the method comprises culturing the host cell of the invention (into which a recombinant expression vector encoding an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 polypeptide has been introduced) in a suitable medium such that an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 polypeptide is produced. In another embodiment, the method further comprises isolating an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 polypeptide from the medium or the host cell.  
      The host cells of the invention can also be used to produce non-human transgenic animals. For example, in one embodiment, a host cell of the invention is a fertilized oocyte or an embryonic stem cell into which MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4- and/or HST-5-coding sequences have been introduced. Such host cells can then be used to create non-human transgenic animals in which exogenous HST-4 and/or HST-5 sequences have been introduced into their genome or homologous recombinant animals in which endogenous MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequences have been altered. Such animals are useful for studying the function and/or activity of an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 and for identifying and/or evaluating modulators of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity. As used herein, a “transgenic animal” is a non-human animal, preferably a mammal, more preferably a rodent such as a rat or mouse, in which one or more of the cells of the animal includes a transgene. Other examples of transgenic animals include non-human primates, sheep, dogs, cows, goats, chickens, amphibians, and the like. A transgene is exogenous DNA which is integrated into the genome of a cell from which a transgenic animal develops and which remains in the genome of the mature animal, thereby directing the expression of an encoded gene product in one or more cell types or tissues of the transgenic animal. As used herein, a “homologous recombinant animal” is a non-human animal, preferably a mammal, more preferably a mouse, in which an endogenous MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 gene has been altered by homologous recombination between the endogenous gene and an exogenous DNA molecule introduced into a cell of the animal, e.g., an embryonic cell of the animal, prior to development of the animal.  
      A transgenic animal of the invention can be created by introducing an MTP-1-encoding nucleic acid into the male pronuclei of a fertilized oocyte, e.g., by microinjection, retroviral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal. The MTP-1 cDNA sequence of SEQ ID NO:1 can be introduced as a transgene into the genome of a non-human animal. Alternatively, a nonhuman homologue of a human MTP-1 gene, such as a mouse or rat MTP-1 gene, can be used as a transgene. Alternatively, an MTP-1 gene homologue, such as another MTP-1 family member, can be isolated based on hybridization to the MTP-1 cDNA sequences of SEQ ID NO:1 or 3, and used as a transgene. Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene. A tissue-specific regulatory sequence(s) can be operably linked to an MTP-1 transgene to direct expression of an MTP-1 protein to particular cells. Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U.S. Pat. Nos. 4,736,866 and 4,870,009, both by Leder et al., U.S. Pat. No. 4,873,191 by Wagner et al. and in Hogan, B., Manipulating the Mouse Embryo, (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Similar methods are used for production of other transgenic animals. A transgenic founder animal can be identified based upon the presence of an MTP-1 transgene in its genome and/or expression of MTP-1 mRNA in tissues or cells of the animals. A transgenic founder animal can then be used to breed additional animals carrying the transgene. Moreover, transgenic animals carrying a transgene encoding an MTP-1 protein can further be bred to other transgenic animals carrying other transgenes.  
      To create a homologous recombinant animal, a vector is prepared which contains at least a portion of an MTP-1 gene into which a deletion, addition or substitution has been introduced to thereby alter, e.g., functionally disrupt, the MTP-1 gene. The MTP-1 gene can be a human gene (e.g., the cDNA of SEQ ID NO:3), but more preferably, is a non-human homologue of a human MTP-1 gene (e.g., a cDNA isolated by stringent hybridization with the nucleotide sequence of SEQ ID NO:1). For example, a mouse MTP-1 gene can be used to construct a homologous recombination nucleic acid molecule, e.g., a vector, suitable for altering an endogenous MTP-1 gene in the mouse genome. In a preferred embodiment, the homologous recombination nucleic acid molecule is designed such that, upon homologous recombination, the endogenous MTP-1 gene is functionally disrupted (i.e., no longer encodes a functional protein; also referred to as a “knock out” vector). Alternatively, the homologous recombination nucleic acid molecule can be designed such that, upon homologous recombination, the endogenous MTP-1 gene is mutated or otherwise altered but still encodes functional protein (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous MTP-1 protein). In the homologous recombination nucleic acid molecule, the altered portion of the MTP-1 gene is flanked at its 5′ and 3′ ends by additional nucleic acid sequence of the MTP-1 gene to allow for homologous recombination to occur between the exogenous MTP-1 gene carried by the homologous recombination nucleic acid molecule and an endogenous MTP-1 gene in a cell, e.g., an embryonic stem cell. The additional flanking MTP-1 nucleic acid sequence is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5′ and 3′ ends) are included in the homologous recombination nucleic acid molecule (see, e.g., Thomas, K. R. and Capecchi, M. R. (1987)  Cell  51:503 for a description of homologous recombination vectors). The homologous recombination nucleic acid molecule is introduced into a cell, e.g., an embryonic stem cell line (e.g., by electroporation) and cells in which the introduced MTP-1 gene has homologously recombined with the endogenous MTP-1 gene are selected (see e.g., Li, E. et al. (1992)  Cell  69:915). The selected cells can then injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras (see e.g., Bradley, A. in  Teratocarcinomas and Embryonic Stem Cells: A Practical Approach,  E. J. Robertson, ed. (IRL, Oxford, 1987) pp. 113-152). A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to term. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination nucleic acid molecules, e.g., vectors, or homologous recombinant animals are described further in Bradley, A. (1991)  Current Opinion in Biotechnology  2:823-829 and in PCT International Publication Nos.: WO 90/11354 by Le Mouellec et al.; WO 91/01140 by Smithies et al.; WO 92/0968 by Zijlstra et al.; and WO 93/04169 by Berns et al.  
      A transgenic animal of the invention can be created by introducing an OAT-encoding nucleic acid into the male pronuclei of a fertilized oocyte, e.g., by microinjection or retroviral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal. The OAT cDNA sequence of SEQ ID NO:4 or 7 can be introduced as a transgene into the genome of a non-human animal. Alternatively, a non-human homologue of a human OAT gene, such as a rat or mouse OAT gene, can be used as a transgene. Alternatively, an OAT gene homologue, such as another OAT family member, can be isolated based on hybridization to the OAT cDNA sequences of SEQ ID NO:4, 6, 7, or 9, (described further in subsection I above) and used as a transgene. Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene. A tissue-specific regulatory sequence(s) can be operably linked to an OAT transgene to direct expression of an OAT protein to particular cells. Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U.S. Pat. Nos. 4,736,866 and 4,870,009, both by Leder et al., U.S. Pat. No. 4,873,191 by Wagner et al. and in Hogan, B.,  Manipulating the Mouse Embryo  (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Similar methods are used for production of other transgenic animals. A transgenic founder animal can be identified based upon the presence of an OAT transgene in its genome and/or expression of OAT mRNA in tissues or cells of the animals. A transgenic founder animal can then be used to breed additional animals carrying the transgene. Moreover, transgenic animals carrying a transgene encoding an OAT protein can further be bred to other transgenic animals carrying other transgenes.  
      To create a homologous recombinant animal, a vector is prepared which contains at least a portion of an OAT gene into which a deletion, addition or substitution has been introduced to thereby alter, e.g., functionally disrupt, the OAT gene. The OAT gene can be a human gene (e.g., the cDNA of SEQ ID NO:4 or 7), but more preferably, is a non-human homologue of a human OAT gene (e.g., a cDNA isolated by stringent hybridization with the nucleotide sequence of SEQ ID NO:4, 6, 7, or 9), For example, a mouse OAT gene can be used to construct a homologous recombination nucleic acid molecule, e.g., a vector, suitable for altering an endogenous OAT gene in the mouse genome. In a preferred embodiment, the homologous recombination nucleic acid molecule is designed such that, upon homologous recombination, the endogenous OAT gene is functionally disrupted (i.e., no longer encodes a functional protein; also referred to as a “knock out” vector). Alternatively, the homologous recombination nucleic acid molecule can be designed such that, upon homologous recombination, the endogenous OAT gene is mutated or otherwise altered but still encodes functional protein (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous OAT protein). In the homologous recombination nucleic acid molecule, the altered portion of the OAT gene is flanked at its 5′ and 3′ ends by additional nucleic acid sequence of the OAT gene to allow for homologous recombination to occur between the exogenous OAT gene carried by the homologous recombination nucleic acid molecule and an endogenous OAT gene in a cell, e.g., an embryonic stem cell. The additional flanking OAT nucleic acid sequence is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5′ and 3′ ends) are included in the homologous recombination nucleic acid molecule (see, e.g., Thomas, K. R. and Capecchi, M. R. (1987)  Cell  51:503 for a description of homologous recombination vectors). The homologous recombination nucleic acid molecule is introduced into a cell, e.g., an embryonic stem cell line (e.g., by electroporation) and cells in which the introduced OAT gene has homologously recombined with the endogenous OAT gene are selected (see e.g., Li, E. et al. (1992)  Cell  69:915). The selected cells can then be injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras (see e.g., Bradley, A. in  Teratocarcinomas and Embryonic Stem Cells: A Practical Approach,  Robertson, E. J. ed. (IRL, Oxford, 1987) pp. 113-152). A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to term. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination nucleic acid molecules, e.g., vectors, or homologous recombinant animals are described further in Bradley, A. (1991)  Current Opinion in Biotechnology  2:823-829 and in PCT International Publication Nos.: WO 90/11354 by Le Mouellec et al.; WO 91/01140 by Smithies et al.; WO 92/0968 by Zijlstra et al.; and WO 93/04169 by Berns et al.  
      A transgenic animal of the invention can be created by introducing an HST-1-encoding nucleic acid into the male pronuclei of a fertilized oocyte, e.g., by microinjection, retroviral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal. The HST-1 cDNA sequence of SEQ ID NO:12 can be introduced as a transgene into the genome of a non-human animal. Alternatively, a nonhuman homologue of a human HST-1 gene, such as a mouse or rat HST-1 gene, can be used as a transgene. Alternatively, an HST-1 gene homologue, such as another HST-1 family member, can be isolated based on hybridization to the HST-1 cDNA sequences of SEQ ID NO:12 or 14 (described further in subsection I above) and used as a transgene. Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene. A tissue-specific regulatory sequence(s) can be operably linked to an HST-1 transgene to direct expression of an HST-1 polypeptide to particular cells. Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U.S. Pat. Nos. 4,736,866 and 4,870,009, both by Leder et al., U.S. Pat. No. 4,873,191 by Wagner et al. and in Hogan, B.,  Manipulating the Mouse Embryo,  (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Similar methods are used for production of other transgenic animals. A transgenic founder animal can be identified based upon the presence of an HST-1 transgene in its genome and/or expression of HST-1 mRNA in tissues or cells of the animals. A transgenic founder animal can then be used to breed additional animals carrying the transgene. Moreover, transgenic animals carrying a transgene encoding an HST-1 polypeptide can further be bred to other transgenic animals carrying other transgenes.  
      To create a homologous recombinant animal, a vector is prepared which contains at least a portion of an HST-1 gene into which a deletion, addition or substitution has been introduced to thereby alter, e.g., functionally disrupt, the HST-1 gene. The HST-1 gene can be a human gene (e.g., the cDNA of SEQ ID NO:14), but more preferably, is a non-human homologue of a human HST-1 gene (e.g., a cDNA isolated by stringent hybridization with the nucleotide sequence of SEQ ID NO:12). For example, a mouse HST-1 gene can be used to construct a homologous recombination nucleic acid molecule, e.g., a vector, suitable for altering an endogenous HST-1 gene in the mouse genome. In a preferred embodiment, the homologous recombination nucleic acid molecule is designed such that, upon homologous recombination, the endogenous HST-1 gene is functionally disrupted (i.e., no longer encodes a functional protein; also referred to as a “knock out” vector). Alternatively, the homologous recombination nucleic acid molecule can be designed such that, upon homologous recombination, the endogenous HST-1 gene is mutated or otherwise altered but still encodes functional polypeptide (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous HST-1 polypeptide). In the homologous recombination nucleic acid molecule, the altered portion of the HST-1 gene is flanked at its 5′ and 3′ ends by additional nucleic acid sequence of the HST-1 gene to allow for homologous recombination to occur between the exogenous HST-1 gene carried by the homologous recombination nucleic acid molecule and an endogenous HST-1 gene in a cell, e.g., an embryonic stem cell. The additional flanking HST-1 nucleic acid sequence is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5′ and 3′ ends) are included in the homologous recombination nucleic acid molecule (see, e.g., Thomas, K. R. and Capecchi, M. R. (1987)  Cell  51:503 for a description of homologous recombination vectors). The homologous recombination nucleic acid molecule is introduced into a cell, e.g., an embryonic stem cell line (e.g., by electroporation) and cells in which the introduced HST-1 gene has homologously recombined with the endogenous HST-1 gene are selected (see e.g., Li, E. et al. (1992)  Cell  69:915). The selected cells can then injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras (see e.g., Bradley, A. in  Teratocarcinomas and Embryonic Stem Cells: A Practical Approach,  E. J. Robertson, ed. (IRL, Oxford, 1987) pp. 113-152). A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to term. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination nucleic acid molecules, e.g., vectors, or homologous recombinant animals are described further in Bradley, A. (1991)  Current Opinion in Biotechnology  2:823-829 and in PCT International Publication Nos.: WO 90/11354 by Le Mouellec et al.; WO 91/01140 by Smithies et al.; WO 92/0968 by Zijistra et al.; and WO 93/04169 by Berns et al.  
      A transgenic animal of the invention can be created by introducing a TP-2-encoding nucleic acid into the male pronuclei of a fertilized oocyte, e.g., by microinjection, retroviral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal. The TP-2 cDNA sequence of SEQ ID NO:15 can be introduced as a transgene into the genome of a non-human animal. Alternatively, a nonhuman homologue of a human TP-2 gene, such as a mouse or rat TP-2 gene, can be used as a transgene. Alternatively, a TP-2 gene homologue, such as another TP-2 family member, can be isolated based on hybridization to the TP-2 cDNA sequences of SEQ ID NO:15 or 17, (described further in subsection I above) and used as a transgene. Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene. A tissue-specific regulatory sequence(s) can be operably linked to a TP-2 transgene to direct expression of a TP-2 polypeptide to particular cells. Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U.S. Pat. Nos. 4,736,866 and 4,870,009, both by Leder et al., U.S. Pat. No. 4,873,191 by Wagner et al. and in Hogan, B.,  Manipulating the Mouse Embryo,  (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Similar methods are used for production of other transgenic animals. A transgenic founder animal can be identified based upon the presence of a TP-2 transgene in its genome and/or expression of TP-2 mRNA in tissues or cells of the animals. A transgenic founder animal can then be used to breed additional animals carrying the transgene. Moreover, transgenic animals carrying a transgene encoding a TP-2 polypeptide can further be bred to other transgenic animals carrying other transgenes.  
      To create a homologous recombinant animal, a vector is prepared which contains at least a portion of a TP-2 gene into which a deletion, addition or substitution has been introduced to thereby alter, e.g., functionally disrupt, the TP-2 gene. The TP-2 gene can be a human gene (e.g., the cDNA of SEQ ID NO:17), but more preferably, is a non-human homologue of a human TP-2 gene (e.g., a cDNA isolated by stringent hybridization with the nucleotide sequence of SEQ ID NO:15). For example, a mouse TP-2 gene can be used to construct a homologous recombination nucleic acid molecule, e.g., a vector, suitable for altering an endogenous TP-2 gene in the mouse genome. In a preferred embodiment, the homologous recombination nucleic acid molecule is designed such that, upon homologous recombination, the endogenous TP-2 gene is functionally disrupted (i.e., no longer encodes a functional protein; also referred to as a “knock out” vector). Alternatively, the homologous recombination nucleic acid molecule can be designed such that, upon homologous recombination, the endogenous TP-2 gene is mutated or otherwise altered but still encodes functional polypeptide (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous TP-2 polypeptide). In the homologous recombination nucleic acid molecule, the altered portion of the TP-2 gene is flanked at its 5′ and 3′ ends by additional nucleic acid sequence of the TP-2 gene to allow for homologous recombination to occur between the exogenous TP-2 gene carried by the homologous recombination nucleic acid molecule and an endogenous TP-2 gene in a cell, e.g., an embryonic stem cell. The additional flanking TP-2 nucleic acid sequence is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5′ and 3′ ends) are included in the homologous recombination nucleic acid molecule (see, e.g., Thomas, K. R. and Capecchi, M. R. (1987)  Cell  51:503 for a description of homologous recombination vectors). The homologous recombination nucleic acid molecule is introduced into a cell, e.g., an embryonic stem cell line (e.g., by electroporation) and cells in which the introduced TP-2 gene has homologously recombined with the endogenous TP-2 gene are selected (see e.g., Li, E. et al. (1992)  Cell  69:915). The selected cells can then injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras (see e.g., Bradley, A. in  Teratocarcinomas and Embryonic Stem Cells: A Practical Approach,  E. J. Robertson, ed. (IRL, Oxford, 1987) pp. 113-152). A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to term. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination nucleic acid molecules, e.g., vectors, or homologous recombinant animals are described further in Bradley, A. (1991)  Current Opinion in Biotechnology  2:823-829 and in PCT International Publication Nos.: WO 90/11354 by Le Mouellec et al.; WO 91/01140 by Smithies et al.; WO 92/0968 by Zijlstra et al.; and WO 93/04169 by Berns et al.  
      A transgenic animal of the invention can be created by introducing a PLTR-1-encoding nucleic acid into the male pronuclei of a fertilized oocyte, e.g., by microinjection or retroviral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal. The PLTR-1 cDNA sequence of SEQ ID NO:19 can be introduced as a transgene into the genome of a non-human animal. Alternatively, a non-human homologue of a human PLTR-1 gene, such as a rat or mouse PLTR-1 gene, can be used as a transgene. Alternatively, a PLTR-1 gene homologue, such as another PLTR-1 family member, can be isolated based on hybridization to the PLTR-1 cDNA sequences of SEQ ID NO:19 or 21, (described further in subsection I above) and used as a transgene. Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene. A tissue-specific regulatory sequence(s) can be operably linked to a PLTR-1 transgene to direct expression of a PLTR-1 protein to particular cells. Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U.S. Pat. Nos. 4,736,866 and 4,870,009, both by Leder et al., U.S. Pat. No. 4,873,191 by Wagner et al. and in Hogan, B.,  Manipulating the Mouse Embryo,  (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Similar methods are used for production of other transgenic animals. A transgenic founder animal can be identified based upon the presence of a PLTR-1 transgene in its genome and/or expression of PLTR-1 mRNA in tissues or cells of the animals. A transgenic founder animal can then be used to breed additional animals carrying the transgene. Moreover, transgenic animals carrying a transgene encoding a PLTR-1 protein can further be bred to other transgenic animals carrying other transgenes.  
      To create a homologous recombinant animal, a vector is prepared which contains at least a portion of a PLTR-1 gene into which a deletion, addition or substitution has been introduced to thereby alter, e.g., functionally disrupt, the PLTR-1 gene. The PLTR-1 gene can be a human gene (e.g., the cDNA of SEQ ID NO:21), but more preferably, is a non-human homologue of a human PLTR-1 gene (e.g., a cDNA isolated by stringent hybridization with the nucleotide sequence of SEQ ID NO:19), For example, a mouse PLTR-1 gene can be used to construct a homologous recombination nucleic acid molecule, e.g., a vector, suitable for altering an endogenous PLTR-1 gene in the mouse genome. In a preferred embodiment, the homologous recombination nucleic acid molecule is designed such that, upon homologous recombination, the endogenous PLTR-1 gene is functionally disrupted (i.e., no longer encodes a functional protein; also referred to as a “knock out” vector). Alternatively, the homologous recombination nucleic acid molecule can be designed such that, upon homologous recombination, the endogenous PLTR-1 gene is mutated or otherwise altered but still encodes functional protein (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous PLTR-1 protein). In the homologous recombination nucleic acid molecule, the altered portion of the PLTR-1 gene is flanked at its 5′ and 3′ ends by additional nucleic acid sequence of the PLTR-1 gene to allow for homologous recombination to occur between the exogenous PLTR-1 gene carried by the homologous recombination nucleic acid molecule and an endogenous PLTR-1 gene in a cell, e.g., an embryonic stem cell. The additional flanking PLTR-1 nucleic acid sequence is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5′ and 3′ ends) are included in the homologous recombination nucleic acid molecule (see, e.g., Thomas, K. R. and Capecchi, M. R. (1987)  Cell  51:503 for a description of homologous recombination vectors). The homologous recombination nucleic acid molecule is introduced into a cell, e.g., an embryonic stem cell line (e.g., by electroporation) and cells in which the introduced PLTR-1 gene has homologously recombined with the endogenous PLTR-1 gene are selected (see e.g., Li, E. et al. (1992)  Cell  69:915). The selected cells can then be injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras (see e.g., Bradley, A., in  Teratocarcinomas and Embryonic Stem Cells: A Practical Approach,  Robertson, E. J. ed. (IRL, Oxford, 1987) pp. 113-152). A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to term. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination nucleic acid molecules, e.g., vectors, or homologous recombinant animals are described further in Bradley, A. (1991)  Curr. Opin. Biotechnol.  2:823-829 and in PCT International Publication Nos.: WO 90/11354 by Le Mouellec et al.; WO 91/01140 by Smithies et al.; WO 92/0968 by Zijlstra et al.; and WO 93/04169 by Berns et al.  
      A transgenic animal of the invention can be created by introducing a TFM-2 and/or TFM-3-encoding nucleic acid into the male pronuclei of a fertilized oocyte, e.g., by microinjection, retroviral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal. The TFM-2 and/or TFM-3 cDNA sequence of SEQ ID NO:27 or SEQ ID NO:30 can be introduced as a transgene into the genome of a non-human animal. Alternatively, a nonhuman homologue of a human TFM-2 and/or TFM-3 gene, such as a mouse or rat TFM-2 and/or TFM-3 gene, can be used as a transgene. Alternatively, a TFM-2 and/or TFM-3 gene homologue, such as another TFM-2 and/or TFM-3 family member, can be isolated based on hybridization to the TFM-2 and/or TFM-3 cDNA sequences of SEQ ID NO:27, 29, 30, or 32 (described further in subsection I above) and used as a transgene. Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene. A tissue-specific regulatory sequence(s) can be operably linked to a TFM-2 and/or TFM-3 transgene to direct expression of a TFM-2 and/or TFM-3 polypeptide to particular cells. Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U.S. Pat. Nos. 4,736,866 and 4,870,009, both by Leder et al., U.S. Pat. No. 4,873,191 by Wagner et al. and in Hogan, B.,  Manipulating the Mouse Embryo,  (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Similar methods are used for production of other transgenic animals. A transgenic founder animal can be identified based upon the presence of a TFM-2 and/or TFM-3 transgene in its genome and/or expression of TFM-2 and/or TFM-3 mRNA in tissues or cells of the animals. A transgenic founder animal can then be used to breed additional animals carrying the transgene. Moreover, transgenic animals carrying a transgene encoding a TFM-2 and/or TFM-3 polypeptide can further be bred to other transgenic animals carrying other transgenes.  
      To create a homologous recombinant animal, a vector is prepared which contains at least a portion of a TFM-2 and/or TFM-3 gene into which a deletion, addition or substitution has been introduced to thereby alter, e.g., functionally disrupt, the TFM-2 and/or TFM-3 gene. The TFM-2 and/or TFM-3 gene can be a human gene (e.g., the cDNA of SEQ ID NO:29 or 32), but more preferably, is a non-human homologue of a human TFM-2 and/or TFM-3 gene (e.g., a cDNA isolated by stringent hybridization with the nucleotide sequence of SEQ ID NO:27 or 30). For example, a mouse TFM-2 and/or TFM-3 gene can be used to construct a homologous recombination nucleic acid molecule, e.g., a vector, suitable for altering an endogenous TFM-2 and/or TFM-3 gene in the mouse genome. In a preferred embodiment, the homologous recombination nucleic acid molecule is designed such that, upon homologous recombination, the endogenous TFM-2 and/or TFM-3 gene is functionally disrupted (i.e., no longer encodes a functional protein; also referred to as a “knock out” vector). Alternatively, the homologous recombination nucleic acid molecule can be designed such that, upon homologous recombination, the endogenous TFM-2 and/or TFM-3 gene is mutated or otherwise altered but still encodes functional polypeptide (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous TFM-2 and/or TFM-3 polypeptide). In the homologous recombination nucleic acid molecule, the altered portion of the TFM-2 and/or TFM-3 gene is flanked at its 5′ and 3′ ends by additional nucleic acid sequence of the TFM-2 and/or TFM-3 gene to allow for homologous recombination to occur between the exogenous TFM-2 and/or TFM-3 gene carried by the homologous recombination nucleic acid molecule and an endogenous TFM-2 and/or TFM-3 gene in a cell, e.g., an embryonic stem cell. The additional flanking TFM-2 and/or TFM-3 nucleic acid sequence is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5′ and 3′ ends) are included in the homologous recombination nucleic acid molecule (see, e.g., Thomas, K. R. and Capecchi, M. R. (1987)  Cell  51:503 for a description of homologous recombination vectors). The homologous recombination nucleic acid molecule is introduced into a cell, e.g., an embryonic stem cell line (e.g., by electroporation) and cells in which the introduced TFM-2 and/or TFM-3 gene has homologously recombined with the endogenous TFM-2 and/or TFM-3 gene are selected (see e.g., Li, E. et al. (1992) Cell 69:915). The selected cells can then injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras (see e.g., Bradley, A. in  Teratocarcinomas and Embryonic Stem Cells: A Practical Approach,  E. J. Robertson, ed. (IRL, Oxford, 1987) pp. 113-152). A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to term. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination nucleic acid molecules, e.g., vectors, or homologous recombinant animals are described further in Bradley, A. (1991)  Current Opinion in Biotechnology  2:823-829 and in PCT International Publication Nos.: WO 90/11354 by Le Mouellec et al.; WO 91/01140 by Smithies et al.; WO 92/0968 by Zijlstra et al.; and WO 93/04169 by Berns et al.  
      A transgenic animal of the invention can be created by introducing a 67118, 67067, and/or 62092-encoding nucleic acid into the male pronuclei of a fertilized oocyte, e.g., by microinjection, retroviral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal. The 67118, 67067, and/or 62092 cDNA sequence of SEQ ID NO:33, 36, or 39 can be introduced as a transgene into the genome of a non-human animal. Alternatively, a nonhuman homologue of a human 67118, 67067, and/or 62092 gene, such as a mouse or rat 67118, 67067, and/or 62092 gene, can be used as a transgene. Alternatively, a 67118, 67067, and/or 62092 gene homologue, such as another 67118, 67067, and/or 62092 family member, can be isolated based on hybridization to the 67118, 67067, and/or 62092 cDNA sequences of SEQ ID NO:33, 35, 36, 38, 39, or 41, (described further in subsection I above) and used as a transgene. Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene. A tissue-specific regulatory sequence(s) can be operably linked to a 67118, 67067, and/or 62092 transgene to direct expression of a 67118, 67067, and/or 62092 polypeptide to particular cells. Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U.S. Pat. Nos. 4,736,866 and 4,870,009, both by Leder et al., U.S. Pat. No. 4,873,191 by Wagner et al. and in Hogan, B., Manipulating the Mouse Embryo, (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Similar methods are used for production of other transgenic animals. A transgenic founder animal can be identified based upon the presence of a 67118, 67067, and/or 62092 transgene in its genome and/or expression of 67118, 67067, and/or 62092 mRNA in tissues or cells of the animals. A transgenic founder animal can then be used to breed additional animals carrying the transgene. Moreover, transgenic animals carrying a transgene encoding a 67118, 67067, and/or 62092 polypeptide can further be bred to other transgenic animals carrying other transgenes.  
      To create a homologous recombinant animal, a vector is prepared which contains at least a portion of a 67118, 67067, and/or 62092 gene into which a deletion, addition or substitution has been introduced to thereby alter, e.g., functionally disrupt, the 67118, 67067, and/or 62092 gene. The 67118, 67067, and/or 62092 gene can be a human gene (e.g., the cDNA of SEQ ID NO:33, 36, or 39, respectively), but more preferably, is a non-human homologue of a human 67118, 67067, and/or 62092 gene (e.g., a cDNA isolated by stringent hybridization with the nucleotide sequence of SEQ II) NO:33, 36, or 39). For example, a mouse 67118, 67067, and/or 62092 gene can be used to construct a homologous recombination nucleic acid molecule, e.g., a vector, suitable for altering an endogenous 67118, 67067, and/or 62092 gene in the mouse genome. In a preferred embodiment, the homologous recombination nucleic acid molecule is designed such that, upon homologous recombination, the endogenous 67118, 67067, and/or 62092 gene is functionally disrupted (i.e., no longer encodes a functional protein; also referred to as a “knock out” vector). Alternatively, the homologous recombination nucleic acid molecule can be designed such that, upon homologous recombination, the endogenous 67118, 67067, and/or 62092 gene is mutated or otherwise altered but still encodes functional polypeptide (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous 67118, 67067, and/or 62092 polypeptide). In the homologous recombination nucleic acid molecule, the altered portion of the 67118, 67067, and/or 62092 gene is flanked at its 5′ and 3′ ends by additional nucleic acid sequence of the 67118, 67067, and/or 62092 gene to allow for homologous recombination to occur between the exogenous 67118, 67067, and/or 62092 gene carried by the homologous recombination nucleic acid molecule and an endogenous 67118, 67067, and/or 62092 gene in a cell, e.g., an embryonic stem cell. The additional flanking 67118, 67067, and/or 62092 nucleic acid sequence is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5′ and 3′ ends) are included in the homologous recombination nucleic acid molecule (see, e.g., Thomas, K. R. and Capecchi, M. R. (1987)  Cell  51:503 for a description of homologous recombination vectors). The homologous recombination nucleic acid molecule is introduced into a cell, e.g., an embryonic stem cell line (e.g., by electroporation) and cells in which the introduced 67118, 67067, and/or 62092 gene has homologously recombined with the endogenous 67118, 67067, and/or 62092 gene are selected (see e.g., Li, E. et al. (1992)  Cell  69:915). The selected cells can then injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras (see e.g., Bradley, A. in  Teratocarcinomas and Embryonic Stem Cells: A Practical Approach,  E. J. Robertson, ed. (IRL, Oxford, 1987) pp. 113-152). A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to term. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination nucleic acid molecules,. e.g., vectors, or homologous recombinant animals are described further in Bradley, A. (1991)  Current Opinion in Biotechnology  2:823-829 and in PCT International Publication Nos.: WO 90/11354 by Le Mouellec et al.; WO 91/01140 by Smithies et al.; WO 92/0968 by Zijlstra et al.; and WO 93/04169 by Berns et al.  
      A transgenic animal of the invention can be created by introducing a HAAT-encoding nucleic acid into the male pronuclei of a fertilized oocyte, e.g., by microinjection or retroviral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal. The HAAT cDNA sequence of SEQ ID NO:51 can be introduced as a transgene into the genome of a non-human animal. Alternatively, a non-human homologue of a human HAAT gene, such as a rat or mouse HAAT gene, can be used as a transgene. Alternatively, a HAAT gene homologue, such as another HAAT family member, can be isolated based on hybridization to the HAAT cDNA sequences of SEQ ID NO:51 or 53, (described further in subsection I above) and used as a transgene. Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene. A tissue-specific regulatory sequence(s) can be operably linked to a HAAT transgene to direct expression of a HAAT protein to particular cells. Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U.S. Pat. Nos. 4,736,866 and 4,870,009, both by Leder et al., U.S. Pat. No. 4,873,191 by Wagner et al. and in Hogan, B., Manipulating the Mouse Embryo, (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Similar methods are used for production of other transgenic animals. A transgenic founder animal can be identified based upon the presence of a HAAT transgene in its genome and/or expression of HAAT mRNA in tissues or cells of the animals. A transgenic founder animal can then be used to breed additional animals carrying the transgene. Moreover, transgenic animals carrying a transgene encoding a HAAT protein can further be bred to other transgenic animals carrying other transgenes.  
      To create a homologous recombinant animal, a vector is prepared which contains at least a portion of a HAAT gene into which a deletion, addition or substitution has been introduced to thereby alter, e.g., functionally disrupt, the HAAT gene. The HAAT gene can be a human gene (e.g., the cDNA of SEQ ID NO:53), but more preferably, is a non-human homologue of a human HAAT gene (e.g., a cDNA isolated by stringent hybridization with the nucleotide sequence of SEQ ID NO:51), For example, a mouse HAAT gene can be used to construct a homologous recombination nucleic acid molecule, e.g., a vector, suitable for altering an endogenous HAAT gene in the mouse genome. In a preferred embodiment, the homologous recombination nucleic acid molecule is designed such that, upon homologous recombination, the endogenous HAAT gene is functionally disrupted (i.e., no longer encodes a functional protein; also referred to as a “knock out” vector). Alternatively, the homologous recombination nucleic acid molecule can be designed such that, upon homologous recombination, the endogenous HAAT gene is mutated or otherwise altered but still encodes functional protein (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous HAAT protein). In the homologous recombination nucleic acid molecule, the altered portion of the HAAT gene is flanked at its 5′ and 3′ ends by additional nucleic acid sequence of the HAAT gene to allow for homologous recombination to occur between the exogenous HAAT gene carried by the homologous recombination nucleic acid molecule and an endogenous HAAT gene in a cell, e.g., an embryonic stem cell. The additional flanking HAAT nucleic acid sequence is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5′ and 3′ ends) are included in the homologous recombination nucleic acid molecule (see, e.g., Thomas, K. R. and Capecchi, M. R. (1987)  Cell  51:503 for a description of homologous recombination vectors). The homologous recombination nucleic acid molecule is introduced into a cell, e.g., an embryonic stem cell line (e.g., by electroporation) and cells in which the introduced HAAT gene has homologously recombined with the endogenous HAAT gene are selected (see e.g., Li, E. et al. (1992)  Cell  69:915). The selected cells can then be injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras (see e.g., Bradley, A. in  Teratocarcinomas and Embryonic Stem Cells: A Practical Approach,  Robertson, E. J. ed. (IRL, Oxford, 1987) pp. 113-152). A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to term. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination nucleic acid molecules, e.g., vectors, or homologous recombinant animals are described further in Bradley, A. (1991)  Curr. Opin. Biotechnol.  2:823-829 and in PCT International Publication Nos.: WO 90/11354 by Le Mouellec et al.; WO 91/01140 by Smithies et al.; WO 92/0968 by Zijlstra et al.; and WO 93/04169 by Berns et al.  
      A transgenic animal of the invention can be created by introducing an HST-4- and/or an HST-5-encoding nucleic acid into the male pronuclei of a fertilized oocyte, e.g., by microinjection, retroviral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal. The HST-4 and/or HST-5 cDNA sequence of SEQ ID NO:54 or 57 can be introduced as a transgene into the genome of a non-human animal. Alternatively, a nonhuman homologue of a human HST-4 and/or HST-5 gene, such as a mouse or rat HST-4 and/or HST-5 gene, can be used as a transgene. Alternatively, an HST-4 and/or an HST-5 gene homologue, such as another HST-4 and/or HST-5 family member, can be isolated based on hybridization to the HST-4 and/or HST-5 cDNA sequences of SEQ ID NO:54, 56, 57, or 59, (described further in subsection I above) and used as a transgene. Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene. A tissue-specific regulatory sequence(s) can be operably linked to an HST-4 and/or an HST-5 transgene to direct expression of an HST-4 and/or an HST-5 polypeptide to particular cells. Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U.S. Pat. Nos. 4,736,866 and 4,870,009, both by Leder et al., U.S. Pat. No. 4,873,191 by Wagner et al. and in Hogan, B.,  Manipulating the Mouse Embryo,  (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Similar methods are used for production of other transgenic animals. A transgenic founder animal can be identified based upon the presence of an HST-4 and/or an HST-5 transgene in its genome and/or expression of HST-4 and/or HST-5 mRNA in tissues or cells of the animals. A transgenic founder animal can then be used to breed additional animals carrying the transgene. Moreover, transgenic animals carrying a transgene encoding an HST-4 and/or an HST-5 polypeptide can further be bred to other transgenic animals carrying other transgenes.  
      To create a homologous recombinant animal, a vector is prepared which contains at least a portion of an HST-4 and/or an HST-5 gene into which a deletion, addition or substitution has been introduced to thereby alter, e.g., functionally disrupt, the HST-4 and/or the HST-5 gene. The HST-4 and/or the HST-5 gene can be a human gene (e.g., the cDNA of SEQ ID NO:56 or 59), but more preferably, is a non-human homologue of a human HST-4 and/or HST-5 gene (e.g., a cDNA isolated by stringent hybridization with the nucleotide sequence of SEQ ID NO:54 or 57). For example, a mouse HST-4 and/or HST-5 gene can be used to construct a homologous recombination nucleic acid molecule, e.g., a vector, suitable for altering an endogenous HST-4 and/or HST-5 gene in the mouse genome. In a preferred embodiment, the homologous recombination nucleic acid molecule is designed such that, upon homologous recombination, the endogenous HST-4 and/or HST-5 gene is functionally disrupted (i.e., no longer encodes a functional protein; also referred to as a “knock out” vector). Alternatively, the homologous recombination nucleic acid molecule can be designed such that, upon homologous recombination, the endogenous HST-4 and/or HST-5 gene is mutated or otherwise altered but still encodes functional polypeptide (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous HST-4 and/or HST-5 polypeptide). In the homologous recombination nucleic acid molecule, the altered portion of the HST-4 and/or the HST-5 gene is flanked at its 5′ and 3′ ends by additional nucleic acid sequence of the HST-4 and/or the HST-5 gene to allow for homologous recombination to occur between the exogenous HST-4 and/or HST-5 gene carried by the homologous recombination nucleic acid molecule and an endogenous HST-4 and/or HST-5 gene in a cell, e.g., an embryonic stem cell. The additional flanking HST-4 and/or HST-5 nucleic acid sequence is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5′ and 3′ ends) are included in the homologous recombination nucleic acid molecule (see, e.g., Thomas, K. R. and Capecchi, M. R. (1987)  Cell  51:503 for a description of homologous recombination vectors). The homologous recombination nucleic acid molecule is introduced into a cell, e.g., an embryonic stem cell line (e.g., by electroporation) and cells in which the introduced HST-4 and/or HST-5 gene has homologously recombined with the endogenous HST-4 and/or HST-5 gene are selected (see e.g., Li, E. et al. (1992)  Cell  69:915). The selected cells can then injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras (see e.g., Bradley, A. in  Teratocarcinomas and Embryonic Stem Cells: A Practical Approach,  E. J. Robertson, ed. (IRL, Oxford, 1987) pp. 113-152). A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to term. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination nucleic acid molecules, e.g., vectors, or homologous recombinant animals are described further in Bradley, A. (1991)  Current Opinion in Biotechnology  2:823-829 and in PCT International Publication Nos.: WO 90/11354 by Le Mouellec et al.; WO 91/01140 by Smithies et al.; WO 92/0968 by Zijlstra et al.; and WO 93/04169 by Berns et al.  
      In another embodiment, transgenic non-human animals can be produced which contain selected systems which allow for regulated expression of the transgene. One example of such a system is the cre/loxP recombinase system of bacteriophage P1. For a description of the cre/loxP recombinase system, see, e.g., Lakso et al. (1992)  Proc. Natl. Acad. Sci. USA  89:6232-6236. Another example of a recombinase system is the FLP recombinase system of Saccharomyces cerevisiae (O&#39;Gorman et al. (1991)  Science  251:1351-1355. If a cre/loxP recombinase system is used to regulate expression of the transgene, animals containing transgenes encoding both the Cre recombinase and a selected protein are required. Such animals can be provided through the construction of “double” transgenic animals, e.g., by mating two transgenic animals, one containing a transgene encoding a selected protein and the other containing a transgene encoding a recombinase.  
      Clones of the non-human transgenic animals described herein can also be produced according to the methods described in Wilmut, I. et al. (1997)  Nature  385:810-813 and PCT International Publication Nos. WO 97/07668 and WO 97/07669. In brief, a cell, e.g., a somatic cell, from the transgenic animal can be isolated and induced to exit the growth cycle and enter G o  phase. The quiescent cell can then be fused, e.g., through the use of electrical pulses, to an enucleated oocyte from an animal of the same species from which the quiescent cell is isolated. The reconstructed oocyte is then cultured such that it develops to morula or blastocyte and then transferred to pseudopregnant female foster animal. The offspring borne of this female foster animal will be a clone of the animal from which the cell, e.g., the somatic cell, is isolated.  
      IV. Pharmaceutical Compositions  
      The MTP-1 nucleic acid molecules, fragments of MTP-1 proteins, and anti-MTP-1 antibodies (also referred to herein as “active compounds”) of the invention can be incorporated into pharmaceutical compositions suitable for administration. Such compositions typically comprise the nucleic acid molecule, protein, or antibody and a pharmaceutically acceptable carrier. As used herein the language “pharmaceutically acceptable carrier” is intended to include any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like, compatible with pharmaceutical administration. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active compound, use thereof in the compositions is contemplated. Supplementary active compounds can also be incorporated into the compositions.  
      The OAT, PLTR-1 and/or HAAT nucleic acid molecules, OAT, PLTR-1 and/or HAAT proteins, fragments thereof, anti-OAT, anti-PLTR-1 and/or anti-HAAT antibodies, and OAT, PLTR-1 and/or HAAT modulators (also referred to herein as “active compounds”) of the invention can be incorporated into pharmaceutical compositions suitable for administration. Such compositions typically comprise the nucleic acid molecule, protein, or antibody and a pharmaceutically acceptable carrier. As used herein the language “pharmaceutically acceptable carrier” is intended to include any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like, compatible with pharmaceutical administration. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active compound, use thereof in the compositions is contemplated. Supplementary active compounds can also be incorporated into the compositions.  
      The HST-1, TP-2, TFM-2 and/or TFM-3 nucleic acid molecules, fragments of HST-1, TP-2, TFM-2 and/or TFM-3 polypeptides, and anti-HST-1, anti-TP-2, anti-TFM-2 and/or anti-TFM-3 antibodies (also referred to herein as “active compounds”) of the invention can be incorporated into pharmaceutical compositions suitable for administration. Such compositions typically comprise the nucleic acid molecule, polypeptide, or antibody and a pharmaceutically acceptable carrier. As used herein the language “pharmaceutically acceptable carrier” is intended to include any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like, compatible with pharmaceutical administration. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active compound, use thereof in the compositions is contemplated. Supplementary active compounds can also be incorporated into the compositions.  
      The 67118, 67067, 62092, HST-4 and/or the HST-5 nucleic acid molecules, fragments of 67118, 67067, 62092, HST-4 and/or HST-5 polypeptides, anti-67118, anti-67067, anti-62092, anti-HST-4 and/or anti-HST-5 antibodies, and/or 67118, 67067, 62092, HST-4 modulators and/or HST-5 modulators (also referred to herein as “active compounds”) of the invention can be incorporated into pharmaceutical compositions suitable for administration. Such compositions typically comprise the nucleic acid molecule, polypeptide, or antibody and a pharmaceutically acceptable carrier. As used herein the language “pharmaceutically acceptable carrier” is intended to include any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like, compatible with pharmaceutical administration. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active compound, use thereof in the compositions is contemplated. Supplementary active compounds can also be incorporated into the compositions.  
      A pharmaceutical composition of the invention is formulated to be compatible with its intended route of administration. Examples of routes of administration include parenteral, e.g., intravenous, intradermal, subcutaneous, oral (e.g., inhalation), transdermal (topical), transmucosal, and rectal administration. Solutions or suspensions used for parenteral, intradermal, or subcutaneous application can include the following components: a sterile diluent such as water for injection, saline solution, fixed oils, polyethylene glycols, glycerine, propylene glycol or other synthetic solvents; antibacterial agents such as benzyl alcohol or methyl parabens; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates and agents for the adjustment of tonicity such as sodium chloride or dextrose. pH can be adjusted with acids or bases, such as hydrochloric acid or sodium hydroxide. The parenteral preparation can be enclosed in ampoules, disposable syringes or multiple dose vials made of glass or plastic.  
      Pharmaceutical compositions suitable for injectable use include sterile aqueous solutions (where water soluble) or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersion. For intravenous administration, suitable carriers include physiological saline, bacteriostatic water, Cremophor EL™ (BASF, Parsippany, N.J.) or phosphate buffered saline (PBS). In all cases, the composition must be sterile and should be fluid to the extent that easy syringeability exists. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyetheylene glycol, and the like), and suitable mixtures thereof. The proper fluidity can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. Prevention of the action of microorganisms can be achieved by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, ascorbic acid, thimerosal, and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars, polyalcohols such as manitol, sorbitol, sodium chloride in the composition. Prolonged absorption of the injectable compositions can be brought about by including in the composition an agent which delays absorption, for example, aluminum monostearate and gelatin.  
      Sterile injectable solutions can be prepared by incorporating the active compound (e.g., a fragment of an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 polypeptide or an anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti- HAAT, anti-HST-4 and/or anti-HST-5 antibody) in the required amount in an appropriate solvent with one or a combination of ingredients enumerated above, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the active compound into a sterile vehicle which contains a basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum drying and freeze-drying which yields a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof.  
      Oral compositions generally include an inert diluent or an edible carrier. They can be enclosed in gelatin capsules or compressed into tablets. For the purpose of oral therapeutic administration, the active compound can be incorporated with excipients and used in the form of tablets, troches, or capsules. Oral compositions can also be prepared using a fluid carrier for use as a mouthwash, wherein the compound in the fluid carrier is applied orally and swished and expectorated or swallowed. Pharmaceutically compatible binding agents, and/or adjuvant materials can be included as part of the composition. The tablets, pills, capsules, troches and the like can contain any of the following ingredients, or compounds of a similar nature: a binder such as microcrystalline cellulose, gum tragacanth or gelatin; an excipient such as starch or lactose, a disintegrating agent such as alginic acid, Primogel, or corn starch; a lubricant such as magnesium stearate or Sterotes; a glidant such as colloidal silicon dioxide; a sweetening agent such as sucrose or saccharin; or a flavoring agent such as peppermint, methyl salicylate, or orange flavoring.  
      For administration by inhalation, the compounds are delivered in the form of an aerosol spray from pressured container or dispenser which contains a suitable propellant, e.g., a gas such as carbon dioxide, or a nebulizer.  
      Systemic administration can also be by transmucosal or transdermal means. For transmucosal or transdermal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art, and include, for example, for transmucosal administration, detergents, bile salts, and fusidic acid derivatives. Transmucosal administration can be accomplished through the use of nasal sprays or suppositories. For transdermal administration, the active compounds are formulated into ointments, salves, gels, or creams as generally known in the art.  
      The compounds can also be prepared in the form of suppositories (e.g., with conventional suppository bases such as cocoa butter and other glycerides) or retention enemas for rectal delivery.  
      In one embodiment, the active compounds are prepared with carriers that will protect the compound against rapid elimination from the body, such as a controlled release formulation, including implants and microencapsulated delivery systems. Biodegradable, biocompatible polymers can be used, such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Methods for preparation of such formulations will be apparent to those skilled in the art. The materials can also be obtained commercially from Alza Corporation and Nova Pharmaceuticals, Inc. Liposomal suspensions (including liposomes targeted to infected cells with monoclonal antibodies to viral antigens) can also be used as pharmaceutically acceptable carriers. These can be prepared according to methods known to those skilled in the art, for example, as described in U.S. Pat. No. 4,522,811.  
      It is especially advantageous to formulate oral or parenteral compositions in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used herein refers to physically discrete units suited as unitary dosages for the subject to be treated; each unit containing a predetermined quantity of active compound calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. The specification for the dosage unit forms of the invention are dictated by and directly dependent on the unique characteristics of the active compound and the particular therapeutic effect to be achieved, and the limitations inherent in the art of compounding such an active compound for the treatment of individuals.  
      Toxicity and therapeutic efficacy of such compounds can be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD50 (the dose lethal to 50% of the population) and the ED50 (the dose therapeutically effective in 50% of the population). The dose ratio between toxic and therapeutic effects is the therapeutic index and it can be expressed as the ratio LD50/ED50. Compounds which exhibit large therapeutic indices are preferred. While compounds that exhibit toxic side effects may be used, care should be taken to design a delivery system that targets such compounds to the site of affected tissue in order to minimize potential damage to uninfected cells and, thereby, reduce side effects.  
      The data obtained from the cell culture assays and animal studies can be used in formulating a range of dosage for use in humans. The dosage of such compounds lies preferably within a range of circulating concentrations that include the ED50 with little or no toxicity. The dosage may vary within this range depending upon the dosage form employed and the route of administration utilized. For any compound used in the method of the invention, the therapeutically effective dose can be estimated initially from cell culture assays. A dose may be formulated in animal models to achieve a circulating plasma concentration range that includes the IC50 (i.e., the concentration of the test compound which achieves a half-maximal inhibition of symptoms) as determined in cell culture. Such information can be used to more accurately determine useful doses in humans. Levels in plasma may be measured, for example, by high performance liquid chromatography.  
      As defined herein, a therapeutically effective amount of polypeptide (i.e., an effective dosage) ranges from about 0.001 to 30 mg/kg body weight, preferably about 0.01 to 25 mg/kg body weight, more preferably about 0.1 to 20 mg/kg body weight, and even more preferably about 1 to 10 mg/kg, 2 to 9 mg/kg, 3 to 8 mg/kg, 4 to 7 mg/kg, or 5 to 6 mg/kg body weight. The skilled artisan will appreciate that certain factors may influence the dosage required to effectively treat a subject, including but not limited to the severity of the disease or disorder, previous treatments, the general health and/or age of the subject, and other diseases present. Moreover, treatment of a subject with a therapeutically effective amount of a polypeptide or antibody can include a single treatment or, preferably, can include a series of treatments.  
      In a preferred example, a subject is treated with antibody or polypeptide in the range of between about 0.1 to 20 mg/kg body weight, one time per week for between about 1 to 10 weeks, preferably between 2 to 8 weeks, more preferably between about 3 to 7 weeks, and even more preferably for about 4, 5, or 6 weeks. It will also be appreciated that the effective dosage of antibody or polypeptide used for treatment may increase or decrease over the course of a particular treatment. Changes in dosage may result and become apparent from the results of diagnostic assays as described herein.  
      The present invention encompasses agents which modulate expression or activity. An agent may, for example, be a small molecule. For example, such small molecules include, but are not limited to, peptides, peptidomimetics, amino acids, amino acid analogs, polynucleotides, polynucleotide analogs, nucleotides, nucleotide analogs, organic or inorganic compounds (i.e.,. including heteroorganic and organometallic compounds) having a molecular weight less than about 10,000 grams per mole, organic or inorganic compounds having a molecular weight less than about 5,000 grams per mole, organic or inorganic compounds having a molecular weight less than about 1,000 grams per mole, organic or inorganic compounds having a molecular weight less than about 500 grams per mole, and salts, esters, and other pharmaceutically acceptable forms of such compounds. It is understood that appropriate doses of small molecule agents depends upon a number of factors within the ken of the ordinarily skilled physician, veterinarian, or researcher. The dose(s) of the small molecule will vary, for example, depending upon the identity, size, and condition of the subject or sample being treated, further depending upon the route by which the composition is to be administered, if applicable, and the effect which the practitioner desires the small molecule to have upon the nucleic acid or polypeptide of the invention.  
      Exemplary doses include milligram or microgram amounts of the small molecule per kilogram of subject or sample weight (e.g., about 1 microgram per kilogram to about 500 milligrams per kilogram, about 100 micrograms per kilogram to about 5 milligrams per kilogram, or about 1 microgram per kilogram to about 50 micrograms per kilogram. It is furthermore understood that appropriate doses of a small molecule depend upon the potency of the small molecule with respect to the expression or activity to be modulated. Such appropriate doses may be determined using the assays described herein. When one or more of these small molecules is to be administered to an animal (e.g., a human) in order to modulate expression or activity of a polypeptide or nucleic acid of the invention, a physician, veterinarian, or researcher may, for example, prescribe a relatively low dose at first, subsequently increasing the dose until an appropriate response is obtained. In addition, it is understood that the specific dose level for any particular animal subject will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, general health, gender, and diet of the subject, the time of administration, the route of administration, the rate of excretion, any drug combination, and the degree of expression or activity to be modulated.  
      In certain embodiments of the invention, a modulator of OAT, PLTR-1 or HAAT activity is administered in combination with other agents (e.g., a small molecule), or in conjunction with another, complementary treatment regime. For example, in one embodiment, a modulator of OAT, PLTR-1 or HAAT activity is used to treat OAT, PLTR-1 or HAAT associated disorder. Accordingly, modulation of OAT, PLTR-1 or HAAT activity may be used in conjunction with, for example, another agent used to treat the disorder.  
      Further, an antibody (or fragment thereof) may be conjugated to a therapeutic moiety such as a cytotoxin, a therapeutic agent or a radioactive metal ion. A cytotoxin or cytotoxic agent includes any agent that is detrimental to cells. Examples include taxol, cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, and puromycin and analogs or homologues thereof. Therapeutic agents include, but are not limited to, antimetabolites (e.g., methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, 5-fluorouracil decarbazine), alkylating agents (e.g., mechlorethamine, thioepa chlorambucil, melphalan, carmustine (BSNU) and lomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol, streptozotocin, mitomycin C, and cis-dichlorodiamine platinum (II) (DDP) cisplatin), anthracyclines (e.g., daunorubicin (formerly daunomycin) and doxorubicin), antibiotics (e.g., dactinomycin (formerly actinomycin), bleomycin, mithramycin, and anthramycin (AMC)), and anti-mitotic agents (e.g., vincristine and vinblastine).  
      The conjugates of the invention can be used for modifying a given biological response, the drug moiety is not to be construed as limited to classical chemical therapeutic agents. For example, the drug moiety may be a protein or polypeptide possessing a desired biological activity. Such proteins may include, for example, a toxin such as abrin, ricin A, pseudomonas exotoxin, or diphtheria toxin; a protein such as tumor necrosis factor, alpha-interferon, beta-interferon, nerve growth factor, platelet derived growth factor, tissue plasminogen activator; or, biological response modifiers such as, for example, lymphokines, interleukin-1 (“IL-1”), interleukin-2 (“IL-2”), interleukin-6 (“IL-6”), granulocyte macrophage colony stimulating factor (“GM-CSF”), granulocyte colony stimulating factor (“G-CSF”), or other growth factors.  
      Techniques for conjugating such therapeutic moiety to antibodies are well known, see, e.g., Arnon et al., “Monoclonal Antibodies For Immunotargeting Of Drugs In Cancer Therapy”, in Monoclonal Antibodies And Cancer Therapy, Reisfeld et al. (eds.), pp. 243-56 (Alan R. Liss, Inc. 1985); Hellstrom et al., “Antibodies For Drug Delivery”, in Controlled Drug Delivery (2nd Ed.), Robinson et al. (eds.), pp. 623-53 (Marcel Dekker, Inc. 1987); Thorpe, “Antibody Carriers Of Cytotoxic Agents In Cancer Therapy: A Review”, in Monoclonal Antibodies &#39;84: Biological And Clinical Applications, Pinchera et al. (eds.), pp. 475-506 (1985); “Analysis, Results, And Future Prospective Of The Therapeutic Use Of Radiolabeled Antibody In Cancer Therapy”, in Monoclonal Antibodies For Cancer Detection And Therapy, Baldwin et al. (eds.), pp. 303-16 (Academic Press 1985), and Thorpe et al., “The Preparation And Cytotoxic Properties Of Antibody-Toxin Conjugates”, Immunol. Rev., 62:119-58 (1982). Alternatively, an antibody can be conjugated to a second antibody to form an antibody heteroconjugate as described by Segal in U.S. Pat. No. 4,676,980.  
      The nucleic acid molecules of the invention can be inserted into vectors and used as gene therapy vectors. Gene therapy vectors can be delivered to a subject by, for example, intravenous injection, local administration (see U.S. Pat. No. 5,328,470) or by stereotactic injection (see e.g., Chen et al. (1994)  Proc. Natl. Acad. Sci. USA  91:3054-3057). The pharmaceutical preparation of the gene therapy vector can include the gene therapy vector in an acceptable diluent, or can comprise a slow release matrix in which the gene delivery vehicle is imbedded. Alternatively, where the complete gene delivery vector can be produced intact from recombinant cells, e.g., retroviral vectors, the pharmaceutical preparation can include one or more cells which produce the gene delivery system.  
      The pharmaceutical compositions can be included in a container, pack, or dispenser together with instructions for administration.  
      V. Uses and Methods of the Invention  
      A. MTP-1  
      The nucleic acid molecules, proteins, protein homologues, and antibodies described herein can be used in one or more of the following methods: a) screening assays; b) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenetics); and c) methods of treatment (e.g., therapeutic and prophylactic). As described herein, an MTP-1 protein of the invention has one or more of the following activities: 1) modulates the import and export of molecules from cells, e.g., lipids, hormones, ions, cytokines, neurotransmitters, and metabolites, 2) modulates intra- or intercellular signaling, 3) modulates removal of potentially harmful compounds from the cell, or facilitate the compartmentalization of these molecules into a sequestered intracellular space (e.g., the peroxisome), and 4) modulates transport of biological molecules across membranes, e.g., the plasma membrane, or the membrane of the mitochondrion, the peroxisome, the lysosome, the endoplasmic reticulum, the nucleus, or the vacuole.  
      The isolated nucleic acid molecules of the invention can be used, for example, to express MTP-1 protein (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect MTP-1 mRNA (e.g., in a biological sample) or a genetic alteration in an MTP-1 gene, and to modulate MTP-1 activity, as described further below. The MTP-1 proteins can be used to treat disorders characterized by insufficient or excessive production of an MTP-1 substrate or production of MTP-1 inhibitors. In addition, the MTP-1 proteins can be used to screen for naturally occurring MTP-1 substrates, to screen for drugs or compounds which modulate MTP-1 activity, as well as to treat disorders characterized by insufficient or excessive production of MTP-1 protein or production of MTP-1 protein forms which have decreased, aberrant or unwanted activity compared to MTP-1 wild type protein, preferably a transporter-associated disorder. As used herein, a “transporter-associated disorder” includes a disorder, disease or condition which is caused or characterized by a misregulation (e.g., downregulation or upregulation) of a transporter-mediated activity. Transporter-associated disorders can detrimentally affect cellular functions such as inflammation, lipid metabolism, hematopoiesis, cellular proliferation, growth, differentiation, or migration, cellular regulation of homeostasis, inter- or intra-cellular communication; tissue function, such as cardiac function or musculoskeletal function; systemic responses in an organism, such as nervous system responses, hormonal responses (e.g., insulin response), or immune responses; and protection of cells from toxic compounds (e.g., carcinogens, toxins, mutagens, and toxic byproducts of metabolic activity (e.g., reactive oxygen species)).  
      Since MTP-1 is preferentially expressed in hematopoietic tissue such as bone marrow cells, MTP-1 molecules may be causatively linked to hematopoietic disorders, examples of which include disorders relating to the proliferation, differentiation, and/or function of cells that appear in the bone marrow, e.g., stem cells (e.g., hematopoietic stem cells), and blood cells, e.g., erythrocytes, platelets, and leukocytes. Thus [x] nucleic acids, proteins, and modulators thereof can be used to treat bone marrow, blood, and hematopoietic associated diseases and disorders, e.g., acute myeloid leukemia, hemophilia, leukemia, anemia (e.g., sickle cell anemia), and thalassemia.  
      In another example, MTP-1 polypeptides, nucleic acids, and modulators thereof can be used to treat leukocytic disorders, such as leukopenias (e.g., neutropenia, monocytopenia, lymphopenia, and granulocytopenia), leukocytosis (e.g., granulocytosis, lymphocytosis, eosinophilia, monocytosis, acute and chronic lymphadenitis), malignant lymphomas (e.g., Non-Hodgkin&#39;s lymphomas, Hodgkin&#39;s lymphomas, leukemias, agnogenic myeloid metaplasia, multiple myeloma, plasmacytoma, Waldenstrom&#39;s macroglobulinemia, heavy-chain disease, monoclonal gammopathy, histiocytoses, eosinophilic granuloma, and angioimmunoblastic lymphadenopathy).  
      Since MTP-1 is homologous to known ABC transporter molecules, which are known to be causatively linked to disorders related to lipid metabolism, MTP-1 molecules may be causatively linked to disorders related to lipid metabolism, adipocyte function and adipocyte-related processes such as, e.g., obesity, regulation of body temperature, lipid metabolism, carbohydrate metabolism, body weight regulation, obesity, anorexia nervosa, diabetes mellitus, unusual susceptibility or insensitivity to heat or cold, arteriosclerosis, atherosclerosis, atherogenesis and disorders involving abnormal vascularization, e.g., vascularization of solid tumors.  
      Examples of transporter-associated disorders also include immunological disorders such as autoimmune disorders (e.g., arthritis, graft rejection (e.g., allograft rejection), T cell disorders (e.g., AIDS)), immune deficiency disorders, e.g., congenital X-linked infantile hypogammaglobulinemia, transient hypogammaglobulinemia, common variable immunodeficiency, selective IgA deficiency, chronic mucocutaneous candidiasis, or severe combined immunodeficiency. Transporter-related disorders also include inflammatory disorders pertaining to, characterized by, causing, resulting from, or becoming affected by inflammation. Examples of inflammatory diseases or disorders include, without limitation, asthma, lung inflammation, chronic granulomatous diseases such as tuberculosis, leprosy, sarcoidosis, silicosis and schistosomiasis, nephritis, amyloidosis, rheumatoid arthritis, ankylosing sponduylitis, chronic bronchitis, scleroderma, lupus, polymyositis, appendicitis, inflammatory bowel disease, ulcers, Sjorgen&#39;s syndrome, Reiter&#39;s syndrome, psoriasis, pelvic inflammatory disease, orbital inflammatory disease, thrombotic disease, and inappropriate allergic responses to environmental stimuli such as poison ivy, pollen, insect stings and certain foods, including atopic dermatitis and contact dermatitis.  
      Examples of transporter-associated disorders also include CNS disorders such as cognitive and neurodegenerative disorders, examples of which include, but are not limited to, Alzheimer&#39;s disease, dementias related to Alzheimer&#39;s disease (such as Pick&#39;s disease), Parkinson&#39;s and other Lewy diffuse body diseases, senile dementia, Huntington&#39;s disease, Gilles de la Tourette&#39;s syndrome, multiple sclerosis, amyotrophic lateral sclerosis, progressive supranuclear palsy, epilepsy, and Jakob-Creutzfieldt disease; autonomic function disorders such as hypertension and sleep disorders, and neuropsychiatric disorders, such as depression, schizophrenia, schizoaffective disorder, korsakoff&#39;s psychosis, mania, anxiety disorders, or phobic disorders; learning or memory disorders, e.g., amnesia or age-related memory loss, attention deficit disorder, dysthymic disorder, major depressive disorder, mania, obsessive-compulsive disorder, psychoactive substance use disorders, anxiety, phobias, panic disorder, as well as bipolar affective disorder, e.g., severe bipolar affective (mood) disorder (BP-1), and bipolar affective neurological disorders, e.g., migraine and obesity. Further CNS-related disorders include, for example, those listed in the American Psychiatric Association&#39;s Diagnostic and Statistical manual of Mental Disorders (DSM), the most current version of which is incorporated herein by reference in its entirety.  
      Further examples of transporter-associated disorders include cardiac-related disorders. Cardiovascular system disorders in which the MTP-1 molecules of the invention may be directly or indirectly involved include arteriosclerosis, ischemia reperfusion injury, restenosis, arterial inflammation, vascular wall remodeling, ventricular remodeling, rapid ventricular pacing, coronary microembolism, tachycardia, bradycardia, pressure overload, aortic bending, coronary artery ligation, vascular heart disease, atrial fibrilation, Jervell syndrome, Lange-Nielsen syndrome, long-QT syndrome, congestive heart failure, sinus node dysfunction, angina, heart failure, hypertension, atrial fibrillation, atrial flutter, dilated cardiomyopathy, idiopathic cardiomyopathy, myocardial infarction, coronary artery disease, coronary artery spasm, and arrhythmia. MTP-1-mediated or related disorders also include disorders of the musculoskeletal system such as paralysis and muscle weakness, e.g., ataxia, myotonia, and myokymia.  
      Transporter disorders also include cellular proliferation, growth, differentiation, or migration disorders. Cellular proliferation, growth, differentiation, or migration disorders include those disorders that affect cell proliferation, growth, differentiation, or migration processes. As used herein, a “cellular proliferation, growth, differentiation, or migration process” is a process by which a cell increases in number, size or content, by which a cell develops a specialized set of characteristics which differ from that of other cells, or by which a cell moves closer to or further from a particular location or stimulus. The MTP-1 molecules of the present invention are involved in signal transduction mechanisms, which are known to be involved in cellular growth, differentiation, and migration processes. Thus, the MTP-1 molecules may modulate cellular growth, differentiation, or migration, and may play a role in disorders characterized by aberrantly regulated growth, differentiation, or migration. Such disorders include cancer, e.g., carcinoma, sarcoma, or leukemia; tumor angiogenesis and metastasis; skeletal dysplasia; hepatic disorders; and hematopoietic and/or myeloproliferative disorders.  
      MTP-1-associated or related disorders also include hormonal disorders, such as conditions or diseases in which the production and/or regulation of hormones in an organism is aberrant. Examples of such disorders and diseases include type I and type II diabetes mellitus, pituitary disorders (e.g., growth disorders), thyroid disorders (e.g., hypothyroidism or hyperthyroidism), and reproductive or fertility disorders (e.g., disorders which affect the organs of the reproductive system, e.g., the prostate gland, the uterus, or the vagina; disorders which involve an imbalance in the levels of a reproductive hormone in a subject; disorders affecting the ability of a subject to reproduce; and disorders affecting secondary sex characteristic development, e.g., adrenal hyperplasia).  
      MTP-1-associated or related disorders also include disorders affecting tissues in which MTP-1 protein is expressed.  
      1. MTP-1 Screening Assays:  
      The invention provides a method (also referred to herein as a “screening assay”) for identifying modulators, i.e., candidate or test compounds or agents (e.g., peptides, peptidomimetics, small molecules (organic or inorganic) or other drugs) which bind to MTP-1 proteins, have a stimulatory or inhibitory effect on, for example, MTP-1 expression or MTP-1 activity, or have a stimulatory or inhibitory effect on, for example, the transport (e.g., import or export) of an MTP-1 substrate (e.g., cytotoxic substances, ions, peptides, metabolites).  
      These assays are designed to identify compounds that bind to a MTP-1 protein, bind to other inter- or extra-cellular proteins that interact with a MTP-1 protein, and/or interfere with the interaction of the MTP-1 protein with other inter- or extra-cellular proteins. For example, in the case of the MTP-1 protein, which is protein that is capable of membrane transport, such techniques can be used to identify ligands for such a protein. A MTP-1 protein modulator can, for example, be used to ameliorate diseases or disorders related to transmembrane lipid transport and/or hematopoietic cells. Such compounds may include, but are not limited to MTP-1 peptides, anti-MTP-1 antibodies, or small organic or inorganic compounds. Such compounds may also include other cellular proteins or peptides.  
      Compounds identified via assays such as those described herein may be useful, for example, for ameliorating hematopoietic and/or immunological and/or lipid metabolism-related diseases or disorders. In instances whereby a hematopoietic and/or immunological and/or lipid metabolism-related disease condition results from an overall lower level of MTP-1 gene expression and/or MTP-1 protein in a cell or tissue, compounds that interact with the MTP-1 protein may include compounds which accentuate or amplify the activity of the bound MTP-1 protein. Such compounds would bring about an effective increase in the level of MTP-1 protein activity, thus ameliorating symptoms.  
      In other instances, mutations within the MTP-1 gene may cause aberrant types or excessive amounts of MTP-1 proteins to be made which have a deleterious effect that leads to a hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder. Similarly, physiological conditions may cause an excessive increase in MTP-1 gene expression leading to a hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder. In such cases, compounds that bind to a MTP-1 protein may be identified that inhibit the activity of the MTP-1 protein. Assays for testing the effectiveness of compounds identified by techniques such as those described in this section are discussed herein.  
      In one embodiment, the invention provides assays for screening candidate or test compounds which are capable of binding to and/or being transported by an MTP-1 protein or polypeptide or biologically active portion thereof. In another embodiment, the invention provides assays for screening candidate or test compounds which bind to or modulate the activity of an MTP-1 protein or polypeptide or biologically active portion thereof, e.g., which modulate the ability of an MTP-1 protein to transport an MTP-1 substrate (e.g., a cytotoxic substance, an ion, a peptide, a metabolite). The test compounds of the present invention can be obtained using any of the numerous approaches in combinatorial library methods known in the art, including: biological libraries; spatially addressable parallel solid phase or solution phase libraries; synthetic library methods requiring deconvolution; the ‘one-bead one-compound’ library method; and synthetic library methods using affinity chromatography selection. The biological library approach is limited to peptide libraries, while the other four approaches are applicable to peptide, non-peptide oligomer or small molecule libraries of compounds (Lam, K. S. (1997)  Anticancer Drug Des.  12:145).  
      Examples of methods for the synthesis of molecular libraries can be found in the art, for example in: DeWitt et al. (1993)  Proc. Natl. Acad. Sci. U.S.A.  90:6909; Erb et al. (1994)  Proc. Natl. Acad. Sci. USA  91:11422; Zuckermann et al. (1994).  J. Med. Chem.  37:2678; Cho et al. (1993)  Science  261:1303; Carrell et al. (1994)  Angew. Chem. Int. Ed. Engl.  33:2059; Carell et al. (1994)  Angew. Chem. Int. Ed. Engl.  33:2061; and in Gallop et al. (1994)  J. Med. Chem.  37: 1233.  
      Libraries of compounds may be presented in solution (e.g., Houghten (1992)  Biotechniques  13:412-421), or on beads (Lam (1991)  Nature  354:82-84), chips (Fodor (1993)  Nature  364:555-556), bacteria (Ladner U.S. Pat. No. 5,223,409), spores (Ladner USP &#39;409), plasmids (Cull et al. (1992)  Proc. Natl. Acad. Sci. USA  89:1865-1869) or on phage (Scott and Smith (1990)  Science  249:386-390); (Devlin (1990)  Science  249:404-406); (Cwirla et al. (1990)  Proc. Natl. Acad. Sci.  87:6378-6382); (Felici (1991)  J. Mol. Biol.  222:301-310); (Ladner supra.).  
      In one embodiment, an assay is a cell-based assay in which a cell which expresses an MTP-1 protein or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate MTP-1 activity is determined. Determining the ability of the test compound to modulate MTP-1 activity can be accomplished by monitoring, for example, the transport of an MTP-1 substrate into or out of a cell which expresses MTP-1. The cell, for example, can be of mammalian origin, e.g., a murine or human cell. The ability of the test compound to modulate MTP-1 transport of a substrate (e.g., cytotoxic substances, ions, peptides, metabolites) or to bind to MTP-1 can also be determined. Determining the ability of the test compound to modulate MTP-1 transport of a substrate (e.g., cytotoxic substances, ions, peptides, metabolites) can be accomplished, for example, by coupling the MTP-1 substrate with a radioisotope or enzymatic label such that transport of the MTP-1 substrate by MTP-1 can be determined by detecting the labeled MTP-1 substrate (e.g., in the cell, extracellularly, or intercompartmentally). Determining the ability of the test compound to bind MTP-1 can be accomplished, for example, by coupling the compound with a radioisotope or enzymatic label such that binding of the compound to MTP-1 can be determined by detecting the labeled MTP-1 compound, for example, complexed to MTP-1 in a cell membrane. For example, compounds (e.g., MTP-1 substrates) can be labeled with  125 I,  35 S,  14 C, or  3 H, either directly or indirectly, and the radioisotope detected by direct counting of radioemission or by scintillation counting. Alternatively, compounds can be enzymatically labeled with, for example, horseradish peroxidase, alkaline phosphatase, or luciferase, and the enzymatic label detected by determination of conversion of an appropriate substrate to product.  
      It is also within the scope of this invention to determine the ability of a compound (e.g., an MTP-1 substrate, e.g., cytotoxic substances, ions, peptides, metabolites) to interact with or to be transported by MTP-1 without the labeling of any of the interactants. For example, a microphysiometer can be used to detect the interaction of a compound with MTP-1 without the labeling of either the compound or the MTP-1. McConnell, H. M. et al. (1992)  Science  257:1906-1912. As used herein, a “microphysiometer” (e.g., Cytosensor) is an analytical instrument that measures the rate at which a cell acidifies its environment using a light-addressable potentiometric sensor (LAPS). Changes in this acidification rate can be used as an indicator of the interaction between a compound and MTP-1.  
      In another embodiment, an assay is a cell-based assay comprising contacting a cell which expresses or produces MTP-1 with an MTP-1 substrate (e.g., a cytotoxic substance, an ion, a peptide, a metabolite) and a test compound and determining the ability of the test compound to modulate (e.g., stimulate or inhibit) the activity (e.g., transport) or cellular location of the MTP-1 substrate molecule.  
      Determining the ability of the MTP-1 protein, or a biologically active fragment thereof, to bind to, interact with, or transport an MTP-1 substrate (e.g., cytotoxic substances, ions, peptides, metabolites) can be accomplished by one of the methods described above for determining direct binding. In a preferred embodiment, determining the ability of the MTP-1 protein to bind to, interact with, or transport an MTP-1 substrate (e.g., cytotoxic substances, ions, peptides, metabolites) can be accomplished by determining the activity or localization of the substrate molecule. For example, the activity of the substrate can be determined by detecting induction of a cellular response (i.e., changes in intracellular K +  levels), detecting a secondary or indirect activity of the substrate on a downstream molecule, detecting the induction of a reporter gene (comprising a substrate-responsive regulatory element operatively linked to a nucleic acid encoding a detectable marker, e.g., luciferase), detecting a substrate-regulated cellular response, or determining the localization of the substrate molecule. In other embodiments, the assays described above are carried out in a cell-free context (e.g., in an artificial membrane, vesicle, or micelle preparation).  
      In one embodiment, an assay of the present invention is a cell-free assay in which an MTP-1 protein or biologically active portion thereof (e.g., a portion which possesses the ability to transport or interact with an MTP-1 substrate, e.g., a cytotoxic substance, an ion, a peptide, or a metabolite) is contacted with a test compound and the ability of the test compound to bind to the MTP-1 protein or biologically active portion thereof is determined. Preferred biologically active portions of the MTP-1 proteins to be used in assays of the present invention include fragments which participate in interactions with non-MTP-1 molecules, e.g., fragments with high surface probability scores. Binding of the test compound to the MTP-1 protein can be determined either directly or indirectly as described above. In a preferred embodiment, the assay includes contacting the MTP-1 protein or biologically active portion (e.g., a portion which possesses the ability to transport or interact with an MTP-1 substrate, e.g., a cytotoxic substance, an ion, a peptide, or a metabolite) thereof with a known compound which binds MTP-1 to form an assay mixture, contacting the assay mixture with a test compound, and determining the ability of the test compound to interact with an MTP-1 protein, wherein determining the ability of the test compound to interact with an MTP-1 protein comprises determining the ability of the test compound to preferentially bind to MTP-1 or biologically active portion thereof as compared to the known compound.  
      In another embodiment, the assay is a cell-free assay in which an MTP-1 protein or biologically active portion thereof (e.g., a portion which possesses the ability to transport or interact with an MTP-1 substrate, e.g., a cytotoxic substance, an ion, a peptide, or a metabolite) is contacted with a test compound and the ability of the test compound to modulate (e.g., stimulate or inhibit) the activity of the MTP-1 protein or biologically active portion thereof is determined. Determining the ability of the test compound to modulate the activity of an MTP-1 protein can be accomplished, for example, by determining the ability of the MTP-1 protein to transport an MTP-1 substrate as described herein. Determining the ability of the MTP-1 protein to bind to an MTP-1 substrate (e.g., cytotoxic substances, ions, peptides, metabolites) can also be accomplished using a technology such as real-time Biomolecular Interaction Analysis (BIA). Sjolander, S. and Urbaniczky, C. (1991)  Anal. Chem.  63:2338-2345 and Szabo et al. (1995)  Curr. Opin. Struct. Biol.  5:699-705. As used herein, “BIA” is a technology for studying biospecific interactions in real time, without labeling any of the interactants (e.g., BIAcore). Changes in the optical phenomenon of surface plasmon resonance (SPR) can be used as an indication of real-time reactions between biological molecules.  
      In more than one embodiment of the above assay methods of the present invention, it may be desirable to immobilize MTP-1 (e.g., MTP-1 in a cell, vesicle, or membrane preparation) MTP-1 protein can be immobilized for example on the surface of any vessel suitable for containing reactants. Examples of such vessels include microtitre plates, test tubes, and micro-centrifuge tubes. For example, an MTP-1 protein can be immobilized utilizing conjugation of biotin and streptavidin. Biotinylated MTP-1 protein can be prepared from biotin-NHS (N-hydroxy-succinimide) using techniques known in the art (e.g., biotinylation kit, Pierce Chemicals, Rockford, Ill.), and immobilized in the wells of streptavidin-coated 96 well plates (Pierce Chemical). Alternatively, antibodies reactive with MTP-1 protein or target molecules but which do not interfere with activity of the MTP-1 protein can be derivatized to the wells of the plate, and unbound MTP-1 protein trapped in the wells by antibody conjugation.  
      In another embodiment, modulators of MTP-1 expression are identified in a method wherein a cell is contacted with a candidate compound and the expression of MTP-1 mRNA or protein in the cell is determined. The level of expression of MTP-1 mRNA or protein in the presence of the candidate compound is compared to the level of expression of MTP-1 mRNA or protein in the absence of the candidate compound. The candidate compound can then be identified as a modulator of MTP-1 expression based on this comparison. For example, when expression of MTP-1 mRNA or protein is greater (statistically significantly greater) in the presence of the candidate compound than in its absence, the candidate compound is identified as a stimulator of MTP-1 mRNA or protein expression. Alternatively, when expression of MTP-1 mRNA or protein is less (statistically significantly less) in the presence of the candidate compound than in its absence, the candidate compound is identified as an inhibitor of MTP-1 mRNA or protein expression. The level of MTP-1 mRNA or protein expression in the cells can be determined by methods described herein for detecting MTP-1 mRNA or protein.  
      In another aspect, the invention pertains to a combination of two or more of the assays described herein. For example, a modulating agent can be identified using a cell-based assay or a cell free assay (e.g., an artificial membrane, micelle, or vesicle preparation), and the ability of the agent to modulate the activity of an MTP-1 protein can be confirmed in vivo, e.g., in an animal such as an animal model for cellular transformation and/or tumorigenesis.  
      This invention further pertains to novel agents identified by the above-described screening assays. Accordingly, it is within the scope of this invention to further use an agent identified as described herein in an appropriate animal model. For example, an agent identified as described herein (e.g., an MTP-1 modulating agent, an antisense MTP-1 nucleic acid molecule, an MTP-1-specific antibody, or an MTP-1-binding partner) can be used in an animal model to determine the efficacy, toxicity, or side effects of treatment with such an agent. Alternatively, an agent identified as described herein can be used in an animal model to determine the mechanism of action of such an agent. Furthermore, this invention pertains to uses of novel agents identified by the above-described screening assays for treatments as described herein. In one embodiment, the invention features a method of treating a subject having a hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder that involves administering to the subject a MTP-1 modulator such that treatment occurs. In another embodiment, the invention features a method of treating a subject having a hematopoietic and/or immunological and/or lipid metabolism-related disease, e.g., atherogenesis, that involves treating a subject with a MTP-1 modulator, such that treatment occurs. Preferred MTP-1 modulators include, but are not limited to, MTP-1 proteins or biologically active fragments, MTP-1 nucleic acid molecules, MTP-1 antibodies, ribozymes, and MTP-1 antisense oligonucleotides designed based on the MTP-1 nucleotide sequences disclosed herein, as well as peptides, organic and non-organic small molecules identified as being capable of modulating MTP-1 expression and/or activity, for example, according to at least one of the screening assays described herein.  
      Any of the compounds, including but not limited to compounds such as those identified in the foregoing assay systems, may be tested for the ability to ameliorate immunological disease or disorder symptoms. Cell-based and animal model-based assays for the identification of compounds exhibiting such an ability to ameliorate hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder systems are described herein.  
      In one aspect, cell-based systems, as described herein, may be used to identify compounds which may act to ameliorate hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms. For example, such cell systems may be exposed to a compound, suspected of exhibiting an ability to ameliorate hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms, at a sufficient concentration and for a time sufficient to elicit such an amelioration of hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms in the exposed cells. After exposure, the cells are examined to determine whether one or more of the hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder cellular phenotypes has been altered to resemble a more normal or more wild type, non-hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder phenotype. Cellular phenotypes that are associated with hematopoietic and/or immunological and/or lipid metabolism-related disease states include aberrant proliferation, growth, and migration, anchorage independent growth, and loss of contact inhibition.  
      In addition, animal-based hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder systems, such as those described herein, may be used to identify compounds capable of ameliorating hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms. Such animal models may be used as test substrates for the identification of drugs, pharmaceuticals, therapies, and interventions which may be effective in treating hematopoietic and/or immunological and/or lipid metabolism-related disorders or diseases. For example, animal models may be exposed to a compound, suspected of exhibiting an ability to hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms, at a sufficient concentration and for a, time sufficient to elicit such an amelioration of hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms in the exposed animals. The response of the animals to the exposure may be monitored by assessing the reversal of disorders or symptoms associated with hematopoietic and/or immunological and/or lipid metabolism-related disease.  
      With regard to intervention, any treatments which reverse any aspect of hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms should be considered as candidates for human hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder therapeutic intervention. Dosages of test agents may be determined by deriving dose-response curves.  
      Additionally, gene expression patterns may be utilized to assess the ability of a compound to ameliorate hematopoietic and/or immunological and/or lipid metabolism-related disease symptoms. For example, the expression pattern of one or more genes may form part of a “gene expression profile” or “transcriptional profile” which may be then be used in such an assessment. “Gene expression profile” or “transcriptional profile”, as used herein, includes the pattern of mRNA expression obtained for a given tissue or cell type under a given set of conditions. Such conditions may include, but are not limited to, cell growth, proliferation, differentiation, transformation, tumorigenesis, metastasis, and carcinogen exposure. Gene expression profiles may be generated, for example, by utilizing a differential display procedure, Northern analysis and/or RT-PCR. In one embodiment, MTP-1 gene sequences may be used as probes and/or PCR primers for the generation and corroboration of such gene expression profiles.  
      Gene expression profiles may be characterized for known states within the cell- and/or animal-based model systems. Subsequently, these known gene expression profiles may be compared to ascertain the effect a test compound has to modify such gene expression profiles, and to cause the profile to more closely resemble that of a more desirable profile.  
      For example, administration of a compound may cause the gene expression profile of a hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder model system to more closely resemble the control system. Administration of a compound may, alternatively, cause the gene expression profile of a control system to begin to mimic a hematopoietic and/or immunological and/or lipid metabolism-related disease state. Such a compound may, for example, be used in further characterizing the compound of interest, or may be used in the generation of additional animal models.  
      B. OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, and/or HST-5  
      The nucleic acid molecules, proteins, protein homologues, and antibodies described herein can be used in one or more of the following methods: a) screening assays; b) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenetics); and c) methods of treatment (e.g., therapeutic and prophylactic). As described herein, an OAT protein of the invention has one or more of the following activities: (i) interaction with an OAT substrate or target molecule; (ii) transport of an OAT substrate across a membrane; (iii) interaction with and/or modulation of a second non-OAT protein; (iv) modulation of cellular signaling and/or gene transcription (e.g., either directly or indirectly); (v) protection of cells and/or tissues from organic anions; and/or (vi) modulation, of hormonal responses.  
      The isolated nucleic acid molecules of the invention can be used, for example, to express OAT protein (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect OAT mRNA (e.g., in a biological sample) or a genetic alteration in an OAT gene, and to modulate OAT activity, as described further below. The OAT proteins can be used to treat disorders characterized by insufficient or excessive transport of an OAT substrate or production of OAT inhibitors. In addition, the OAT proteins can be used to screen for naturally occurring OAT substrates or target molecules, to screen for drugs or compounds which modulate OAT activity, as well as to treat disorders characterized by insufficient or excessive production of OAT protein or production of OAT protein forms which have decreased, aberrant or unwanted activity compared to OAT wild type protein (e.g., an OAT-associated disorder).  
      Moreover, the anti-OAT antibodies of the invention can be used to detect and isolate OAT proteins, regulate the bioavailability of OAT proteins, and modulate OAT activity.  
      The nucleic acid molecules, proteins, protein homologues, and antibodies described herein can be used in one or more of the following methods: a) screening assays; b) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenetics); and c) methods of treatment (e.g., therapeutic and prophylactic). As described herein, an HST-1 polypeptide of the invention has one or more of the following activities: (1) maintain sugar homeostasis in a cell, (2) influence insulin and/or glucagon secretion, (3) bind a monosaccharide, e.g., D-glucose, D-fructose, and/or D-galactose, and (4) transport monosaccharides across a cell membrane.  
      The isolated nucleic acid molecules of the invention can be used, for example, to express HST-1 polypeptides (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect HST-1 mRNA (e.g., in a biological sample) or a genetic alteration in an HST-1 gene, and to modulate HST-1 activity, as described further below. The HST-1 polypeptides can be used to treat disorders characterized by insufficient or excessive production of an HST-1 substrate or production of HST-1 inhibitors. In addition, the HST-1 polypeptides can be used to screen for naturally occurring HST-1 substrates, to screen for drugs or compounds which modulate HST-1 activity, as well as to treat disorders characterized by insufficient or excessive production of HST-1 polypeptide or production of HST-1 polypeptide forms which have decreased, aberrant or unwanted activity compared to HST-1 wild type polypeptide (e.g., sugar transporter disorders). Moreover, the anti-HST-1 antibodies of the invention can be used to detect and isolate HST-1 polypeptides, to regulate the bioavailability of HST-1 polypeptides, and modulate HST-1 activity.  
      The nucleic acid molecules, proteins, protein homologues, and antibodies described herein can be used in one or more of the following methods: a) screening assays; b) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenetics); and c) methods of treatment (e.g., therapeutic and prophylactic). As described herein, a TP-2 polypeptide of the invention has one or more of the following activities: (1) modulate the import and export of molecules, e.g., hormones, ions, cytokines, neurotransmitters, monosaccharides, and metabolites, from cells, 2) modulate intra- or inter-cellular signaling, 3) modulate removal of potentially harmful compounds from the cell, or facilitate the compartmentalization of these molecules into a sequestered intra-cellular space (e.g., the peroxisome), and 4) modulate transport of biological molecules across membranes, e.g., the plasma membrane, or the membrane of the mitochondrion, the peroxisome, the lysosome, the endoplasmic reticulum, the nucleus, or the vacuole.  
      The isolated nucleic acid molecules of the invention can be used, for example, to express TP-2 polypeptides (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect TP-2 mRNA (e.g., in a biological sample) or a genetic alteration in a TP-2 gene, and to modulate TP-2 activity, as described further below. The TP-2 polypeptides can be used to treat disorders characterized by insufficient or excessive production of a TP-2 substrate or production of TP-2 inhibitors. In addition, the TP-2 polypeptides can be used to screen for naturally occurring TP-2 substrates, to screen for drugs or compounds which modulate TP-2 activity, as well as to treat disorders characterized by insufficient or excessive production of TP-2 polypeptide or production of TP-2 polypeptide forms which have decreased, aberrant or unwanted activity compared to TP-2 wild type polypeptide (e.g., transporter-associated disorders). Moreover, the anti-TP-2 antibodies of the invention can be used to detect and isolate TP-2 polypeptides, to regulate the bioavailability of TP-2 polypeptides, and modulate TP-2 activity.  
      The nucleic acid molecules, proteins, protein homologues, protein fragments, antibodies, peptides, peptidomimetics, and small molecules described herein can be used in one or more of the following methods: a) screening assays; b) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenetics); and c) methods of treatment (e.g., therapeutic and prophylactic). As described herein, a PLTR-1 protein of the invention has one or more of the following activities: (i) interaction with a PLTR-1 substrate or target molecule (e.g., a phospholipid, ATP, or a non-PLTR-1 protein); (ii) transport of a PLTR-l substrate or target molecule (e.g., an aminophospholipid such as phosphatidylserine or phosphatidylethanolamine) from one side of a cellular membrane to the other; (iii) the ability to be phosphorylated or dephosphorylated; (iv) adoption of an E1 conformation or an E2 conformation; (v) conversion of a PLTR-1 substrate or target molecule to a product (e.g., hydrolysis of ATP); (vi) interaction with a second non-PLTR-1 protein; (vii) modulation of substrate or target molecule location (e.g., modulation of phospholipid location within a cell and/or location with respect to a cellular membrane); (viii) maintenance of aminophospholipid gradients; (ix) modulation of blood coagulation; (x) modulation of intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (xi) modulation of cellular proliferation, growth, differentiation, apoptosis, absorption, or secretion.  
      The isolated nucleic acid molecules of the invention can be used, for example, to express PLTR-1 protein (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect PLTR-1 mRNA (e.g., in a biological sample) or a genetic alteration in a PLTR-1 gene, and to modulate PLTR-1 activity, as described further below. The PLTR-1 proteins can be used to treat disorders characterized by insufficient or excessive production or transport of a PLTR-1 substrate or production of PLTR-1 inhibitors, for example, PLTR-1 associated disorders.  
      As used interchangeably herein, a “phospholipid transporter associated disorder” or a “PLTR-1 associated disorder” includes a disorder, disease or condition which is caused or characterized by a misregulation (e.g., downregulation or upregulation) of PLTR-1 activity. PLTR-1 associated disorders can detrimentally affect cellular functions such as cellular proliferation, growth, differentiation, inter- or intra-cellular communication; tissue function, such as cardiac function or musculoskeletal function; systemic responses in an organism, such as nervous system responses, hormonal responses (e.g., insulin response), or immune responses; and protection of cells from toxic compounds (e.g., carcinogens, toxins, or mutagens).  
      Preferred examples of PLTR-1 associated disorders include cardiovascular or cardiac-related disorders. Cardiovascular system disorders in which the PLTR-1 molecules of the invention may be directly or indirectly involved include arteriosclerosis, ischemia reperfusion injury, restenosis, arterial inflammation, vascular wall remodeling, ventricular remodeling, rapid ventricular pacing, coronary microembolism, tachycardia, bradycardia, pressure overload, aortic bending, coronary artery ligation, vascular heart disease, atrial fibrilation, Jervell syndrome, Lange-Nielsen syndrome, long-QT syndrome, congestive heart failure, sinus node dysfunction, angina, heart failure, hypertension, atrial fibrillation, atrial flutter, dilated cardiomyopathy, idiopathic cardiomyopathy, myocardial infarction, coronary artery disease, coronary artery spasm, and arrhythmia. PLTR-1 associated disorders also include disorders of the musculoskeletal system such as paralysis and muscle weakness, e.g., ataxia, myotonia, and myokymia.  
      Other examples of PLTR-1 associated disorders include lipid homeostasis disorders such as atherosclerosis, obesity, diabetes, insulin resistance, hyperlipidemia, hypolipidemia, dyslipidemia, hypercholesterolemia, hypocholesterolemia, triglyceride storage disease, cardiovascular disease, coronary artery disease, hypertension, stroke, overweight, anorexia, cachexia, hyperlipoproteinemia, hypolipoproteinemia, Niemann Pick disease, hypertriglyceridemia, hypotriglyceridemia, pancreatitis, diffuse idiopathic skeletal hyperostosis (DISH), atherogenic lipoprotein phenotype (ALP), epilepsy, liver disease, fatty liver, steatohepatitis, and polycystic ovarian syndrome.  
      Further examples of PLTR-1 associated disorders include CNS disorders such as cognitive and neurodegenerative disorders, examples of which include, but are not limited to, Alzheimer&#39;s disease, dementias related to Alzheimer&#39;s disease (such as Pick&#39;s disease), Parkinson&#39;s and other Lewy diffuse body diseases, senile dementia, Huntington&#39;s disease, Gilles de la Tourette&#39;s syndrome, multiple sclerosis, amyotrophic lateral sclerosis, progressive supranuclear palsy, epilepsy, seizure disorders, and Jakob-Creutzfieldt disease; autonomic function disorders such as hypertension and sleep disorders, and neuropsychiatric disorders, such as depression, schizophrenia, schizoaffective disorder, korsakoff&#39;s psychosis, mania, anxiety disorders, or phobic disorders; learning or memory disorders, e.g., amnesia or age-related memory loss, attention deficit disorder, dysthymic disorder, major depressive disorder, mania, obsessive-compulsive disorder, psychoactive substance use disorders, anxiety, phobias, panic disorder, as well as bipolar affective disorder, e.g., severe bipolar affective (mood) disorder (BP-1), and bipolar affective neurological disorders, e.g., migraine and obesity. Further CNS-related disorders include, for example, those listed in the American Psychiatric Association&#39;s Diagnostic and Statistical manual of Mental Disorders (DSM), the most current version of which is incorporated herein by reference in its entirety.  
      PLTR-1 associated disorders also include cellular proliferation, growth, or differentiation disorders. Cellular proliferation, growth, or differentiation disorders include those disorders that affect cell proliferation, growth, or differentiation processes. As used herein, a “cellular proliferation, growth, or differentiation process” is a process by which a cell increases in number, size or content, or by which a cell develops a specialized set of characteristics which differ from that of other cells. The PLTR-1 molecules of the present invention are involved in phospholipid transport mechanisms, which are known to be involved in cellular growth, proliferation, and differentiation processes. Thus, the PLTR-1 molecules may modulate cellular growth, proliferation, or differentiation, and may play a role in disorders characterized by aberrantly regulated growth, proliferation, or differentiation. Such disorders include cancer, e.g., carcinoma, sarcoma, or leukemia; tumor angiogenesis and metastasis; skeletal dysplasia; hepatic disorders; and hematopoietic and/or myeloproliferative disorders.  
      PLTR-1 associated or related disorders also include hormonal disorders, such as conditions or diseases in which the production and/or regulation of hormones in an organism is aberrant. Examples of such disorders and diseases include type I and type II diabetes mellitus, pituitary disorders (e.g., growth disorders), thyroid disorders (e.g., hypothyroidism or hyperthyroidism), and reproductive or fertility disorders (e.g., disorders which affect the organs of the reproductive system, e.g., the prostate gland, the uterus, or the vagina; disorders which involve an imbalance in the levels of a reproductive hormone in a subject; disorders affecting the ability of a subject to reproduce; and disorders affecting secondary sex characteristic development, e.g., adrenal hyperplasia).  
      PLTR-1 associated or related disorders also include immune disorders, such as autoimmune disorders or immune deficiency disorders, e.g., congenital X-linked infantile hypogammaglobulinemia, transient hypogammaglobulinemia, common variable immunodeficiency, selective IgA deficiency, chronic mucocutaneous candidiasis, or severe combined immunodeficiency.  
      PLTR-1 associated or related disorders also include disorders affecting tissues in which PLTR-1 protein is expressed (e.g., vessels).  
      In addition, the PLTR-1 proteins can be used to screen for naturally occurring PLTR-1 substrates, to screen for drugs or compounds which modulate PLTR-1 activity, as well as to treat disorders characterized by insufficient or excessive production of PLTR-1 protein or production of PLTR-1 protein forms which have decreased, aberrant or unwanted activity compared to PLTR-1 wild type protein (e.g., a PLTR-1-associated disorder).  
      Moreover, the anti-PLTR-1 antibodies of the invention can be used to detect and isolate PLTR-1 proteins, regulate the bioavailability of PLTR-1 proteins, and modulate PLTR-1 activity.  
      The nucleic acid molecules, proteins, protein homologues, and antibodies described herein can be used in one or more of the following methods: a) screening assays; b) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenetics); and c) methods of treatment (e.g., therapeutic and prophylactic). As described herein, a TFM-2 and/or TFM-3 polypeptide of the invention has one or more of the following activities: (1) modulate the import and export of molecules, e.g., hormones, ions, cytokines, neurotransmitters, monocarboxylates, monosaccharides, and metabolites, from cells, 2) modulate intra- or inter-cellular signaling, 3) modulate removal of potentially harmful compounds from the cell, or facilitate the compartmentalization of these molecules into a sequestered intra-cellular space (e.g., the peroxisome), and 4) modulate transport of biological molecules across membranes, e.g., the plasma membrane, or the membrane of the mitochondrion, the peroxisome, the lysosome, the endoplasmic reticulum, the nucleus, or the vacuole.  
      The isolated nucleic acid molecules of the invention can be used, for example, to express TFM-2 and/or TFM-3 polypeptides (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect TFM-2 and/or TFM-3 mRNA (e.g., in a biological sample) or a genetic alteration in a TFM-2 and/or TFM-3 gene, and to modulate TFM-2 and/or TFM-3 activity, as described further below. The TFM-2 and/or TFM-3 polypeptides can be used to treat disorders characterized by insufficient or excessive production of a TFM-2 and/or TFM-3 substrate or production of TFM-2 and/or TFM-3 inhibitors. In addition, the TFM-2 and/or TFM-3 polypeptides can be used to screen for naturally occurring TFM-2 and/or TFM-3 substrates, to screen for drugs or compounds which modulate TFM-2 and/or TFM-3 activity, as well as to treat disorders characterized by insufficient or excessive production of TFM-2 and/or TFM-3 polypeptide or production of TFM-2 and/or TFM-3 polypeptide forms which have decreased, aberrant or unwanted activity compared to TFM-2 and/or TFM-3 wild type polypeptide (e.g., transporter-associated disorders). Moreover, the anti-TFM-2 and/or anti-TFM-3 antibodies of the invention can be used to detect and isolate TFM-2 and/or TFM-3 polypeptides, to regulate the bioavailability of TFM-2 and/or TFM-3 polypeptides, and modulate TFM-2 and/or TFM-3 activity.  
      The nucleic acid molecules, proteins, protein homologues, antibodies, and modulators described herein can be used in one or more of the following methods: a) screening assays; b) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenetics); and c) methods of treatment (e.g., therapeutic and prophylactic). As described herein, a 67118 or 67067 polypeptide of the invention has one or more of the following activities: (i) interaction with a 67118 or 67067 substrate or target molecule (e.g., a phospholipid, ATP, or a non-67118 or 67067 protein); (ii) transport of a 67118 or 67067 substrate or target molecule (e.g., an aminophospholipid such as phosphatidylserine or phosphatidylethanolamine) from one side of a cellular membrane to the other; (iii) the ability to be phosphorylated or dephosphorylated; (iv) adoption of an E1 conformation or an E2 conformation; (v) conversion of a 67118 or 67067 substrate or target molecule to a product (e.g., hydrolysis of ATP); (vi) interaction with a second non-67118 or 67067 protein; (vii) modulation of substrate or target molecule location (e.g., modulation of phospholipid location within a cell and/or location with respect to a cellular membrane); (viii) maintenance of aminophospholipid gradients; (ix) modulation of intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (x) modulation of cellular proliferation, growth, differentiation, apoptosis, absorption, or secretion.  
      The isolated nucleic acid molecules of the invention can be used, for example, to express 67118 or 67067 polypeptides (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect 67118 or 67067 mRNA (e.g., in a biological sample) or a genetic alteration in a 67118 or 67067 gene, and to modulate 67118 or 67067 activity, as described further below. The 67118 or 67067 polypeptides can be used to treat disorders characterized by insufficient or excessive production of a 67118 or 67067 substrate or production or transport of 67118 or 67067 inhibitors, for example, 67118 or 67067 associated disorders.  
      As described herein, a 62092 protein of the invention has one or more of the following activities: (i) interaction with a 62092 substrate or target molecule (e.g., a nucleotide such as a purine mononucleotide or a dinucleoside polyphosphate, or a non-62092 protein); (ii) conversion of a 62092 substrate or target molecule to a product (e.g., cleavage of a nucleoside polyphosphate); (iii) interaction with a second non-62092 protein; (iv) sensation of cellular stress signals; (v) regulation of substrate or target molecule availability or activity; (vi) modulation of intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (vii) modulation of cellular proliferation, growth, differentiation, and/or apoptosis.  
      The isolated nucleic acid molecules of the invention can be used, for example, to express 62092 protein (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect 62092 mRNA (e.g., in a biological sample) or a genetic alteration in a 62092 gene, and to modulate 62092 activity, as described further below. The 62092 proteins can be used to treat disorders characterized by insufficient or excessive production of a 62092 substrate or production of 62092 inhibitors, for example, histidine triad family associated disorders.  
      As used interchangeably herein, a “phospholipid transporter associated disorder” or a “67118 or 67067 associated disorder” includes a disorder, disease or condition which is caused or characterized by a misregulation (e.g., downregulation or upregulation) of 67118 or 67067 activity. 67118 or 67067 associated disorders can detrimentally affect cellular functions such as cellular proliferation, growth, differentiation, inter- or intra-cellular communication; tissue function, such as cardiac function or musculoskeletal function; systemic responses in an organism, such as nervous system responses, hormonal responses (e.g., insulin response), or immune responses; and protection of cells from toxic compounds (e.g., carcinogens, toxins, or mutagens). Examples of 67118 or 67067 associated disorders include CNS disorders such as cognitive and neurodegenerative disorders, examples of which include, but are not limited to, Alzheimer&#39;s disease, dementias related to Alzheimer&#39;s disease (such as Pick&#39;s disease), Parkinson&#39;s and other Lewy diffuse body diseases, senile dementia, Huntington&#39;s disease, Gilles de la Tourette&#39;s syndrome, multiple sclerosis, amyotrophic lateral sclerosis, progressive supranuclear palsy, epilepsy, seizure disorders, and Jakob-Creutzfieldt disease; autonomic function disorders such as hypertension and sleep disorders, and neuropsychiatric disorders, such as depression, schizophrenia, schizoaffective disorder, korsakoff&#39;s psychosis, mania, anxiety disorders, or phobic disorders; learning or memory disorders, e.g., amnesia or age-related memory loss, attention deficit disorder, dysthymic disorder, major depressive disorder, mania, obsessive-compulsive disorder, psychoactive substance use disorders, anxiety, phobias, panic disorder, as well as bipolar affective disorder, e.g., severe bipolar affective (mood) disorder (BP-1), and bipolar affective neurological disorders, e.g., migraine and obesity. Further CNS-related disorders include, for example, those listed in the American Psychiatric Association&#39;s Diagnostic and Statistical manual of Mental Disorders (DSM), the most current version of which is incorporated herein by reference in its entirety.  
      Further examples of 67118 or 67067 associated disorders include cardiac-related disorders. Cardiovascular system disorders in which the 67118 or 67067 molecules of the invention may be directly or indirectly involved include arteriosclerosis, ischemia reperfusion injury, restenosis, arterial inflammation, vascular wall remodeling, ventricular remodeling, rapid ventricular pacing, coronary microembolism, tachycardia, bradycardia, pressure overload, aortic bending, coronary artery ligation, vascular heart disease, atrial fibrilation, Jervell syndrome, Lange-Nielsen syndrome, long-QT syndrome, congestive heart failure, sinus node dysfunction, angina, heart failure, hypertension, atrial fibrillation, atrial flutter, dilated cardiomyopathy, idiopathic cardiomyopathy, myocardial infarction, coronary artery disease, coronary artery spasm, and arrhythmia. 67118 or 67067 associated disorders also include disorders of the musculoskeletal system such as paralysis and muscle weakness, e.g., ataxia, myotonia, and myokymia.  
      67118 or 67067 associated disorders also include cellular proliferation, growth, or differentiation disorders. Cellular proliferation, growth, or differentiation disorders include those disorders that affect cell proliferation, growth, or differentiation processes. As used herein, a “cellular proliferation, growth, or differentiation process” is a process by which a cell increases in number, size or content, or by which a cell develops a specialized set of characteristics which differ from that of other cells. The 67118 or 67067 molecules of the present invention are involved in phospholipid transport mechanisms, which are known to be involved in cellular growth, proliferation, and differentiation processes. Thus, the 67118 or 67067 molecules may modulate cellular growth, proliferation, or differentiation, and may play a role in disorders characterized by aberrantly regulated growth, proliferation, or differentiation. Such disorders include cancer, e.g., carcinoma, sarcoma, or leukemia; tumor angiogenesis and metastasis; skeletal dysplasia; hepatic disorders; and hematopoietic and/or myeloproliferative disorders.  
      67118 or 67067 associated or related disorders also include hormonal disorders, such as conditions or diseases in which the production and/or regulation of hormones in an organism is aberrant. Examples of such disorders and diseases include type I and type II diabetes mellitus, pituitary disorders (e.g., growth disorders), thyroid disorders (e.g., hypothyroidism or hyperthyroidism), and reproductive or fertility disorders (e.g., disorders which affect the organs of the reproductive system, e.g., the prostate gland, the uterus, or the vagina; disorders which involve an imbalance in the levels of a reproductive hormone in a subject; disorders affecting the ability of a subject to reproduce; and disorders affecting secondary sex characteristic development, e.g., adrenal hyperplasia).  
      67118 or 67067 associated or related disorders also include immune disorders, such as autoimmune disorders or immune deficiency disorders, e.g., congenital X-linked infantile hypogammaglobulinemia, transient hypogammaglobulinemia, common variable immunodeficiency, selective IgA deficiency, chronic mucocutaneous candidiasis, or severe combined immunodeficiency.  
      67118 or 67067 associated or related disorders also include disorders affecting tissues in which 67118 or 67067 protein is expressed.  
      As used interchangeably herein, a “histidine triad family associated disorder” or a “62092-associated disorder” includes a disorder, disease or condition which is caused or characterized by a misregulation (e.g., downregulation or upregulation) of 62092 activity. 62092 associated disorders can detrimentally affect cellular functions such as cellular proliferation, growth, differentiation, inter- or intra-cellular communication; tissue function, such as cardiac function or musculoskeletal function; systemic responses in an organism, such as nervous system responses, hormonal responses (e.g., insulin response), or immune responses; and protection of cells from toxic compounds (e.g., carcinogens, toxins, or mutagens).  
      In a preferred embodiment, 62092 associated disorders include cellular proliferation, growth, differentiation, or apoptosis disorders. Cellular proliferation, growth, differentiation, or apoptosis disorders include those disorders that affect cell proliferation, growth, differentiation, or apoptosis processes. As used herein, a “cellular proliferation, growth, differentiation, or apoptosis process” is a process by which a cell increases in number, size or content, by which a cell develops a specialized set of characteristics which differ from that of other cells, or by which a cell undergoes programmed cell death. The 62092 molecules of the present invention are involved in nucleotide binding, which are known to be involved in cellular growth, proliferation, differentiation, and apoptosis processes. Thus, the 62092 molecules may modulate cellular growth, proliferation, differentiation, or apoptosis, and may play a role in disorders characterized by aberrantly regulated growth, proliferation, differentiation, or apoptosis. Such disorders include cancer, e.g., carcinoma, sarcoma, or leukemia; tumor angiogenesis and metastasis; skeletal dysplasia; hepatic disorders; and hematopoietic and/or myeloproliferative disorders.  
      62092 associated disorders also include CNS disorders.  
      Further examples of 62092 associated disorders include cardiac-related disorders, hormonal disorders, and autoimmune disorders or immune deficiency disorders, as defined herein.  
      62092 associated or related disorders also include disorders affecting tissues in which 62092 protein is expressed.  
      In addition, the 67118, 67067, and/or 62092 polypeptides can be used to screen for naturally occurring 67118, 67067, and/or 62092 substrates, to screen for drugs or compounds which modulate 67118, 67067, and/or 62092 activity, as well as to treat disorders characterized by insufficient or excessive production of 67118, 67067, and/or 62092 polypeptide or production of 67118, 67067, and/or 62092 polypeptide forms which have decreased, aberrant or unwanted activity compared to 67118, 67067, and/or 62092 wild type polypeptide (e.g., phospholipid transporter-associated disorders). Moreover, the anti-67118 and/or anti-67067 antibodies of the invention can be used to detect and isolate 67118, 67067,. and/or 62092 polypeptides, to regulate the bioavailability of 67118, 67067, and/or 62092 polypeptides, and modulate 67118, 67067, and/or 62092 activity.  
      The nucleic acid molecules, proteins, protein homologues, protein fragments, antibodies, peptides, peptidomimetics, and small molecules described herein can be used in one or more of the following methods: a) screening assays; b) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenetics); and c) methods of treatment (e.g., therapeutic and prophylactic). As described herein, a HAAT protein of the invention has one or more of the following activities: (i) interaction with a HAAT substrate or target molecule (e.g., an amino acid); (ii) transport of a HAAT substrate or target molecule (e.g., an amino acid) from one side of a cellular membrane to the other; (iii) conversion of a HAAT substrate or target molecule to a product (e.g., glucose production); (iv) interaction with a second non-HAAT protein; (v) modulation of substrate or target molecule location (e.g., modulation of amino acid location within a cell and/or location with respect to a cellular membrane); (vi) maintenance of amino acid gradients; (vii) modulation of hormone metabolism and/or nerve transmission (e.g., either directly or indirectly); (viii) modulation of cellular proliferation, growth, differentiation, and production of metabolic energy; and/or (ix) modulation of amino acid homeostasis.  
      The isolated nucleic acid molecules of the invention can be used, for example, to express HAAT protein (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect HAAT mRNA (e.g., in a biological sample) or a genetic alteration in a HAAT gene, and to modulate HAAT activity, as described further below. The HAAT proteins can be used to treat disorders characterized by insufficient or excessive production or transport of a HAAT substrate or production of HAAT inhibitors, for example, HAAT associated disorders.  
      As used interchangeably herein, a “human amino acid transporter associated disorder” or a “HAAT associated disorder” includes a disorder, disease or condition which is caused or characterized by a misregulation (e.g., downregulation or upregulation) of HAAT activity. HAAT associated disorders can detrimentally affect cellular functions such as protein synthesis, hormone metabolism, nerve transmission, cellular activation, regulation of cell growth, production of metabolic energy, synthesis of purines and pyrimidines, nitrogen metabolism, and/or biosynthesis of urea. Examples of HAAT associated disorders include: retinitis pigmentosa; tumorigenesis; nephrolithiasis; chronic lymphocytic leukemia; neurodegenerative diseases such as epilepsy, ischemia (i.e. hypoxia, stroke), amyotrophic lateral sclerosis; Hatnup disease; hyperdibasic aminoaciduria; isolated lysinuria; iminoglycinuria; familial protein intolerance; dicarboxylic aminoaciduria; cystinuria; lysinuric protein intolerance; and endotoxic shock.  
      Further examples of HAAT associated disorders include CNS disorders such as cognitive and neurodegenerative disorders, examples of which include, but are not limited to, Alzheimer&#39;s disease, dementias related to Alzheimer&#39;s disease (such as Pick&#39;s disease), Parkinson&#39;s and other Lewy diffuse body diseases, senile dementia, Huntington&#39;s disease, Gilles de la Tourette&#39;s syndrome, multiple sclerosis, amyotrophic lateral sclerosis, progressive supranuclear palsy, epilepsy, seizure disorders, and Jakob-Creutzfieldt disease; autonomic function disorders such as hypertension and sleep disorders, and neuropsychiatric disorders, such as depression, schizophrenia, schizoaffective disorder, korsakoff&#39;s psychosis, mania, anxiety disorders, or phobic disorders; learning or memory disorders, e.g., amnesia or age-related memory loss, attention deficit disorder, dysthymic disorder, major depressive disorder, mania, obsessive-compulsive disorder, psychoactive substance use disorders, anxiety, phobias, panic disorder, as well as bipolar affective disorder, e.g., severe bipolar affective (mood) disorder (BP-1), and bipolar affective neurological disorders, e.g., migraine and obesity. Further CNS-related disorders include, for example, those listed in the American Psychiatric Association&#39;s Diagnostic and Statistical manual of Mental Disorders (DSM), the most current version of which is incorporated herein by reference in its entirety.  
      As used herein, the term “metabolic disorder” includes a disorder, disease or condition which is caused or characterized by an abnormal metabolism (i.e., the chemical changes in living cells by which energy is provided for vital processes and activities) in a subject. Metabolic disorders include diseases, disorders, or conditions associated with aberrant thermogenesis or aberrant adipose cell (e.g., brown or white adipose cell) content or function. Metabolic disorders can be characterized by a misregulation (e.g., downregulation or upregulation) of HAAT activity. Metabolic disorders can detrimentally affect cellular functions such as cellular proliferation, growth, differentiation, or migration, cellular regulation of homeostasis, inter- or intra-cellular communication; tissue function, such as liver function, muscle function, or adipocyte function; systemic responses in an organism, such as hormonal responses (e.g., insulin response). Examples of metabolic disorders include obesity, diabetes, hyperphagia, endocrine abnormalities, triglyceride storage disease, Bardet-Biedl syndrome, Lawrence-Moon syndrome, Prader-Labhart-Willi syndrome, anorexia, and cachexia. Obesity is defined as a body mass index (BMI) of 30 kg/2m or more (National Institute of Health, Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults (1998)). However, the present invention is also intended to include a disease, disorder, or condition that is characterized by a body mass index (BMI) of 25 kg/ 2 m or more, 26 kg/ 2 m or more, 27 kg/ 2 m or more, 28 kg/ 2 m or more, 29 kg/ 2 m or more, 29.5 kg/ 2 m or more, or 29.9 kg/ 2 m or more, all of which are typically referred to as overweight (National Institute of Health, Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults (1998)).  
      HAAT associated disorders also include cellular proliferation, growth, or differentiation disorders. Cellular proliferation, growth, or differentiation disorders include those disorders that affect cell proliferation, growth, or differentiation processes. As used herein, a “cellular proliferation, growth, or differentiation process” is a process by which a cell increases in number, size or content, or by which a cell develops a specialized set of characteristics which differ from that of other cells. The HAAT molecules of the present invention are involved in amino acid transport mechanisms, which are known to be involved in cellular growth, proliferation, and differentiation processes. Thus, the HAAT molecules may modulate cellular growth, proliferation, or differentiation, and may play a role in disorders characterized by aberrantly regulated growth, proliferation, or differentiation. Such disorders include cancer, e.g., carcinoma, sarcoma, or leukemia; tumor angiogenesis and metastasis; skeletal dysplasia; hepatic disorders; and hematopoietic and/or myeloproliferative disorders.  
      In addition, the HAAT proteins can be used to screen for naturally occurring HAAT substrates, to screen for drugs or compounds which modulate HAAT activity, as well as to treat disorders characterized by insufficient or excessive production of HAAT protein or production of HAAT protein forms which have decreased, aberrant or unwanted activity compared to HAAT wild type protein (e.g., a HAAT-associated disorder).  
      Moreover, the anti-HAAT antibodies of the invention can be used to detect and isolate HAAT proteins, regulate the bioavailability of HAAT proteins, and modulate HAAT activity.  
      The nucleic acid molecules, proteins, protein homologues, antibodies, and modulators described herein can be used in one or more of the following methods: a) screening assays; b) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenetics); and c) methods of treatment (e.g., therapeutic and prophylactic). As described herein, an HST-4 and/or an HST-5 polypeptide of the invention has one or more of the following activities: (1) bind a monosaccharide, e.g., D-glucose, D-fructose, D-galactose, and/or mannose; (2) transport monosaccharides across a cell membrane; (3) influence insulin and/or glucagon secretion; (4) maintain sugar homeostasis in a cell; and (5) mediate trans-epithelial movement in a cell.  
      The isolated nucleic acid molecules of the invention can be used, for example, to express HST-4 and/or HST-5 polypeptides (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect HST-4 and/or HST-5 mRNA (e.g., in a biological sample) or a genetic alteration in an HST-4 and/or an HST-5 gene, and to modulate HST-4 and/or HST-5 activity, as described further below. The HST-4 and/or HST-5 polypeptides, or modulators thereof, can be used to treat disorders characterized by insufficient or excessive production of an HST-4 and/or an HST-5 substrate or production of HST-4 and/or HST-5 inhibitors. In addition, the HST-4 and/or the HST-5 polypeptides can be used to screen for naturally occurring HST-4 and/or HST-5 substrates, to screen for drugs or compounds which modulate HST-4 and/or HST-5 activity, as well as to treat disorders characterized by insufficient or excessive production of HST-4 and/or HST-5 polypeptide or production of HST-4 and/or HST-5 polypeptide forms which have decreased, aberrant or unwanted activity compared to HST-4 and/or HST-5 wild type polypeptide (e.g., sugar transporter disorders). Moreover, the anti-HST-4 and/or anti-HST-5 antibodies of the invention can be used to detect and isolate HST-4 and/or HST-5 polypeptides, to regulate the bioavailability of HST-4 and/or HST-5 polypeptides, and modulate HST-4 and/or HST-5 activity.  
      1. OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 Screening Assays:  
      The invention provides a method (also referred to herein as a “screening assay”) for identifying modulators, i.e., candidate or test compounds or agents (e.g., peptides, peptidomimetics, small molecules or other drugs) which bind to OAT proteins, PLTR-1 proteins, HAAT proteins have a stimulatory or inhibitory effect on, for example, OAT, PLTR-1, HAAT expression or OAT, PLTR-1, HAAT activity, or have a stimulatory or inhibitory effect on, for example, the transport, expression or activity of an OAT substrate or target molecule, a PLTR-1 substrate, a HAAT substrate.  
      The invention provides a method (also referred to herein as a “screening assay”) for identifying modulators, i.e., candidate or test compounds or agents (e.g., peptides, peptidomimetics, small molecules or other drugs) which bind to HST-1 polypeptides, TP-2 polypeptides, TFM-2 polypeptides, TFM-3 polypeptides, 67118, 67067, and/or 62092 polypeptides, HAAT polypeptides, HST-4 and/or HST-5 polypeptides have a stimulatory or inhibitory effect on, for example, HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression or HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity, or have a stimulatory or inhibitory effect on, for example, the expression or activity of HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, and/or 62092, HAAT, HST-4 and/or HST-5 substrate.  
      In one embodiment, the invention provides assays for screening candidate or test compounds which are substrates or target molecules of an OAT protein or polypeptide or biologically active portion thereof, an HST-1 polypeptide or biologically active portion thereof, a TP-2 polypeptide or biologically active portion thereof, a PLTR-1 protein or polypeptide or biologically active portion thereof, a TFM-2 polypeptide or biologically active portion thereof, a TFM-3 polypeptide or biologically active portion thereof, a 67118, 67067, and/or 62092 polypeptide or biologically active portion thereof, a HAAT protein or polypeptide or biologically active portion thereof, HST-4 and/or HST-5 polypeptide or biologically active portion thereof. In another embodiment, the invention provides assays for screening candidate or test compounds which bind to or modulate the activity of an OAT protein or polypeptide or biologically active portion thereof. The test compounds of the present invention can be obtained using any of the numerous approaches in combinatorial library methods known in the art, including: biological libraries; spatially addressable parallel solid phase or solution phase libraries; synthetic library methods requiring deconvolution; the ‘one-bead one-compound’ library method; and synthetic library methods using affinity chromatography selection. The biological library approach is limited to peptide libraries, while the other four approaches are applicable to peptide, non-peptide oligomer or small molecule libraries of compounds (Lam, K. S. (1997)  Anticancer Drug Des.  12:45).  
      Examples of methods for the synthesis of molecular libraries can be found in the art, for example, in: DeWitt et al. (1993)  Proc. Natl. Acad. Sci. USA  90:6909; Erb et al. (1994)  Proc. Natl. Acad. Sci. USA  91:11422; Zuckermann et al. (1994).  J. Med. Chem.  37:2678; Cho et al. (1993)  Science  261:1303; Carrell et al. (1994)  Angew. Chem. Int. Ed. Engl.  33:2059; Carell et al. (1994)  Angew. Chem. Int. Ed. Engl.  33:2061; and Gallop et al. (1994)  J. Med. Chem.  37:1233.  
      Libraries of compounds may be presented in solution (e.g., Houghten (1992)  Biotechniques  13:412-421), or on beads (Lam (1991)  Nature  354:82-84), chips (Fodor (1993)  Nature  364:555-556), bacteria (Ladner U.S. Pat. No. 5,223,409), spores (Ladner U.S. Pat. No. &#39;409), plasmids (Cull et al. (1992)  Proc. Natl. Acad. Sci. USA  89:1865-1869) or on phage (Scott and Smith (1990)  Science  249:386-390); (Devlin (1990)  Science  249:404-406); (Cwirla et al. (1990)  Proc. Natl. Acad. Sci. USA  87:6378-6382); (Felici (1991)  J. Mol. Biol.  222:301-310); (Ladner supra.).  
      In one embodiment, an assay is a cell-based assay in which a cell which expresses an OAT protein or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate OAT activity is determined. Determining the ability of the test compound to modulate OAT activity can be accomplished by monitoring, for example, transport of substrates across membranes and/or levels of gene transcription. The cell, for example, can be of a mammalian origin.  
      In one embodiment, an assay is a cell-based assay in which a cell which expresses an HST-1 polypeptide or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate HST-1 activity is determined. Determining the ability of the test compound to modulate HST-1 activity can be accomplished by monitoring, for example, intracellular or extracellular D-glucose, D-fructose or D-galactose concentration, or insulin or glucagon secretion. The cell, for example, can be of mammalian origin, e.g., a liver cell, fat cell, muscle cell, or a blood cell, such as an erythrocyte.  
      In one embodiment, an assay is a cell-based assay in which a cell which expresses a TP-2 polypeptide or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate TP-2 activity is determined. Determining the ability of the test compound to modulate TP-2 activity can be accomplished by monitoring, for example, intra- or extra-cellular D-glucose, D-fructose or D-galactose concentration, or insulin or glucagon secretion. The cell, for example, can be of mammalian origin, e.g., a liver cell, fat cell, muscle cell, or a blood cell, such as an erythrocyte.  
      In one embodiment, an assay is a cell-based assay in which a cell which expresses a PLTR-1 protein or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate PLTR-1 activity is determined. Determining the ability of the test compound to modulate PLTR-1 activity can be accomplished by monitoring, for example: (i) interaction of PLTR-1 with a PLTR-1 substrate or target molecule (e.g., a phospholipid, ATP, or a non-PLTR-1 protein); (ii) transport of a PLTR-1 substrate or target molecule (e.g., an aminophospholipid such as phosphatidylserine or phosphatidylethanolamine) from one side of a cellular membrane to the other; (iii) the ability of PLTR-1 to be phosphorylated or dephosphorylated; (iv) adoption by PLTR-1 of an E1 conformation or an E2 conformation; (v) conversion of a PLTR-1 substrate or target molecule to a product (e.g., hydrolysis of ATP); (vi) interaction of PLTR-1 with a second non-PLTR-1 protein; (vii) modulation of substrate or target molecule location (e.g., modulation of phospholipid location within a cell and/or location with respect to a cellular membrane); (viii) maintenance of aminophospholipid gradients; (ix) modulation of blood coagulation; (x) modulation of intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (xi) modulation of cellular proliferation, growth, differentiation, apoptosis, absorption, and/or secretion.  
      In one embodiment, an assay is a cell-based assay in which a cell which expresses a TFM-2 and/or TFM-3 polypeptide or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate TFM-2 and/or TFM-3 activity is determined. Determining the ability of the test compound to modulate TFM-2 and/or TFM-3 activity can be accomplished by monitoring, for example, intra- or extra-cellular lactate, pyruvate, branched chain oxoacid, ketone body, mannose, D-glucose, D-fructose or D-galactose concentration, or insulin or glucagon secretion. The cell, for example, can be of mammalian origin, e.g., a brain cell, a heart cell, a liver cell, fat cell, muscle cell, a tumor cell, or a blood cell, such as an erythrocyte.  
      In one embodiment, an assay is a cell-based assay in which a cell which expresses a 67118 and/or 67067 polypeptide or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate 67118 and/or 67067 activity is determined. Determining the ability of the test compound to modulate 67118 and/or 67067 activity can be accomplished by monitoring, for example, (i) interaction of 67118 and/or 67067 with a 67118 and/or 67067 substrate or target molecule (e.g., a phospholipid, ATP, or a non-67118 and/or 670672 protein); (ii) transport of a 67118 and/or 67067 substrate or target molecule (e.g., an aminophospholipid such as phosphatidylserine or phosphatidylethanolamine) from one side of a cellular membrane to the other; (iii) the ability of 67118 and/or 67067 to be phosphorylated or dephosphorylated; (iv) adoption by 67118 and/or 67067 of an E1 conformation or an E2 conformation; (v) conversion of a 67118 and/or 67067 substrate or target molecule to a product (e.g., hydrolysis of ATP); (vi) interaction of 67118 and/or 67067 with a second non-67118 and/or 67067 protein; (vii) modulation of substrate or target molecule location (e.g., modulation of phospholipid location within a cell and/or location with respect to a cellular membrane); (viii) maintenance of aminophospholipid gradients; (ix) modulation of intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (x) modulation of cellular proliferation, growth, differentiation, apoptosis, absorption, and/or secretion.  
      In another embodiment, an assay is a cell-based assay in which a cell which expresses a 62092 protein or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate 62092 activity is determined. Determining the ability of the test compound to modulate 62092 activity can be accomplished by monitoring, for example: (i) interaction with a 62092 substrate or target molecule (e.g., a nucleotide such as a purine mononucleotide or a dinucleoside polyphosphate, or a non-62092 protein); (ii) conversion of a 62092 substrate or target molecule to a product (e.g., cleavage of a nucleoside polyphosphate); (iii) interaction with a second non-62092 protein; (iv) sensation of cellular stress signals; (v) regulation of substrate or target molecule availability or activity; (vi) modulation of intra- or intercellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (vii) modulation of cellular proliferation, growth, differentiation, and/or apoptosis.  
      In one embodiment, an assay is a cell-based assay in which a cell which expresses a HAAT protein or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate HAAT activity is determined. Determining the ability of the test compound to modulate HAAT activity can be accomplished by monitoring, for example: (i) interaction with a HAAT substrate or target molecule (e.g., an amino acid); (ii) transport of a HAAT substrate or target molecule (e.g., an amino acid) from one side of a cellular membrane to the other; (iii) conversion of a HAAT substrate or target molecule to a product (e.g., glucose production); (iv) interaction with a second non-HAAT protein; (v) modulation of substrate or target molecule location (e.g., modulation of amino acid location within a cell and/or location with respect to a cellular membrane); (vi) maintenance of amino acid gradients; (vii) modulation of hormone metabolism and/or nerve transmission (e.g., either directly or indirectly); (viii) modulation of cellular proliferation, growth, differentiation, and production of metabolic energy; and/or (ix) modulation of amino acid homeostasis.  
      The activity of the HAAT protein in promoting the uptake of amino acids can be monitored by expression cloning the HAAT protein in an oocyte. By incubating the HAAT protein with a  14 C labeled amino acid, the transport of the labeled amino acid into the oocyte by the HAAT protein can be measured. Further, the substrate selectivity of the HAAT protein can be measured by monitoring the uptake of the  14 C labeled amino acid in the presence of other non-labeled amino acids which may inhibit the uptake of the labeled amino acid.  
      In one embodiment, an assay is a cell-based assay in which a cell which expresses an HST-4 and/or an HST-5 polypeptide or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate HST-4 and/or HST-5 activity is determined. Determining the ability of the test compound to modulate HST-4 and/or HST-5 activity can be accomplished by monitoring, for example, intracellular or extracellular D-glucose, D-fructose, D-galactose, and/or mannose concentration, or insulin or glucagon secretion. The cell, for example, can be of mammalian origin, e.g., a liver cell, fat cell, muscle cell, or a blood cell, such as an erythrocyte.  
      The ability of the test compound to modulate binding of a substrate or target molecule to OAT can also be determined. The ability of the test compound to modulate HST-1 binding to a substrate or to bind to HST-1 can also be determined. The ability of the test compound to modulate TP-2 binding to a substrate or to bind to TP-2 can also be determined. The ability of the test compound to modulate PLTR-1 binding to a substrate or to bind to PLTR-1 can also be determined. The ability of the test compound to modulate TFM-2 and/or TFM-3 binding to a substrate or to bind to TFM-2 and/or TFM-3 can also be determined. The ability of the test compound to modulate 67118, 67067, and/or 62092 binding to a substrate or to bind to 67118, 67067, and/or 62092 can also be determined. The ability of the test compound to modulate HAAT binding to a substrate or to bind to HAAT can also be determined. The ability of the test compound to modulate HST-4 and/or HST-5 binding to a substrate or to bind to HST-4 and/or HST-5 can also be determined. Determining the ability of the test compound to modulate OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 binding to a substrate or target molecule can be accomplished, for example, by coupling the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate or target molecule with a radioisotope or enzymatic label such that binding of the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate or target molecule to OAT can be determined by detecting the labeled OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate or target molecule in a complex. Alternatively, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 could be coupled with a radioisotope or enzymatic label to monitor the ability of a test compound to modulate OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 binding to an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate or target molecule in a complex. Determining the ability of the test compound to bind OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 can be accomplished, for example, by coupling the compound with a radioisotope or enzymatic label such that binding of the compound to OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 can be determined by detecting the labeled compound in a complex. For example, compounds (e.g., OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrates) can be labeled with  125 I,  35 S,  14 C, or  3 H, either directly or indirectly, and the radioisotope detected by direct counting of radioemission or by scintillation counting. Alternatively, compounds can be enzymatically labeled with, for example, horseradish peroxidase, alkaline phosphatase, or luciferase, and the enzymatic label detected by determination of an appropriate substrate to product.  
      It is also within the scope of this invention to determine the ability of a compound (e.g., an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate) to interact with OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 without the labeling of any of the interactants. For example, a microphysiometer can be used to detect the interaction of a compound with OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 without the labeling of either the compound or the OAT. McConnell, H. M. et al. (1992)  Science  257:1906-1912. As used herein, a “microphysiometer” (e.g., Cytosensor) is an analytical instrument that measures the rate at which a cell acidifies its environment using a light-addressable potentiometric sensor (LAPS). Changes in this acidification rate can be used as an indicator of the interaction between a compound and OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5.  
      In another embodiment, an assay is a cell-based assay comprising contacting a cell which expresses OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 with an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 target molecule (e.g., an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate) and a test compound and determining the ability of the test compound to modulate (e.g., stimulate or inhibit) the activity (e.g., transport) or cellular location of the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate or target molecule. Determining the ability of the test compound to modulate the activity of an OAT, HST-1, TP-2, TFM-2, TFM-3, HAAT, HST-4 and/or HST-5 substrate or target molecule can be accomplished, for example, by determining the ability of the OAT, HST-1, TP-2, TFM-2, TFM-3, HAAT, HST-4 and/or HST-5 protein to bind to or interact with the OAT, HST-1, TP-2, TFM-2, TFM-3, HAAT, HST-4 and/or HST-5 substrate or target molecule or by determining the cellular localization of the OAT, HST-1, TP-2, TFM-2, TFM-3, HAAT, HST-4 and/or HST-5 substrate or target molecule. Determining the ability of the test compound to modulate the activity of a PLTR-1 target molecule can be accomplished, for example, by determining the ability of a PLTR-1 protein to bind to or interact with the PLTR-1 target molecule, by determining the cellular location of the target molecule, or by determining whether the target molecule (e.g., ATP) has been hydrolyzed. Determining the ability of the test compound to modulate the activity of a 67118, 67067, and/or 62092 target molecule can be accomplished, for example, by determining the cellular location of the target molecule, or by determining whether the target molecule (e.g., a 67118 or 67067 target molecule such as ATP, or a 62092 target molecule) has been hydrolyzed.  
      Determining the ability of the OAT protein, or a biologically active fragment thereof, to bind to or interact with or transport an OAT substrate or target molecule can be accomplished by one of the methods described above for determining direct binding. In a preferred embodiment, determining the ability of the OAT protein to bind to or interact with an OAT substrate or target molecule can be accomplished by determining the activity or cellular localization of the substrate or target molecule. For example, the activity of the substrate or target molecule can be determined by detecting induction of a cellular response (e.g., changes in intracellular substrate concentration), detecting a secondary or indirect activity of the substrate or target molecule, detecting the induction of a reporter gene (comprising a target-responsive regulatory element operatively linked to a nucleic acid encoding a detectable marker, e.g., luciferase), or detecting a target-regulated cellular response (i.e., a hormonal response). In other embodiments, the assays described above are carried out in a cell-free context (e.g., in an artificial membrane, vesicle, or micelle preparation).  
      Determining the ability of the HST-1 polypeptide, or a biologically active fragment thereof, to bind to or interact with an HST-1 target molecule can be accomplished by one of the methods described above for determining direct binding. In a preferred embodiment, determining the ability of the HST-1 polypeptide to bind to or interact with an HST-1 target molecule can be accomplished by determining the activity of the target molecule. For example, the activity of the target molecule can be determined by detecting induction of a cellular second messenger of the target (i.e., intracellular Ca 2+ , diacylglycerol, IP 3 , and the like), detecting catalytic/enzymatic activity of the target using an appropriate substrate, detecting the induction of a reporter gene (comprising a target-responsive regulatory element operatively linked to a nucleic acid encoding a detectable marker, e.g., luciferase), or detecting a target-regulated cellular response.  
      Determining the ability of the TP-2 polypeptide, or a biologically active fragment thereof, to bind to or interact with a TP-2 target molecule can be accomplished by one of the methods described above for determining direct binding. In a preferred embodiment, determining the ability of the TP-2 polypeptide to bind to or interact with a TP-2 target molecule can be accomplished by determining the activity of the target molecule. For example, the activity of the target molecule can be determined by detecting induction of a cellular second messenger of the target (i.e., intra-cellular Ca 2+ , diacylglycerol, IP 3 , and the like), detecting catalytic/enzymatic activity of the target using an appropriate substrate, detecting the induction of a reporter gene (comprising a target-responsive regulatory element operatively linked to a nucleic acid encoding a detectable marker, e.g., luciferase), or detecting a target-regulated cellular response.  
      Determining the ability of the PLTR-1 protein, or a biologically active fragment thereof, to bind to or interact with a PLTR-1 target molecule can be accomplished by one of the methods described above for determining direct binding. In a preferred embodiment, determining the ability of the PLTR-1 protein to bind to or interact with a PLTR-1 target molecule can be accomplished by determining the activity of the target molecule. For example, the activity of the target molecule can be determined by detecting the cellular location of target molecule, detecting catalytic/enzymatic activity of the target molecule upon an appropriate substrate, detecting induction of a metabolite of the target molecule (e.g., detecting the products of ATP hydrolysis) detecting the induction of a reporter gene (comprising a target-responsive regulatory element operatively linked to a nucleic acid encoding a detectable marker, e.g., luciferase), or detecting a target-regulated cellular response (i.e., cell growth or differentiation).  
      Determining the ability of the TFM-2 and/or TFM-3 polypeptide, or a biologically active fragment thereof, to bind to or interact with a TFM-2 and/or TFM-3 target molecule can be accomplished by one of the methods described above for determining direct binding. In a preferred embodiment, determining the ability of the TFM-2 and/or TFM-3 polypeptide to bind to or interact with a TFM-2 and/or TFM-3 target molecule can be accomplished by determining the activity of the target molecule. For example, the activity of the target molecule can be determined by detecting induction of a cellular second messenger of the target (i.e., intra-cellular Ca 2+ , diacylglycerol, IP 3 , and the like), detecting catalytic/enzymatic activity of the target using an appropriate substrate, detecting the induction of a reporter gene (comprising a target-responsive regulatory element operatively linked to a nucleic acid encoding a detectable marker, e.g., luciferase), or detecting a target-regulated cellular response.  
      Determining the ability of the 67118, 67067, and/or 62092 polypeptide, or a biologically active fragment thereof, to bind to or interact with a 67118, 67067, and/or 62092 target molecule can be accomplished by one of the methods described above for determining direct binding. In a preferred embodiment, determining the ability of the 67118, 67067, and/or 62092 polypeptide to bind to or interact with a 67118, 67067, and/or 62092 target molecule can be accomplished by determining the activity of the target molecule. For example, the activity of the target molecule can be determined by detecting the cellular location of target molecule, detecting catalytic/enzymatic activity of the target molecule upon an appropriate substrate, detecting induction of a metabolite of the target molecule (e.g., detecting the products of ATP hydrolysis) detecting the induction of a reporter gene (comprising a target-responsive regulatory element operatively linked to a nucleic acid encoding a detectable marker, e.g., luciferase), or detecting a target-regulated cellular response (i.e., cell growth or differentiation).  
      Determining the ability of the HST-4 and/or the HST-5 polypeptide, or a biologically active fragment thereof, to bind to or interact with an HST-4 and/or an HST-5 target molecule can be accomplished by one of the methods described above for determining direct binding. In a preferred embodiment, determining the ability of the HST-4 and/or the HST-5 polypeptide to bind to or interact with an HST-4 and/or an HST-5 target molecule can be accomplished by determining the activity of the target molecule. For example, the activity of the target molecule can be determined by detecting induction of a cellular second messenger of the target, detecting catalytic/enzymatic activity of the target using an appropriate substrate, detecting the induction of a reporter gene (comprising a target-responsive regulatory element operatively linked to a nucleic acid encoding a detectable marker, e.g., luciferase), or detecting a target-regulated cellular response.  
      In yet another embodiment, an assay of the present invention is a cell-free assay in which an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein or biologically active portion (e.g., a portion which possesses the ability to transport or interact with a substrate or target molecule) thereof is contacted with a test compound and the ability of the test compound to bind to the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein or biologically active portion thereof is determined. Preferred biologically active portions of the OAT proteins to be used in assays of the present invention include fragments which participate in interactions with non-OAT molecules, e.g., fragments with high surface probability scores (see, for example,  FIGS. 4 and 5 ). Preferred biologically active portions of the HST-1 polypeptides to be used in assays of the present invention include fragments which participate in interactions with non-HST-1 molecules, e.g., fragments with high surface probability scores (see, for example,  FIG. 7 ). Preferred biologically active portions of the TP-2 polypeptides to be used in assays of the present invention include fragments which participate in interactions with non-TP-2 molecules, e.g., fragments with high surface probability scores (see, for example,  FIG. 11 ). Preferred biologically active portions of the PLTR-1 proteins to be used in assays of the present invention include fragments which participate in interactions with non-PLTR-1 molecules, e.g., fragments with high surface probability scores (see, for example,  FIG. 15 ). Preferred biologically active portions of the TFM-2 and/or TFM-3 polypeptides to be used in assays of the present invention include fragments which participate in interactions with non-TFM-2 and/or non-TFM-3 molecules, e.g., fragments with high surface probability scores (see, for example,  FIGS. 16 and 18 ). Preferred biologically active portions of the 67118, 67067, and/or 62092 polypeptides to be used in assays of the present invention include fragments which participate in interactions with non-67118, non-67067, and/or non-62092 molecules, e.g., fragments with high surface probability scores (see, for example,  FIGS. 20, 22 , and  24 ). Preferred biologically active portions of the HAAT proteins to be used in assays of the present invention include fragments which participate in interactions with non-HAAT molecules. Preferred biologically active portions of the HST-4 and/or the HST-5 polypeptides to be used in assays of the present invention include fragments which participate in interactions with non-HST-4 and/or non-HST-5 molecules, e.g., fragments with high surface probability scores (see, for example,  FIGS. 29 and 30 ). Binding of the test compound to the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein can be determined either directly or indirectly as described above. In a preferred embodiment, the assay includes contacting the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein or biologically active portion thereof with a known compound which binds OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 to form an assay mixture, contacting the assay mixture with a test compound, and determining the ability of the test compound to interact with an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein, wherein determining the ability of the test compound to interact with an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein comprises determining the ability of the test compound to preferentially bind to OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 or biologically active portion thereof as compared to the known compound.  
      In another embodiment, the assay is a cell-free assay in which a TFM-2 and/or TFM-3 polypeptide, or biologically active portion thereof, is contacted with a test compound and the ability of the test compound to modulate the intrinsic fluorescence of the TFM-2 and/or TFM-3 polypeptide, or biologically active portion thereof, is monitored. It is common for a molecule&#39;s intrinsic fluorescence to change when binding occurs with or near fluorescent aminoacids (e.g., tryptophan and tyrosine).  
      In another embodiment, the assay is a cell-free assay in which an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate (e.g., stimulate or inhibit) the activity of the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein or biologically active portion thereof is determined. Determining the ability of the test compound to modulate the activity of an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein can be accomplished, for example, by determining the ability of the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein to bind to an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate or target molecule by one of the methods described above for determining direct binding. Determining the ability of the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein to bind to an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate or target molecule can also be accomplished using a technology such as real-time Biomolecular Interaction Analysis (BIA). Sjolander, S. and Urbaniczky, C. (1991)  Anal. Chem.  63:2338-2345 and Szabo et al. (1995)  Curr. Opin. Struct. Biol.  5:699-705. As used herein, “BIA” is a technology for studying biospecific interactions in real time, without labeling any of the interactants (e.g., BIAcore). Changes in the optical phenomenon of surface plasmon resonance (SPR) can be used as an indication of real-time reactions between biological molecules.  
      In an alternative embodiment, determining the ability of the test compound to modulate the activity of an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein can be accomplished by determining the ability of the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein to further modulate the activity of a downstream effector of an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 target molecule. For example, the activity of the effector molecule on an appropriate target can be determined or the binding of the effector to an appropriate target can be determined as previously described.  
      In yet another embodiment, the cell-free assay involves contacting an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein or biologically active portion thereof with a known compound which binds to or is transported by the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein to form an assay mixture, contacting the assay mixture with a test compound, and determining the ability of the test compound to interact with the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein, wherein determining the ability of the test compound to interact with the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein comprises determining the ability of the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein to preferentially bind to, transport, or modulate the activity of an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate or target molecule.  
      The cell-free assays of the present invention are amenable to use of both soluble and/or membrane-bound forms of isolated proteins (e.g., OAT, PLTR-1, 67118, 67067, and/or 62092 or HAAT proteins or biologically active portions thereof). In the case of cell-free assays in which a membrane-bound form of an isolated protein is used it may be desirable to utilize a solubilizing agent such that the membrane-bound form of the isolated protein is maintained in solution. Examples of such solubilizing agents include non-ionic detergents such as n-octylglucoside, n-dodecylglucoside, n-dodecylmaltoside, octanoyl-N-methylglucamide, decanoyl-N-methylglucamide, Triton® X-100, Triton® X-114, Thesit®, Isotridecypoly(ethylene glycol ether) n , 3-[(3-cholamidopropyl)dimethylamminio]-1-propane sulfonate (CHAPS), 3-[(3-cholamidopropyl)dimethylamminio]-2-hydroxy-1-propane sulfonate (CHAPSO), or N-dodecyl=N,N-dimethyl-3-ammonio-1-propane sulfonate.  
      In more than one embodiment of the above assay methods of the present invention, it may be desirable to immobilize either OAT or its substrate or target molecule to facilitate separation of complexed from uncomplexed forms of one or both of the proteins, as well as to accommodate automation of the assay. Binding of a test compound to an OAT protein, or interaction of an OAT protein with a substrate or target molecule in the presence and absence of a candidate compound, can be accomplished in any vessel suitable for containing the reactants. Examples of such vessels include microtiter plates, test tubes, and micro-centrifuge tubes. In one embodiment, a fusion protein can be provided which adds a domain that allows one or both of the proteins to be bound to a matrix. For example, glutathione-S-transferase/OAT fusion proteins or glutathione-S-transferase/target fusion proteins can be adsorbed onto glutathione sepharose beads (Sigma Chemical, St. Louis, Mo.) or glutathione derivatized micrometer plates, which are then combined with the test compound or the test compound and either the non-adsorbed target protein or OAT protein, and the mixture incubated under conditions conducive to complex formation (e.g., at physiological conditions for salt and pH). Following incubation, the beads or microtiter plate wells are washed to remove any unbound components, the matrix immobilized in the case of beads, complex determined either directly or indirectly, for example, as described above. Alternatively, the complexes can be dissociated from the matrix, and the level of OAT binding or activity determined using standard techniques.  
      In more than one embodiment of the above assay methods of the present invention, it may be desirable to immobilize either HST-1 or its target molecule, either TP-2 or its target molecule, either PLTR-1 or its target molecule, either TFM-2 or its target molecule, either TFM-3 or its target molecule, either 67118, 67067, and/or 62092 or their target molecules, HAAT or its target molecule, HST-4 or its target molecule, and/or HST-5 or its target molecule, to facilitate separation of complexed from uncomplexed forms of one or both of the proteins, as well as to accommodate automation of the assay. Binding of a test compound to a HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide, or interaction of a HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide with a target molecule in the presence and absence of a candidate compound, can be accomplished in any vessel suitable for containing the reactants. Examples of such vessels include microtiter plates, test tubes, and micro-centrifuge tubes. In one embodiment, a fusion protein can be provided which adds a domain that allows one or both of the proteins to be bound to a matrix. For example, glutathione-S-transferase/HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 fusion proteins or glutathione-S-transferase/target fusion proteins can be adsorbed onto glutathione sepharose beads (Sigma Chemical, St. Louis, Mo.) or glutathione derivatized micrometer plates, which are then combined with the test compound or the test compound and either the non-adsorbed target protein or HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide, and the mixture incubated under conditions conducive to complex formation (e.g., at physiological conditions for salt and pH). Following incubation, the beads or micrometer plate wells are washed to remove any unbound components, the matrix immobilized in the case of beads, complex determined either directly or indirectly, for example, as described above. Alternatively, the complexes can be dissociated from the matrix, and the level of HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 binding or activity determined using standard techniques.  
      Other techniques for immobilizing proteins on matrices can also be used in the screening assays of the invention. For example, either an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein or an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 substrate or target molecule can be immobilized utilizing conjugation of biotin and streptavidin. Biotinylated OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein, substrates or target molecules can be prepared from biotin-NHS (N-hydroxy-succinimide) using techniques known in the art (e.g., biotinylation kit, Pierce Chemicals, Rockford, Ill.), and immobilized in the wells of streptavidin-coated 96 well plates (Pierce Chemical). Alternatively, antibodies reactive with OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein, substrates or target molecules but which do not interfere with binding of the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein to its substrate, or target molecule can be derivatized to the wells of the plate, and unbound target or OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein trapped in the wells by antibody conjugation. Methods for detecting such complexes, in addition to those described above for the GST-immobilized complexes, include immunodetection of complexes using antibodies reactive with the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein or target molecule, as well as enzyme-linked assays which rely on detecting an enzymatic activity associated with the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein or target molecule.  
      In another embodiment, modulators of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression are identified in a method wherein a cell is contacted with a candidate compound and the expression of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or protein in the cell is determined. The level of expression of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or protein in the presence of the candidate compound is compared to the level of expression of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or protein in the absence of the candidate compound. The candidate compound can then be identified as a modulator of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression based on this comparison. For example, when expression of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or protein is greater (statistically significantly greater) in the presence of the candidate compound than in its absence, the candidate compound is identified as a stimulator of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or protein expression. Alternatively, when expression of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or protein is less (statistically significantly less) in the presence of the candidate compound than in its absence, the candidate compound is identified as an inhibitor of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or protein expression. The level of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or protein expression in the cells can be determined by methods described herein for detecting OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or protein.  
      In yet another aspect of the invention, the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 proteins can be used as “bait proteins” in a two-hybrid assay or three-hybrid assay (see, e.g., U.S. Pat. No. 5,283,317; Zervos et al. (1993)  Cell  72:223-232; Madura et al. (1993)  J. Biol. Chem.  268:12046-12054; Bartel et al. (1993)  Biotechniques  14:920-924; Iwabuchi et al. (1993)  Oncogene  8:1693-1696; and Brent WO94/10300), to identify other proteins, which bind to or interact with OAT (“OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-binding proteins” or “OAT-bp”, “HST-1-bp”, “TP-2-bp”, “PLTR-1-bp”, “TFM-2-bp”, “TFM-3-bp”, “67118-bp”, “67067-bp”, “62092-bp”, “HAAT-bp”, “HST-4-bp” and/or “HST-5-bp”) and are involved in OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity. Such OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-binding proteins are also likely to be involved in the propagation of signals by the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 proteins or OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 targets as, for example, downstream elements of an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-mediated signaling pathway. Alternatively, such OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-binding proteins may be OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 inhibitors.  
      The two-hybrid system is based on the modular nature of most transcription factors, which consist of separable DNA-binding and activation domains. Briefly, the assay utilizes two different DNA constructs. In one construct, the gene that codes for an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein is fused to a gene encoding the DNA binding domain of a known transcription factor (e.g., GAL-4). In the other construct, a DNA sequence, from a library of DNA sequences, that encodes an unidentified protein (“prey” or “sample”) is fused to a gene that codes for the activation domain of the known transcription factor. If the “bait” and the “prey” proteins are able to interact, in vivo, forming an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-dependent complex, the DNA-binding and activation domains of the transcription factor are brought into close proximity. This proximity allows transcription of a reporter gene (e.g., LacZ) which is operably linked to a transcriptional regulatory site responsive to the transcription factor. Expression of the reporter gene can be detected and cell colonies containing the functional transcription factor can be isolated and used to obtain the cloned gene which encodes the protein which interacts with the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 protein.  
      In another aspect, the invention pertains to a combination of two or more of the assays described herein. For example, a modulating agent can be identified using a cell-based or a cell free assay, and the ability of the agent to modulate the activity of an OAT protein can be confirmed in vivo, e.g., in an animal such as an animal model for organic anion sensitivity or an animal model with dysregulated organic anion transport.  
      In another aspect, the invention pertains to a combination of two or more of the assays described herein. For example, a modulating agent can be identified using a cell-based or a cell free assay, and the ability of the agent to modulate the activity of an HST-1 polypeptide can be confirmed in vivo, e.g., in an animal such as an animal model for obesity, or diabetes. Examples of animals that can be used include the transgenic mouse described in U.S. Pat. No. 5,932,779 that contains a mutation in an endogenous melanocortin-4-receptor (MC4-R) gene; animals having mutations which lead to syndromes that include obesity symptoms (described in, for example, Friedman, J. M. et al. (1991)  Mamm. Gen.  1:130-144; Friedman, J. M. and Liebel, R. L. (1992)  Cell  69:217-220; Bray, G. A. (1992)  Prog. Brain Res.  93:333-341; and Bray, G. A. (1989)  Amer. J. Clin. Nutr.  5:891-902); the animals described in Stubdal H. et al. (2000)  Mol. Cell Biol.  20(3):878-82 (the mouse tubby phenotype characterized by maturity-onset obesity); the animals described in Abadie J. M. et al.  Lipids  (2000) 35(6):613-20 (the obese Zucker rat (ZR), a genetic model of human youth-onset obesity and type 2 diabetes mellitus); the animals described in Shaughnessy S. et al. (2000)  Diabetes  49(6):904-11 (mice null for the adipocyte fatty acid binding protein); or the animals described in Loskutoff D. J. et al. (2000)  Ann. N. Y Acad. Sci.  902:272-81 (the fat mouse). Other examples of animals that may be used include non-recombinant, non-genetic animal models of obesity such as, for example, rabbit, mouse, or rat models in which the animal has been exposed to either prolonged cold or long-term over-eating, thereby, inducing hypertrophy of BAT and increasing BAT thermogenesis (Himms-Hagen, J. (1990), supra). Additionally, animals created by ablation of BAT through use of targeted expression of a toxin gene (Lowell, B. et al. (1993)  Nature  366:740-742) may be used.  
      In another aspect, the invention pertains to a combination of two or more of the assays described herein. For example, a modulating agent can be identified using a cell-based or a cell free assay, and the ability of the agent to modulate the activity of a TP-2 polypeptide can be confirmed in vivo, e.g., in an animal such as an animal model for cellular transformation and/or tumorigenesis.  
      In another aspect, the invention pertains to a combination of two or more of the assays described herein. For example, a modulating agent can be identified using a cell-based or a cell-free assay, and the ability of the agent to modulate the activity of a PLTR-1 protein can be confirmed in vivo, e.g., in an animal such as an animal model for cellular transformation and/or tumorigenesis.  
      In another aspect, the invention pertains to a combination of two or more of the assays described herein. For example, a modulating agent can be identified using a cell-based or a cell free assay, and the ability of the agent to modulate the activity of a TFM-2 and/or TFM-3 polypeptide can be confirmed in vivo, e.g., in an animal such as an animal model for cellular transformation and/or tumorigenesis, an animal model for obesity, or an animal model for a deficiency in sugar transport. Examples of animals that can be used include animals having mutations which lead to syndromes that include obesity symptoms (described in, for example, Friedman, J. M. et al. (1991)  Mamm. Gen.  1:130-144; Friedman, J. M. and Liebel, R. L. (1992)  Cell  69:217-220; Bray, G. A. (1992)  Prog. Brain Res.  93:333-341; and Bray, G. A. (1989)  Amer. J. Clin. Nutr.  5:891-902); the animals described in Stubdal H. et al. (2000)  Mol. Cell Biol.  20(3):878-82 (the mouse tubby phenotype characterized by maturity-onset obesity); the animals described in Abadie J. M. et al.  Lipids  (2000) 35(6):613-20 (the obese Zucker rat (ZR), a genetic model of human youth-onset obesity and type 2 diabetes mellitus); the animals described in Shaughnessy S. et al. (2000)  Diabetes  49(6):904-11 (mice null for the adipocyte fatty acid binding protein); or the animals described in Loskutoff D. J. et al. (2000)  Ann. N. Y. Acad. Sci.  902:272-81 (the fat mouse).  
      In another aspect, the invention pertains to a combination of two or more of the assays described herein. For example, a modulating agent can be identified using a cell-based or a cell free assay, and the ability of the agent to modulate the activity of a 67118, 67067, and/or 62092 polypeptide can be confirmed in vivo, e.g., in an animal such as an animal model for cellular transformation and/or tumorigenesis, such as animal models for colon cancer or lung cancer. Animal based models for studying tumorigenesis in vivo are well known in the art (reviewed in Animal Models of Cancer Predisposition Syndromes, Hiai, H and Hino, O (eds.) 1999,  Progress in Experimental Tumor Research,  Vol. 35; Clarke A R  Carcinogenesis  (2000) 21:435-41) and include, for example, carcinogen-induced tumors (Rithidech, K et al.  Mutat. Res. ( 1999) 428:33-39; Miller, M. L. et al.  Environ Mol Mutagen ( 2000) 35:319-327), injection and/or transplantation of tumor cells into an animal, as well as animals bearing mutations in growth regulatory genes, for example, oncogenes (e.g., ras) (Arbeit, J M et al.  Am J Pathol  (1993) 142:1187-1197; Sinn, E et al.  Cell  (1987) 49:465-475; Thorgeirsson, S S et al.  Toxicol Lett  (2000) 112-113:553-555) and tumor suppressor genes (e.g., p 53) (Vooijs, M et al.  Oncogene  (1999) 18:5293-5303; Clark A R  Cancer Metast Rev  (1995) 14:125-148; Kumar, T R et al.  J Intern Med  (1995) 238:233-238; Donehower, L A et al. (1992) Nature 356215-221). Furthermore, experimental model systems are available for the study of, for example, ovarian cancer (Hamilton, T C et al.  Semin Oncol  (1984) 11:285-298; Rahman, N A et al.  Mol Cell Endocrinol  (1998) 145:167-174; Beamer, W G et al.  Toxicol Pathol  (1998) 26:704-710), gastric cancer (Thompson, J et al. (2000)  Int. J. Cancer  86:863-869; Fodde, R et al.  Cytogenet Cell Genet  (1999) 86:105-111), breast cancer (Li, M et al.  Oncogene  (2000) 19:1010-1019; Green, J E et al.  Oncogene  (2000) 19:1020-1027), melanoma (Satyamoorthy, K et al.  Cancer Metast Rev  (1999) 18:401-405), and prostate cancer (Shirai, T et al.  Mutat. Res.  (2000) 462:219-226; Bostwick, D G et al.  Prostate  (2000) 43:286-294).  
      In yet another aspect of the invention, the HAAT proteins can be used as “bait proteins” in a two-hybrid assay or three-hybrid assay (see, e.g., U.S. Pat. No. 5,283,317; Zervos et al. (1993)  Cell  72:223-232; Madura et al. (1993)  J. Biol. Chem.  268:12046-12054; Bartel et al. (1993)  Biotechniques  14:920-924; Iwabuchi et al. (1993)  Oncogene  8:1693-1696; and Brent WO94/10300) to identify other proteins which bind to or interact with HAAT (“HAAT-binding proteins” or “HAAT-bp”) and are involved in HAAT activity.  
      In another aspect, the invention pertains to a combination of two or more of the assays described herein. For example, a modulating agent can be identified using a cell-based or a cell free assay, and the ability of the agent to modulate the activity of an HST-4 and/or an HST-5 polypeptide can be confirmed in vivo, e.g., in animal models for obesity, anorexia, type-1 diabetes, type-2 diabetes, hypoglycemia, glycogen storage disease (Von Gierke disease), type I glycogenosis, bipolar disorder, seasonal affective disorder, cluster B personality disorders, cellular transformation, and/or tumorigenesis. Examples of animal models which may be used include animals having mutations which lead to syndromes that include obesity symptoms (described in, for example, Friedman, J. M. et al. (1991)  Mamm. Gen.  1:130-144; Friedman, J. M. and Liebel, R. L. (1992) Cell 69:217-220; Bray, G. A. (1992)  Prog. Brain Res.  93:333-341; and Bray, G. A. (1989)  Amer. J. Clin. Nutr.  5:891-902); the animals described in Stubdal H. et al. (2000)  Mol. Cell Biol.  20(3):878-82 (the mouse tubby phenotype characterized by maturity-onset obesity); the animals described in Abadie J. M. et al.  Lipids  (2000) 35(6):613-20 (the obese Zucker rat (ZR), a genetic model of human youth-onset obesity and type 2 diabetes mellitus); the animals described in Shaughnessy S. et al. (2000)  Diabetes  49(6):904-11 (mice null for the adipocyte fatty acid binding protein); or the animals described in Loskutoff D. J. et al. (2000)  Ann. N. Y. Acad. Sci.  902:272-81 (the fat mouse).  
      This invention further pertains to novel agents identified by the above-described screening assays. Accordingly, it is within the scope of this invention to further use an agent identified as described herein in an appropriate animal model. For example, an agent identified as described herein (e.g., an OAT substrate, an OAT target molecule, an OAT modulating agent, an antisense OAT nucleic acid molecule, an OAT-specific antibody, or an OAT binding partner, an HST-1 modulating agent, an antisense HST-1 nucleic acid molecule, an HST-1-specific antibody, or an HST-1-binding partner, a TP-2 modulating agent, an antisense TP-2 nucleic acid molecule, a TP-2-specific antibody, or a TP-2-binding partner, a PLTR-1 modulating agent, an antisense PLTR-1 nucleic acid molecule, a PLTR-1-specific antibody, or a PLTR-1 binding partner, a TFM-2 and/or TFM-3 modulating agent, an anti sense TFM-2 and/or TFM-3 nucleic acid molecule, a TFM-2 and/or TFM-3-specific antibody, or a TFM-2 and/or TFM-3-binding partner, a 67118, 67067, and/or 62092 modulating agent, an antisense 67118, 67067, and/or 62092 nucleic acid molecule, a 67118, 67067, and/or 62092-specific antibody, or a 67118, 67067, and/or 62092-binding partner, a HAAT modulating agent, an antisense HAAT nucleic acid molecule, a HAAT-specific antibody, or a HAAT binding partner, an HST-4 and/or an HST-5 modulating agent, an antisense HST-4 and/or HST-5 nucleic acid molecules, an HST-4- and/or an HST-5-specific antibody, or an HST-4- and/or an HST-5-binding partner) can be used in an animal model to determine the efficacy, toxicity, or side effects of treatment with such an agent. Alternatively, an agent identified as described herein can be used in an animal model to determine the mechanism of action of such an agent. Furthermore, this invention pertains to uses of novel agents identified by the above-described screening assays for treatments as described herein.  
      C. Detection Assays  
      Portions or fragments of the cDNA sequences identified herein (and the corresponding complete gene sequences) can be used in numerous ways as polynucleotide reagents. For example, these sequences can be used to: (i) map their respective genes on a chromosome; and, thus, locate gene regions associated with genetic disease; (ii) identify an individual from a minute biological sample (tissue typing); and (iii) aid in forensic identification of a biological sample. These applications are described in the subsections below.  
      1. Chromosome Mapping  
      Once the sequence (or a portion of the sequence) of a gene has been isolated, this sequence can be used to map the location of the gene on a chromosome. This process is called chromosome mapping. Accordingly, portions or fragments of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 nucleotide sequences, described herein, can be used to map the location of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 genes on a chromosome. The mapping of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 sequences to chromosomes is an important first step in correlating these sequences with genes associated with disease.  
      Briefly, MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 genes can be mapped to chromosomes by preparing PCR primers (preferably 15-25 bp in length) from the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 nucleotide sequences. Computer analysis of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 sequences can be used to predict primers that do not span more than one exon in the genomic DNA, thus complicating the amplification process. These primers can then be used for PCR screening of somatic cell hybrids containing individual human chromosomes. Only those hybrids containing the human gene corresponding to the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 sequences will yield an amplified fragment.  
      Somatic cell hybrids are prepared by fusing somatic cells from different mammals (e.g., human and mouse cells). As hybrids of human and mouse cells grow and divide, they gradually lose human chromosomes in random order, but retain the mouse chromosomes. By using media in which mouse cells cannot grow, because they lack a particular enzyme, but human cells can, the one human chromosome that contains the gene encoding the needed enzyme, will be retained. By using various media, panels of hybrid cell lines can be established. Each cell line in a panel contains either a single human chromosome or a small number of human chromosomes, and a full set of mouse chromosomes, allowing easy mapping of individual genes to specific human chromosomes. (D&#39;Eustachio P. et al. (1983)  Science  220:919-924). Somatic cell hybrids containing only fragments of human chromosomes can also be produced by using human chromosomes with translocations and deletions.  
      PCR mapping of somatic cell hybrids is a rapid procedure for assigning a particular sequence to a particular chromosome. Three or more sequences can be assigned per day using a single thermal cycler. Using the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 nucleotide sequences to design oligonucleotide primers, sublocalization can be achieved with panels of fragments from specific chromosomes. Other mapping strategies which can similarly be used to map an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 sequence to its chromosome include in situ hybridization (described in Fan, Y. et al. (1990)  Proc. Natl. Acad. Sci. USA,  87:6223-27), pre-screening with labeled flow-sorted chromosomes, and pre-selection by hybridization to chromosome specific cDNA libraries.  
      Fluorescence in situ hybridization (FISH) of a DNA sequence to a metaphase chromosomal spread can further be used to provide a precise chromosomal location in one step. Chromosome spreads can be made using cells whose division has been blocked in metaphase by a chemical such as colcemid that disrupts the mitotic spindle. The chromosomes can be treated briefly with trypsin, and then stained with Giemsa. A pattern of light and dark bands develops on each chromosome, so that the chromosomes can be identified individually. The FISH technique can be used with a DNA sequence as short as 500 or 600 bases. However, clones larger than 1,000 bases have a higher likelihood of binding to a unique chromosomal location with sufficient signal intensity for simple detection. Preferably 1,000 bases, and more preferably 2,000 bases will suffice to get good results at a reasonable amount of time. For a review of this technique, see Verma et al., Human Chromosomes: A Manual of Basic Techniques (Pergamon Press, New York 1988).  
      Reagents for chromosome mapping can be used individually to mark a single chromosome or a single site on that chromosome, or panels of reagents can be used for marking multiple sites and/or multiple chromosomes. Reagents corresponding to noncoding regions of the genes actually are preferred for mapping purposes. Coding sequences are more likely to be conserved within gene families, thus increasing the chance of cross hybridizations during chromosomal mapping.  
      Once a sequence has been mapped to a precise chromosomal location, the physical position of the sequence on the chromosome can be correlated with genetic map data. (Such data are found, for example, in V. McKusick, Mendelian Inheritance in Man, available on-line through Johns Hopkins University Welch Medical Library). The relationship between a gene and a disease, mapped to the same chromosomal region, can then be identified through linkage analysis (co-inheritance of physically adjacent genes), described in, for example, Egeland, J. et al. (1987)  Nature,  325:783-787.  
      Moreover, differences in the DNA sequences between individuals affected and unaffected with a disease associated with the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 gene, can be determined. If a mutation is observed in some or all of the affected individuals but not in any unaffected individuals, then the mutation is likely to be the causative agent of the particular disease. Comparison of affected and unaffected individuals generally involves first looking for structural alterations in the chromosomes, such as deletions or translocations that are visible from chromosome spreads or detectable using PCR based on that DNA sequence. Ultimately, complete sequencing of genes from several individuals can be performed to confirm the presence of a mutation and to distinguish mutations from polymorphisms.  
      2. Tissue Typing  
      The MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 sequences of the present invention can also be used to identify individuals from minute biological samples. The United States military, for example, is considering the use of restriction fragment length polymorphism (RFLP) for identification of its personnel. In this technique, an individual&#39;s genomic DNA is digested with one or more restriction enzymes, and probed on a Southern blot to yield unique bands for identification. This method does not suffer from the current limitations of “Dog Tags” which can be lost, switched, or stolen, making positive identification difficult. The sequences of the present invention are useful as additional DNA markers for RFLP (described in U.S. Pat. No. 5,272,057).  
      Furthermore, the sequences of the present invention can be used to provide an alternative technique which determines the actual base-by-base DNA sequence of selected portions of an individual&#39;s genome. Thus, the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 nucleotide sequences described herein can be used to prepare two PCR primers from the 5′ and 3′ ends of the sequences. These primers can then be used to amplify an individual&#39;s DNA and subsequently sequence it.  
      Panels of corresponding DNA sequences from individuals, prepared in this manner, can provide unique individual identifications, as each individual will have a unique set of such DNA sequences due to allelic differences. The sequences of the present invention can be used to obtain such identification sequences from individuals and from tissue. The MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 nucleotide sequences of the invention uniquely represent portions of the human genome. Allelic variation occurs to some degree in the coding regions of these sequences, and to a greater degree in the noncoding regions. It is estimated that allelic variation between individual humans occurs with a frequency of about once per each 500 bases. Each of the sequences described herein can, to some degree, be used as a standard against which DNA from an individual can be compared for identification purposes. Because greater numbers of polymorphisms occur in the noncoding regions, fewer sequences are necessary to differentiate individuals. The noncoding sequences of SEQ ID NO:1, 4, 7, 12, 15, 19, 27, 30, 33, 36, 39, 51, 54 or 57 can comfortably provide positive individual identification with a panel of perhaps 10 to 1,000 primers which each yield a noncoding amplified sequence of 100 bases. If predicted coding sequences, such as those in SEQ ID NO:3, 6, 9, 14, 17, 21, 29, 32, 35, 38, 41, 53, 56, or 59 are used, a more appropriate number of primers for positive individual identification would be 500-2,000.  
      If a panel of reagents from MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleotide sequences described herein is used to generate a unique identification database for an individual, those same reagents can later be used to identify tissue from that individual. Using the unique identification database, positive identification of the individual, living or dead, can be made from extremely small tissue samples.  
      3. Use of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and HST-5 Sequences in Forensic Biology  
      DNA-based identification techniques can also be used in forensic biology. Forensic biology is a scientific field employing genetic typing of biological evidence found at a crime scene as a means for positively identifying, for example, a perpetrator of a crime. To make such an identification, PCR technology can be used to amplify DNA sequences taken from very small biological samples such as tissues, e.g., hair or skin, or body fluids, e.g., blood, saliva, or semen found at a crime scene. The amplified sequence can then be compared to a standard, thereby allowing identification of the origin of the biological sample.  
      The sequences of the present invention can be used to provide polynucleotide reagents, e.g., PCR primers, targeted to specific loci in the human genome, which can enhance the reliability of DNA-based forensic identifications by, for example, providing another “identification marker” (i.e. another DNA sequence that is unique to a particular individual). As mentioned above, actual base sequence information can be used for identification as an accurate alternative to patterns formed by restriction enzyme generated fragments. Sequences targeted to noncoding regions of SEQ ID NO:1, 4, 7, 12, 15, 19, 27, 30, 33, 36, 39, 51, 54 or 57 are particularly appropriate for this use as greater numbers of polymorphisms occur in the noncoding regions, making it easier to differentiate individuals using this technique. Examples of polynucleotide reagents include the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 nucleotide sequences or portions thereof, e.g., fragments derived from the noncoding regions of SEQ ID NO:1, 4, 7, 12, 15, 19, 27, 30, 33, 36, 39, 51, 54 or 57 having a length of at least 20 bases, preferably at least 30 bases.  
      The MTP-1 nucleotide sequences described herein can further be used to provide polynucleotide reagents, e.g., labeled or labelable probes which can be used in, for example, an in situ hybridization technique, to identify a specific tissue, e.g., thymus or brain tissue. This can be very useful in cases where a forensic pathologist is presented with a tissue of unknown origin. Panels of such MTP-1 probes can be used to identify tissue by species and/or by organ type.  
      The OAT nucleotide sequences described herein can further be used to provide polynucleotide reagents, e.g., labeled or labelable probes which can be used in, for example, an in situ hybridization technique, to identify a specific tissue, e.g., an OAT-expressing tissue. This can be very useful in cases where a forensic pathologist is presented with a tissue of unknown origin. Panels of such OAT probes can be used to identify tissue by species and/or by organ type.  
      The PLTR-1 or HAAT nucleotide sequences described herein can further be used to provide polynucleotide reagents, e.g., labeled or labelable probes which can be used in, for example, an in situ hybridization technique, to identify a specific tissue, e.g., a tissue which expresses PLTR-1 or a tissue which expresses HAAT. This can be very useful in cases where a forensic pathologist is presented with a tissue of unknown origin. Panels of such PLTR-1 or HAAT probes can be used to identify tissue by species and/or by organ type.  
      The HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HST-4 and/or the HST-5 nucleotide sequences described herein can further be used to provide polynucleotide reagents, e.g., labeled or labelable probes which can be used in, for example, an in situ hybridization technique, to identify a specific tissue, e.g., brain tissue. This can be very useful in cases where a forensic pathologist is presented with a tissue of unknown origin. Panels of such HST-1, TP-2, TFM-2, TFM-3, 67118, 67067, 62092, HST-4 and/or HST-5 probes can be used to identify tissue by species and/or by organ type.  
      In a similar fashion, these reagents, e.g., MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 primers or probes can be used to screen tissue culture for contamination (i.e. screen for the presence of a mixture of different types of cells in a culture).  
      D. Predictive Medicine:  
      The present invention also pertains to the field of predictive medicine in which diagnostic assays, prognostic assays, and monitoring clinical trials are used for prognostic (predictive) purposes to thereby treat an individual prophylactically. Accordingly, one aspect of the present invention relates to diagnostic assays for determining MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide and/or nucleic acid expression as well as MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity, in the context of a biological sample (e.g., blood, serum, cells, tissue) to thereby determine whether an individual is afflicted with a disease or disorder, or is at risk of developing a disorder, associated with aberrant or unwanted MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression or activity. The invention also provides for prognostic (or predictive) assays for determining whether an individual is at risk of developing a disorder associated with MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, nucleic acid expression or activity. For example, mutations in an MTP-1, OAT, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 gene can be assayed in a biological sample. Such assays can be used for prognostic or predictive purpose to thereby prophylactically treat an individual prior to the onset of a disorder characterized by or associated with MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, nucleic acid expression or activity.  
      Another aspect of the invention pertains to monitoring the influence of agents (e.g., drugs, compounds) on the expression or activity of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 in clinical trials.  
      These and other agents are described in further detail in the following sections.  
      1. Regarding MTP-1  
      The present invention encompasses methods for diagnostic and prognostic evaluation of hematopoietic and/or immunological and/or lipid metabolism-related disorders or diseases, e.g., atherogenesis, including, but not limited to colon cancer and lung cancer, and for the identification of subjects exhibiting a predisposition to such conditions.  
      An exemplary method for detecting the presence or absence of MTP-1 protein or nucleic acid in a biological sample involves obtaining a biological sample from a test subject and contacting the biological sample with a compound or an agent capable of detecting MTP-1 protein or nucleic acid (e.g., mRNA, or genomic DNA) that encodes MTP-1 protein such that the presence of MTP-1 protein or nucleic acid is detected in the biological sample. A preferred agent for detecting MTP-1 mRNA or genomic DNA is a labeled nucleic acid probe capable of hybridizing to MTP-1 mRNA or genomic DNA. The nucleic acid probe can be, for example, the MTP-1 nucleic acid set forth in SEQ ID NO:1 or 3, or a portion thereof, such as an oligonucleotide of at least 15, 30, 50, 100, 250 or 500 nucleotides in length and sufficient to specifically hybridize under stringent conditions to MTP-1 mRNA or genomic DNA. Other suitable probes for use in the diagnostic assays of the invention are described herein.  
      2. Regarding OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and HST-5  
      An exemplary method for detecting the presence or absence of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides or nucleic acids in a biological sample involves obtaining a biological sample from a test subject and contacting the biological sample with a compound or an agent capable of detecting OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides or nucleic acids (e.g., mRNA, or genomic DNA) that encodes OAT, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides such that the presence of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides or nucleic acids is detected in the biological sample. In another aspect, the present invention provides a method for detecting the presence of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity in a biological sample by contacting the biological sample with an agent capable of detecting an indicator of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity such that the presence of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity is detected in the biological sample. A preferred agent for detecting OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or genomic DNA is a labeled nucleic acid probe capable of hybridizing to OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or genomic DNA. The nucleic acid probe can be, for example, the OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 nucleic acid set forth in SEQ ID NO:4, 6, 7, 9, 12, 14, 15, 17, 19, 21, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 51, 53, 54, 56, 57, or 59, or a portion thereof, such as an oligonucleotide of at least 15, 30, 50, 100, 250 or 500 nucleotides in length and sufficient to specifically hybridize under stringent conditions to OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA or genomic DNA. Other suitable probes for use in the diagnostic assays of the invention are described herein.  
      3. Diagnostic Assays  
      A preferred agent for detecting MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides is an antibody capable of binding to MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, preferably an antibody with a detectable label. Antibodies can be polyclonal, or more preferably, monoclonal. An intact antibody, or a fragment thereof (e.g., Fab or F(ab′)2) can be used. The term “labeled”, with regard to the probe or antibody, is intended to encompass direct labeling of the probe or antibody by coupling (i.e., physically linking) a detectable substance to the probe or antibody, as well as indirect labeling of the probe or antibody by reactivity with another reagent that is directly labeled. Examples of indirect labeling include detection of a primary antibody using a fluorescently labeled secondary antibody and end-labeling of a DNA probe with biotin such that it can be detected with fluorescently labeled streptavidin. The term “biological sample” is intended to include tissues, cells and biological fluids isolated from a subject, as well as tissues, cells and fluids present within a subject. That is, the detection method of the invention can be used to detect MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA, polypeptides, or genomic DNA in a biological sample in vitro as well as in vivo. For example, in vitro techniques for detection of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 mRNA include Northern hybridizations and in situ hybridizations. In vitro techniques for detection of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides include enzyme linked immunosorbent assays (ELISAs), Western blots, immunoprecipitations and immunofluorescence. In vitro techniques for detection of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 genomic DNA include Southern hybridizations. Furthermore, in vivo techniques for detection of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides include introducing into a subject a labeled anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti-HAAT, anti-HST-4 and/or anti-HST-5 antibody. For example, the antibody can be labeled with a radioactive marker whose presence and location in a subject can be detected by standard imaging techniques.  
      The present invention also provides diagnostic assays for identifying the presence or absence of a genetic alteration characterized by at least one of (i) aberrant modification or mutation of a gene encoding an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide; (ii) aberrant expression of a gene encoding an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide; (iii) mis-regulation of the gene; and (iv) aberrant post-translational modification of an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide, wherein a wild-type form of the gene encodes a polypeptide with an OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 an activity. “Misexpression or aberrant expression”, as used herein, refers to a non-wild type pattern of gene expression, at the RNA or protein level. It includes, but is not limited to, expression at non-wild type levels (e.g., over or under expression); a pattern of expression that differs from wild type in terms of the time or stage at which the gene is expressed (e.g., increased or decreased expression (as compared with wild type) at a predetermined developmental period or stage); a pattern of expression that differs from wild type in terms of decreased expression (as compared with wild type) in a predetermined cell type or tissue type; a pattern of expression that differs from wild type in terms of the splicing size, amino acid sequence, post-transitional modification, or biological activity of the expressed polypeptide; a pattern of expression that differs from wild type in terms of the effect of an environmental stimulus or extracellular stimulus on expression of the gene (e.g., a pattern of increased or decreased expression (as compared with wild type) in the presence of an increase or decrease in the strength of the stimulus).  
      In one embodiment, the biological sample contains protein molecules from the test subject. Alternatively, the biological sample can contain mRNA molecules from the test subject or genomic DNA molecules from the test subject. A preferred biological sample is a serum sample isolated by conventional means from a subject.  
      In another embodiment, the methods further involve obtaining a control biological sample from a control subject, contacting the control sample with a compound or agent capable of detecting MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, mRNA, or genomic DNA, such that the presence of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, mRNA or genomic DNA is detected in the biological sample, and comparing the presence of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, mRNA or genomic DNA in the control sample with the presence of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides, mRNA or genomic DNA in the test sample.  
      The invention also encompasses kits for detecting the presence of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 in a biological sample. For example, the kit can comprise a labeled compound or agent capable of detecting MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides or mRNA in a biological sample; means for determining the amount of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 in the sample; and means for comparing the amount of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 in the sample with a standard. The compound or agent can be packaged in a suitable container. The kit can further comprise instructions for using the kit to detect MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides or nucleic acid.  
      4. Prognostic Assays  
      The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant or unwanted MTP-1 expression or activity. As used herein, the term “aberrant” includes an MTP-1 expression or activity which deviates from the wild type MTP-1 expression or activity. Aberrant expression or activity includes increased or decreased expression or activity, as well as expression or activity which does not follow the wild type developmental pattern of expression or the subcellular pattern of expression. For example, aberrant MTP-1 expression or activity is intended to include the cases in which a mutation in the MTP-1 gene causes the MTP-1 gene to be under-expressed or over-expressed and situations in which such mutations result in a non-functional MTP-1 protein or a protein which does not function in a wild-type fashion, e.g., a protein which does not interact with an MTP-1 substrate, or one which interacts with a non-MTP-1 substrate. As used herein, the term “unwanted” includes an unwanted phenomenon involved in a biological response such as inflammation and/or lipid metabolism. For example, the term unwanted includes an MTP-1 expression or activity which is undesirable in a subject.  
      The assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing a disorder associated with a misregulation in MTP-1 protein activity or nucleic acid expression, such as a hematopoietic and/or immunological and/or lipid metabolism-related disorder, a CNS disorder (e.g., a cognitive or neurodegenerative disorder), a cellular proliferation, growth, differentiation, or migration disorder, a cardiovascular disorder, musculoskeletal disorder, an immune disorder, or a hormonal disorder. Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disorder associated with a misregulation in MTP-1 protein activity or nucleic acid expression, such as a hematopoietic disorder, an immunological disorder, a lipid metabolism-related disorder, a CNS disorder, a cellular proliferation, growth, differentiation, or migration disorder, a musculoskeletal disorder, a cardiovascular disorder, an immune disorder, or a hormonal disorder. Thus, the present invention provides a method for identifying a disease or disorder associated with aberrant or unwanted MTP-1 expression or activity in which a test sample is obtained from a subject and MTP-1 protein or nucleic acid (e.g., mRNA or genomic DNA) is detected, wherein the presence of MTP-1 protein or nucleic acid is diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant or unwanted MTP-1 expression or activity. As used herein, a “test sample” refers to a biological sample obtained from a subject of interest. For example, a test sample can be a biological fluid (e.g., cerebrospinal fluid or serum), cell sample, or tissue.  
      Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate) to treat a disease or disorder associated with aberrant or unwanted MTP-1 expression or activity. For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a hematopoietic disorder, an immunological disorder, a lipid metabolism-related disorder, a CNS disorder, a muscular disorder, a cellular proliferation, growth, differentiation, or migration disorder, an immune disorder, or a hormonal disorder. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant or unwanted MTP-1 expression or activity in which a test sample is obtained and MTP-1 protein or nucleic acid expression or activity is detected (e.g., wherein the abundance of MTP-1 protein or nucleic acid expression or activity is diagnostic for a subject that can be administered the agent to treat a disorder associated with aberrant or unwanted MTP-1 expression or activity).  
      The methods of the invention can also be used to detect genetic alterations in an MTP-1 gene, thereby determining if a subject with the altered gene is at risk for a disorder characterized by misregulation in MTP-1 protein activity or nucleic acid expression, such as a hematopoietic disorder, an immunological disorder, a lipid metabolism-related disorder, a CNS disorder, a musculoskeletal disorder, a cellular proliferation, growth, differentiation, or migration disorder, a cardiovascular disorder, an immune disorder, or a hormonal disorder. In preferred embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic alteration characterized by at least one of an alteration affecting the integrity of a gene encoding an MTP-1-protein, or the mis-expression of the MTP-1 gene. For example, such genetic alterations can be detected by ascertaining the existence of at least one of 1) a deletion of one or more nucleotides from an MTP-1 gene; 2) an addition of one or more nucleotides to an MTP-1 gene; 3) a substitution of one or more nucleotides of an MTP-1 gene, 4) a chromosomal rearrangement of an MTP-1 gene; 5) an alteration in the level of a messenger RNA transcript of an MTP-1 gene, 6) aberrant modification of an MTP-1 gene, such as of the methylation pattern of the genomic DNA, 7) the presence of a non-wild type splicing pattern of a messenger RNA transcript of an MTP-1 gene, 8) a non-wild type level of an MTP-1-protein, 9) allelic loss of an MTP-1 gene, and 10) inappropriate post-translational modification of an MTP-1-protein. As described herein, there are a large number of assays known in the art which can be used for detecting alterations in an MTP-1 gene. A preferred biological sample is a tissue or serum sample isolated by conventional means from a subject.  
      The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant or unwanted OAT expression or activity. As used herein, the term “aberrant” includes an OAT expression or activity which deviates from the wild type OAT expression or activity. Aberrant expression or activity includes increased or decreased expression or activity, as well as expression or activity which does not follow the wild type developmental pattern of expression or the subcellular pattern of expression. For example, aberrant OAT expression or activity is intended to include the cases in which a mutation in the OAT gene causes the OAT gene to be under-expressed or over-expressed and situations in which such mutations result in a non-functional OAT protein or a protein which does not function in a wild-type fashion, e.g., a protein which does not interact with or transport an OAT substrate or target molecule, or one which interacts with a non-OAT substrate or target molecule. As used herein, the term “unwanted” includes an unwanted phenomenon involved in a biological response such as the improper cellular localization of an OAT substrate or deregulated cell proliferation. For example, the term unwanted includes an OAT expression or activity which is undesirable in a subject.  
      The assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing an OAT associated disorder, e.g., a disorder associated with a misregulation in OAT protein activity or nucleic acid expression, such as a CNS disorder (e.g., a cognitive or neurodegenerative disorder), a cellular proliferation, growth, differentiation, or migration disorder, a cardiovascular disorder, a musculoskeletal disorder, an immune disorder, or a hormonal disorder. Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disorder associated with a misregulation in OAT protein activity or nucleic acid expression, such as a CNS disorder (e.g., a cognitive or neurodegenerative disorder), a cellular proliferation, growth, differentiation, or migration disorder, a cardiovascular disorder, a musculoskeletal disorder, an immune disorder, or a hormonal disorder. Thus, the present invention provides a method for identifying a disease or disorder associated with aberrant or unwanted OAT expression or activity in which a test sample is obtained from a subject and OAT protein or nucleic acid (e.g., mRNA or genomic DNA) is detected, wherein the presence of OAT protein or nucleic acid is diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant or unwanted OAT expression or activity. As used herein, a “test sample” refers to a biological sample obtained from a subject of interest. For example, a test sample can be a biological fluid (e.g., serum), cell sample, or tissue.  
      Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate) to treat a disease or disorder associated with aberrant or unwanted OAT expression or activity. For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a CNS disorder (e.g., a cognitive or neurodegenerative disorder), a cellular proliferation, growth, differentiation, or migration disorder, a cardiovascular disorder, a musculoskeletal disorder, an immune disorder, or a hormonal disorder. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant or unwanted OAT expression or activity in which a test sample is obtained and OAT protein or nucleic acid expression or activity is detected (e.g., wherein the abundance of OAT protein or nucleic acid expression or activity is diagnostic for a subject that can be administered the agent to treat a disorder associated with aberrant or unwanted OAT expression or activity).  
      The methods of the invention can also be used to detect genetic alterations in an OAT gene, thereby determining if a subject with the altered gene is at risk for a disorder characterized by misregulation in OAT protein activity or nucleic acid expression, such as a CNS disorder (e.g., a cognitive or neurodegenerative disorder), a cellular proliferation, growth, differentiation, or migration disorder, a cardiovascular disorder, a musculoskeletal disorder, an immune disorder, or a hormonal disorder. In preferred embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic alteration characterized by at least one of an alteration affecting the integrity of a gene encoding an OAT-protein, or the mis-expression of the OAT gene. For example, such genetic alterations can be detected by ascertaining the existence of at least one of 1) a deletion of one or more nucleotides from an OAT gene; 2) an addition of one or more nucleotides to an OAT gene; 3) a substitution of one or more nucleotides of an OAT gene, 4) a chromosomal rearrangement of an OAT gene; 5) an alteration in the level of a messenger RNA transcript of an OAT gene, 6) aberrant modification of an OAT gene, such as of the methylation pattern of the genomic DNA, 7) the presence of a non-wild type splicing pattern of a messenger RNA transcript of an OAT gene, 8) a non-wild type level of an OAT-protein, 9) allelic loss of an OAT gene, and 10) inappropriate post-translational modification of an OAT-protein. As described herein, there are a large number of assays known in the art which can be used for detecting alterations in an OAT gene. A preferred biological sample is a tissue or serum sample isolated by conventional means from a subject.  
      The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant or unwanted HST-1 expression or activity. As used herein, the term “aberrant” includes an HST-1 expression or activity which deviates from the wild type HST-1 expression or activity. Aberrant expression or activity includes increased or decreased expression or activity, as well as expression or activity which does not follow the wild type developmental pattern of expression or the subcellular pattern of expression. For example, aberrant HST-1 expression, or activity is intended to include the cases in which a mutation in the HST-1 gene causes the HST-1 gene to be under-expressed or over-expressed and situations in which such mutations result in a non-functional HST-1 polypeptide or a polypeptide which does not function in a wild-type fashion, e.g., a polypeptide which does not interact with an HST-1 substrate, e.g., a sugar transporter subunit or ligand, or one which interacts with a non-HST-1 substrate, e.g. a non-sugar transporter subunit or ligand. As used herein, the term “unwanted” includes an unwanted phenomenon involved in a biological response, such as cellular proliferation. For example, the term unwanted includes an HST-1 expression or activity which is undesirable in a subject.  
      The assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing a disorder associated with a misregulation in HST-1 polypeptide activity or nucleic acid expression, such as a sugar transporter disorder. Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disorder associated with a misregulation in HST-1 polypeptide activity or nucleic acid expression, such as a sugar transporter disorder. Thus, the present invention provides a method for identifying a disease or disorder associated with aberrant or unwanted HST-1 expression or activity in which a test sample is obtained from a subject and HST-1 polypeptide or nucleic acid (e.g., mRNA or genomic DNA) is detected, wherein the presence of HST-1 polypeptide or nucleic acid is diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant or unwanted HST-1 expression or activity. As used herein, a “test sample” refers to a biological sample obtained from a subject of interest. For example, a test sample can be a biological fluid (e.g., serum), cell sample, or tissue.  
      Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate) to treat a disease or disorder associated with aberrant or unwanted HST-1 expression or activity. For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a sugar transporter disorder. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant or unwanted HST-1 expression or activity in which a test sample is obtained and HST-1 polypeptide or nucleic acid expression or activity is detected (e.g., wherein the abundance of HST-1 polypeptide or nucleic acid expression or activity is diagnostic for a subject that can be administered the agent to treat a disorder associated with aberrant or unwanted HST-1 expression or activity).  
      The methods of the invention can also be used to detect genetic alterations in an HST-1 gene, thereby determining if a subject with the altered gene is at risk for a disorder characterized by misregulation in HST-1 polypeptide activity or nucleic acid expression, such as a sugar transporter disorder, a sugar homeostasis disorder, or a disorder of cellular growth, differentiation, or migration. In preferred embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic alteration characterized by at least one of an alteration affecting the integrity of a gene encoding an HST-1-polypeptide, or the mis-expression of the HST-1 gene. For example, such genetic alterations can be detected by ascertaining the existence of at least one of 1) a deletion of one or more nucleotides from an HST-1 gene; 2) an addition of one or more nucleotides to an HST-1 gene; 3) a substitution of one or more nucleotides of an HST-1 gene, 4) a chromosomal rearrangement of an HST-1 gene; 5) an alteration in the level of a messenger RNA transcript of an HST-1 gene, 6) aberrant modification of an HST-1 gene, such as of the methylation pattern of the genomic DNA, 7) the presence of a non-wild type splicing pattern of a messenger RNA transcript of an HST-1 gene, 8) a non-wild type level of an HST-1-polypeptide, 9) allelic loss of an HST-1 gene, and 10) inappropriate post-translational modification of an HST-1-polypeptide. As described herein, there are a large number of assays known in the art which can be used for detecting alterations in an HST-1 gene. A preferred biological sample is a tissue or serum sample isolated by conventional means from a subject.  
      The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant or unwanted TP-2 expression or activity. As used herein, the term “aberrant” includes a TP-2 expression or activity which deviates from the wild type TP-2 expression or activity. Aberrant expression or activity includes increased or decreased expression or activity, as well as expression or activity which does not follow the wild type developmental pattern of expression or the subcellular pattern of expression. For example, aberrant TP-2 expression or activity is intended to include the cases in which a mutation in the TP-2 gene causes the TP-2 gene to be under-expressed or over-expressed and situations in which such mutations result in a non-functional TP-2 polypeptide or a polypeptide which does not function in a wild-type fashion, e.g., a polypeptide which does not interact with a TP-2 substrate, e.g., a transporter subunit or ligand, or one which interacts with a non-TP-2 substrate, e.g. a non-transporter subunit or ligand. As used herein, the term “unwanted” includes an unwanted phenomenon involved in a biological response, such as cellular proliferation. For example, the term unwanted includes a TP-2 expression or activity which is undesirable in a subject.  
      The assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing a disorder associated with a misregulation in TP-2 polypeptide activity or nucleic acid expression, such as a transporter-associated disorder. Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disorder associated with a misregulation in TP-2 polypeptide activity or nucleic acid expression, such as a transporter-associated disorder. Thus, the present invention provides a method for identifying a disease or disorder associated with aberrant or unwanted TP-2 expression or activity in which a test sample is obtained from a subject and TP-2 polypeptide or nucleic acid (e.g., mRNA or genomic DNA) is detected, wherein the presence of TP-2 polypeptide or nucleic acid is diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant or unwanted TP-2 expression or activity. As used herein, a “test sample” refers to a biological sample obtained from a subject of interest. For example, a test sample can be a biological fluid (e.g., serum), cell sample, or tissue.  
      Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate) to treat a disease or disorder associated with aberrant or unwanted TP-2 expression or activity. For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a transporter-associated disorder. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant or unwanted TP-2 expression or activity in which a test sample is obtained and TP-2 polypeptide or nucleic acid expression or activity is detected (e.g., wherein the abundance of TP-2 polypeptide or nucleic acid expression or activity is diagnostic for a subject that can be administered the agent to treat a disorder associated with aberrant or unwanted TP-2 expression or activity).  
      The methods of the invention can also be used to detect genetic alterations in a TP-2 gene, thereby determining if a subject with the altered gene is at risk for a disorder characterized by misregulation in TP-2 polypeptide activity or nucleic acid expression, such as a transporter-associated disorder. In preferred embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic alteration characterized by at least one of an alteration affecting the integrity of a gene encoding a TP-2 -polypeptide, or the mis-expression of the TP-2 gene. For example, such genetic alterations can be detected by ascertaining the existence of at least one of 1) a deletion of one or more nucleotides from a TP-2 gene; 2) an addition of one or more nucleotides to a TP-2 gene; 3) a substitution of one or more nucleotides of a TP-2 gene, 4) a chromosomal rearrangement of a TP-2 gene; 5) an alteration in the level of a messenger RNA transcript of a TP-2 gene, 6) aberrant modification of a TP-2 gene, such as of the methylation pattern of the genomic DNA, 7) the presence of a non-wild type splicing pattern of a messenger RNA transcript of a TP-2 gene, 8) a non-wild type level of a TP-2-polypeptide, 9) allelic loss of a TP-2 gene, and 10) inappropriate post-translational modification of a TP-2-polypeptide. As described herein, there are a large number of assays known in the art which can be used for detecting alterations in a TP-2 gene. A preferred biological sample is a tissue or serum sample isolated by conventional means from a subject.  
      The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant or unwanted PLTR-1 expression or activity (e.g., a cardiovascular disorder). As used herein, the term “aberrant” includes a PLTR-1 expression or activity which deviates from the wild type PLTR-1 expression or activity. Aberrant expression or activity includes increased or decreased expression or activity, as well as expression or activity which does not follow the wild type developmental pattern of expression or the subcellular pattern of expression. For example, aberrant PLTR-1 expression or activity is intended to include the cases in which a mutation in the PLTR-1 gene causes the PLTR-1 gene to be under-expressed or over-expressed and situations in which such mutations result in a non-functional PLTR-1 protein or a protein which does not function in a wild-type fashion, e.g., a protein which does not interact with or transport a PLTR-1 substrate, or one which interacts with or transports a non-PLTR-1 substrate. As used herein, the term “unwanted” includes an unwanted phenomenon involved in a biological response such as deregulated cell proliferation. For example, the term unwanted includes a PLTR-1 expression or activity which is undesirable in a subject.  
      The assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing a disorder associated with a misregulation in PLTR-1 protein activity or nucleic acid expression, such as a cardiovascular disorder or a cell growth, proliferation and/or differentiation disorder. Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disorder associated with a misregulation in PLTR-1 protein activity or nucleic acid expression, such as a cardiovascular disorder or a cell growth, proliferation and/or differentiation disorder. Thus, the present invention provides a method for identifying a disease or disorder associated with aberrant or unwanted PLTR-1 expression or activity in which a test sample is obtained from a subject and PLTR-1 protein or nucleic acid (e.g., mRNA or genomic DNA) is detected, wherein the presence of PLTR-1 protein or nucleic acid is diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant or unwanted PLTR-1 expression or activity. As used herein, a “test sample” refers to a biological sample obtained from a subject of interest. For example, a test sample can be a biological fluid (e.g., serum), cell sample, or tissue.  
      Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate) to treat a disease or disorder associated with aberrant or unwanted PLTR-1 expression or activity (e.g., a cardiovascular disorder). For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a cardiovascular disorder, a drug or toxin sensitivity disorder, or a cell proliferation and/or differentiation disorder. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant or unwanted PLTR-1 expression or activity in which a test sample is obtained and PLTR-1 protein or nucleic acid expression or activity is detected (e.g., wherein the abundance of PLTR-1 protein or nucleic acid expression or activity is diagnostic for a subject that can be administered the agent to treat a disorder associated with aberrant or unwanted PLTR-1 expression or activity).  
      The methods of the invention can also be used to detect genetic alterations in a PLTR-1 gene, thereby determining if a subject with the altered gene is at risk for a disorder characterized by misregulation in PLTR-1 protein activity or nucleic acid expression, such as a cardiovascular disorder or a cell growth, proliferation and/or differentiation disorder. In preferred embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic alteration characterized by at least one of an alteration affecting the integrity of a gene encoding a PLTR-1-protein, or the mis-expression of the PLTR-1 gene. For example, such genetic alterations can be detected by ascertaining the existence of at least one of 1) a deletion of one or more nucleotides from a PLTR-1 gene; 2) an addition of one or more nucleotides to a PLTR-1 gene; 3) a substitution of one or more nucleotides of a PLTR-1 gene, 4) a chromosomal rearrangement of a PLTR-1 gene; 5) an alteration in the level of a messenger RNA transcript of a PLTR-1 gene, 6) aberrant modification of a PLTR-1 gene, such as of the methylation pattern of the genomic DNA, 7) the presence of a non-wild type splicing pattern of a messenger RNA transcript of a PLTR-1 gene, 8) a non-wild type level of a PLTR-1-protein, 9) allelic loss of a PLTR-1 gene, and 10) inappropriate post-translational modification of a PLTR-1-protein. As described herein, there are a large number of assays known in the art which can be used for detecting alterations in a PLTR-1 gene. A preferred biological sample is a tissue or serum sample isolated by conventional means from a subject.  
      The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant or unwanted TFM-2 and/or TFM-3 expression or activity. As used herein, the term “aberrant” includes a TFM-2 and/or TFM-3 expression or activity which deviates from the wild type TFM-2 and/or TFM-3 expression or activity. Aberrant expression or activity includes increased or decreased expression or activity, as well as expression or activity which does not follow the wild type developmental pattern of expression or the subcellular pattern of expression. For example, aberrant TFM-2 and/or TFM-3 expression or activity is intended to include the cases in which a mutation in the TFM-2 and/or TFM-3 gene causes the TFM-2 and/or TFM-3 gene to be under-expressed or over-expressed and situations in which such mutations result in a non-functional TFM-2 and/or TFM-3 polypeptide or a polypeptide which does not function in a wild-type fashion, e.g., a polypeptide which does not interact with a TFM-2 and/or TFM-3 substrate, e.g., a transporter subunit or ligand, or one which interacts with a non-TFM-2 and/or TFM-3 substrate, e.g. a non-transporter subunit or ligand. As used herein, the term “unwanted” includes an unwanted phenomenon involved in a biological response, such as cellular proliferation. For example, the term unwanted includes a TFM-2 and/or TFM-3 expression or activity which is undesirable in a subject.  
      The assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing a disorder associated with a misregulation in TFM-2 and/or TFM-3 polypeptide activity or nucleic acid expression, such as a transporter-associated disorder. Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disorder associated with a misregulation in TFM-2 and/or TFM-3 polypeptide activity or nucleic acid expression, such as a transporter-associated disorder. Thus, the present invention provides a method for identifying a disease or disorder associated with aberrant or unwanted TFM-2 and/or TFM-3 expression or activity in which a test sample is obtained from a subject and TFM-2 and/or TFM-3 polypeptide or nucleic acid (e.g., mRNA or genomic DNA) is detected, wherein the presence of TFM-2 and/or TFM-3 polypeptide or nucleic acid is diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant or unwanted TFM-2 and/or TFM-3 expression or activity. As used herein, a “test sample” refers to a biological sample obtained from a subject of interest. For example, a test sample can be a biological fluid (e.g., serum), cell sample, or tissue.  
      Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate) to treat a disease or disorder associated with aberrant or unwanted TFM-2 and/or TFM-3 expression or activity. For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a transporter-associated disorder. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant or unwanted TFM-2 and/or TFM-3 expression or activity in which a test sample is obtained and TFM-2 and/or TFM-3 polypeptide or nucleic acid expression or activity is detected (e.g., wherein the abundance of TFM-2 and/or TFM-3 polypeptide or nucleic acid expression or activity is diagnostic for a subject that can be administered the agent to treat a disorder associated with aberrant or unwanted TFM-2 and/or TFM-3 expression or activity).  
      The methods of the invention can also be used to detect genetic alterations in a TFM-2 and/or TFM-3 gene, thereby determining if a subject with the altered gene is at risk for a disorder characterized by misregulation in TFM-2 and/or TFM-3 polypeptide activity or nucleic acid expression, such as a transporter-associated disorder. In preferred embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic alteration characterized by at least one of an alteration affecting the integrity of a gene encoding a TFM-2 and/or TFM-3-polypeptide, or the mis-expression of the TFM-2 and/or TFM-3 gene. For example, such genetic alterations can be detected by ascertaining the existence of at least one of 1) a deletion of one or more nucleotides from a TFM-2 and/or TFM-3 gene; 2) an addition of one or more nucleotides to a TFM-2 and/or TFM-3 gene; 3) a substitution of one or more nucleotides of a TFM-2 and/or TFM-3 gene, 4) a chromosomal rearrangement of a TFM-2 and/or TFM-3 gene; 5) an alteration in the level of a messenger RNA transcript of a TFM-2 and/or TFM-3 gene, 6) aberrant modification of a TFM-2 and/or TFM-3 gene, such as of the methylation pattern of the genomic DNA, 7) the presence of a non-wild type splicing pattern of a messenger RNA transcript of a TFM-2 and/or TFM-3 gene, 8) a non-wild type level of a TFM-2 and/or TFM-3-polypeptide, 9) allelic loss of a TFM-2 and/or TFM-3 gene, and 10) inappropriate post-translational modification of a TFM-2 and/or TFM-3-polypeptide. As described herein, there are a large number of assays known in the art which can be used for detecting alterations in a TFM-2 and/or TFM-3 gene. A preferred biological sample is a tissue or serum sample isolated by conventional means from a subject.  
      The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant or unwanted 67118, 67067, and/or 62092 expression or activity. As used herein, the term “aberrant” includes a 67118, 67067, and/or 62092 expression or activity which deviates from the wild type 67118, 67067, and/or 62092 expression or activity. Aberrant expression or activity includes increased or decreased expression or activity, as well as expression or activity which does not follow the wild type developmental pattern of expression or the subcellular pattern of expression. For example, aberrant 67118, 67067, and/or 62092 expression or activity is intended to include the cases in which a mutation in the 67118, 67067, and/or 62092 gene causes the 67118, 67067, and/or 62092 gene to be under-expressed or over-expressed and situations in which such mutations result in a non-functional 67118, 67067, and/or 62092 polypeptide or a polypeptide which does not function in a wild-type fashion, e.g., a protein which does not interact with or transport a 67118, 67067, and/or 62092 substrate, or one which interacts with or transports a non-67118, 67067, and/or 62092 substrate. As used herein, the term “unwanted” includes an unwanted phenomenon involved in a biological response such as deregulated cell proliferation. For example, the term unwanted includes a 67118, 67067, and/or 62092 expression or activity which is undesirable in a subject.  
      The assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing a disorder associated with a misregulation in 67118, 67067, and/or 62092 polypeptide activity or nucleic acid expression, such as a as a cell growth, proliferation and/or differentiation disorder, e.g., cancer, including, but not limited to colon cancer or lung cancer. Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disorder associated with a misregulation in 67118, 67067, and/or 62092 polypeptide activity or nucleic acid expression, such as a cell growth, proliferation and/or differentiation disorder. Thus, the present invention provides a method for identifying a disease or disorder associated with aberrant or unwanted 67118, 67067, and/or 62092 expression or activity in which a test sample is obtained from a subject and 67118, 67067, and/or 62092 polypeptide or nucleic acid (e.g., mRNA or genomic DNA) is detected, wherein the presence of 67118, 67067, and/or 62092 polypeptide or nucleic acid is diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant or unwanted 67118, 67067, and/or 62092 expression or activity. As used herein, a “test sample” refers to a biological sample obtained from a subject of interest. For example, a test sample can be a biological fluid (e.g., serum), cell sample, or tissue, e.g., a colon tumor sample or a lung tumor sample.  
      Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate) to treat a disease or disorder associated with aberrant or unwanted 67118, 67067, and/or 62092 expression or activity. For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a transporter-associated disorder. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant or unwanted 67118, 67067, and/or 62092 expression or activity in which a test sample is obtained and 67118, 67067, and/or 62092 polypeptide or nucleic acid expression or activity is detected (e.g., wherein the abundance of 67118, 67067, and/or 62092 polypeptide or nucleic acid expression or activity is diagnostic for a subject that can be administered the agent to treat a disorder associated with aberrant or unwanted 67118, 67067, and/or 62092 expression or activity).  
      The methods of the invention can also be used to detect genetic alterations in a 67118, 67067, and/or 62092 gene, thereby determining if a subject with the altered gene is at risk for a disorder characterized by misregulation in 67118, 67067, and/or 62092 polypeptide activity or nucleic acid expression, such as a cell growth, proliferation and/or differentiation disorder. In preferred embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic alteration characterized by at least one of an alteration affecting the integrity of a gene encoding a 67118, 67067, and/or 62092-polypeptide, or the mis-expression of the 67118, 67067, and/or 62092 gene. For example, such genetic alterations can be detected by ascertaining the existence of at least one of 1) a deletion of one or more nucleotides from a 67118, 67067, and/or 62092 gene; 2) an addition of one or more nucleotides to a 67118, 67067, and/or 62092 gene; 3) a substitution of one or more nucleotides of a 67118, 67067, and/or 62092 gene, 4) a chromosomal rearrangement of a 67118, 67067, and/or 62092 gene; 5) an alteration in the level of a messenger RNA transcript of a 67118, 67067, and/or 62092 gene, 6) aberrant modification of a 67118, 67067, and/or 62092 gene, such as of the methylation pattern of the genomic DNA, 7) the presence of a non-wild type splicing pattern of a messenger RNA transcript of a 67118, 67067, and/or 62092 gene, 8) a non-wild type level of a 67118, 67067, and/or 62092-polypeptide, 9) allelic loss of a 67118, 67067, and/or 62092 gene, and 10) inappropriate post-translational modification of a 67118, 67067, and/or 62092-polypeptide. As described herein, there are a large number of assays known in the art which can be used for detecting alterations in a 67118, 67067, and/or 62092 gene. A preferred biological sample is a tissue or serum sample isolated by conventional means from a subject.  
      The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant or unwanted HAAT expression or activity. As used herein, the term “aberrant” includes a HAAT expression or activity which deviates from the wild type HAAT expression or activity. Aberrant expression or activity includes increased or decreased expression or activity, as well as expression or activity which does not follow the wild type developmental pattern of expression or the subcellular pattern of expression. For example, aberrant HAAT expression or activity is intended to include the cases in which a mutation in the HAAT gene causes the HAAT gene to be under-expressed or over-expressed and situations in which such mutations result in a non-functional HAAT protein or a protein which does not function in a wild-type fashion, e.g., a protein which does not interact with or transport a HAAT substrate, or one which interacts with or transports a non-HAAT substrate.  
      The assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing a disorder associated with a misregulation in HAAT protein activity or nucleic acid expression, such as tumorigenesis and/or nerve transmission. Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disorder associated with a misregulation in HAAT protein activity or nucleic acid expression, such as a tumorigenesis and/or nerve transmission disorder. Thus, the present invention provides a method for identifying a disease or disorder associated with aberrant or unwanted HAAT expression or activity in which a test sample is obtained from a subject and HAAT protein or nucleic acid (e.g., mRNA or genomic DNA) is detected, wherein the presence of HAAT protein or nucleic acid is diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant or unwanted HAAT expression or activity. As used herein, a “test sample” refers to a biological sample obtained from a subject of interest. For example, a test sample can be a biological fluid (e.g., serum), cell sample, or tissue.  
      Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate) to treat a disease or disorder associated with aberrant or unwanted HAAT expression or activity. For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a drug or toxin sensitivity disorder or a tumorigenesis and/or nerve transmission disorder. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant or unwanted HAAT expression or activity in which a test sample is obtained and HAAT protein or nucleic acid expression or activity is detected (e.g., wherein the abundance of HAAT protein or nucleic acid expression or activity is diagnostic for a subject that can be administered the agent to treat a disorder associated with aberrant or unwanted HAAT expression or activity).  
      The methods of the invention can also be used to detect genetic alterations in a HAAT gene, thereby determining if a subject with the altered gene is at risk for a disorder characterized by misregulation in HAAT protein activity or nucleic acid expression, such as a tumorigenesis and/or nerve transmission disorder. In preferred embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic alteration characterized by at least one of an alteration affecting the integrity of a gene encoding a HAAT-protein, or the mis-expression of the HAAT gene. For example, such genetic alterations can be detected by ascertaining the existence of at least one of 1) a deletion of one or more nucleotides from a HAAT gene; 2) an addition of one or more nucleotides to a HAAT gene; 3) a substitution of one or more nucleotides of a HAAT gene, 4) a chromosomal rearrangement of a HAAT gene; 5) an alteration in the level of a messenger RNA transcript of a HAAT gene, 6) aberrant modification of a HAAT gene, such as of the methylation pattern of the genomic DNA, 7) the presence of a non-wild type splicing pattern of a messenger RNA transcript of a HAAT gene, 8) a non-wild type level of a HAAT-protein, 9) allelic loss of a HAAT gene, and 10) inappropriate post-translational modification of a HAAT-protein. As described herein, there are a large number of assays known in the art which can be used for detecting alterations in a HAAT gene. A preferred biological sample is a tissue or serum sample isolated by conventional means from a subject.  
      The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant or unwanted HST-4 and/or HST-5 expression or activity. As used herein, the term “aberrant” includes an HST-4 and/or an HST-5 expression or activity which deviates from the wild type HST-4 and/or HST-5 expression or activity. Aberrant expression or activity includes increased or decreased expression or activity, as well as expression or activity which does not follow the wild type developmental pattern of expression or the subcellular pattern of expression. For example, aberrant HST-4 and/or HST-5 expression or activity is intended to include the cases in which a mutation in the HST-4 and/or the HST-5 gene causes the HST-4 and/or the HST-5 gene to be under-expressed or over-expressed and situations in which such mutations result in a non-functional HST-4 and/or HST-5 polypeptides or polypeptides which do not function in a wild-type fashion, e.g., polypeptides which do not interact with an HST-4 and/or an HST-5 substrate, e.g., a sugar transporter subunit or ligand, or one which interacts with a non-HST-4 and/or a non-HST-5 substrate, e.g. a non-sugar transporter subunit or ligand. As used herein, the term “unwanted” includes an unwanted phenomenon involved in a biological response, such as cellular proliferation. For example, the term unwanted includes an HST-4 and/or an HST-5 expression or activity which is undesirable in a subject.  
      The assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing a disorder associated with a misregulation in HST-4 and/or HST-5 polypeptide activity or nucleic acid expression, such as a sugar transporter disorder. Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disorder associated with a misregulation in HST-4 and/or HST-5 polypeptide activity or nucleic acid expression, such as a sugar transporter disorder. Thus, the present invention provides a method for identifying a disease or disorder associated with aberrant or unwanted HST-4 and/or HST-5 expression or activity in which a test sample is obtained from a subject and HST-4 and/or HST-5 polypeptides or nucleic acids (e.g., mRNA or genomic DNA) are detected, wherein the presence of HST-4 and/or HST-5 polypeptides or nucleic acids are diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant or unwanted HST-4 and/or HST-5 expression or activity. As used herein, a “test sample” refers to a biological sample obtained from a subject of interest. For example, a test sample can be a biological fluid (e.g., serum), cell sample, or tissue.  
      Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate) to treat a disease or disorder associated with aberrant or unwanted HST-4 and/or HST-5 expression or activity. For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a sugar transporter disorder. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant or unwanted HST-4 and/or HST-5 expression or activity in which a test sample is obtained and HST-4 and/or HST-5 polypeptide or nucleic acid expression or activity is detected (e.g., wherein the abundance of HST-4 and/or HST-5 polypeptide or nucleic acid expression or activity is diagnostic for a subject that can be administered the agent to treat a disorder associated with aberrant or unwanted HST-4 and/or HST-5 expression or activity).  
      The methods of the invention can also be used to detect genetic alterations in an HST-4 and/or an HST-5 gene, thereby determining if a subject with the altered gene is at risk for a disorder characterized by misregulation in HST-4 and/or HST-5 polypeptide activity or nucleic acid expression, such as a sugar transporter disorder, a sugar homeostasis disorder, or a disorder of cellular growth, differentiation, or migration. In preferred embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic alteration characterized by at least one of an alteration affecting the integrity of a gene encoding an HST-4-polypeptide and/or an HST-5-polypeptide, or the mis-expression of the HST-4 and/or the HST-5 gene. For example, such genetic alterations can be detected by ascertaining the existence of at least one of 1) a deletion of one or more nucleotides from an HST-4 and/or an HST-5 gene; 2) an addition of one or more nucleotides to an HST-4 and/or an HST-5 gene; 3) a substitution of one or more nucleotides of an HST-4 and/or an HST-5 gene, 4) a chromosomal rearrangement of an HST-4 and/or an HST-5 gene; 5) an alteration in the level of a messenger RNA transcript of an HST-4 and/or an HST-5 gene, 6) aberrant modification of an HST-4 and/or an HST-5 gene, such as of the methylation pattern of the genomic DNA, 7) the presence of a non-wild type splicing pattern of a messenger RNA transcript of an HST-4 and/or an HST-5 gene, 8) a non-wild type level of an HST-4-polypeptide and/or an HST-5-polypeptide, 9) allelic loss of an HST-4 and/or an HST-5 gene, and 10) inappropriate post-translational modification of an HST-4-polypeptide and/or an HST-5-polypeptide. As described herein, there are a large number of assays known in the art which can be used for detecting alterations in an HST-4 and/or an HST-5 gene. A preferred biological sample is a tissue or serum sample isolated by conventional means from a subject.  
      In certain embodiments, detection of the alteration involves the use of a probe/primer in a polymerase chain reaction (PCR) (see, e.g., U.S. Pat. Nos. 4,683,195 and 4,683,202), such as anchor PCR or RACE PCR, or, alternatively, in a ligation chain reaction (LCR) (see, e.g., Landegran et al. (1988)  Science  241:1077-1080; and Nakazawa et al. (1994)  Proc. Natl. Acad. Sci. USA  91:360-364), the latter of which can be particularly useful for detecting point mutations in the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4-gene and/or the HST-5-gene (see Abravaya et al. (1995)  Nucleic Acids Res.  23:675-682). This method can include the steps of collecting a sample of cells from a subject, isolating nucleic acid (e.g., genomic, mRNA or both) from the cells of the sample, contacting the nucleic acid sample with one or more primers which specifically hybridize to an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 gene under conditions such that hybridization and amplification of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4-gene and/or the HST-5-gene (if present) occurs, and detecting the presence or absence of an amplification product, or detecting the size of the amplification product and comparing the length to a control sample. It is anticipated that PCR and/or LCR may be desirable to use as a preliminary amplification step in conjunction with any of the techniques used for detecting mutations described herein.  
      Alternative amplification methods include: self sustained sequence replication (Guatelli, J. C. et al., (1990)  Proc. Natl. Acad. Sci. USA  87:1874-1878), transcriptional amplification system (Kwoh, D. Y. et al., (1989)  Proc. Natl. Acad. Sci. USA  86:1173-1177), Q-Beta Replicase (Lizardi, P. M. et al. (1988)  Bio - Technology  6:1197), or any other nucleic acid amplification method, followed by the detection of the amplified molecules using techniques well known to those of skill in the art. These detection schemes are especially useful for the detection of nucleic acid molecules if such molecules are present in very low numbers.  
      In an alternative embodiment, mutations in an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 gene from a sample cell can be identified by alterations in restriction enzyme cleavage patterns. For example, sample and control DNA is isolated, amplified (optionally), digested with one or more restriction endonucleases, and fragment length sizes are determined by gel electrophoresis and compared. Differences in fragment length sizes between sample and control DNA indicates mutations in the sample DNA. Moreover, the use of sequence specific ribozymes (see, for example, U.S. Pat. No. 5,498,531) can be used to score for the presence of specific mutations by development or loss of a ribozyme cleavage site.  
      In other embodiments, genetic mutations in MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 can be identified by hybridizing a sample and control nucleic acids, e.g., DNA or RNA, to high density arrays containing hundreds or thousands of oligonucleotides probes (Cronin, M. T. et al. (1996)  Human Mutation  7: 244-255; Kozal, M. J. et al. (1996)  Nature Medicine  2: 753-759). For example, genetic mutations in MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 can be identified in two dimensional arrays containing light-generated DNA probes as described in Cronin, M. T. et al. supra. Briefly, a first hybridization array of probes can be used to scan through long stretches of DNA in a sample and control to identify base changes between the sequences by making linear arrays of sequential overlapping probes. This step allows the identification of point mutations. This step is followed by a second hybridization array that allows the characterization of specific mutations by using smaller, specialized probe arrays complementary to all variants or mutations detected. Each mutation array is composed of parallel probe sets, one complementary to the wild-type gene and the other complementary to the mutant gene.  
      In yet another embodiment, any of a variety of sequencing reactions known in the art can be used to directly sequence the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 gene and detect mutations by comparing the sequence of the sample MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 with the corresponding wild-type (control) sequence. Examples of sequencing reactions include those based on techniques developed by Maxam and Gilbert ((1977)  Proc. Natl. Acad. Sci. USA  74:560) or Sanger ((1977)  Proc. Natl. Acad. Sci. USA  74:5463). It is also contemplated that any of a variety of automated sequencing procedures can be utilized when performing the diagnostic assays ((1995)  Biotechniques  19:448), including sequencing by mass spectrometry (see, e.g., PCT International Publication No. WO 94/16101; Cohen et al. (1996)  Adv. Chromatogr.  36:127-162; and Griffin et al. (1993)  Appl. Biochem. Biotechnol.  38:147-159).  
      Other methods for detecting mutations in the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 gene include methods in which protection from cleavage agents is used to detect mismatched bases in RNA/RNA or RNA/DNA heteroduplexes (Myers et al. (1985)  Science  230:1242). In general, the art technique of “mismatch cleavage” starts by providing heteroduplexes of formed by hybridizing (labeled) RNA or DNA containing the wild-type HST-4 and/or HST-5 sequence with potentially mutant RNA or DNA obtained from a tissue sample. The double-stranded duplexes are treated with an agent which cleaves single-stranded regions of the duplex such as which will exist due to basepair mismatches between the control and sample strands. For instance, RNA/DNA duplexes can be treated with RNase and DNA/DNA hybrids treated with S1 nuclease to enzymatically digesting the mismatched regions. In other embodiments, either DNA/DNA or RNA/DNA duplexes can be treated with hydroxylamine or osmium tetroxide and with piperidine in order to digest mismatched regions. After digestion of the mismatched regions, the resulting material is then separated by size on denaturing polyacrylamide gels to determine the site of mutation. See, for example, Cotton et al. (1988)  Proc. Natl. Acad. Sci. USA  85:4397; Saleeba et al. (1992)  Methods Enzymol.  217:286-295. In a preferred embodiment, the control DNA or RNA can be labeled for detection.  
      In still another embodiment, the mismatch cleavage reaction employs one or more proteins that recognize mismatched base pairs in double-stranded DNA (so called “DNA mismatch repair” enzymes) in defined systems for detecting and mapping point mutations in MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 cDNAs obtained from samples of cells. For example, the mutY enzyme of  E. coli  cleaves A at G/A mismatches and the thymidine DNA glycosylase from HeLa cells cleaves T at G/T mismatches (Hsu et al. (1994)  Carcinogenesis  15:1657-1662). According to an exemplary embodiment, a probe based on an HST-4 and/or an HST-5 sequence, e.g., a wild-type MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence, is hybridized to a cDNA or other DNA product from a test cell(s). The duplex is treated with a DNA mismatch repair enzyme, and the cleavage products, if any, can be detected from electrophoresis protocols or the like. See, for example, U.S. Pat. No. 5,459,039.  
      In other embodiments, alterations in electrophoretic mobility will be used to identify mutations in MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 genes. For example, single strand conformation polymorphism (SSCP) may be used to detect differences in electrophoretic mobility between mutant and wild type nucleic acids (Orita et al. (1989)  Proc Natl. Acad. Sci USA:  86:2766, see also Cotton (1993)  Mutat. Res.  285:125-144; and Hayashi (1992)  Genet. Anal. Tech. Appl.  9:73-79). Single-stranded DNA fragments of sample and control MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acids will be denatured and allowed to renature. The secondary structure of single-stranded nucleic acids varies according to sequence, the resulting alteration in electrophoretic mobility enables the detection of even a single base change. The DNA fragments may be labeled or detected with labeled probes. The sensitivity of the assay may be enhanced by using RNA (rather than DNA), in which the secondary structure is more sensitive to a change in sequence. In a preferred embodiment, the subject method utilizes heteroduplex analysis to separate double stranded heteroduplex molecules on the basis of changes in electrophoretic mobility (Keen et al. (1991)  Trends Genet  7:5).  
      In yet another embodiment the movement of mutant or wild-type fragments in polyacrylamide gels containing a gradient of denaturant is assayed using denaturing gradient gel electrophoresis (DGGE) (Myers et al. (1985)  Nature  313:495). When DGGE is used as the method of analysis, DNA will be modified to insure that it does not completely denature, for example by adding a GC clamp of approximately 40 bp of high-melting GC-rich DNA by PCR. In a further embodiment, a temperature gradient is used in place of a denaturing gradient to identify differences in the mobility of control and sample DNA (Rosenbaum and Reissner (1987)  Biophys Chem  265:12753).  
      Examples of other techniques for detecting point mutations include, but are not limited to, selective oligonucleotide hybridization, selective amplification, or selective primer extension. For example, oligonucleotide primers may be prepared in which the known mutation is placed centrally and then hybridized to target DNA under conditions which permit hybridization only if a perfect match is found (Saiki et al. (1986)  Nature  324:163); Saiki et al. (1989)  Proc. Natl. Acad. Sci. USA  86:6230). Such allele specific oligonucleotides are hybridized to PCR amplified target DNA or a number of different mutations when the oligonucleotides are attached to the hybridizing membrane and hybridized with labeled target DNA.  
      Alternatively, allele specific amplification technology which depends on selective PCR amplification may be used in conjunction with the instant invention. Oligonucleotides used as primers for specific amplification may carry the mutation of interest in the center of the molecule (so that amplification depends on differential hybridization) (Gibbs et al. (1989)  Nucleic Acids Res.  17:2437-2448) or at the extreme 3′ end of one primer where, under appropriate conditions, mismatch can prevent, or reduce polymerase extension (Prossner (1993)  Tibtech  11:238). In addition it may be desirable to introduce a novel restriction site in the region of the mutation to create cleavage-based detection (Gasparini et al. (1992)  Mol. Cell Probes  6:1). It is anticipated that in certain embodiments amplification may also be performed using Taq ligase for amplification (Barany (1991)  Proc. Natl. Acad. Sci USA  88:189). In such cases, ligation will occur only if there is a perfect match at the 3′ end of the 5′ sequence making it possible to detect the presence of a known mutation at a specific site by looking for the presence or absence of amplification.  
      The methods described herein may be performed, for example, by utilizing pre-packaged diagnostic kits comprising at least one probe nucleic acid or antibody reagent described herein, which may be conveniently used, e.g., in clinical settings to diagnose patients exhibiting symptoms or family history of a disease or illness involving an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 gene.  
      Furthermore, any cell type or tissue in which MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 is expressed may be utilized in the prognostic assays described herein.  
      5. Monitoring of Effects During Clinical Trials  
      Monitoring the influence of agents (e.g., drugs) on the expression or activity of an MTP-1 protein (e.g., the maintenance of cellular homeostasis) can be applied not only in basic drug screening, but also in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase MTP-1 gene expression, protein levels, or upregulate MTP-1 activity, can be monitored in clinical trials of subjects exhibiting decreased MTP-1 gene expression, protein levels, or downregulated MTP-1 activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease MTP-1 gene expression, protein levels, or downregulate MTP-1 activity, can be monitored in clinical trials of subjects exhibiting increased MTP-1 gene expression, protein levels, or upregulated MTP-1 activity. In such clinical trials, the expression or activity of an MTP-1 gene, and preferably, other genes that have been implicated in, for example, an MTP-1-associated disorder can be used as a “read out” or markers of the phenotype of a particular cell.  
      For example, and not by way of limitation, genes, including MTP-1, that are modulated in cells by treatment with an agent (e.g., compound, drug or small molecule) which modulates MTP-1 activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on MTP-1-associated disorders (e.g., disorders characterized by deregulated hematopoiesis and/or inflammation and/or lipid metabolism), for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of MTP-1 and other genes implicated in the MTP-1-associated disorder, respectively. The levels of gene expression (e.g., a gene expression pattern) can be quantified by northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of protein produced, by one of the methods as described herein, or by measuring the levels of activity of MTP-1 or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during treatment of the individual with the agent.  
      Monitoring the influence of agents (e.g., drugs) on the expression or activity of an OAT protein (e.g., the modulation of gene expression, and or cell growth and differentiation mechanisms) can be applied not only in basic drug screening, but also in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase OAT gene expression, protein levels, or upregulate OAT activity, can be monitored in clinical trials of subjects exhibiting decreased OAT gene expression, protein levels, or downregulated OAT activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease OAT gene expression, protein levels, or downregulate OAT activity, can be monitored in clinical trials of subjects exhibiting increased OAT gene expression, protein levels, or upregulated OAT activity. In such clinical trials, the expression or activity of an OAT gene, and preferably, other genes that have been implicated in, for example, an OAT-associated disorder can be used as a “read out” or markers of the phenotype of a particular cell.  
      For example, and not by way of limitation, genes, including OAT, that are modulated in cells by treatment with an agent (e.g., compound, drug or small molecule) which modulates OAT activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on OAT-associated disorders (e.g., disorders characterized by deregulated organic anion transport, gene expression, and/or cell growth and differentiation mechanisms), for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of OAT and other genes implicated in the OAT-associated disorder, respectively. The levels of gene expression (e.g., a gene expression pattern) can be quantified by northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of protein produced, by one of the methods as described herein, or by measuring the levels of activity of OAT or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during treatment of the individual with the agent.  
      Monitoring the influence of agents (e.g., drugs) on the expression or activity of an HST-1 polypeptide (e.g., the modulation of sugar transport) can be applied not only in basic drug screening, but also in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase HST-1 gene expression, polypeptide levels, or upregulate HST-l activity, can be monitored in clinical trials of subjects exhibiting decreased HST-1 gene expression, polypeptide levels, or downregulated HST-1 activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease HST-1 gene expression, polypeptide levels, or downregulate HST-1 activity, can be monitored in clinical trials of subjects exhibiting increased HST-1 gene expression, polypeptide levels, or upregulated HST-1 activity. In such clinical trials, the expression or activity of an HST-1 gene, and preferably, other genes that have been implicated in, for example, an HST-1-associated disorder can be used as a “read out” or markers of the phenotype of a particular cell.  
      For example, and not by way of limitation, genes, including HST-1, that are modulated in cells by treatment with an agent (e.g., compound, drug or small molecule) which modulates HST-1 activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on HST-1-associated disorders (e.g., disorders characterized by deregulated signaling or sugar transport), for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of HST-1 and other genes implicated in the HST-1-associated disorder, respectively. The levels of gene expression (e.g., a gene expression pattern) can be quantified by northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of polypeptide produced, by one of the methods as described herein, or by measuring the levels of activity of HST-1 or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during treatment of the individual with the agent.  
      Monitoring the influence of agents (e.g., drugs) on the expression or activity of a TP-2 polypeptide (e.g., the modulation of transport of biological molecules across membranes) can be applied not only in basic drug screening, but also in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase TP-2 gene expression, polypeptide levels, or upregulate TP-2 activity, can be monitored in clinical trials of subjects exhibiting decreased TP-2 gene expression, polypeptide levels, or downregulated TP-2 activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease TP-2 gene expression, polypeptide levels, or downregulate TP-2 activity, can be monitored in clinical trials of subjects exhibiting increased TP-2 gene expression, polypeptide levels, or upregulated TP-2 activity. In such clinical trials, the expression or activity of a TP-2 gene, and preferably, other genes that have been implicated in, for example, a TP-2-associated disorder can be used as a “read out” or markers of the phenotype of a particular cell.  
      For example, and not by way of limitation, genes, including TP-2, that are modulated in cells by treatment with an agent (e.g., compound, drug or small molecule) which modulates TP-2 activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on transporter-associated disorders, for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of TP-2 and other genes implicated in the transporter-associated disorder, respectively. The levels of gene expression (e.g., a gene expression pattern) can be quantified by northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of polypeptide produced, by one of the methods as described herein, or by measuring the levels of activity of TP-2 or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during treatment of the individual with the agent.  
      Monitoring the influence of agents (e.g., drugs) on the expression or activity of a PLTR-1 protein (e.g., the modulation of gene expression, cellular signaling, PLTR-1 activity, phospholipid transporter activity, and/or cell growth, proliferation, differentiation, absorption, and/or secretion mechanisms) can be applied not only in basic drug screening, but also in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase PLTR-1 gene expression, protein levels, or upregulate PLTR-1 activity, can be monitored in clinical trials of subjects exhibiting decreased PLTR-1 gene expression, protein levels, or downregulated PLTR-1 activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease PLTR-1 gene expression, protein levels, or downregulate PLTR-1 activity, can be monitored in clinical trials of subjects exhibiting increased PLTR-1 gene expression, protein levels, or upregulated PLTR-1 activity. In such clinical trials, the expression or activity of a PLTR-1 gene, and preferably, other genes that have been implicated in, for example, a PLTR-1-associated disorder can be used as a “read out” or markers of the phenotype of a particular cell.  
      For example, and not by way of limitation, genes, including PLTR-1, that are modulated in cells by treatment with an agent (e.g., compound, drug or small molecule) which modulates PLTR-1 activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on PLTR-1-associated disorders (e.g., disorders characterized by deregulated gene expression, cellular signaling, PLTR-1 activity, phospholipid transporter activity, and/or cell growth, proliferation, differentiation, absorption, and/or secretion mechanisms), for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of PLTR-1 and other genes implicated in the PLTR-1-associated disorder, respectively. The levels of gene expression (e.g., a gene expression pattern) can be quantified by northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of protein produced, by one of the methods as described herein, or by measuring the levels of activity of PLTR-1 or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during treatment of the individual with the agent.  
      Monitoring the influence of agents (e.g., drugs) on the expression or activity of a TFM-2 and/or TFM-3 polypeptide (e.g., the modulation of transport of biological molecules across membranes) can be applied not only in basic drug screening, but also in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase TFM-2 and/or TFM-3 gene expression, polypeptide levels, or upregulate TFM-2 and/or TFM-3 activity, can be monitored in clinical trials of subjects exhibiting decreased TFM-2 and/or TFM-3 gene expression, polypeptide levels, or downregulated TFM-2 and/or TFM-3 activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease TFM-2 and/or TFM-3 gene expression, polypeptide levels, or downregulate TFM-2 and/or TFM-3 activity, can be monitored in clinical trials of subjects exhibiting increased TFM-2 and/or TFM-3 gene expression, polypeptide levels, or upregulated TFM-2 and/or TFM-3 activity. In such clinical trials, the expression or activity of a TFM-2 and/or TFM-3 gene, and preferably, other genes that have been implicated in, for example, a TFM-2 and/or TFM-3-associated disorder can be used as a “read out” or markers of the phenotype of a particular cell.  
      For example, and not by way of limitation, genes, including TFM-2 and/or TFM-3, that are modulated in cells by treatment with an agent (e.g., compound, drug or small molecule) which modulates TFM-2 and/or TFM-3 activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on transporter-associated disorders, for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of TFM-2 and/or TFM-3 and other genes implicated in the transporter-associated disorder, respectively. The levels of gene expression (e.g., a gene expression pattern) can be quantified by northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of polypeptide produced, by one of the methods as described herein, or by measuring the levels of activity of TFM-2 and/or TFM-3 or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during treatment of the individual with the agent.  
      Monitoring the influence of agents (e.g., drugs) on the expression or activity of a 67118, 67067, and/or 62092 polypeptide (e.g., the modulation of gene expression, cellular signaling, 67118, 67067, and/or 62092 activity, phospholipid transporter activity, and/or cell growth, proliferation, differentiation, absorption, and/or secretion mechanisms) can be applied not only in basic drug screening, but also in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase 67118, 67067, and/or 62092 gene expression, polypeptide levels, or upregulate 67118, 67067, and/or 62092 activity, can be monitored in clinical trials of subjects exhibiting decreased 67118, 67067, and/or 62092 gene expression, polypeptide levels, or downregulated 67118, 67067, and/or 62092 activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease 67118, 67067, and/or 62092 gene expression, polypeptide levels, or downregulate 67118, 67067, and/or 62092 activity, can be monitored in clinical trials of subjects exhibiting increased 67118, 67067, and/or 62092 gene expression, polypeptide levels, or upregulated 67118, 67067, and/or 62092 activity. In such clinical trials, the expression or activity of a 67118, 67067, and/or 62092 gene, and preferably, other genes that have been implicated in, for example, a 67118, 67067, and/or 62092-associated disorder can be used as a “read out” or markers of the phenotype of a particular cell.  
      For example, and not by way of limitation, genes, including 67118, 67067, and/or 62092, that are modulated in cells by treatment with an agent (e.g., compound, drug or small molecule) which modulates 67118, 67067, and/or 62092 activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on 67118, 67067, or 62092-associated disorders (e.g., disorders characterized by deregulated gene expression, cellular signaling, 67118 or 67067 activity, phospholipid transporter activity, and/or cell growth, proliferation, differentiation, absorption, and/or secretion mechanisms or disorders characterized by 62092 activity, nucleotide binding activity, and/or apoptosis mechanisms), for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of 67118, 67067, and/or 62092 and other genes implicated in the 67118, 67067, or 62092-associated disorder, respectively. The levels of gene expression (e.g., a gene expression pattern) can be quantified by northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of polypeptide produced, by one of the methods as described herein, or by measuring the levels of activity of 67118, 67067, and/or 62092 or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during treatment of the individual with the agent.  
      Monitoring the influence of agents (e.g., drugs) on the expression or activity of a HAAT protein (e.g., the modulation of protein synthesis, hormone metabolism, nerve transmission, cellular activation, regulation of cell growth, production of metabolic energy, synthesis of purines and pyrimidines, nitrogen metabolism, and/or biosynthesis of urea) can be applied not only in basic drug screening, but also in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase HAAT gene expression, protein levels, or upregulate HAAT activity, can be monitored in clinical trials of subjects exhibiting decreased HAAT gene expression, protein levels, or downregulated HAAT activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease HAAT gene expression, protein levels, or downregulate HAAT activity, can be monitored in clinical trials of subjects exhibiting increased HAAT gene expression, protein levels, or upregulated HAAT activity. In such clinical trials, the expression or activity of a HAAT gene, and preferably, other genes that have been implicated in, for example, a HAAT-associated disorder can be used as a “read out” or markers of the phenotype of a particular cell.  
      For example, and not by way of limitation, genes, including HAAT, that are modulated in cells by treatment with an agent (e.g., compound, drug or small molecule) which modulates HAAT activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on HAAT-associated disorders (e.g., disorders characterized by deregulated protein synthesis, hormone metabolism, nerve transmission, cellular activation, regulation of cell growth, production of metabolic energy, synthesis of purines and pyrimidines, nitrogen metabolism, and/or biosynthesis of urea), for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of HAAT and other genes implicated in the HAAT-associated disorder, respectively. The levels of gene expression (e.g., a gene expression pattern) can be quantified by northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of protein produced, by one of the methods as described herein, or by measuring the levels of activity of HAAT or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during treatment of the individual with the agent.  
      Monitoring the influence of agents (e.g., drugs) on the expression or activity of an HST-4 and/or an HST-5 polypeptide (e.g., the modulation of sugar transport) can be applied not only in basic drug screening, but also in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase HST-4 and/or HST-5 gene expression, polypeptide levels, or upregulate HST-4 and/or HST-5 activity, can be monitored in clinical trials of subjects exhibiting decreased HST-4 and/or HST-5 gene expression, polypeptide levels, or downregulated HST-4 and/or HST-5 activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease HST-4 and/or HST-5 gene expression, polypeptide levels, or downregulate HST-4 and/or HST-5 activity, can be monitored in clinical trials of subjects exhibiting increased HST-4 and/or HST-5 gene expression, polypeptide levels, or upregulated HST-4 and/or HST-5 activity. In such clinical trials, the expression or activity of an HST-4 and/or HST-5 gene, and preferably, other genes that have been implicated in, for example, an HST-4- and/or an HST-5-associated disorder can be used as a “read out” or markers of the phenotype of a particular cell.  
      For example, and not by way of limitation, genes, including HST-4 and/or HST-5, that are modulated in cells by treatment with an agent (e.g., compound, drug or small molecule) which modulates HST-4 and/or HST-5 activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on HST-4- and/or HST-5-associated disorders (e.g., disorders characterized by deregulated signaling or sugar transport), for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of HST-4 and/or HST-5 and other genes implicated in the HST-4- and/or the HST-5-associated disorder, respectively. The levels of gene expression (e.g., a gene expression pattern) can be quantified by northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of polypeptide produced, by one of the methods as described herein, or by measuring the levels of activity of HST-4 and/or HST-5 or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during treatment of the individual with the agent.  
      In a preferred embodiment, the present invention provides a method for monitoring the effectiveness of treatment of a subject with an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate identified by the screening assays described herein) including the steps of (i) obtaining a pre-administration sample from a subject prior to administration of the agent; (ii) detecting the level of expression of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide, mRNA, or genomic DNA in the preadministration sample; (iii) obtaining one or more post-administration samples from the subject; (iv) detecting the level of expression or activity of the HST-4 and/or the HST-5 polypeptide, mRNA, or genomic DNA in the post-administration samples; (v) comparing the level of expression or activity of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptide, mRNA, or genomic DNA in the pre-administration sample with the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 polypeptide, mRNA, or genomic DNA in the post administration sample or samples; and (vi) altering the administration of the agent to the subject accordingly. For example, increased administration of the agent may be desirable to increase the expression or activity of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 to higher levels than detected, i.e., to increase the effectiveness of the agent. Alternatively, decreased administration of the agent may be desirable to decrease expression or activity of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 to lower levels than detected, i.e. to decrease the effectiveness of the agent. According to such an embodiment, MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression or activity may be used as an indicator of the effectiveness of an agent, even in the absence of an observable phenotypic response.  
      E. Methods of Treatment:  
      The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having a disorder associated with aberrant or unwanted MTP-1 expression or activity, e.g., a transporter-associated disorder such as a hematopoietic disorder, an immunological disorder, a lipid metabolism-related disorder, a CNS disorder; a cellular proliferation, growth, differentiation, or migration disorder; a, musculoskeletal disorder; a cardiovascular disorder; an immune disorder; or a hormonal disorder. The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having an OAT-associated disorder, e.g., a disorder associated with aberrant or unwanted OAT expression or activity. The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having a disorder associated with aberrant or unwanted HST-1 expression or activity, e.g. a sugar transporter disorder. The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having a disorder associated with aberrant or unwanted TP-2 expression or activity, e.g. a transporter-associated disorder. The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having a PLTR-1-associated disorder, e.g., a disorder associated with aberrant or unwanted PLTR-1 expression or activity (e.g., a cardiovascular disorder). The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having a disorder associated with aberrant or unwanted TFM-2 and/or TFM-3 expression or activity, e.g. a transporter-associated disorder. The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having a disorder associated with aberrant or unwanted 67118, 67067, and/or 62092 expression or activity, e.g. a phospholipid transporter-associated disorder. The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having a HAAT-associated disorder, e.g., a disorder associated with aberrant or unwanted HAAT expression or activity. The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having a disorder associated with aberrant or unwanted HST-4 and/or HST-5 expression or activity, e.g. a sugar transporter disorder. “Treatment”, as used herein, is defined as the application or administration of a therapeutic agent to a patient, or application or administration of a therapeutic agent to an isolated tissue or cell from a patient, who has a disease or disorder, a symptom of disease or disorder or a predisposition toward a disease or disorder, or is at risk of (or susceptible to) a disease or disorder, with the purpose to cure, heal, alleviate, relieve, alter, remedy, ameliorate, improve or affect the disease or disorder, the symptoms of disease or disorder, the risk of (or susceptibility to) the disease or disorder or the predisposition toward a disease or disorder. A therapeutic agent includes, but is not limited to, small molecules, peptides, polypeptides, antibodies, ribozymes and antisense oligonucleotides.  
      With regards to both prophylactic and therapeutic methods of treatment, such treatments may be specifically tailored or modified, based on knowledge obtained from the field of pharmacogenomics. “Pharmacogenomics”, as used herein, refers to the application of genomics technologies such as gene sequencing, statistical genetics, and gene expression analysis to drugs in clinical development and on the market. More specifically, the term refers the study of how a patient&#39;s genes determine his or her response to a drug (e.g., a patient&#39;s “drug response phenotype”, or “drug response genotype”). Thus, another aspect of the invention provides methods for tailoring an individual&#39;s prophylactic or therapeutic treatment with either the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 molecules of the present invention or MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 modulators according to that individual&#39;s drug response genotype. Pharmacogenomics allows a clinician or physician to target prophylactic or therapeutic treatments to patients who will most benefit from the treatment and to avoid treatment of patients who will experience toxic drug-related side effects.  
      1. Prophylactic Methods  
      In one aspect, the invention provides a method for preventing in a subject, a disease or condition associated with an aberrant or unwanted MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression or activity, by administering to the subject an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 or an agent which modulates MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression or at least one MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity. Subjects at risk for a disease which is caused or contributed to by aberrant or unwanted MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression or activity can be identified by, for example, any or a combination of diagnostic or prognostic assays as described herein. Administration of a prophylactic agent can occur prior to the manifestation of symptoms characteristic of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 aberrancy, such that a disease or disorder is prevented or, alternatively, delayed in its progression. Depending on the type of MTP-1, OAT, HST-1, TP-2, PLTR-1,-TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 aberrancy, for example, MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 agonist or MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 antagonist agent can be used for treating the subject. The appropriate agent can be determined based on screening assays described herein.  
      2. Therapeutic Methods  
      Another aspect of the invention pertains to methods of modulating MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression or activity for therapeutic purposes. Accordingly, in an exemplary embodiment, the modulatory method of the invention involves contacting a cell capable of expressing MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 with an agent that modulates one or more of the activities of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptide activity associated with the cell, such that MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity in the cell is modulated. An agent that modulates MTP-1 protein activity can be an agent as described herein, such as a nucleic acid or a protein, a naturally-occurring substrate molecule of an MTP-1 protein (e.g., cytotoxic substances, ions, peptides, metabolites), an MTP-1 antibody, an MTP-1 agonist or antagonist, a peptidomimetic of an MTP-1 agonist or antagonist, or other small molecule. An agent that modulates OAT protein activity can be an agent as described herein, such as a nucleic acid or a protein, a naturally-occurring target molecule of an OAT protein (e.g., an OAT substrate), an OAT antibody, an OAT agonist or antagonist, a peptidomimetic of an OAT agonist or antagonist, or other small molecule. An agent that modulates HST-1 polypeptide activity can be an agent as described herein, such as a nucleic acid or a polypeptide, a naturally-occurring target molecule of an HST-1 polypeptide (e.g., an HST-1 substrate), an HST-1 antibody, an HST-1 agonist or antagonist, a peptidomimetic of an HST-1 agonist or antagonist, or other small molecule. An agent that modulates TP-2 polypeptide activity can be an agent as described herein, such as a nucleic acid or a polypeptide, a naturally-occurring target molecule of a TP-2 polypeptide (e.g., a TP-2 substrate), a TP-2 antibody, a TP-2 agonist or antagonist, a peptidomimetic of a TP-2 agonist or antagonist, or other small molecule. An agent that modulates PLTR-1 protein activity can be an agent as described herein, such as a nucleic acid or a protein, a naturally-occurring target molecule of a PLTR-1 protein (e.g., a PLTR-1 substrate), a PLTR-1 antibody, a PLTR-1 agonist or antagonist, a peptidomimetic of a PLTR-1 agonist or antagonist, or other small molecule. An agent that modulates TFM-2 and/or TFM-3 polypeptide activity can be an agent as described herein, such as a nucleic acid or a polypeptide, a naturally-occurring target molecule of a TFM-2 and/or TFM-3 polypeptide (e.g., a TFM-2 and/or TFM-3 substrate), a TFM-2 and/or TFM-3 antibody, a TFM-2 and/or TFM-3 agonist or antagonist, a peptidomimetic of a TFM-2 and/or TFM-3 agonist or antagonist, or other small molecule. An agent that modulates 67118, 67067, and/or 62092 polypeptide activity can be an agent as described herein, such as a nucleic acid or a polypeptide, a naturally-occurring target molecule of a 67118, 67067, and/or 62092 polypeptide (e.g., a 67118, 67067, and/or 62092 substrate), a 67118, 67067, and/or 62092 antibody, a 67118, 67067, and/or 62092 agonist or antagonist, a peptidomimetic of a 67118, 67067, and/or 62092 agonist or antagonist, or other small molecule. An agent that modulates HAAT protein activity can be an agent as described herein, such as a nucleic acid or a protein, a naturally-occurring target molecule of a HAAT protein (e.g., a HAAT substrate), a HAAT antibody, a HAAT agonist or antagonist, a peptidomimetic of a HAAT agonist or antagonist, or other small molecule. An agent that modulates HST-4 and/or HST-5 polypeptide activity can be an agent as described herein, such as a nucleic acid or a polypeptide, a naturally-occurring target molecule of an HST-4 and/or an HST-5 polypeptide (e.g., an HST-4 and/or an HST-5 substrate), an HST-4 and/or an HST-5 antibody, an HST-4 and/or an HST-5 agonist or antagonist, a peptidomimetic of an HST-4 and/or an HST-5 agonist or antagonist, or other small molecule. In one embodiment, the agent stimulates one or more MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activities. Examples of such stimulatory agents include active MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides and nucleic acid molecules encoding MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 that have been introduced into the cell. In another embodiment, the agent inhibits one or more MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activities. Examples of such inhibitory agents include antisense MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 nucleic acid molecules, anti-HST-4 and/or -HST-5 antibodies, and MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 inhibitors. These modulatory methods can be performed in vitro (e.g., by culturing the cell with the agent) or, alternatively, in vivo (e.g., by administering the agent to a subject). As such, the present invention provides methods of treating an individual afflicted with a disease or disorder characterized by aberrant or unwanted expression or activity of an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide or nucleic acid molecule. In one embodiment, the method involves administering an agent (e.g., an agent identified by a screening assay described herein), or combination of agents that modulates (e.g., upregulates or downregulates) MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression or activity. In another embodiment, the method involves administering an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or an HST-5 polypeptide or nucleic acid molecule as therapy to compensate for reduced, aberrant, or unwanted MTP-1, OAT, HST-1, TP-2, PLTR-1,-TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression or activity.  
      Stimulation of MTP-1 activity is desirable in situations in which MTP-1 is abnormally downregulated and/or in which increased MTP-1 activity is likely to have a beneficial effect. Likewise, inhibition of MTP-1 activity is desirable in situations in which MTP-1 is abnormally upregulated and/or in which decreased MTP-1 activity is likely to have a beneficial effect.  
      (i) Methods for Inhibiting Target Gene MTP-1 Expression, Synthesis, or Activity  
      As discussed above, genes involved in hematopoietic and/or immunological and/or lipid metabolism-related diseases or disorders may cause such disorders via an increased level of gene activity. In some cases, such up-regulation may have a causative or exacerbating effect on the disease state. A variety of techniques may be used to inhibit the expression, synthesis, or activity of such genes and/or proteins.  
      For example, compounds such as those identified through assays described above, which exhibit inhibitory activity, may be used in accordance with the invention to ameliorate hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms. Such molecules may include, but are not limited to, small organic molecules, peptides, antibodies, and the like.  
      For example, compounds can be administered that compete with endogenous ligand for the MTP-1 protein. The resulting reduction in the amount of ligand-bound MTP-1 protein will modulate endothelial cell physiology. Compounds that can be particularly useful for this purpose include, for example, soluble proteins or peptides, such as peptides comprising one or more of the extra-membrane domains, or portions and/or analogs thereof, of the MTP-1 protein, including, for example, soluble fusion proteins such as Ig-tailed fusion proteins. (For a discussion of the production of Ig-tailed fusion proteins, see, for example, U.S. Pat. No. 5,116,964). Alternatively, compounds, such as ligand analogs or antibodies, that bind to the MTP-1 active site, but do not activate the protein, can be effective in inhibiting MTP-1 protein activity.  
      Further, antisense and ribozyme molecules, as described herein, which inhibit expression of the MTP-1 gene may also be used in accordance with the invention to inhibit aberrant MTP-1 gene activity. Still further, triple helix molecules may be utilized in inhibiting aberrant MTP-1 gene activity.  
      Antibodies that are both specific for the MTP-1 protein and interfere with its activity may also be used to modulate or inhibit MTP-1 protein function. Such antibodies may be generated using standard techniques described herein, against the MTP-1 protein itself or against peptides corresponding to portions of the protein. Such antibodies include but are not limited to polyclonal, monoclonal, Fab fragments, single chain antibodies, or chimeric antibodies.  
      In instances where the target gene protein is intracellular and whole antibodies are used, internalizing antibodies may be preferred. Lipofectin liposomes may be used to deliver the antibody or a fragment of the Fab region which binds to the target epitope into cells. Where fragments of the antibody are used, the smallest inhibitory  
      fragment which binds to the target protein&#39;s binding domain is preferred. For example, peptides having an amino acid sequence corresponding to the domain of the variable region of the antibody that binds to the target gene protein may be used. Such peptides may be synthesized chemically or produced via recombinant DNA technology using  
      methods well known in the art (described in, for example, Creighton (1983), supra; and Sambrook et al. (1989) supra). Single chain neutralizing antibodies which bind to intracellular target gene epitopes may also be administered. Such single chain antibodies may be administered, for example, by expressing nucleotide sequences encoding single-chain antibodies within the target cell population by utilizing, for example, techniques such as those described in Marasco et al. (1993)  Proc. Natl. Acad. Sci. USA  90:7889-7893).  
      Any of the administration techniques described below which are appropriate for peptide administration may be utilized to effectively administer inhibitory target gene antibodies to their site of action.  
      (ii) Methods for Restoring or Enhancing Target Gene MTP-1 Activity  
      Genes that cause hematopoietic and/or immunological and/or lipid metabolism-related diseases or disorders may be underexpressed within cellular growth or proliferative situations. Alternatively, the activity of the protein products of such genes may be decreased, leading to the development of hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms. Such down-regulation of gene expression or decrease of protein activity might have a causative or exacerbating effect on the disease state.  
      In some cases, genes that are up-regulated in the disease state might be exerting a protective effect. A variety of techniques may be used to increase the expression, synthesis, or activity of genes and/or proteins that exert a protective effect in response to hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder conditions.  
      Described in this section are methods whereby the level MTP-1 activity may be, increased to levels wherein hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms are ameliorated. The level of MTP-1 activity may be increased, for example, by either increasing the level of MTP-1 gene expression or by increasing the level of active MTP-1 protein which is present.  
      For example, a MTP-1 protein, at a level sufficient to ameliorate hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms may be administered to a patient exhibiting such symptoms. Any of the techniques discussed below may be used for such administration. One of skill in the art will readily be able to ascertain the concentration of effective, non-toxic doses of the MTP-1 protein, utilizing techniques such as those described above.  
      Additionally, RNA sequences encoding a MTP-1 protein may be directly administered to a patient exhibiting hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms, at a concentration sufficient to produce a level of MTP-1 protein such that hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms are ameliorated. Any of the techniques discussed below, which achieve intracellular administration of compounds, such as, for example, liposome administration, may be used for the administration of such RNA molecules. The RNA molecules may be produced, for example, by recombinant techniques such as those described herein.  
      Further, subjects may be treated by gene replacement therapy. One or more copies of a MTP-1 gene, or a portion thereof, that directs the production of a normal MTP-1 protein with MTP-1 function, may be inserted into cells using vectors which include, but are not limited to adenovirus, adeno-associated virus, and retrovirus vectors, in addition to other particles that introduce DNA into cells, such as liposomes. Additionally, techniques such as those described above may be used for the introduction of MTP-1 gene sequences into human cells.  
      Cells, preferably, autologous cells, containing MTP-1 expressing gene sequences may then be introduced or reintroduced into the subject at positions which allow for the amelioration of hematopoietic and/or immunological and/or lipid metabolism-related disease or disorder symptoms. Such cell replacement techniques may be preferred, for example, when the gene product is a secreted, extracellular gene product.  
      Stimulation of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity is desirable in situations in which OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 is abnormally downregulated and/or in which increased OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity is likely to have a beneficial effect. Likewise, inhibition of OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity is desirable in situations in which OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 is abnormally upregulated and/or in which decreased OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 activity is likely to have a beneficial effect.  
      3. Pharmacogenomics  
      The MTP-1 molecules of the present invention, as well as agents, or modulators which have a stimulatory or inhibitory effect on MTP-1 activity (e.g., MTP-1 gene expression) as identified by a screening assay described herein can be administered to individuals to treat (prophylactically or therapeutically) MTP-1-associated disorders (e.g., proliferative disorders, CNS disorders, cardiac disorders, metabolic disorders, or muscular disorders) associated with aberrant or unwanted MTP-1 activity. In conjunction with such treatment, pharmacogenomics (i.e., the study of the relationship between an individual&#39;s genotype and that individual&#39;s response to a foreign compound or drug) may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drug. Thus, a physician or clinician may consider applying knowledge obtained in relevant pharmacogenomics studies in determining whether to administer an MTP-1 molecule or MTP-1 modulator as well as tailoring the dosage and/or therapeutic regimen of treatment with an MTP-1 molecule or MTP-1 modulator.  
      The OAT molecules of the present invention, as well as agents, or modulators which have a stimulatory or inhibitory effect on OAT activity (e.g., OAT gene expression) as identified by a screening assay described herein can be administered to individuals to treat (prophylactically or therapeutically) OAT-associated disorders (e.g., disorders characterized by aberrant organic anion transport, and/or gene expression, CNS, cardiac, musculoskeletal, metabolic, cell proliferation and/or differentiation disorders) associated with aberrant or unwanted OAT activity. In conjunction with such treatment, pharmacogenomics (i.e., the study of the relationship between an individual&#39;s genotype and that individual&#39;s response to a foreign compound or drug) may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drug. Thus, a physician or clinician may consider applying knowledge obtained in relevant pharmacogenomics studies in determining whether to administer an OAT molecule or OAT modulator as well as tailoring the dosage and/or therapeutic regimen of treatment with an OAT molecule or OAT modulator.  
      The HST-1 molecules of the present invention, as well as agents, or modulators which have a stimulatory or inhibitory effect on HST-1 activity (e.g., HST-1 gene expression) as identified by a screening assay described herein can be administered to individuals to treat (prophylactically or therapeutically) HST-1-associated disorders (e.g., proliferative disorders) associated with aberrant or unwanted HST-1 activity. In conjunction with such treatment, pharmacogenomics (i.e., the study of the relationship between an individual&#39;s genotype and that individual&#39;s response to a foreign compound or drug) may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drug. Thus, a physician or clinician may consider applying knowledge obtained in relevant pharmacogenomics studies in determining whether to administer an HST-1 molecule or HST-1 modulator as well as tailoring the dosage and/or therapeutic regimen of treatment with an HST-1 molecule or HST-1 modulator.  
      The TP-2 molecules of the present invention, as well as agents, or modulators which have a stimulatory or inhibitory effect on TP-2 activity (e.g., TP-2 gene expression) as identified by a screening assay described herein can be administered to individuals to treat (prophylactically or therapeutically) transporter-associated disorders (e.g., proliferative disorders) associated with aberrant or unwanted TP-2 activity. In conjunction with such treatment, pharmacogenomics (i.e., the study of the relationship between an individual&#39;s genotype and that individual&#39;s response to a foreign compound or drug) may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drug. Thus, a physician or clinician may consider applying knowledge obtained in relevant pharmacogenomics studies in determining whether to administer a TP-2 molecule or TP-2 modulator as well as tailoring the dosage and/or therapeutic regimen of treatment with a TP-2 molecule or TP-2 modulator.  
      The PLTR-1 molecules of the present invention, as well as agents, or modulators which have a stimulatory or inhibitory effect on PLTR-1 activity (e.g., PLTR-1 gene expression) as identified by a screening assay described herein can be administered to individuals to treat (prophylactically or therapeutically) PLTR-1-associated disorders (e.g., disorders characterized by aberrant gene expression, PLTR-1 activity, phospholipid transporter activity, cellular signaling, and/or cell growth, proliferation, differentiation, absorption, and/or secretion) associated with aberrant or unwanted PLTR-1 activity. In conjunction with such treatment, pharmacogenomics (i.e., the study of the relationship between an individual&#39;s genotype and that individual&#39;s response to a foreign compound or drug) may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drug. Thus, a physician or clinician may consider applying knowledge obtained in relevant pharmacogenomics studies in determining whether to administer a PLTR-1 molecule or PLTR-1 modulator as well as tailoring the dosage and/or therapeutic regimen of treatment with a PLTR-1 molecule or PLTR-1 modulator.  
      The TFM-2 and/or TFM-3 molecules of the present invention, as well as agents, or modulators which have a stimulatory or inhibitory effect on TFM-2 and/or TFM-3 activity (e.g., TFM-2 and/or TFM-3 gene expression) as identified by a screening assay described herein can be administered to individuals to treat (prophylactically or therapeutically) transporter-associated disorders (e.g., proliferative disorders) associated with aberrant or unwanted TFM-2 and/or TFM-3 activity. In conjunction with such treatment, pharmacogenomics (i.e., the study of the relationship between an individual&#39;s genotype and that individual&#39;s response to a foreign compound or drug) may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drug. Thus, a physician or clinician may consider applying knowledge obtained in relevant pharmacogenomics studies in determining whether to administer a TFM-2 and/or TFM-3 molecule or TFM-2 and/or TFM-3 modulator as well as tailoring the dosage and/or therapeutic regimen of treatment with a TFM-2 and/or TFM-3 molecule or TFM-2 and/or TFM-3 modulator.  
      The 67118, 67067, and/or 62092 molecules of the present invention, as well as agents, or modulators which have a stimulatory or inhibitory effect on 67118, 67067, and/or 62092 activity (e.g., 67118, 67067, and/or 62092 gene expression) as identified by a screening assay described herein can be administered to individuals to treat (prophylactically or therapeutically) 67118, 67067, or 62092-associated disorders (e.g., disorders characterized by aberrant gene expression, 67118, 67067, and/or 62092 activity, phospholipid transporter activity, cellular signaling, and/or cell growth, proliferation, differentiation, absorption, and/or secretion disorders or disorders characterized by 62092 activity, nucleotide binding activity, and/or apoptosis mechanisms) associated with aberrant or unwanted 67118, 67067, and/or 62092 activity. In conjunction with such treatment, pharmacogenomics (i.e., the study of the relationship between an individual&#39;s genotype and that individual&#39;s response to a foreign compound or drug) may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drug. Thus, a physician or clinician may consider applying knowledge obtained in relevant pharmacogenomics studies in determining whether to administer a 67118, 67067, and/or 62092 molecule or 67118, 67067, and/or 62092 modulator as well as tailoring the dosage and/or therapeutic regimen of treatment with a 67118, 67067, and/or 62092 molecule or 67118, 67067, and/or 62092 modulator.  
      The HAAT molecules of the present invention, as well as agents, or modulators which have a stimulatory or inhibitory effect on HAAT activity (e.g., HAAT gene expression) as identified by a screening assay described herein can be administered to individuals to treat (prophylactically or therapeutically) HAAT-associated disorders (e.g., disorders characterized by aberrant protein synthesis, hormone metabolism, nerve transmission, cellular activation, regulation of cell growth, production of metabolic energy, synthesis of purines and pyrimidines, nitrogen metabolism, and/or biosynthesis of urea) associated with aberrant or unwanted HAAT activity. In conjunction with such treatment, pharmacogenomics (i.e., the study of the relationship between an individual&#39;s genotype and that individual&#39;s response to a foreign compound or drug) may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drug. Thus, a physician or clinician may consider applying knowledge obtained in relevant pharmacogenomics studies in determining whether to administer a HAAT molecule or HAAT modulator as well as tailoring the dosage and/or therapeutic regimen of treatment with a HAAT molecule or HAAT modulator.  
      The HST-4 and/or HST-5 molecules of the present invention, as well as agents, or modulators which have a stimulatory or inhibitory effect on HST-4 and/or HST-5 activity (e.g., HST-4 and/or HST-5 gene expression) as identified by a screening assay described herein can be administered to individuals to treat (prophylactically or therapeutically) HST-4- and/or HST-5-associated disorders (e.g., proliferative disorders) associated with aberrant or unwanted HST-4 and/or HST-5 activity. In conjunction with such treatment, pharmacogenomics (i.e., the study of the relationship between an individual&#39;s genotype and that individual&#39;s response to a foreign compound or drug) may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drug. Thus, a physician or clinician may consider applying knowledge obtained in relevant pharmacogenomics studies in determining whether to administer an HST-4 molecule and/or an HST-5 molecule or an HST-4 modulator and/or an HST-5 modulator as well as tailoring the dosage and/or therapeutic regimen of treatment with an HST-4 molecule and/or an HST-5 molecule or an HST-4 modulator and/or an HST-5 modulator.  
      Pharmacogenomics deals with clinically significant hereditary variations in the response to drugs due to altered drug disposition and abnormal action in affected persons. See, for example, Eichelbaum, M. et al. (1996)  Clin. Exp. Pharmacol. Physiol.  23(10-11): 983-985 and Linder, M. W. et al. (1997)  Clin. Chem.  43(2):254-266. In general, two types of pharmacogenetic conditions can be differentiated. Genetic conditions transmitted as a single factor altering the way drugs act on the body (altered drug action) or genetic conditions transmitted as single factors altering the way the body acts on drugs (altered drug metabolism). These pharmacogenetic conditions can occur either as rare genetic defects or as naturally-occurring polymorphisms. For example, glucose-6-phosphate dehydrogenase deficiency (G6PD) is a common inherited enzymopathy in which the main clinical complication is haemolysis after ingestion of oxidant drugs (anti-malarials, sulfonamides, analgesics, nitrofurans) and consumption of fava beans.  
      One pharmacogenomics approach to identifying genes that predict drug response, known as “a genome-wide association”, relies primarily on a high-resolution map of the human genome consisting of already known gene-related markers (e.g., a “bi-allelic” gene marker map which consists of 60,000-100,000 polymorphic or variable sites on the human genome, each of which has two variants.) Such a high-resolution genetic map can be compared to a map of the genome of each of a statistically significant number of patients taking part in a Phase II/III drug trial to identify markers associated with a particular observed drug response or side effect. Alternatively, such a high resolution map can be generated from a combination of some ten-million known single nucleotide polymorphisms (SNPs) in the human genome. As used herein, a “SNP” is a common alteration that occurs in a single nucleotide base in a stretch of DNA. For example, a SNP may occur once per every 1000 bases of DNA. A SNP may be involved in a disease process, however, the vast majority may not be disease-associated. Given a genetic map based on the occurrence of such SNPs, individuals can be grouped into genetic categories depending on a particular pattern of SNPs in their individual genome. In such a manner, treatment regimens can be tailored to groups of genetically similar individuals, taking into account traits that may be common among such genetically similar individuals.  
      Alternatively, a method termed the “candidate gene approach”, can be utilized to identify genes that predict drug response. According to this method, if a gene that encodes a drugs target is known (e.g., an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 polypeptide of the present invention), all common variants of that gene can be fairly easily identified in the population and it can be determined if having one version of the gene versus another is associated with a particular drug response.  
      As an illustrative embodiment, the activity of drug metabolizing enzymes is a major determinant of both the intensity and duration of drug action. The discovery of genetic polymorphisms of drug metabolizing enzymes (e.g., N-acetyltransferase 2 (NAT 2) and cytochrome P450 enzymes CYP2D6 and CYP2C19) has provided an explanation as to why some patients do not obtain the expected drug effects or show exaggerated drug response and serious toxicity after taking the standard and safe dose of a drug. These polymorphisms are expressed in two phenotypes in the population, the extensive metabolizer (EM) and poor metabolizer (PM). The prevalence of PM is different among different populations. For example, the gene coding for CYP2D6 is highly polymorphic and several mutations have been identified in PM, which all lead to the absence of functional CYP2D6. Poor metabolizers of CYP2D6 and CYP2C19 quite frequently experience exaggerated drug response and side effects when they receive standard doses. If a metabolite is the active therapeutic moiety, PM show no therapeutic response, as demonstrated for the analgesic effect of codeine mediated by its CYP2D6-formed metabolite morphine. The other extreme are the so called ultra-rapid metabolizers who do not respond to standard doses. Recently, the molecular basis of ultra-rapid metabolism has been identified to be due to CYP2D6 gene amplification.  
      Alternatively, a method termed the “gene expression profiling”, can be utilized to identify genes that predict drug response. For example, the gene expression of an animal dosed with a drug (e.g., an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 molecule and/or an HST-5 molecule or an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 modulator and/or an HST-5 modulator of the present invention) can give an indication whether gene pathways related to toxicity have been turned on.  
      Information generated from more than one of the above pharmacogenomics approaches can be used to determine appropriate dosage and treatment regimens for prophylactic or therapeutic treatment an individual. This knowledge, when applied to dosing or drug selection, can avoid adverse reactions or therapeutic failure and thus enhance therapeutic or prophylactic efficiency when treating a subject with an MTP-1, an OAT, n HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 molecule or an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 modulator, such as a modulator identified by one of the exemplary screening assays described herein.  
      4. Use of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118,67067, 62092, HAAT, HST-4 and HST-5 Molecules as Surrogate Markers  
      The MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and HST-5 molecules of the invention are also useful as markers of disorders or disease states, as markers for precursors of disease states, as markers for predisposition of disease states, as markers of drug activity, or as markers of the pharmacogenomic profile of a subject. Using the methods described herein, the presence, absence and/or quantity of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 molecules of the invention may be detected, and may be correlated with one or more biological states in vivo. For example, the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 molecules of the invention may serve as surrogate markers for one or more disorders or disease states or for conditions leading up to disease states. As used herein, a “surrogate marker” is an objective biochemical marker which correlates with the absence or presence of a disease or disorder, or with the progression of a disease or disorder (e.g., with the presence or absence of a tumor). The presence or quantity of such markers is independent of the disease. Therefore, these markers may serve to indicate whether a particular course of treatment is effective in lessening a disease state or disorder. Surrogate markers are of particular use when the presence or extent of a disease state or disorder is difficult to assess through standard methodologies (e.g., early stage tumors), or when an assessment of disease progression is desired before a potentially dangerous clinical endpoint is reached (e.g., an assessment of cardiovascular disease may be made using cholesterol levels as a surrogate marker, and an analysis of HIV infection may be made using HIV RNA levels as a surrogate marker, well in advance of the undesirable clinical outcomes of myocardial infarction or fully-developed AIDS). Examples of the use of surrogate markers in the art include: Koomen et al. (2000)  J. Mass. Spectrom.  35: 258-264; and James (1994)  AIDS Treatment News Archive  209.  
      The MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 molecules of the invention are also useful as pharmacodynamic markers. As used herein, a “pharmacodynamic marker” is an objective biochemical marker which correlates specifically with drug effects. The presence or quantity of a pharmacodynamic marker is not related to the disease state or disorder for which the drug is being administered; therefore, the presence or quantity of the marker is indicative of the presence or activity of the drug in a subject. For example, a pharmacodynamic marker may be indicative of the concentration of the drug in a biological tissue, in that the marker is either expressed or transcribed or not expressed or transcribed in that tissue in relationship to the level of the drug. In this fashion, the distribution or uptake of the drug may be monitored by the pharmacodynamic marker. Similarly, the presence or quantity of the pharmacodynamic marker may be related to the presence or quantity of the metabolic product of a drug, such that the presence or quantity of the marker is indicative of the relative breakdown rate of the drug in vivo. Pharmacodynamic markers are of particular use in increasing the sensitivity of detection of drug effects, particularly when the drug is administered in low doses. Since even a small amount of a drug may be sufficient to activate multiple rounds of marker (e.g., an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 marker) transcription or expression, the amplified marker may be in a quantity which is more readily detectable than the drug itself. Also, the marker may be more easily detected due to the nature of the marker itself; for example, using the methods described herein, anti-MTP-1, anti-OAT, anti-HST-1, anti-TP-2, anti-PLTR-1, anti-TFM-2, anti-TFM-3, anti-67118, anti-67067, anti-62092, anti-HAAT, anti-HST-4 and/or anti-HST-5 antibodies may be employed in an immune-based detection system for an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 polypeptide marker, or MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4- and/or HST-5-specific radiolabeled probes may be used to detect an MTP-1, an OAT, an HST-1, a TP-2, a PLTR-1, a TFM-2, a TFM-3, a 67118, a 67067, a 62092, a HAAT, an HST-4 and/or an HST-5 mRNA marker. Furthermore, the use of a pharmacodynamic marker may offer mechanism-based prediction of risk due to drug treatment beyond the range of possible direct observations. Examples of the use of pharmacodynamic markers in the art include: Matsuda et al. U.S. Pat. No. 6,033,862; Hattis et al. (1991)  Env. Health Perspect.  90: 229-238; Schentag (1999)  Am. J. Health - Syst. Pharm.  56 Suppl. 3: S21-S24; and Nicolau (1999)  Am, J. Health - Syst. Pharm.  56 Suppl. 3: S16-S20.  
      The MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or the HST-5 molecules of the invention are also useful as pharmacogenomic markers. As used herein, a “pharmacogenomic marker” is an objective biochemical marker which correlates with a specific clinical drug response or susceptibility in a subject (see, e.g., McLeod et al. (1999)  Eur. J. Cancer  35(12): 1650-1652). The presence or quantity of the pharmacogenomic marker is related to the predicted response of the subject to a specific drug or class of drugs prior to administration of the drug. By assessing the presence or quantity of one or more pharmacogenomic markers in a subject, a drug therapy which is most appropriate for the subject, or which is predicted to have a greater degree of success, may be selected. For example, based on the presence or quantity of RNA, or polypeptide (e.g., MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 polypeptides or RNAs) for specific tumor markers in a subject, a drug or course of treatment may be selected that is optimized for the treatment of the specific tumor likely to be present in the subject. Similarly, the presence or absence of a specific sequence mutation in MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 DNA may correlate MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 drug response. The use of pharmacogenomic markers therefore permits the application of the most appropriate treatment for each subject without having to administer the therapy.  
      F. Electronic Apparatus-Readable Media and Arrays  
      Electronic apparatus readable media comprising MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information is also provided. As used herein, “MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information” refers to any nucleotide and/or amino acid sequence information particular to the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 molecules of the present invention, including but not limited to full-length nucleotide and/or amino acid sequences, partial nucleotide and/or amino acid sequences, polymorphic sequences including single nucleotide polymorphisms (SNPs), epitope sequences, and the like. Moreover, information “related to” said MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information includes detection of the presence or absence of a sequence (e.g., detection of expression of a sequence, fragment, polymorphism, etc.), determination of the level of a sequence (e.g., detection of a level of expression, for example, a quantitative detection), detection of a reactivity to a sequence (e.g., detection of protein expression and/or levels, for example, using a sequence-specific antibody), and the like. As used herein, “electronic apparatus readable media” refers to any suitable medium for storing, holding or containing data or information that can be read and accessed directly by an electronic apparatus. Such media can include, but are not limited to: magnetic storage media, such as floppy discs, hard disc storage medium, and magnetic tape; optical storage media such as compact disc; electronic storage media such as RAM, ROM, EPROM, EEPROM and the like; general hard disks and hybrids of these categories such as magnetic/optical storage media. The medium is adapted or configured for having recorded thereon a sequence of the present invention.  
      As used herein, the term “electronic apparatus” is intended to include any suitable computing or processing apparatus or other device configured or adapted for storing data or information. Examples of electronic apparatus suitable for use with the present invention include stand-alone computing apparatus; networks, including a local area network (LAN), a wide area network (WAN) Internet, Intranet, and Extranet; electronic appliances such as a personal digital assistants (PDAs), cellular phone, pager and the like; and local and distributed processing systems.  
      As used herein, “recorded” refers to a process for storing or encoding information on the electronic apparatus readable medium. Those skilled in the art can readily adopt any of the presently known methods for recording information on known media to generate manufactures comprising the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information.  
      A variety of software programs and formats can be used to store the sequence information on the electronic apparatus readable medium. For example, the sequence information can be represented in a word processing text file, formatted in commercially-available software such as WordPerfect and Microsoft Word, or represented in the form of an ASCII file, stored in a database application, such as DB2, Sybase, Oracle, or the like, as well as in other forms. Any number of dataprocessor structuring formats (e.g., text file or database) may be employed in order to obtain or create a medium having recorded thereon the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information.  
      By providing MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information in readable form, one can routinely access the sequence information for a variety of purposes. For example, one skilled in the art can use the sequence information in readable form to compare a target sequence or target structural motif with the sequence information stored within the data storage means. Search means are used to identify fragments or regions of the sequences of the invention which match a particular target sequence or target motif.  
      The present invention therefore provides a medium for holding instructions for performing a method for determining whether a subject has a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder) or a pre-disposition to a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder, wherein the method comprises the steps of determining MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information associated with the subject and based on the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information, determining whether the subject has a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder) or a pre-disposition to a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder and/or recommending a particular treatment for the disease, disorder or pre-disease condition.  
      The present invention further provides in an electronic system and/or in a network, a method for determining whether a subject has a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder) or a pre-disposition to a disease associated with a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 wherein the method comprises the steps of determining MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information associated with the subject, and based on the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information, determining whether the subject has a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder) or a pre-disposition to a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder, and/or recommending a particular treatment for the disease, disorder or pre-disease condition. The method may further comprise the step of receiving phenotypic information associated with the subject and/or acquiring from a network phenotypic information associated with the subject.  
      The present invention also provides in a network, a method for determining whether a subject has a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder) or a pre-disposition to a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder associated with MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5, said method comprising the steps of receiving MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence information from the subject and/or information related thereto, receiving phenotypic information associated with the subject, acquiring information from the network corresponding to MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 and/or a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or corresponding to a HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder), and based on one or more of the phenotypic information, the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 information (e.g., sequence information and/or information related thereto), and the acquired information, determining whether the subject has a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder) or a pre-disposition to a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder. The method may further comprise the step of recommending a particular treatment for the disease, disorder or pre-disease condition.  
      The present invention also provides a business method for determining whether a subject has a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder) or a pre-disposition to a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder, said method comprising the steps of receiving information related to MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 (e.g., sequence information and/or information related thereto), receiving phenotypic information associated with the subject, acquiring information from the network related to MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 and/or related to a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder), and based on one or more of the phenotypic information, the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 information, and the acquired information, determining whether the subject has a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder) or a pre-disposition to a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder. The method may further comprise the step of recommending a particular treatment for the disease, disorder or pre-disease condition.  
      The invention also includes an array comprising a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 sequence of the present invention. The array can be used to assay expression of one or more genes in the array. In one embodiment, the array can be used to assay gene expression in a tissue to ascertain tissue specificity of genes in the array. In this manner, up to about 7600 genes can be simultaneously assayed for expression, one of which can be MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5. This allows a profile to be developed showing a battery of genes specifically expressed in one or more tissues.  
      In addition to such qualitative determination, the invention allows the quantitation of gene expression. Thus, not only tissue specificity, but also the level of expression of a battery of genes in the tissue is ascertainable. Thus, genes can be grouped on the basis of their tissue expression per se and level of expression in that tissue. This is useful, for example, in ascertaining the relationship of gene expression between or among tissues. Thus, one tissue can be perturbed and the effect on gene expression in a second tissue can be determined. In this context, the effect of one cell type on another cell type in response to a biological stimulus can be determined. Such a determination is useful, for example, to know the effect of cell-cell interaction at the level of gene expression. If an agent is administered therapeutically to treat one cell type but has an undesirable effect on another cell type, the invention provides an assay to determine the molecular basis of the undesirable effect and thus provides the opportunity to co-administer a counteracting agent or otherwise treat the undesired effect. Similarly, even within a single cell type, undesirable biological effects can be determined at the molecular level. Thus, the effects of an agent on expression of other than the target gene can be ascertained and counteracted.  
      In another embodiment, the array can be used to monitor the time course of expression of one or more genes in the array. This can occur in various biological contexts, as disclosed herein, for example development of a MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder), progression of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder (e.g., a blood sugar or metabolic disorder), and processes, such a cellular transformation associated with the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5-associated disease or disorder.  
      The array is also useful for ascertaining the effect of the expression of a gene on the expression of other genes in the same cell or in different cells (e.g., ascertaining the effect of MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 expression on the expression of other genes). This provides, for example, for a selection of alternate molecular targets for therapeutic intervention if the ultimate or downstream target cannot be regulated.  
      The array is also useful for ascertaining differential expression patterns of one or more genes in normal and abnormal cells. This provides a battery of genes (e.g., including MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5) that could serve as a molecular target for diagnosis or therapeutic intervention.  
      The contents of the Sequence Listing are submitted herewith on compact disc in a Word file named “sequence listing.doc” and are incorporated herein by this reference. The compact disc was created on Jan. 21, 2005, and sequence listing.doc has 620 kilobytes.  
      This invention is further illustrated by the following examples which should not be construed as limiting. The contents of all references, patents and published patent applications cited throughout this application, as well as the Figures and the Sequence Listing, are incorporated herein by reference.  
     EXAMPLES  
     Example 1  
     Identification and Characterization of Human MTP-1 cDNA  
      In this example, the identification and characterization of the gene encoding human MTP-1 (clone Fbh38594) is described.  
      Isolation of the MTP-1 cDNA  
      The invention is based, at least in part, on the discovery of a human genes encoding a novel protein, referred to herein as MTP-1. The entire sequence of human clones Fbh38594, was determined and found to contain an open reading frame termed human “MTP-1”. The MTP-1 protein sequence set forth in SEQ ID NO:2 comprises about 2144 amino acids. The coding region (open reading frame) of SEQ ID NO:1, is set forth as SEQ ID NO:3.  
      Analysis of the Human MTP-1 Molecule  
      An analysis of the possible cellular localization of the MTP-1 protein based on its amino acid sequence was performed using the methods and algorithms described in Nakai and Kanehisa (1992)  Genomics  14:897-911, and at http://psort.nibb.ac.jp. The results of the analysis show that human MTP-1 (SEQ ID NO:2) may be localized to the endoplasmic reticulum, vesicles of the secretory system, and the nucleus.  
      A search of the amino acid sequence of MTP-1 was performed against the Memsat database ( FIG. 1 ). This search resulted in the identification of twelve transmembrane domains in the amino acid sequence of human MTP-1 (SEQ ID NO:2) at about residues 23-40, 548-564, 588-612, 624-646, 653-675, 1006-1023, 1236-1258, 1534-1556, 1587-1603, 1645-1667, 1732-1749, 1931-1947.  
      A search of the amino acid sequence of MTP-1 was also performed against the HMM database. This search resulted in the identification of two “ABC transporter domains” in the amino acid sequence of MTP-1 (SEQ ID NO:2) at about residues 832-1012 and about 1818-1999 (scores: 206.0 and 144.2, respectively). Further domain motifs were identified by using the amino acid sequence of MTP-1 (SEQ ID NO:2) to search through the ProDom database (http://protein.toulouse.inra.fr/prodom.html). Numerous matches against protein domains described as ATP-binding transporters, ABC transporters, ABCR transporters, ABC-C transporters and the like were identified.  
      A search was also performed against the Prosite database, and resulted in the identification of two “ATP/GTP binding site motifs (P-loop)” at residues 839-846, and 1825-1832 (Prosite accession number PS00017). This search also revealed an “ABC transporter family signature motif” at residues 938-952 (Prosite accession number PS00211).  
      BLASTN analysis using the nucleotide sequence of human MTP-1 resulted in the identification of a partial cDNA having significant identity to nucleotides 2852-2987 of SEQ ID NO:1. This partial cDNA is described as belonging to the ATP binding cassette (ABC) transporter protein family, etiologically involved in cholesterol driven atherogenic processes and inflammatory diseases like psoriasis, lupus erythematosus and others.  
      In combination with the other examples described herein, these data suggest that MTP-1 is a novel ABC transporter molecule, involved in lipid metabolism and/or inflammation and/or hematopoiesis.  
     Example 2  
     Expression of Recombinant MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and HST-5 Polypeptides in Bacterial Cells  
      In this example, In this example, human MTP-1, human OAT, human HST-1, human TP-2, human PLTR-1, human TFM-2, human TFM-3, human 67118, human 67067, human 62092, human HAAT, human HST-4 and/or human HST-5 is expressed as a recombinant glutathione-S-transferase (GST) fusion polypeptide in  E. coli  and the fusion polypeptide is isolated and characterized. Specifically, MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and/or HST-5 is fused to GST and this fusion polypeptide is expressed in  E. coli,  e.g., strain PEB199. Expression of the GST- MTP-1, GST-OAT, GST-HST-1, GST-TP-2, GST-PLTR-1, GST-TFM-2, GST-TFM-3, GST-67118, GST-67067, GST-62092, GST-HAAT, GST-HST-4, or GST-HST-5 fusion protein in PEB199 is induced with IPTG. The recombinant fusion polypeptide is purified from crude bacterial lysates of the induced PEB199 strain by affinity chromatography on glutathione beads. Using polyacrylamide gel electrophoretic analysis of the polypeptide purified from the bacterial lysates, the molecular weight of the resultant fusion polypeptide is determined.  
     Example 3  
     Expression of Recombinant MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4 and HST-5 Protein in Cos Cells  
      To express the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, or HST-5 gene in COS cells, the pcDNA/Amp vector by Invitrogen Corporation (San Diego, Calif.) is used. This vector contains an SV40 origin of replication, an ampicillin resistance gene, an  E. coli  replication origin, a CMV promoter followed by a polylinker region, and an SV40 intron and polyadenylation site. A DNA fragment encoding the entire MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, or HST-5 protein and an HA tag (Wilson et al. (1984)  Cell  37:767) or a FLAG tag fused in-frame to its 3′ end of the fragment is cloned into the polylinker region of the vector, thereby placing the expression of the recombinant protein under the control of the CMV promoter.  
      To construct the plasmid, the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, or HST-5 DNA sequence is amplified by PCR using two primers. The 5′ primer contains the restriction site of interest followed by approximately twenty nucleotides of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, or HST-5 coding sequence starting from the initiation codon; the 3′ end sequence contains complementary sequences to the other restriction site of interest, a translation stop codon, the HA tag or FLAG tag and the last 20 nucleotides of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, or HST-5 coding sequence. The PCR amplified fragment and the pCDNA/Amp vector are digested with the appropriate restriction enzymes and the vector is dephosphorylated using the CIAP enzyme (New England Biolabs, Beverly, Mass.). Preferably the two restriction sites chosen are different so that the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, or HST-5 gene is inserted in the correct orientation. The ligation mixture is transformed into  E. coli  cells (strains HB101, DH5α, SURE, available from Stratagene Cloning Systems, La Jolla, Calif., can be used), the transformed culture is plated on ampicillin media plates, and resistant colonies are selected. Plasmid DNA is isolated from transformants and examined by restriction analysis for the presence of the correct fragment.  
      COS cells are subsequently transfected with the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, or HST-5-pcDNA/Amp plasmid DNA using the calcium phosphate or calcium chloride co-precipitation methods, DEAE-dextran-mediated transfection, lipofection, or electroporation. Other suitable methods for transfecting host cells can be found in Sambrook, J., Fritsh, E. F., and Maniatis, T.  Molecular Cloning: A Laboratory Manual.  2 nd, ed., Cold Spring Harbor Laboratory,  Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989. The expression of the MTP-1 polypeptide is detected by radiolabeling ( 35 S-methionine or  35 S-cysteine available from NEN, Boston, Mass., can be used) and immunoprecipitation (Harlow, E. and Lane, D.  Antibodies: A Laboratory Manual,  Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1988) using an HA specific monoclonal antibody. Briefly, the cells are labeled for 8 hours with  35 S-methionine (or  35 S-cysteine). The culture media are then collected and the cells are lysed using detergents (RIPA buffer, 150 mM NaCl, 1% NP-40, 0.1% SDS, 0.5% DOC, 50 mM Tris, pH 7.5). Both the cell lysate and the culture media are precipitated with an HA-specific monoclonal antibody. Precipitated polypeptides are then analyzed by SDS-PAGE.  
      Alternatively, DNA containing the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, or HST-5 coding sequence is cloned directly into the polylinker of the pCDNA/Amp vector using the appropriate restriction sites. The resulting plasmid is transfected into COS cells in the manner described above, and the expression of the MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, or HST-5 polypeptide is detected by radiolabeling and immunoprecipitation using an MTP-1, OAT, HST-1, TP-2, PLTR-1, TFM-2, TFM-3, 67118, 67067, 62092, HAAT, HST-4, or HST-5 specific monoclonal antibody.  
     Example 4  
     Tissue Distribution of MTP-1 mRNA  
      In this example, endogenous gene expression was determined using the Perkin-Elmer/AsI 7700 Sequence Detection System which employs TaqMan technology. Briefly, TaqMan technology relies on standard RT-PCR with the addition of a third gene-specific oligonucleotide (referred to as a probe) which has a fluorescent dye coupled to its 5′ end (typically 6-FAM) and a quenching dye at the 3′ end (typically TAMRA). When the fluorescently tagged oligonucleotide is intact, the fluorescent signal from the 5′ dye is quenched. As PCR proceeds, the 5′ to 3′ nucleolytic activity of taq polymerase digests the labeled primer, producing a free nucleotide labeled with 6-FAM, which is now detected as a fluorescent signal. The PCR cycle where fluorescence is first released and detected is directly proportional to the starting amount of the gene of interest in the test sample, thus providing a way of quantitating the initial template concentration. Samples can be internally controlled by the addition of a second set of primers/probe specific for a housekeeping gene such as GAPDH which has been labeled with a different fluor on the 5′ end (typically JOE).  
      To determine the level of MTP-1 in various tissues a primer/probe set was designed using Primer Express software and primary cDNA sequence information. Total RNA was prepared from a series of tissues using an RNeasy kit from Qiagen First strand cDNA was prepared from one μg total RNA using an oligo dT primer and Superscript II reverse transcriptase (GIBCO-BRL). cDNA obtained from approximately 50 ng total RNA was used per TaqMan reaction. An array of human tissues were tested. The results of one such analysis are depicted in FIGS.  2 A-C. Expression was greatest in brain, vein, adipose, skin, fetal liver, tonsil, and lymph node. Expression was also noted in liver, colon, skeletal muscle, kidney, lung, thyroid, bone marrow, testis, placenta, fetal heart, spleen, and thymus.  
      In addition, a second array of human tissues was tested according to the above-described Taqman procedure, the array including additional samples of the erythroid and hematopoietic lineage. Notably, in addition to increased expression in tonsil and lymph node tissue, significant expression was also observed in bone marrow mononuclear cells, megakaryocytes and neutrophils, with quite dramatic expression being detected in erythroid cells.  
                               TABLE I                       Tissue Type   Mean   β 2 Mean   ∂∂ Ct   Expression                                                    Artery normal   34.5   23.43   9.08   1.8478       Aorta diseased   33.95   23.5   8.46   2.8398       Vein normal   37.27   21.48   13.8   0       Coronary SMC   34.41   22.07   10.36   0.7635       HUVEC   30.69   22.52   6.18   13.7922       Hemangioma   33.1   21.05   10.07   0.9335       Heart normal   33.34   22.2   9.14   1.7664       Heart CHF   33.51   22.09   9.43   1.4548       Kidney   30.5   21.41   7.11   7.2641       Skeletal Muscle   31.26   23.18   6.09   14.68       Adipose normal   34.95   21.89   11.07   0.4652       Pancreas   32.16   23.35   6.83   8.82       primary osteoblasts   30.86   21.93   6.93   8.1725       Osteoclasts   32.65   18.93   11.72   0.2964       Skin normal   33.91   23.2   8.72   2.3633       Spinal cord normal   33.01   22.13   8.89   2.1006       Brain Cortex normal   30.45   23.5   4.96   32.1286       Brain Hypothalamus normal   33.28   23.63   7.66   4.9444       Nerve   35.15   23.34   9.82   0       DRG (Dorsal Root Ganglion)   30.59   22.94   5.66   19.8461       Breast normal   33.94   22.18   9.77   1.1493       Breast tumor   32.81   21.99   8.83   2.1974       Ovary normal   34.65   21.23   11.43   0.3624       Ovary Tumor   30.8   19.73   9.09   1.8414       Prostate Normal   32.9   20.93   9.98   0.9868       Prostate Tumor   32.58   21.3   9.29   1.5919       Salivary glands   32.64   20.8   9.85   1.0836       Colon normal   34.74   19.81   12.95   0.1268       Colon Tumor   31.76   22.48   7.29   6.3899       Lung normal   31.25   19.34   9.91   1.0358       Lung tumor   29.82   21.58   6.25   13.0935       Lung   32.22   19.77   10.47   0.7075       Colon   32.47   18.8   11.69   0.3037       Liver normal   36.3   21.14   13.17   0       Liver fibrosis   33.8   21.87   9.94   1.0216       Spleen normal   30.26   19.77   8.5   2.7621       Tonsil normal   28.23   19.76   6.48   11.2028       Lymph node normal   29.54   21.32   6.24   13.2763       Small intestine normal   35.99   21.38   12.63   0       Macrophages   33.92   18.14   13.8   0.0701       Synovium   34.2   20.9   11.32   0.3925       BM-MNC   28.88   20.05   6.84   8.6986       Activated PBMC   32.9   19.48   11.43   0.3624       Neutrophils   28.03   19.42   6.62   10.1667       Megakaryocytes   27.09   20.12   4.97   31.7962       Erythroid   25.68   21.81   1.88   271.6837       positive control   30.11   21.34   6.77   9.1628                  
 
      To further investigate the high expression in hematopoietic tissue, MTP-1 expression levels were measured in various hematopoietic cells by quantitative PCR using the Taqman™ procedure as described above. The relative levels of MTP-1 expression in various hematopoietic and non-hemapoietic cells is depicted in Table II.  
               TABLE II                          Expression on MTP-1 in various types of hematopoietic cells.                                 Fam Mean       Relative           38594   Vic Mean Beta2   Expression                                         Lung MPI 131   29   19   18       Kidney MPI 58   28   21   255       Brain MPI 167   33   24   34       Heart PIT 273   34   20   2       Colon MPI 60   32   21   10       NHLF CTN 49 hr   30   19   9       NHLF TGF 10 ng   30   19   12       hepG2 CTN   29   20   67       Tonsil MPI 37   26   19   204       Lymph nodes NDR 79   26   19   225       spleen MPI 380   23   17   287       Fetal liver MPI 133   30   21   65       pooled liver   31   20   16       Liv Fib NDR 190   36   25   16       Liv Fib NDR 191   30   20   37       Liv Fib NDR 194   35   25   38       Liv Fib NDR 113   31   19   7       Th1 48 hr M4   30   17   3       Th1 48 hr M5   30   17   3       Th2 48 hr M5   30   17   3       Grans   27   20   218       CD19   28   18   18       CD14   30   17   2       PBMC mock   25   16   63       PBMC PHA   27   16   8       PBMC IL 10   28   17   8       NHBE mock   32   20   8       NHBE IL13-1   32   21   10       BM-MNC   32   21   10       mPB CD34+   27   20   351       ABM CD34+   29   19   18       Erythroid   30   20   22       Megs   31   18   4       Neutrophil   30   19   14       mBM CD11b+   33   18   1       mBM CD15+   32   18   2       mBM CD11b−   30   18   4       BM/GPA   28   20   91       BM CD71   27   18   60       HepG2 A   29   22   202       HepG2 2.12-a   28   22   412       NTC   40   40                  
 
      Notably, MTP-1 expression was increased in non-hemapoietic cells such as HepG2, brain, liver and kidney. Interesting, expression was most increased in hematopoietic cells such as CD34-positive murine peripheral blood cells. Expression was also significantly increased in other hemapoietic cells such as glycophorin A-positive bone marrow cells (“BM-GPA”), CD71-positive bone marrow cells (BM-CD71”), mock-treated peripheral blood mononuclear cells, granulocytes, tonsils, lymph nodes and spleen. These data indicate that MTP-1 is a novel ABC-transporter molecule that is preferentially expressed in various hemapoietic cells.  
     Example 5  
     Identification and Characterization of Human Oat cDNA  
      In this example, the identification and characterization of the genes encoding human OAT4 (clone Fbh57312) and human OAT5 (clone Fbh53659) is described.  
      Isolation of the Human OAT cDNA  
      The invention is based, at least in part, on the discovery of genes encoding novel members of the organic anion transporter family. The entire sequence of human clone Fbh57312 was determined and found to contain an open reading frame termed human “OAT4”. The entire sequence of human clone Fbh53659 was determined and found to contain an open reading frame termed human “OAT5”.  
      The nucleotide sequence encoding the human OAT4 is shown is set forth as SEQ ID NO:4. The protein encoded by this nucleic acid comprises about 550 amino acids and has the amino acid sequence set forth as SEQ ID NO:5. The coding region (open reading frame) of SEQ ID NO:4 is set forth as SEQ ID NO:6.  
      The nucleotide sequence encoding the human OAT5 is set forth as SEQ ID NO:7. The protein encoded by this nucleic acid comprises about 724 amino acids and has the amino acid sequence set forth as SEQ ID NO:8. The coding region (open reading frame) is set forth as SEQ ID NO:9.  
      Analysis of the Human OAT Molecules  
      The amino acid sequences of human OAT4 and OAT5 were analyzed using the program PSORT (available online) to predict the localization of the proteins within the cell. This program assesses the presence of different targeting and localization amino acid sequences within the query sequence. The results of the analyses show that human OAT4 may be localized to the endoplasmic reticulum, the nucleus, or the mitochondria. The results of the analyses further show that human OAT 5 may be localized to the endoplasmic reticulum, vacuoles, secretory vesicles, or the mitochondria.  
      Additionally, searches of the amino acid sequences of human OAT4 and OAT5 were performed against the Memsat database. These searches resulted in the identification of 12 transmembrane domains in the amino acid sequence of human OAT4 at residues 1-31, 148-165, 172-195, 202-219, 228-252, 260-276, 347-365, 375-399, 406-422, 431-451, 466-484, and 495-512 of SEQ ID NO:5 ( FIG. 4 ). These searches further resulted in the identification of 12 transmembrane domains in the amino acid sequence of human OAT5 at residues 106-130, 143-166, 174-191, 230-254, 265-284, 314-335, 382-405, 419-443, 456-473, 579-603, 613-636, and 667-690 of SEQ ID NO:8 ( FIG. 5 ).  
      Searches of the amino acid sequences of human OAT4 and OAT5 were also performed against the HMM database. These searches resulted in the identification of a “sugar (and other) transporter domain” at about residues 103-527 (score=34.7) of SEQ ID NO:5 . These searches further resulted in the identification of a “sugar (and other) transporter domain” at about residues 141-555 of SEQ ID NO:8.  
      Searches of the amino acid sequence of human OAT were further performed against the Prosite database. These searches resulted in the identification of two ATP/GTP-binding site motif A (P-loop) domains in the amino acid sequence of human OAT5 at about residues 343-350 and 360-367 of SEQ ID NO:8. These searches also resulted in the identification of a number of potential N-glycosylation sites, protein kinase C phosphorylation sites, casein kinase II phosphorylation sites, N-myristoylation sites, amidation sites, and leucine zipper patterns in the amino acid sequence of human OAT4. These searches further resulted in the identification in the amino acid sequence of human OAT5 of a potential cAMP- and cGMP-dependent protein kinase phosphorylation site and an number of potential N-glycosylation sites, protein kinase C phosphorylation sites, casein kinase II phosphorylation sites, and N-myristoylation sites.  
      Tissue Distribution of OAT mRNA  
      This example describes the tissue distribution of human OAT mRNA, as may be determined using in situ hybridization analysis. For in situ analysis, various tissues, e.g., tissues obtained from brain, are first frozen on dry ice. Ten-micrometer-thick sections of the tissues are postfixed with 4% formaldehyde in DEPC-treated 1× phosphate-buffered saline at room temperature for 10 minutes before being rinsed twice in DEPC 1× phosphate-buffered saline and once in 0.1 M triethanolamine-HCl (pH 8.0). Following incubation in 0.25% acetic anhydride-0.1 M triethanolamine-HCl for 10 minutes, sections are rinsed in DEPC 2×SSC (1×SSC is 0.15 M NaCl plus 0.015 M sodium citrate). Tissue is then dehydrated through a series of ethanol washes, incubated in 100% chloroform for 5 minutes, and then rinsed in 100% ethanol for 1 minute and 95% ethanol for 1 minute and allowed to air dry.  
      Hybridizations are performed with  35 S-radiolabeled (5×10 7  cpm/ml) cRNA probes. Probes are incubated in the presence of a solution containing 600 mM NaCl, 10 mM Tris (pH 7.5), 1 mM EDTA, 0.01% sheared salmon sperm DNA, 0.01% yeast tRNA, 0.05% yeast total RNA type X1, 1× Denhardt&#39;s solution, 50% formamide, 10% dextran sulfate, 100 mM dithiothreitol, 0.1% sodium dodecyl sulfate (SDS), and 0.1% sodium thiosulfate for 18 hours at 55° C.  
      After hybridization, slides are washed with 2×SSC. Sections are then sequentially incubated at 37° C. in TNE (a solution containing 10 mM Tris-HCl (pH 7.6), 500 mM NaCl, and 1 mM EDTA), for 10 minutes, in TNE with 10 μg of RNase A per ml for 30 minutes, and finally in TNE for 10 minutes. Slides are then rinsed with 2×SSC at room temperature, washed with 2×SSC at 50° C. for 1 hour, washed with 0.2×SSC at 55° C. for 1 hour, and 0.2×SSC at 60° C. for 1 hour. Sections are then dehydrated rapidly through serial ethanol-0.3 M sodium acetate concentrations before being air dried and exposed to Kodak Biomax MR scientific imaging film for 24 hours and subsequently dipped in NB-2 photoemulsion and exposed at 4° C. for 7 days before being developed and counter stained.  
      Analysis of Human OAT Expression Using the Taqman Procedure  
      The Taqman™ procedure is a quantitative, real-time PCR-based approach to detecting mRNA. The RT-PCR reaction exploits the 5′ nuclease activity of AmpliTaq Gold™ DNA Polymerase to cleave a TaqMan™ probe during PCR. Briefly, cDNA was generated from the samples of interest and served as the starting material for PCR amplification. In addition to the 5′ and 3′ gene-specific primers, a gene-specific oligonucleotide probe (complementary to the region being amplified) was included in the reaction (i.e., the Taqman™ probe). The TaqMan™ probe included an oligonucleotide with a fluorescent reporter dye covalently linked to the 5′ end of the probe (such as FAM (6-carboxyfluorescein), TET (6-carboxy-4,7,2′,7′-tetrachlorofluorescein), JOE (6-carboxy-4,5-dichloro-2,7-dimethoxyfluorescein), or VIC) and a quencher dye (TAMRA (6-carboxy-N,N,N′,N′-tetramethylrhodamine) at the 3′ end of the probe.  
      During the PCR reaction, cleavage of the probe separated the reporter dye and the quencher dye, resulting in increased fluorescence of the reporter. Accumulation of PCR products was detected directly by monitoring the increase in fluorescence of the reporter dye. When the probe was intact, the proximity of the reporter dye to the quencher dye resulted in suppression of the reporter fluorescence. During PCR, if the target of interest was present, the probe specifically annealed between the forward and reverse primer sites. The 5′-3′ nucleolytic activity of the AmpliTaq™ Gold DNA Polymerase cleaved the probe between the reporter and the quencher only if the probe hybridized to the target. The probe fragments were then displaced from the target, and polymerization of the strand continued. The 3′ end of the probe was blocked to prevent extension of the probe during PCR. This process occurred in every cycle and did not interfere with the exponential accumulation of product. RNA was prepared using the trizol method and treated with DNase to remove contaminating genomic DNA. cDNA was synthesized using standard techniques. Mock cDNA synthesis in the absence of reverse transcriptase resulted in samples with no detectable PCR amplification of the control GAPDH or β-actin gene confirming efficient removal of genomic DNA contamination.  
      Taqman analysis showed that human OAT5 was highly expressed in the kidney, primary osteoblasts, brain cortex, lung, liver, bone marrow mononuclear cells (BM-MNC), and neutrophils (see  FIG. 6 ).  
     Example 6  
     Identification and Characterization of Human HST-1 cDNA  
      In this example, the identification and characterization of the gene encoding human HST-1 (clone 57250) is described.  
      Isolation of the Human HST-1 cDNA  
      The invention is based, at least in part, on the discovery of a human gene encoding a novel polypeptide, referred to herein as human HST-1. The entire sequence of the human clone 57250 was determined and found to contain an open reading frame termed human “HST-1.” The nucleotide sequence of the human HST-1 gene is set forth in the Sequence Listing as SEQ ID NO:12. The amino acid sequence of the human HST-1 expression product is set forth in the Sequence Listing as SEQ ID NO:13. The HST-1 polypeptide comprises 572 amino acids. The coding region (open reading frame) of SEQ ID NO:12 is set forth as SEQ ID NO:14.  
      Analysis of the Human HST-1 Molecules  
      The human HST-1 amino acid sequence was aligned with the amino acid sequence of the potent brain type organic ion transporter from  Homo sapiens  (Accession No. AB040056) using the CLUSTAL W (1.74) multiple sequence alignment program. The results of the alignment are set forth in  FIG. 9 .  
      A search using the polypeptide sequence of SEQ ID NO:13 was performed against the HMM database in PFAM resulting in the identification of a sugar transporter family domain in the amino acid sequence of human HST-1 at about residues 117-536 of SEQ ID NO:13, a potential UL25 domain in the amino acid sequence of human HST-1 at about residues 577-597 of SEQ ID NO:13 (score=3.0), and a potential sodium: galactoside symporter family domain in the amino acid sequence of human HST-1 at about residues 287-541 of SEQ ID NO:13.  
      The amino acid sequence of human HST-1 was analyzed using the program PSORT (see the PSORT website) to predict the localization of the proteins within the cell. This program assesses the presence of different targeting and localization amino acid sequences within the query sequence. The results of this analysis indicated that human HST-1 may be localized to the endoplasmic reticulum, nucleus, secretory vesicles or mitochondria.  
      Searches of the amino acid sequence of human HST-1 were further performed against the Prosite database. These searches resulted in the identification in the amino acid sequence of human HST-1 of a potential N-glycosylation site, a number of potential protein kinase C phosphorylation sites, a number of potential casein kinase II phosphorylation sites, a number of potential N-myristoylation sites, a number of potential amidation sites, a potential prokaryotic membrane lipoprotein lipid attachment site, and a number of potential leucine zipper motifs.  
      A MEMSAT analysis of the polypeptide sequence of SEQ ID NO:13 was also performed ( FIG. 8 ), predicting twelve transmembrane domains in the amino acid sequence of human HST-1 (SEQ ID NO:13) at about residues 20-36, 150-167, 174-196, 204-220, 231-255, 263-282, 355-372, 387-405, 413-431, 438-462, 469-485, and 505-521.  
      Further domain motifs were identified by using the amino acid sequence of HST-1 (SEQ ID NO:13) to search through the ProDom database. Numerous matches against protein domains described as “transporter organic cation MBOCT potent brain type”, “transporter organic cation anion transmembrane glycoprotein monoamine”, “DNA packaging” and the like were identified.  
     Example 7  
     Tissue Distribution of Human HST-1 mRNA Using Taqman™ Analysis  
      This example describes the tissue distribution of human HST-1 mRNA in a variety of cells and tissues, as determined using the TaqMan™ procedure. The Taqman™ procedure is a quantitative, reverse transcription PCR-based approach for detecting mRNA. The RT-PCR reaction exploits the 5′ nuclease activity of AmpliTaq Gold™ DNA Polymerase to cleave a TaqMan™ probe during PCR. Briefly, cDNA was generated from the samples of interest, e.g., various human tissue samples, and used as the starting material for PCR amplification. In addition to the 5′ and 3′ gene-specific primers, a gene-specific oligonucleotide probe (complementary to the region being amplified) was included in the reaction (i.e., the Taqman™ probe). The TaqMan™ probe includes the oligonucleotide with a fluorescent reporter dye covalently linked to the 5′ end of the probe (such as FAM (6-carboxyfluorescein), TET (6-carboxy-4,7,2′,7′-tetrachlorofluorescein), JOE (6-carboxy-4,5-dichloro-2,7-dimethoxyfluorescein), or VIC) and a quencher dye (TAMRA (6-carboxy-N,N,N′,N′-tetramethylrhodamine) at the 3′ end of the probe.  
      During the PCR reaction, cleavage of the probe separates the reporter dye and the quencher dye, resulting in increased fluorescence of the reporter. Accumulation of PCR products is detected directly by monitoring the increase in fluorescence of the reporter dye. When the probe is intact, the proximity of the reporter dye to the quencher dye results in suppression of the reporter fluorescence. During PCR, if the target of interest is present, the probe specifically anneals between the forward and reverse primer sites. The 5′-3′ nucleolytic activity of the AmpliTaq™ Gold DNA Polymerase cleaves the probe between the reporter and the quencher only if the probe hybridizes to the target. The probe fragments are then displaced from the target, and polymerization of the strand continues. The 3′ end of the probe is blocked to prevent extension of the probe during PCR. This process occurs in every cycle and does not interfere with the exponential accumulation of product. RNA was prepared using the trizol method and treated with DNase to remove contaminating genomic DNA. cDNA was synthesized using standard techniques. Mock cDNA synthesis in the absence of reverse transcriptase resulted in samples with no detectable PCR amplification of the control gene confirms efficient removal of genomic DNA contamination.  
      As indicated in  FIG. 10 , strong expression of HST-1 was detected in human coronary smooth muscle cells and neutrophils, as well as in normal human pancreatic tissue and human lung tissue derived from normal, tumor, and chronic obstructive pulmonary disease samples. In addition, HST-1 expression was detected at moderate levels in normal ovary and lymph node tissues, breast tumor tissue, prostate tumor tissue, and in bone marrow mononuclear cells.  
     Example 8  
     Identification and Characterization of Human TP-2 cDNA  
      In this example, the identification and characterization of the gene encoding human TP-2 (clone 63760) is described.  
      Isolation of the Human TP-2 cDNA  
      The invention is based, at least in part, on the discovery of a human gene encoding a novel polypeptide, referred to herein as human TP-2. The entire sequence of the human clone 63760 was determined and found to contain an open reading frame termed human “TP-2.” The nucleotide sequence of the human TP-2 gene is set forth in the Sequence Listing as SEQ ID NO:15. The amino acid sequence of the human TP-2 expression product is set forth in the Sequence Listing as SEQ ID NO:16. The TP-2 polypeptide comprises 474 amino acids. The coding region (open reading frame) of SEQ ID NO:15 is set forth as SEQ ID NO:17.  
      Analysis of the Human TP-2 Molecules  
      The human TP-2 amino acid sequence was aligned with the amino acid sequence of the tetracycline-6-hydroxylase/oxygenase homolog gene from  Salmonella typhi  (SEQ ID NO:18) using the CLUSTAL W (1.74) multiple sequence alignment program. The results of the alignment are set forth in  FIG. 13 .  
      A search using the polypeptide sequence of SEQ ID NO:16 was performed against the HMM database in PFAM resulting in the identification of a potential sugar transporter domain in the amino acid sequence of human TP-2 at about residues 37-454 of SEQ ID NO:16 (score=−101.1), a potential LacY proton/sugar symporter domain in the amino acid sequence of human TP-2 at about residues 39-383 of SEQ ID NO:16 (score=−336.7), a potential glutamine amidotransferases class-II domain in the amino acid sequence of human TP-2 at about residues 165-170 of SEQ ID NO:16 (score=1.2), and a potential MCT domain in the amino acid sequence of human TP-2 at about residues 33-458 of SEQ ID NO:16 (score=−167.8).  
      The amino acid sequence of human TP-2 was analyzed using the program PSORT (http://www.psort.nibb.ac.jp) to predict the localization of the proteins within the cell. This program assesses the presence of different targeting and localization amino acid sequences within the query sequence. The results of this analysis show that human TP-2 may be localized to the endoplasmic reticulum, secretory vesicles, or mitochondria.  
      Searches of the amino acid sequence of human TP-2 were further performed against the Prosite database. These searches resulted in the identification in the amino acid sequence of human TP-2 of two potential glycosaminoglycan attachment sites at about residues 176-179 and 464-467 of SEQ ID NO:16, two potential cAMP- and cGMP-dependent protein kinase phosphorylation sites at about residues 108-111 and 460-463 of SEQ ID NO:16, a number of potential protein kinase C phosphorylation sites at about residues 228-230, 253-255, and 260-262 of SEQ ID NO:16, a number of potential casein kinase II phosphorylation sites at about residues 28-31, 191-194, 247-250, and 463-466 of SEQ ID NO:16, a number of potential N-myristoylation sites at about residues 38-43, 75-80, 82-87, 127-132, 187-192, 332-337, 403-408, 409-414, 415-420, and 445-450 of SEQ ID NO:16, one potential amidation site at about residues 106-109 of SEQ ID NO:16, and a potential prokaryotic membrane lipoprotein lipid attachment site at about residues 99-114 of SEQ ID NO:16.  
      A MEMSAT analysis of the polypeptide sequence of SEQ ID NO:16 was also performed ( FIG. 12 ), predicting eleven potential transmembrane domains in the amino acid sequence of human TR-2 (SEQ ID NO:16) at about residues 45-69, 80-102, 112-136, 167-190, 197-218, 288-310, 323-343, 352-368, 375-391, 409-433, and 422-458. However, a structural, hydrophobicity, and antigenicity analysis ( FIG. 11 ) resulted in the identification of twelve transmembrane domains. Accordingly, the TP-2 protein of SEQ ID NO:16 is predicted to have at least 12 transmembrane domains, which are identified in  FIGS. 11 and 12  as transmembrane (TM) domains 1 through 12. TM1 is at about residues 45-69, TM2 is at about residues 80-102, TM3 is at about residues 112-126, TM4 is at about residues 133-156, TM5 is at about residues 167-190, TM6 is at about residues 197-218, TM7 is at about residues 288-310, TM8 is at about residues 323-343, TM9 is at about residues 352-368, TM10 is at about residues 375-391, TM11 is at about residues 409-433, and TM12 is at about residues 442-458.  
      A search of the amino acid sequence of human TP-2 was also performed against the ProDom database. These searches resulted in the identification of a “kinase activity integral membrane domain” at about amino acid residues 36-235, a “transport integral membrane” at about amino acid residues 41-190, a “YFKF transporter MFS transmembrane domain” at about amino acid residues 45-229, a “multidrug transmembrane domain” at about amino acid residues 130-250, a “transporter-like polyspecific organic subtransferable suppressing membrane tumor domain” at about amino acid residues 133-214, a “transport membrane domain” at about amino acid residues 163-244, a “NORA domain” at about amino acid residues 190-462, and a “family C2-domain” at about amino acid residues 399-466 in the amino acid protein sequence of TP-2 (SEQ ID NO:16).  
     Example 9  
     Identification and Characterization of Human PLTR-1 cDNA  
      In this example, the identification and characterization of the gene encoding human PLTR-1 (clone 49938) is described.  
      Isolation of the Human PLTR-1 cDNA  
      The invention is based, at least in part, on the discovery of genes encoding novel members of the phospholipid transporter family. The entire sequence of human clone Fbh49938 was determined and found to contain an open reading frame termed human “PLTR-1”.  
      The nucleotide sequence encoding the human PLTR-1 is set forth as SEQ ID NO:19. The protein encoded by this nucleic acid comprises about 1190 amino acids and has the amino acid sequence is set forth as SEQ ID NO:20. The coding region (open reading frame) of SEQ ID NO:19 is set forth as SEQ ID NO:21.  
      Analysis of the Human PLTR-1 Molecules  
      The amino acid sequence of human PLTR-1 was analyzed for the presence of sequence motifs specific for P-type ATPases (as defined in Tang, X. et al. (1996)  Science  272:1495-1497 and Fagan, M. J. and Saier, M. H. (1994)  J. Mol. Evol.  38:57). These analyses resulted in the identification of a P-type ATPase sequence 1 motif in the amino acid sequence of human PLTR-1 at residues 164-172 of SEQ ID NO:20. These analyses also resulted in the identification of a P-type ATPase sequence 2 motif in the amino acid sequence of human PLTR-1 at residues 389-398 of SEQ ID NO:20. These analyses further resulted in the identification of a P-type ATPase sequence 3 motif in the amino acid sequence of human PLTR-1 at residues 812-822 of SEQ ID NO:20.  
      The amino acid sequence of human PLTR-1 was also analyzed for the presence of phospholipid transporter specific amino acid residues (as defined in Tang, X. et al. (1996)  Science  272:1495-1497). These analyses resulted in the identification of phospholipid transporter specific amino acid residues in the amino acid sequence of human PLTR-1 at about residues 164, 165, 168, 390, 812, 821, and 822 of SEQ ID NO:20 (FIGS.  14 A-B).  
      The amino acid sequence of human PLTR-1 was also analyzed for the presence of large extramembrane domains. An N-terminal large extramembrane domain was identified in the amino acid sequence of human PLTR-1 at residues 95-275 of SEQ ID NO:20. A C-terminal large extramembrane domain was identified in the amino acid sequence of human PLTR-1 at residues 345-879 of SEQ ID NO:20.  
      The amino acid sequence of human PLTR-1 was further analyzed using the program PSORT (available online; see Nakai, K. and Kanehisa, M. (1992)  Genomics  14:897-911) to predict the localization of the proteins within the cell. This program assesses the presence of different targeting and localization amino acid sequences within the query sequence. The results of the analyses show that human PLTR-1 is most likely localized to the endoplasmic reticulum or to vesicles of the secretory system.  
      Analysis of the amino acid sequence of human PLTR-1 was performed using MEMSAT. This analysis resulted in the identification of 10 possible transmembrane domains in the amino acid sequence of human PLTR-1 at about residues 55-71, 78-94, 276-298, 320-344, 880-897, 904-924, 954-977, 993-1011, 1022-1038, and 1066-1084 of SEQ ID NO:20 (see FIGS.  14 A-B and  15 ).  
      Searches of the amino acid sequence of human PLTR-1 were further performed against the Prosite database. These searches resulted in the identification of an “E1-E2 ATPases phosphorylation site” at about residues 498-504 of SEQ ID NO:20 (see FIGS.  14 A-B). These searches also resulted in the identification in the amino acid sequence of human PLTR-1 of a potential N-glycosylation site (at about amino acid residues 579-582) and a number of potential cAMP- and cGMP-dependent protein kinase phosphorylation sites (at about residues 265-268, 367-370, 542-545, and 1171-1174), protein kinase C phosphorylation sites (at about residues 36-38, 259-261, 391-393, 514-516, 687-689, 723-725, 739-741, 1098-1100, 1124-1126, 1143-1145, 1158-1160, and 1168-1170), casein kinase II phosphorylation sites (at about residues 153-156, 267-270, 370-373, 378-381, 413-416, 452-455, 493-496, 519-522, 573-576, 580-583, 624-627, 631-634, 646-649, 705-708, 732-735, 744-747, 832-835, 899-902, 980-983, 1132-1135, and 1164-1167), tyrosine phosphorylation sites (at about residues 17-23, 482-489, and 601-608), and N-myristoylation sites (at about residues 288-293, 497-502, 524-529, 655-660, 728-733, 828-833, 961-966, 984-989, 1010-1015, 1055-1060, and 1123-1128) in the amino acid sequence of SEQ ID NO:20.  
      A search of the amino acid sequence of human PLTR-1 was also performed against the ProDom database (available online through the Centre National de la Recherche Scientifique, France; see Corpet, F. et al. (2000)  Nucleic Acids Res.  28:267-269). This search resulted in the identification of homology between the PLTR-1 protein and phospholipid transporting ATPases (ProDom Accession Numbers PD004932, PD004982, PD030421, PD004657, PD304524, and PD116286).  
      Tissue Distribution of PLTR-1 mRNA Using in Situ Analysis  
      This example describes the tissue distribution of human PLTR-1 mRNA, as may be determined using in situ hybridization analysis. For in situ analysis, various tissues, e.g., tissues obtained from brain or vessels, are first frozen on dry ice. Ten-micrometer-thick sections of the tissues are postfixed with 4% formaldehyde in DEPC-treated 1× phosphate-buffered saline at room temperature for 10 minutes before being rinsed twice in DEPC 1× phosphate-buffered saline and once in 0.1 M triethanolamine-HCl (pH 8.0). Following incubation in 0.25% acetic anhydride-0.1 M triethanolamine-HCl for 10 minutes, sections are rinsed in DEPC 2×SSC (1×SSC is 0.15 M NaCl plus 0.015 M sodium citrate). Tissue is then dehydrated through a series of ethanol washes, incubated in 100% chloroform for 5 minutes, and then rinsed in 100% ethanol for 1 minute and 95% ethanol for 1 minute and allowed to air dry.  
      Hybridizations are performed with  35 S-radiolabeled (5×10 7  cpm/ml) cRNA probes. Probes are incubated in the presence of a solution containing 600 mM NaCl, 10 mM Tris (pH 7.5), 1 mM EDTA, 0.01% sheared salmon sperm DNA, 0.01% yeast tRNA, 0.05% yeast total RNA type X1, 1× Denhardt&#39;s solution, 50% formamide, 10% dextran sulfate, 100 mM dithiothreitol, 0.1% sodium dodecyl sulfate (SDS), and 0.1% sodium thiosulfate for 18 hours at 55° C.  
      After hybridization, slides are washed with 2×SSC. Sections are then sequentially incubated at 37° C. in TNE (a solution containing 10 mM Tris-HCl (pH 7.6), 500 mM NaCl, and 1 mM EDTA), for 10 minutes, in TNE with 10 μg of RNase A per ml for 30 minutes, and finally in TNE for 10 minutes. Slides are then rinsed with 2×SSC at room temperature, washed with 2×SSC at 50° C. for 1 hour, washed with 0.2×SSC at 55° C. for 1 hour, and 0.2×SSC at 60° C. for 1 hour. Sections are then dehydrated rapidly through serial ethanol-0.3 M sodium acetate concentrations before being air dried and exposed to Kodak Biomax MR scientific imaging film for 24 hours and subsequently dipped in NB-2 photoemulsion and exposed at 4° C. for 7 days before being developed and counter stained.  
     Example 10  
     Analysis of Human PLTR-1 Expression  
      This example describes the expression of human PLTR-1 mRNA in various human vessels, as determined using the TaqMan™ procedure.  
      The Taqman™ procedure is a quantitative, real-time PCR-based approach to detecting mRNA. The RT-PCR reaction exploits the 5′ nuclease activity of AmpliTaq Gold™ DNA Polymerase to cleave a TaqMan™ probe during PCR. Briefly, cDNA was generated from the samples of interest and served as the starting material for PCR amplification. In addition to the 5′ and 3′ gene-specific primers, a gene-specific oligonucleotide probe (complementary to the region being amplified) was included in the reaction (i.e., the Taqman™ probe). The TaqMan™ probe included an oligonucleotide with a fluorescent reporter dye covalently linked to the 5′ end of the probe (such as FAM (6-carboxyfluorescein), TET (6-carboxy-4,7,2′,7′-tetrachlorofluorescein), JOE (6-carboxy-4,5-dichloro-2,7-dimethoxyfluorescein), or VIC) and a quencher dye (TAMRA (6-carboxy-N,N,N′,N′-tetramethylrhodamine) at the 3′ end of the probe.  
      During the PCR reaction, cleavage of the probe separated the reporter dye and the quencher dye, resulting in increased fluorescence of the reporter. Accumulation of PCR products was detected directly by monitoring the increase in fluorescence of the reporter dye. When the probe was intact, the proximity of the reporter dye to the quencher dye resulted in suppression of the reporter fluorescence. During PCR, if the target of interest was present, the probe specifically annealed between the forward and reverse primer sites. The 5′-3′ nucleolytic activity of the AmpliTaq™ Gold DNA Polymerase cleaved the probe between the reporter and the quencher only if the probe hybridized to the target. The probe fragments were then displaced from the target, and polymerization of the strand continued. The 3′ end of the probe was blocked to prevent extension of the probe during PCR. This process occurred in every cycle and did not interfere with the exponential accumulation of product. RNA was prepared using the trizol method and treated with DNase to remove contaminating genomic DNA. cDNA was synthesized using standard techniques. Mock cDNA synthesis in the absence of reverse transcriptase resulted in samples with no detectable PCR amplification of the control GAPDH or β-actin gene confirming efficient removal of genomic DNA contamination.  
      The expression of human PLTR-1 was examined in various human vessels using Taqman analysis. The results, set forth below in Table III, indicate that human PLTR-1 is highly expressed in aortic smooth muscle cells (SMCs), coronary smooth muscle cells (SMCs), normal artery, interior mammary artery, diseased iliac artery, diseased tibial artery, diseased aorta, and normal saphenous vein.  
                               TABLE III                       Tissue Type   Mean   β 2 Mean   ∂∂ Ct   Expression                                                     1. Human umbilicial vein   23.27   19.37   3.9   67.2184          endothelial cells          (HUVECs) - Static        2. HUVECs - Laminar   23.23   19.41   3.82   70.8052          shear stress (LSS)        3. Aortic smooth muscle   24.77   19.75   5.01   30.9268          cells (SMCs)        4. Coronary SMCs   25.84   20.27   5.57   21.0505        5. Human adipose tissue   30.41   18.8   11.61   0.3199        6. Normal human carotid artery   24.55   18.56   5.99   15.7337        7. Normal human artery   26.4   19.64   6.75   9.2585        8. Normal human artery   28.46   19.44   9.02   1.9262        9. Normal human artery   34.9   22.47   12.43   0.1818       10. Internal mammary artery   29.98   23.05   6.93   8.1725       11. Internal mammary artery   27.82   23.09   4.72   37.8123       12. Internal mammary artery   29.67   22.57   7.11   7.2641       13. Internal mammary artery   27.91   22.26   5.64   19.9841       14. Internal mammary artery   26.76   21.31   5.45   22.8763       15. Internal mammary artery   27.21   21.15   6.07   14.9366       16. Internal mammary artery   33.2   24.45   8.76   2.3146       17. Diseased human iliac artery   26.38   20.27   6.11   14.5282       18. Diseased human tibial artery   23.11   18.15   4.96   32.0174       19. Diseased human aorta   27   20.84   6.16   14.0333       20. Diseased aorta   28.11   22.31   5.81   17.8244       21. Diseased aorta   27.75   21.95   5.8   17.9484       22. Diseased aorta   28.28   21.52   6.75   9.2585       23. Normal human saphenous   28.83   21.2   7.63   5.0658          vein       24. Normal human saphenous   23.88   17.48   6.39   11.9239          vein       25. Normal human saphenous   22.54   16.92   5.62   20.3335          vein       26. Normal human vein   28.08   19.19   8.89   2.1079       27. Normal human saphenous   28.11   20.05   8.07   3.7212          vein       28. Normal human vein   26.58   19.2   7.38   6.0243       29. Normal human vein   30.28   21.31   8.97   1.9942                  
 
      Taqman analysis was further used to examine the expression of human PLTR-1 in human umbilical vein endothelial cells (HUVECs), human aortic endothelial cells (HAECs), and human microvascular endothelial cells (HMVECs) treated with mevastatin for varying amounts of time and at varying amounts. The results are set forth below in Table IV. Mevastatin is a cholesterol-lowering drug that functions by inhibition of HMG-CoA Reductase. As shown below, human PLTR-1 is upregulated by mevastatin treatment, PLTR-1 activity may be useful in screening assays for therapeutic modulators (e.g., positive modulators).  
                               TABLE IV                       Cells/Treatment   Mean   β 2 Mean   ∂∂ Ct   Expression                                                    HUVEC Vehicle   25.32   19.65   5.67   19.709       HUVEC Mev   24.11   18.98   5.13   28.6564       HAEC Vehicle   25.06   19.34   5.72   18.9062       HAEC MEV   26.02   20.98   5.03   30.6069       HMVEC/Vehicle/24 hr   26.36   18.12   8.24   3.2962       HMVEC/Mev/24 hr/1X   25.82   18.11   7.71   4.7925       HMVEC/MEV/24 HR/2.5X   25.25   18.03   7.22   6.6843       HMVEC/MEV/48 HR/1X   26.16   18.61   7.56   5.2992       HMVEC/MEV/48 HR/2.5X   25.19   18.28   6.91   8.3154       HUVEC/Vehicle/24 hr   25.2   17.56   7.63   5.0308       HUVEC/Mev/24 hr/1X   24.07   18.12   5.95   16.176       HUVEC/MEV/24 HR/2.5X   24.91   18.88   6.04   15.1977       HUVEC/MEV/48 HR/1X   26.69   20.66   6.03   15.3566       HUVEC/MEV/48 HR/2.5X   30.02   22.24   7.78   4.5655                  
 
     Example 11  
     Identification and Characterization of Human TFM-2 and TFM-3 cDNAs  
      In this example, the identification and characterization of the gene encoding human TFM-2 (clone 32146) and human TFM-3 (clone 57259) is described.  
      Isolation of the Human TFM-2 and TFM-3 cDNAs  
      The invention is based, at least in part, on the discovery of two human genes encoding novel polypeptides, referred to herein as human TFM-2 and TFM-3. The entire sequence of the human clone 32146 was determined and found to contain an open reading frame termed human “TFM-2.” The nucleotide sequence of the human TFM-2 gene is set forth in the Sequence Listing as SEQ ID NO:27. The amino acid sequence of the human TFM-2 expression product is set forth in the Sequence Listing as SEQ ID NO:28. The TFM-2 polypeptide comprises 392 amino acids. The coding region (open reading frame) of SEQ ID NO:27 is set forth as SEQ ID NO:29.  
      The entire sequence of the human clone 57259 was determined and found to contain an open reading frame termed human “TFM-3.” The nucleotide sequence of the human TFM-3 gene is set forth in the Sequence Listing as SEQ ID NO:30. The amino acid sequence of the human TFM-3 expression product is set forth in the Sequence Listing as SEQ ID NO:31. The TFM-3 polypeptide comprises 405 amino acids. The coding region (open reading frame) of SEQ ID NO:30 is set forth as SEQ ID NO:32.  
      Analysis of the Human TFM-2 and TFM-3 Molecules  
      A search using the polypeptide sequence of SEQ ID NO:28 was performed against the HMM database in PFAM resulting in the identification of a potential monocarboxylate transporter domain in the amino acid sequence of human TFM-2 at about residues 1-332 of SEQ ID NO:28 (score=35.5), a potential LacY proton/sugar symporter domain in the amino acid sequence of human TFM-2 at about residues 42-322 of SEQ ID NO:28 (score=−341.8), a potential polysaccharide biosynthesis domain in the amino acid sequence of human TFM-2 at about residues 77-353 of SEQ ID NO:28 (score=−96.2), and a potential domain of unknown function, DUF20, in the amino acid sequence of human TFM-2 at about residues 26-326 of SEQ ID NO:28 (score=−133.4).  
      The amino acid sequence of human TFM-2 was analyzed using the program PSORT (Nakai, K. and Horton, P. (1999)  Trends. Biochem. Sci.  24(1) 34-35) to predict the localization of the proteins within the cell. This program assesses the presence of different targeting and localization amino acid sequences within the query sequence. The results of this analysis show that human TFM-2 may be localized to the endoplasmic reticulum, mitochondria or nucleus.  
      Searches of the amino acid sequence of human TFM-2 were further performed against the Prosite database. These searches resulted in the identification in the amino acid sequence of human TFM-2 of a potential glycosaminoglycan attachment site (e.g., at residues 216-219 of SEQ ID NO:28), a number of potential cAMP- and cGMP-dependent protein kinase phosphorylation sites (e.g., at residues 151-154, 385-388 of SEQ ID NO:28), a number of potential protein kinase C phosphorylation sites (e.g., at residues 110-112, 127-129, 134-136, 149-151, 351-353, 361-363 of SEQ ID NO:28), a number of potential casein kinase II phosphorylation sites (e.g., at residues 40-43, 134-137, 361-364 of SEQ ID NO:28), a number of potential N-myristoylation sites (e.g., at residues 17-22, 25-30, 32-37, 50-55, 56-61, 77-82, 106-111, 141-146, 176-181, 213-218, 260-265, 270-275, 340-345 of SEQ ID NO:28), a potential membrane lipoprotein lipid attachment site (e.g., at residues 45-55 of SEQ ID NO:28), and a potential leucine zipper site (e.g., at residues 241-262 of SEQ ID NO:28).  
      A MEMSAT analysis of the polypeptide sequence of SEQ ID NO:28 was also performed ( FIG. 17 ), predicting ten potential transmembrane domains in the amino acid sequence of human TFM-2 (SEQ ID NO:28) at about residues 22-42, 49-69, 76-98, 105-128, 167-186, 207-223, 236-253, 261-285, 296-318, and 327-349.  
      A search of the amino acid sequence of human TFM-2 was also performed against the ProDom database. This search resulted in the local alignment of the human TFM-2 protein with various transporter proteins.  
      A search using the polypeptide sequence of SEQ ID NO:31 was performed against the HMM database in PFAM resulting in the identification of a potential sugar transporter domain in the amino acid sequence of human TFM-3 at about residues 1-353 of SEQ ID NO:31 (score=−160.9).  
      The amino acid sequence of human TFM-3 was also analyzed using the program PSORT The results of this analysis show that human TFM-3 may be localized to the endoplasmic reticulum, mitochondria, secretory vesicles or vacuole.  
      Searches of the amino acid sequence of human TFM-3 were further performed against the Prosite database. These searches resulted in the identification in the amino acid sequence of human TFM-3 of a potential N-glycosylation site (e.g., at residues 348-351 of SEQ ID NO:31), a number of potential protein kinase C phosphorylation sites (e.g., at residues 4-6, 85-87, 97-99, 106-108, 129-131, 250-252 of SEQ ID NO:31), a number of potential casein kinase II phosphorylation sites (e.g., at residues 250-253, 350-353, 373-376, 392-395 of SEQ ID NO:31), a number of potential N-myristoylation sites (e.g., at residues 15-20, 162-167, 246-251, 263-268, 292-297, 382-387, 396-401 of SEQ ID NO:31), a number of potential amidation sites (e.g., at residues 30-33,209-212 of SEQ ID NO:31), and a number of potential prokaryotic membrane lipoprotein lipid attachment sites (e.g., at residues 189-199, 315-325 of SEQ ID NO:31).  
      A MEMSAT analysis of the polypeptide sequence of SEQ ID NO:31 was also performed ( FIG. 19 ), predicting nine potential transmembrane domains in the amino acid sequence of human TFM-3 (SEQ ID NO:31) at about residues 7-23, 34-57, 66-82, 150-168, 188-206, 213-237, 255-279, 288-308, and 321-337.  
      A search of the amino acid sequence of human TFM-3 was also performed against the ProDom database. This search resulted in the local alignment of the human TFM-3 protein with various transporter proteins.  
     Example 12  
     Identification and Characterization of Human 67118 and 67067 cDNAs  
      In this example, the identification and characterization of the gene encoding human 67118 (clone 67118) and 67067 (clone 67067) is described.  
      Isolation of the Human 67118 and 67067 cDNAs  
      The invention is based, at least in part, on the discovery of two human genes encoding a novel polypeptides, referred to herein as human 67118 and 67067. The entire sequence of the human clone 67118 was determined and found to contain an open reading frame termed human “67118.” The nucleotide sequence of the human 67118 gene is set forth in the Sequence Listing as SEQ ID NO:33. The amino acid sequence of the human 67118 expression product is set forth in the Sequence Listing as SEQ ID NO:34. The 67118 polypeptide comprises 1134 amino acids. The coding region (open reading frame) of SEQ ID NO:33 is set forth as SEQ ID NO:35.  
      The entire sequence of the human clone 67067 was determined and found to contain an open reading frame termed human “67067.” The nucleotide sequence of the human 67067 gene is set forth in and in the Sequence Listing as SEQ ID NO:36. The amino acid sequence of the human 67067 expression product is set forth in the Sequence Listing as SEQ ID NO:37. The 67067 polypeptide comprises 1588 amino acids. The coding region (open reading frame) of SEQ ID NO:36 is set forth as SEQ ID NO:38.  
      Analysis of the Human 67118 and 67067 Molecules  
      The amino acid sequences of human 67118 and human 67067 were analyzed for the presence of sequence motifs specific for P-type ATPases (as defined in Tang, X. et al. (1996)  Science  272:1495-1497 and Fagan, M. J. and Saier, M. H. (1994)  J. Mol. Evol.  38:57). These analyses resulted in the identification of a P-type ATPase sequence I motif in the amino acid sequence of human 67118 at residues 179-187 of SEQ ID NO:34 and in the amino acid sequence of human 67067 at residues 175-183 of SEQ ID NO:37. These analyses also resulted in the identification of a P-type ATPase sequence 2 motif in the amino acid sequence of human 67118 at residues 411-420 of SEQ ID NO:34. These analyses also resulted in the identification of a P-type ATPase sequence 2 motif in the amino acid sequence of human 67067 at residues 431-440 of SEQ ID NO:37. These analyses further resulted in the identification of a P-type ATPase sequence 3 motif in the amino acid sequence of human 67118 at residues 823-833 of SEQ ID NO:34. These analyses further resulted in the identification of a P-type ATPase sequence 3 motif in the amino acid sequence of human 67067 at residues 1180-1190 of SEQ ID NO:37.  
      The amino acid sequences of human 67118 and 67067 were also analyzed for the presence of phospholipid transporter specific amino acid residues (as defined in Tang, X. et al. (1996)  Science  272:1495-1497). These analyses resulted in the identification of phospholipid transporter specific amino acid residues in the amino acid sequence of human 67118 at residues 179, 183, 442, 823, 832, and 833 of SEQ ID NO:34 (FIGS.  21 A-B). These analyses resulted in the identification of phospholipid transporter specific amino acid residues 175, 176, 179, 432, 1180, 1189, and 1190 in the amino acid sequence of human 67067 at residues of SEQ ID NO:37 (FIGS.  23 A-B).  
      The amino acid sequences of human 67118 and human 67067 were also analyzed for the presence of extramembrane domains. An N-terminal large extramembrane domain was identified in the amino acid sequence of human 67118 at residues 111-294 of SEQ ID NO:34. A C-terminal large extramembrane domain was identified in the amino acid sequence of human 67118 at residues 369-890 of SEQ ID NO:34. An N-terminal large extramembrane domain was identified in the amino acid sequence of human 67067 at residues 105-286 of SEQ ID NO:37. A C-terminal large extramembrane domain was identified in the amino acid sequence of human 67067 at residues 389-1238 of SEQ ID NO:37.  
      The amino acid sequence of human 67118 was analyzed using the program PSORT to predict the localization of the proteins within the cell. This program assesses the presence of different targeting and localization amino acid sequences within the query sequence. The results of this analysis predict that human 67118 may be localized to the endoplasmic reticulum.  
      Searches of the amino acid sequence of human 67118 were further performed against the Prosite database. These searches resulted in the identification in the amino acid sequence of human 67118 of a number of potential N-glycosylation sites at about residues 397-400, 745-748, 921-924, 989-992, and 1001-1004 of SEQ ID NO:34, a number of potential cAMP-and cGMP-dependent protein kinase phosphorylation sites at about residues 140-143, 558-561, and 705-708 of SEQ ID NO:34, a number of potential protein kinase C phosphorylation sites at about residues 52-54, 143-145, 169-171, 188-190, 255-257, 259-261, 283-285, 335-337, 413-415, 555-557, 714-716, 1017-1019, and 1105-1107 of SEQ ID NO:34, a number of casein kinase II phosphorylation sites at about residues 203-206, 269-272, 287-290, 333-336, 380-383, 418-421, 451-454, 507-510, 659-662, 722-725, 910-913, 933-936, and 1103-1106 of SEQ ID NO:34, a number of potential tyrosine kinase phosphorylation sites at about residues 878-885, 1019-1026 of SEQ ID NO:34, a number of N-myristoylation sites at about residues 208-213, 498-503, 577-582, 762-767, 775-780, 972-977, and 996-1001 of SEQ ID NO:34, an RGD cell attachment sequence at about residues 171-173 of SEQ ID NO:34, and an E1-E2 ATPases phosphorylation site at about residues 414-420 of SEQ ID NO:34.  
      A MEMSAT analysis of the polypeptide sequence of SEQ ID NO:34 was also performed, predicting ten potential transmembrane domains in the amino acid sequence of human 67118 (SEQ ID NO:34) at about residues 71-87, 94-110, 295-314, 349-368, 891-907, 915-935, 964-987, 1002-1018, 1033-1057, and 1064-1088.  
      A search of the amino acid sequence of human 67118 was also performed against the ProDom database, resulting in the identification of several ATPase, hydrolase, and/or transmembrane domain-containing proteins.  
      The amino acid sequence of human 67067 was analyzed using the program PSORT. The results of this analysis predict that human 67067 may be localized to the endoplasmic reticulum.  
      Searches of the amino acid sequence of human 67067 were further performed against the Prosite database. These searches resulted in the identification in the amino acid sequence of human 67067 of a number of potential N-glycosylation sites at about residues 270-273, 340-343, 355-358, 1060-1063, 1318-1321, and 1400-1403 of SEQ ID NO:37, a glycosaminoglycan attachment site at about residues 820-823 of SEQ ID NO:37, a number of potential cAMP- and cGMP-dependent protein kinase phosphorylation sites at about residues 447-450, 694-697, 898-901, and 1575-1578 of SEQ ID NO:37, a number of protein kinase C phosphorylation sites at about residues 29-31, 45-47, 115-117, 128-130, 247-249, 433-435, 473-475, 521-523, 535-537, 555-557, 564-566, 567-569, 579-581, 733-735, 737-739, 874-876, 895-897, 949-951, 981-983, 1030-1032, 1055-1057, 1475-1477, 1508-1510, 1574-1576, and 1578-1580 of SEQ ID NO:37, a number of potential casein kinase II phosphorylation sites at about residues 29-32, 128-131, 195-198, 279-282, 342-345, 438-441, 457-460, 535-538, 541-544, 607-610, 632-635, 648-651, 666-669, 717-720, 743-746, 770-773, 785-788, 797-800, 801-804, 810-813, 824-827, 848-851, 972-975, 1014-1017, 1030-1033, 1179-1182, 1200-1203, 1267-1270, 1325-1328, 1347-1350, 1500-1503, and 1549-1552 of SEQ ID NO:37, a tyrosine kinase phosphorylation site at about residues 1140-1148 of SEQ ID NO:37, a number of potential N-myristoylation sites at about residues 303-308, 453-458, 714-719, 779-784, 798-803, 805-810, 821-826, 880-885, 1023-1028, 1196-1201, 1355-1360, and 1501-1506 of SEQ ID NO:37, a potential amidation site at about residues 4-7 of SEQ ID NO:37, an ATP/GTP-binding site motif (P-loop) at about residues 1122-1129 of SEQ ID NO:37, a leucine zipper pattern at about residues 990-1011 of SEQ ID NO:37, and an E1-E2 ATPases phosphorylation site at about residues 434-440 of SEQ ID NO:37.  
      A MEMSAT analysis of the polypeptide sequence of SEQ ID NO:37 was also performed, predicting eight potential transmembrane domains in the amino acid sequence of human 67067 (SEQ ID NO:37). However, a structural, hydrophobicity, and antigenicity analysis ( FIG. 22 ) resulted in the identification of ten transmembrane domains. Accordingly, the 67067 protein of SEQ ID NO:37 is predicted to have at least ten transmembrane domains, at about residues 65-82, 89-105, 287-304, 366-388, 1239-1259, 1322-1343, 1274-1292, 1351-1368, 1377-1399, 1425-1446.  
      A search of the amino acid sequence of human 67067 was also performed against the ProDom database, resulting in the identification of several ATPase, hydrolase, and/or transmembrane domain-containing proteins.  
     Example 13  
     Tissue Distribution of 67118 mRNA Using Taqman™ Analysis  
      This example describes the tissue distribution of human 67118 mRNA in a variety of cells and tissues, as determined using the TaqMan™ procedure. The Taqman™ procedure is a quantitative, reverse transcription PCR-based approach for detecting mRNA. The RT-PCR reaction exploits the 5′ nuclease activity of AmpliTaq Gold™ DNA Polymerase to cleave a TaqMan™ probe during PCR. Briefly, cDNA was generated from the samples of interest, including, for example, various normal and diseased vascular and arterial samples, and used as the starting material for PCR amplification. In addition to the 5′ and 3′ gene-specific primers, a gene-specific oligonucleotide probe (complementary to the region being amplified) was included in the reaction (i.e., the Taqman™ probe). The TaqMan™ probe includes the oligonucleotide with a fluorescent reporter dye covalently linked to the 5′ end of the probe (such as FAM (6-carboxyfluorescein), TET (6-carboxy-4,7,2′,7′-tetrachlorofluorescein), JOE (6-carboxy-4,5-dichloro-2,7-dimethoxyfluorescein), or VIC) and a quencher dye (TAMRA (6-carboxy-N,N,N′,N′-tetramethylrhodamine) at the 3′ end of the probe.  
      During the PCR reaction, cleavage of the probe separates the reporter dye and the quencher dye, resulting in increased fluorescence of the reporter. Accumulation of PCR products is detected directly by monitoring the increase in fluorescence of the reporter dye. When the probe is intact, the proximity of the reporter dye to the quencher dye results in suppression of the reporter fluorescence. During PCR, if the target of interest is present, the probe specifically anneals between the forward and reverse primer sites. The 5′-3′ nucleolytic activity of the AmpliTaq™ Gold DNA Polymerase cleaves the probe between the reporter and the quencher only if the probe hybridizes to the target. The probe fragments are then displaced from the target, and polymerization of the strand continues. The 3′ end of the probe is blocked to prevent extension of the probe during PCR. This process occurs in every cycle and does not interfere with the exponential accumulation of product. RNA was prepared using the trizol method and treated with DNase to remove contaminating genomic DNA. cDNA was synthesized using standard techniques. Mock cDNA synthesis in the absence of reverse transcriptase resulted in samples with no detectable PCR amplification of the control gene confirms efficient removal of genomic DNA contamination.  
      The expression levels of human 67118 mRNA in various human cell types and tissues were analyzed using the Taqman procedure. As shown in Table V, the highest 67118 expression was detected in static Human Umbilical Vein Endothelial Cells (HUVEC), followed by Human Aortic Endothelial Cells (HAEC) treated with Mevastatin, HUVEC treated with Mevastatin, HUVEC Vehicle, HUVEC LSS, coronary smooth muscle cells, and aortic smooth muscle cells.  
                               TABLE V                       Tissue Type   Mean   β 2 Mean   ∂∂ Ct   Expression                                                    Aortic SMC   26.02   20.25   5.77   18.3255       Coronary SMC   26.39   20.75   5.64   19.9841       Huvec Static   22.2   18.98   3.22   107.3207       Huvec LSS   24.13   18.61   5.53   21.7175       H/Adipose/MET 9   32.55   18.07   14.48   0.0438       H/Artery/Normal/Carotid/   33.1   18.61   14.49   0.0435       CLN 595       H/Artery/Normal/Carotid/   35.92   19.82   16.1   0       CLN 598       H/Artery/normal/NDR 352   31.34   20.75   10.6   0.6465       H/IM Artery/Normal/AMC 73   39.19   22.92   16.27   0       H/Muscular Artery/Normal/   32.06   24.05   8.02   3.8525       AMC 236/       H/Muscular Artery/Normal/   35.73   22.98   12.75   0       AMC 247/       H/Muscular Artery/Normal/   32.99   22.48   10.52   0.6834       AMC 254/       H/Muscular Artery/Normal/   30.56   21.32   9.23   1.6595       AMC 259/       H/Muscular Artery/Normal/   31.06   21.65   9.4   1.4751       AMC 261/       H/Muscular Artery/Normal/   30.89   23.39   7.5   5.5243       AMC 275/       H/Aorta/Diseased/PIT 732   32.84   21.31   11.54   0.337       H/Aorta/Diseased/PIT 710   30.74   22.4   8.35   3.0754       H/Aorta/Diseased/PIT 711   30.75   22.13   8.62   2.5417       H/Aorta/Diseased/PIT 712   29.51   21.91   7.61   5.1365       H/Artery/Diseased/iliac/   27.44   18.02   9.41   1.4649       NDR 753       H/Artery/Diseased/Tibial/   33.13   19.41   13.72   0.0744       PIT 679       H/Vein/Normal/SaphenousAMC   30.36   20.02   10.34   0.7715       107       H/Vein/Normal/NDR 239   37.15   20.83   16.32   0       H/Vein/Normal/Saphenous/   31.2   20   11.21   0.4236       NDR 237       H/Vein/Normal/PIT 1010   27.36   20.09   7.27   6.4791       H/Vein/Normal/AMC 191   29.32   21.59   7.73   4.7102       H/Vein/Normal/AMC 130   28.72   20.66   8.06   3.7342       H/Vein/Normal/AMC 188   31.63   24.34   7.28   6.4343       HUVEC Vehicle   25.46   19.84   5.63   20.2631       HUVEC Mev   24.61   19.27   5.34   24.6034       HAEC Vehicle   25.65   20   5.65   19.915       HAEC Mev   26.72   21.76   4.96   32.1286                  
 
     Example 14  
     Tissue Distribution of 67067 mRNA Using Taqman™ Analysis  
      The tissue distribution of human 67067 mRNA in a variety of cells and tissues was determined using the TaqMan™ procedure, as described above.  
      As shown in Table VI, below, 67067 is overexpressed in colon tumor tissue as compared to normal tumor tissue, indicating a possible role for 67067 in cellular proliferation disorders, e.g., cancer, including, but not limited to colon cancer. Human 67067 mRNA is also highly expressed in normal brain cortex tissue and normal ovary, for example.  
                               TABLE VI                       Tissue Type   Mean   β 2 Mean   ∂∂ Ct   Expression                                                    Artery normal   32.95   22.56   10.4   0.7401       Aorta diseased   34.75   23.2   11.55   0.3335       Vein normal   38.53   21.36   17.18   0       Coronary SMC   38.67   22.54   16.14   0       HUVEC   39.28   22.79   16.49   0       Hemangioma   33.84   21.3   12.54   0.1679       Heart normal   36.09   21.05   15.04   0       Heart CHF   35.33   21.5   13.82   0       Kidney   31.6   21.34   10.26   0.8155       Skeletal Muscle   36.3   23.51   12.79   0       Adipose normal   40   23.07   16.93   0       Pancreas   31.49   23.73   7.76   4.5973       primary osteoblasts   40   21.06   18.95   0       Osteoclasts (diff)   35.04   18.19   16.85   0       Skin normal   34.23   23.73   10.51   0.6858       Spinal cord normal   30.47   22.32   8.14   3.5327       Brain Cortex normal   28.66   23.72   4.95   32.4643       Brain Hypothalamus   30.32   24.07   6.25   13.139       normal       Nerve   30.95   22.55   8.4   2.9501       DRG (Dorsal Root   30.07   22.88   7.2   6.8248       Ganglion)       Breast normal   37.3   22.5   14.8   0       Breast tumor   36.56   22.38   14.19   0       Ovary normal   27.73   21.25   6.47   11.2807       Ovary Tumor   31.93   20.57   11.36   0.3805       Prostate Normal   37.28   19.95   17.34   0       Prostate Tumor   33.87   21.14   12.73   0.1472       Salivary glands   32.1   20.75   11.35   0.3831       Colon normal   27.24   20.11   7.13   7.1146       Colon Tumor   26.34   22.9   3.44   91.823       Lung normal   35.78   19.95   15.84   0       Lung tumor   28.48   20.66   7.82   4.4253       Lung COPD   36.01   19.41   16.61   0       Colon IBD   25.16   19.02   6.14   14.18       Liver normal   37.01   21.58   15.43   0       Liver fibrosis   35.28   22.5   12.79   0       Spleen normal   38.06   19.98   18.08   0       Tonsil normal   28.32   18.69   9.63   1.2621       Lymph node normal   34.88   20.49   14.39   0.0467       Small intestine normal   28.99   21.86   7.13   7.1641       Macrophages   36.06   18.16   17.89   0       Synovium   34.62   21.27   13.35   0.0958       BM-MNC   40   20.75   19.25   0       Activated PBMC   36.87   18.41   18.47   0       Neutrophils   40   19.59   20.41   0       Megakaryocytes   37.98   20   17.98   0       Erythroid   40   23.07   16.93   0       positive control   29.45   21.89   7.57   5.2809                  
 
     Example 15  
     Identification and Characterization of Human 62092 cDNA  
      In this example, the identification and characterization of the gene encoding human 62092 (clone 62092) is described.  
      Isolation of the Human 62092 cDNA  
      The invention is based, at least in part, on the discovery of genes encoding novel members of the histidine triad family. The entire sequence of human clone Fbh62092 was determined and found to contain an open reading frame termed human “62092”.  
      The nucleotide sequence encoding the human 62092 is set forth as SEQ ID NO:39. The protein encoded by this nucleic acid comprises about 163 amino acids and has the amino acid sequence set forth as SEQ ID NO:40. The coding region (open reading frame) of SEQ ID NO:39 is set forth as SEQ ID NO:41.  
      Analysis of the Human 62092 Molecules  
      The amino acid sequence of human 62092 was analyzed using the program PSORT to predict the localization of the proteins within the cell. This program assesses the presence of different targeting and localization amino acid sequences within the query sequence. The results of the analyses show that human 62092 is most likely localized to the mitochondria.  
      Searches of the amino acid sequence of human 62092 were also performed against the HMM database. These searches resulted in the identification of a “HIT family domain” at about residues 54-155 (score=180.3).  
      Searches of the amino acid sequence of human 62092 were further performed against the Prosite™ database. These searches resulted in the identification of a “HIT family signature motif” at about residues 136-151 of SEQ ID NO:40. These searches further resulted in the identification in the amino acid sequence of human 62092 of a potential protein kinase C phosphorylation site at about residues 121-123 of SEQ ID NO:40, a potential casein kinase II phosphorylation site at about residues 101-104 of SEQ ID NO:40, and a number of N-myristoylation sites at about residues 10-15, 22-27, 33-38, 50-55, and 126-131 of SEQ ID NO:40.  
      A search of the amino acid sequence of human 62092 was also performed against the ProDom database, resulting in the identification of a “protein HIT-like domain” at amino acid residues 54-155 of SEQ ID NO:40.  
     Example 16  
     Tissue Distribution of 62092 mRNA Using Taqman™ Analysis  
      The tissue distribution of human 62092 mRNA in a variety of cells and tissues was determined using the TaqMan™ procedure, as described above.  
      As shown in Table VII, below, 62092 is notably overexpressed in lung tumor tissue as compared to normal lung tissue, indicating a possible role for 62092 in cellular proliferation disorders, e.g., cancer, including, but not limited to lung cancer. Human 62092 mRNA is also highly expressed in activated PMBC, erythroid cells, normal brain cortex and hypothalamus, and normal liver tissue, for example.  
                               TABLE VII                       Tissue Type   Mean   β 2 Mean   ∂∂ Ct   Expression                                                    Artery normal   28.59   22.41   4.2   54.5983       Aorta diseased   30.42   23.1   5.34   24.7745       Vein normal   28.43   20.7   5.74   18.7106       Coronary SMC   28.11   23.03   3.1   117.034       HUVEC   27.15   22.81   2.36   195.4674       Hemangioma   28.3   20.66   5.66   19.8461       Heart normal   27.23   20.69   4.55   42.6888       Heart CHF   26.16   21.15   3.02   123.2791       Kidney   26.25   21.32   2.94   130.3082       Skeletal Muscle   27.87   23.18   2.7   153.8931       Adipose normal   28.24   22.71   3.54   85.6739       Pancreas   28.21   23.65   2.58   167.2409       primary osteoblasts   30.15   21.09   7.08   7.3911       Osteoclasts (diff)   27.38   18.06   7.34   6.1936       Skin normal   30   23.63   4.39   47.6956       Spinal cord normal   29.34   22.31   5.04   30.2903       Brain Cortex normal   28.2   25.26   0.95   515.8416       Brain Hypothalamus normal   27.98   23.97   2.02   246.5582       Nerve   29.12   22.73   4.41   47.039       DRG (Dorsal Root Ganglion)   27.6   22.63   2.98   126.3064       Breast normal   28.19   22.42   3.79   72.544       Breast tumor   30.18   22.86   5.33   24.8605       Ovary normal   27.4   21.17   4.24   52.9216       Ovary Tumor   26.63   20.82   3.83   70.3162       Prostate Normal   26.62   19.69   4.95   32.4643       Prostate Tumor   26.46   21.15   3.33   99.4421       Salivary glands   27.92   20.61   5.33   24.8605       Colon normal   26.43   20.09   4.36   48.8669       Colon Tumor   28.53   22.93   3.61   81.8996       Lung normal   27.1   19.63   5.49   22.328       Lung tumor   24.89   23.47   −0.56   1479.3875       Lung COPD   26.18   19.24   4.96   32.1286       Colon IBD   26.08   18.84   5.25   26.1871       Liver normal   25.48   21.27   2.22   214.6414       Liver fibrosis   27.26   22.46   2.81   142.1021       Spleen normal   28.93   19.84   7.11   7.2641       Tonsil normal   26.32   18.84   5.5   22.0971       Lymph node normal   28.49   20.27   6.24   13.2304       Small intestine normal   28.91   21.65   5.28   25.8266       Macrophages   32.22   18.07   12.16   0.2185       Synovium   30.86   21.7   7.18   6.8961       BM-MNC   32.14   20.59   9.56   1.3248       Neutrophils   27.84   19.34   6.52   10.8964       Megakaryocytes   24.32   19.77   2.57   168.4042       Erythroid   26.68   23.36   1.33   397.7682       Activated PBMC   28.11   26.91   −0.79   1723.0923       positive control   26.71   21.86   2.87   137.2616                  
 
     Example 17  
     Tissue Distribution of 67118,67067, and 62092 mRNA Using in situ Analysis  
      This example describes the tissue distribution of human 67118, 67067, and/or 62092 mRNA, as may be determined using in situ hybridization analysis. For in situ analysis, various tissues are first frozen on dry ice. Ten-micrometer-thick sections of the tissues are postfixed with 4% formaldehyde in DEPC-treated 1× phosphate-buffered saline at room temperature for 10 minutes before being rinsed twice in DEPC 1× phosphate-buffered saline and once in 0.1 M triethanolamine-HCl (pH 8.0). Following incubation in 0.25% acetic anhydride-0.1 M triethanolamine-HCl for 10 minutes, sections are rinsed in DEPC 2×SSC (1×SSC is 0.15 M NaCl plus 0.015 M sodium citrate). Tissue is then dehydrated through a series of ethanol washes, incubated in 100% chloroform for 5 minutes, and then rinsed in 100% ethanol for 1 minute and 95% ethanol for 1 minute and allowed to air dry.  
      Hybridizations are performed with  35 S-radiolabeled (5×10 7  cpm/ml) cRNA probes. Probes are incubated in the presence of a solution containing 600 mM NaCl, 10 mM Tris (pH 7.5), 1 mM EDTA, 0.01% sheared salmon sperm DNA, 0.01% yeast tRNA, 0.05% yeast total RNA type X1, 1× Denhardt&#39;s solution, 50% formamide, 10% dextran sulfate, 100 mM dithiothreitol, 0.1% sodium dodecyl sulfate (SDS), and 0.1% sodium thiosulfate for 18 hours at 55° C.  
      After hybridization, slides are washed with 2×SSC. Sections are then sequentially incubated at 37° C. in TNE (a solution containing 10 mM Tris-HCl (pH 7.6), 500 mM NaCl, and 1 mM EDTA), for 10 minutes, in TNE with 10 μg of RNase A per ml for 30 minutes, and finally in TNE for 10 minutes. Slides are then rinsed with 2×SSC at room temperature, washed with 2×SSC at 50° C. for 1 hour, washed with 0.2×SSC at 55° C. for 1 hour, and 0.2×SSC at 60° C. for 1 hour. Sections are then dehydrated rapidly through serial ethanol-0.3 M sodium acetate concentrations before being air dried and exposed to Kodak Biomax MR scientific imaging film for 24 hours and subsequently dipped in NB-2 photoemulsion and exposed at 4° C. for 7 days before being developed and counter stained.  
     Example 18  
     Detection of 67118,67067, and 62092 Transcripts and Structure by RT-PCR Analysis  
      This example describes a method for determining the structure and expression level of human 67118, 67067, or 62092, as may be determined using RT-PCR analysis. For RT-PCR analysis, total RNA is first isolated from various tissues. Total RNA is reverse-transcribed using oligodeoxythymidylate primers and the resulting single-stranded cDNA products used as templates for first round PCR amplification. First round PCR amplification is performed using primers designed using the 67118, 67067, or 62092 sequence set forth as SEQ ID NO:33, 36, ot 39, respectively. Second round PCR amplification is performed using nested primers derived from the 67118, 67067, or 62092 sequence (SEQ ID NO:33, 36, or 39, respectively). Amplification products are electrophoresed in agarose gels and detected by ethidium bromide staining.  
      Quantitation of the signal generated by RT-PCR analysis gives a measure of the expression level of human 67118, 67067, or 62092.  
      The structure of human 67118, 67067, or 62092 can be determined by excising the RT-PCR product from an agarose gel, purifying it, and sequencing it to determine if there are missense or point mutations, or if there is a deletion within the human 67118, 67067, or 62092 gene.  
     Example 19  
     Identification and Characterization of Human HAAT cDNA  
      In this example, the identification and characterization of the gene encoding human HAAT (clone Fbh58295FL) is described.  
      Isolation of the Human HAAT cDNA  
      The invention is based, at least in part, on the discovery of genes encoding novel members of the amino acid transporter family. The entire sequence of human clone Fbh58295FL was determined and found to contain an open reading frame termed human “HAAT”.  
      The nucleotide sequence encoding the human HAAT is set forth as SEQ ID NO:51. The protein encoded by this nucleic acid comprises about 485 amino acids and has the amino acid sequence set forth as SEQ ID NO:52. The coding region (open reading frame) of SEQ ID NO:51 is set forth as SEQ ID NO:53.  
      Analysis of the Human HAAT Molecules  
      The HAAT amino acid sequence (SEQ ID NO:52) was aligned with the amino acid sequence of the rat amino acid system A transporter (ratATA2) using the CLUSTAL W (1.74) multiple sequence alignment program.  
      An analysis of the amino acid sequence of HAAT was performed using MEMSAT. This analysis resulted in the identification of 10 possible transmembrane domains in the amino acid sequence of HAAT at residues 68-72, 135-156, 190-207, 214-232, 256-274, 287-308, 334-356, 373-390, 397-421, and 435-453 of SEQ ID NO:52 ( FIG. 28 ). An additional predicted transmembrane domain (i.e., TM1 is also shown.)  
      A search using the polypeptide sequence of SEQ ID NO:52 was performed against the HMM database in PFAM resulting in the identification of a transmembrane amino acid transporter domain in the amino acid sequence of HAAT at about residues 64 to 445 of SEQ ID NO:52 (score=187.2).  
      The amino acid sequence of HAAT was further analyzed using the program PSORT (which can be found on the National Institute for Basic Biology web site) to predict the localization of the proteins within the cell. This program assesses the presence of different targeting and localization amino acid sequences within the query sequence. The results of the analysis show that HAAT is most likely localized to the endoplasmic reticulum.  
      To further identify potential structural and/or functional properties in a protein of interest, the amino acid sequence of the protein is searched against a database of annotated protein domains (e.g., the ProDom database) using the default parameters (available at http://www.toulouse.inra.fr/prodom.html). A search of the amino acid sequence of HAAT (SEQ ID NO:52) was performed against the ProDom database. This search resulted in the local alignment of the HAAT protein with various  C. Elegans  and/or amino acid protein transporter/permease proteins. Specifically, amino acid residues 288-456, 136-300, and 35-325 of SEQ ID NO:52 have significant identity to various  C. elegans -related proteins. Amino acid residues 36-346 of SEQ ID NO:52 have significant identity to various amino acid protein transporter/permease-related proteins.  
      A search of the amino acid sequence of HAAT (SEQ ID NO:52) was performed against the Prosite database. These searches resulted in the identification in the amino acid sequence of HAAT of a number of potential glycosylation sites, e.g., at amino acid residues 175-178, 221-224, 434-437, and 476-479; a potential cAMP and cGMP-dependent protein kinase phosphorylation site, e.g., at amino acid residues 103-106; a number of potential protein kinase C phosphorylation sites, e.g., at amino acid residues 281-283, 331-333, 360-362, and 460-462; a number of potential casein kinase II phosphorylation sites, e.g., at amino acid residues 16-19, 134-137, and 452-455; a potential tyrosine kinase phosphorylation site, e.g., at amino acid residues 185-193; and a number of potential N-myristoylation sites, e.g., at amino acid residues 52-57, 60-65, 293-298, 339-344, 401-406, and 448-453.  
      Tissue Distribution of HAAT mRNA  
      This example describes the tissue distribution of human HAAT mRNA, as may be determined using in situ hybridization analysis. For in situ analysis, various tissues, e.g. tissues obtained from brain, are first frozen on dry ice. Ten-micrometer-thick sections of the tissues are postfixed with 4% formaldehyde in DEPC-treated 1× phosphate-buffered saline at room temperature for 10 minutes before being rinsed twice in DEPC 1× phosphate-buffered saline and once in 0.1 M triethanolamine-HCl (pH 8.0). Following incubation in 0.25% acetic anhydride-0.1 M triethanolamine-HCl for 10 minutes, sections are rinsed in DEPC 2×SSC (1×SSC is 0.15 M NaCl plus 0.015 M sodium citrate). Tissue is then dehydrated through a series of ethanol washes, incubated in 100% chloroform for 5 minutes, and then rinsed in 100% ethanol for 1 minute and 95% ethanol for 1 minute and allowed to air dry.  
      Hybridizations are performed with  35 S-radiolabeled (5×10 7  cpm/ml) cRNA probes. Probes are incubated in the presence of a solution containing 600 mM NaCl, 10 mM Tris (pH 7.5), 1 mM EDTA, 0.01% sheared salmon sperm DNA, 0.01% yeast tRNA, 0.05% yeast total RNA type X1, 1× Denhardt&#39;s solution, 50% formamide, 10% dextran sulfate, 100 mM dithiothreitol, 0.1% sodium dodecyl sulfate (SDS), and 0.1% sodium thiosulfate for 18 hours at 55° C.  
      After hybridization, slides are washed with 2×SSC. Sections are then sequentially incubated at 37° C. in TNE (a solution containing 10 mM Tris-HCl (pH 7.6), 500 mM NaCl, and 1 mM EDTA), for 10 minutes, in TNE with 10 μg of RNase A per ml for 30 minutes, and finally in TNE for 10 minutes. Slides are then rinsed with 2×SSC at room temperature, washed with 2×SSC at 50° C. for 1 hour, washed with 0.2×SSC at 55° C. for 1 hour, and 0.2×SSC at 60° C. for 1 hour. Sections are then dehydrated rapidly through serial ethanol-0.3 M sodium acetate concentrations before being air dried and exposed to Kodak Biomax MR scientific imaging film for 24 hours and subsequently dipped in NB-2 photoemulsion and exposed at 4° C. for 7 days before being developed and counter stained.  
     Example 20  
     Tissue Expression Analysis of HAAT mRNA Using Taqman Analysis  
      This example describes the tissue distribution of HAAT in a variety of cells and tissues, as determined using the TaqMan™ procedure. The Taqman™ procedure is a quantitative, reverse transcription PCR-based approach for detecting mRNA. The RT-PCR reaction exploits the 5′ nuclease activity of AmpliTaq Gold™ DNA Polymerase to cleave a TaqMan™ probe during PCR. Briefy, cDNA was generated from the samples of interest, including, for example, various normal and diseased vascular and arterial samples, and used as the starting material for PCR amplification. In addition to the 5′ and 3′ gene-specific primers, a gene-specific oligonucleotide probe (complementary to the region being amplified) was included in the reaction (i.e., the Taqman™ probe). The TaqMan™ probe includes the oligonucleotide with a fluorescent reporter dye covalently linked to the 5′ end of the probe (such as FAM (6-carboxyfluorescein), TET (6-carboxy-4,7,2′,7′-tetrachlorofluorescein), JOE (6-carboxy-4,5-dichloro-2,7-dimethoxyfluorescein), or VIC) and a quencher dye (TAMRA (6-carboxy-N,N,N′,N′-tetramethylrhodamine) at the 3′ end of the probe.  
      During the PCR reaction, cleavage of the probe separates the reporter dye and the quencher dye, resulting in increased fluorescence of the reporter. Accumulation of PCR products is detected directly by monitoring the increase in fluorescence of the reporter dye. When the probe is intact, the proximity of the reporter dye to the quencher dye results in suppression of the reporter fluorescence. During PCR, if the target of interest is present, the probe specifically anneals between the forward and reverse primer sites. The 5′-3′ nucleolytic activity of the AmpliTaq™ Gold DNA Polymerase cleaves the probe between the reporter and the quencher only if the probe hybridizes to the target. The probe fragments are then displaced from the target, and polymerization of the strand continues. The 3′ end of the probe is blocked to prevent extension of the probe during PCR. This process occurs in every cycle and does not interfere with the exponential accumulation of product. RNA was prepared using the trizol method and treated with DNase to remove contaminating genomic DNA. cDNA was synthesized using standard techniques. Mock cDNA synthesis in the absence of reverse transcriptase resulted in samples with no detectable PCR amplification of the control gene confirms efficient removal of genomic DNA contamination.  
      The expression levels of HAAT mRNA in various human cell types and tissues were analyzed using the Taqman procedure. As shown in Table VIII, the highest HAAT expression was detected in brain cortex and brain hypothalamus, followed by Human Umbilical Vein Endothelial Cells (HUVEC), followed by lung tumor cells.  
                               TABLE VIII                       Tissue Type   Mean   β 2 Mean   ∂∂ Ct   Expression                                                    Artery normal   32.62   21.77   10.84   0.5456       Aorta diseased   35.84   22.43   13.41   0       Vein normal   34.13   20.47   13.65   0.0775       Coronary SMC   30.76   21.59   9.17   1.736       HUVEC   29.41   21.81   7.6   5.1543       Hemangioma   35.07   20.97   14.1   0       Heart normal   32.7   20.89   11.81   0.2795       Heart CHF   33.63   21.02   12.62   0.1594       Kidney   31.55   20.51   11.04   0.4749       Skeletal Muscle   35.09   22.86   12.22   0       Adipose normal   37.84   22.04   15.81   0       Pancreas   33.67   23.13   10.55   0.6693       primary osteoblasts   32   20.4   11.6   0.3233       Osteoclasts (diff)   33.98   17.84   16.15   0.0138       Skin normal   36.29   22.2   14.1   0       Spinal cord normal   32.73   21.68   11.05   0.4716       Brain Cortex normal   28.95   23.01   5.95   16.2322       Brain Hypothalamus normal   30   23.47   6.53   10.8212       Nerve   33.59   21.82   11.77   0.2873       DRG (Dorsal Root Ganglion)   31.25   21.5   9.76   1.1573       Breast normal   34.73   21.56   13.18   0.1081       Breast tumor   34.16   21.5   12.66   0.154       Ovary normal   32.03   20.81   11.23   0.4178       Ovary Tumor   36.33   19.5   16.82   0       Prostate Normal   32.02   19.65   12.37   0.1896       Prostate Tumor   33.36   20.43   12.93   0.1281       Salivary glands   36.17   20.1   16.07   0       Colon normal   36.33   19.33   17   0       Colon Tumor   36.05   22.23   13.82   0       Lung normal   34.79   19.38   15.41   0.023       Lung tumor   28.02   20.03   7.99   3.9471       Lung COPD   33.26   18.61   14.65   0.039       Colon IBD   34.37   18.07   16.3   0.0124       Liver normal   33.95   20.64   13.32   0.0981       Liver fibrosis   35.04   21.56   13.48   0       Spleen normal   35.76   19.43   16.34   0       Tonsil normal   32.28   18.5   13.79   0.0708       Lymph node normal   34.31   20.06   14.25   0.0513       Small intestine normal   35.59   20.93   14.65   0       Macrophages   31.75   17.61   14.14   0.0556       Synovium   37.21   21.02   16.2   0       BM-MNC   32.71   20.16   12.55   0.1673       Activated PBMC   31.84   18.16   13.69   0.0759       Neutrophils   28.14   18.25   9.89   1.0539       Megakaryocytes   32.52   19.1   13.43   0.0909       Erythroid   32.9   21.09   11.81   0.2795       positive control   30.11   20.97   9.15   1.7603                  
 
     Example 21  
     Identification and Characterization of Human HST-4 and HST-5 cDNAs  
      In this example, the identification and characterization of the gene encoding human HST-4 (clone 57255FL) and HST-5 (clone 57255alt) is described.  
      Isolation of the Human HST-4 and HST-5 cDNAs  
      The invention is based, at least in part, on the discovery of a human gene encoding a novel polypeptide, referred to herein as human HST-4. The entire sequence of the human clone 57255FL was determined and found to contain an open reading frame termed human “HST-4.” The nucleotide sequence of the human HST-4 gene is set forth in the Sequence Listing as SEQ ID NO:54. The amino acid sequence of the human HST-4 expression product is set forth in the Sequence Listing as SEQ ID NO:55. The HST-4 polypeptide comprises 438 amino acids. The coding region (open reading frame) of SEQ ID NO:54 is set forth as SEQ ID NO:56. The HST-4 protein is predicted to contain a signal peptide of 43 residues in the amino-terminal end, which would be cleaved off to result in a mature peptide comprising amino acid residues 44-438 of SEQ I) NO:55.  
      The invention is further based, at least in part, on the discovery of a human gene encoding a novel polypeptide, referred to herein as human HST-5. The entire sequence of the human clone 57255alt was determined and found to contain an open reading frame termed human “HST-5.” The nucleotide sequence of the human HST-5 gene is set forth in the Sequence Listing as SEQ ID NO:57. The amino acid sequence of the human HST-5 expression product is set forth in the Sequence Listing as SEQ ID NO:58. The HST-5 polypeptide comprises 436 amino acids. The coding region (open reading frame) of SEQ ID NO:57 is set forth as SEQ ID NO:59. The HST-5 protein is predicted to contain a signal peptide of 43 residues in the amino-terminal end, which would be cleaved off to result in a mature peptide comprising amino acid residues 44-436 of SEQ ID NO:58.  
      HST-4 and HST-5 are splice variants. Splice variants are variants which result from alternative splicing of the same gene.  
      Analysis of the Human HST-4 and HST-5 Molecules HST-4  
      The amino acid sequence of human HST-4 (SEQ ID NO:55) was analyzed using the program PSORT (www.psort.nibb.ac.jp) to predict the localization of the proteins within the cell. This program assesses the presence of different targeting and localization amino acid sequences within the query sequence. The results of this analysis show that human HST-4 may be localized to the endoplasmic reticulum and mitochondria.  
      A search using the polypeptide sequence of SEQ ID NO:55 was performed against the HMM database in PFAM resulting in the identification of a sugar transporter family domain in the amino acid sequence of human HST-4 at about residues 25-418 of SEQ ID NO:55 (score=−210.9), and a monocarboxylate transporter family domain in the amino acid sequence of human HST-4 at about residues 23-431 of SEQ ID NO:55 (score=−144.9).  
      Searches of the amino acid sequence of human HST-4 were further performed against the Prosite database. These searches resulted in the identification in the amino acid sequence of human HST-4 of a potential N-glycosylation site, a number of potential protein kinase C phosphorylation sites, a number of potential casein kinase II phosphorylation sites, a number of potential N-myristoylation sites, and a potential sugar transport protein signature 2.  
      A MEMSAT analysis of the polypeptide sequence of SEQ ID NO:55 was also performed, predicting ten transmembrane domains in the amino acid sequence of human HST-4 (SEQ ID NO:55) at about amino acid residues 25-49, 62-80, 92-113, 126-143, 154-178, 186-202, 278-298, 318-337, 372-395, and 402-423. This protein was also predicted to contain a signal peptide of 43 residues in the amino-terminal end, which would be cleaved off to result in a mature peptide comprising amino acid residues 44-438 of SEQ ID NO:55. A MEMSAT analysis of the presumed mature polypeptide sequence was also performed, predicting nine transmembrane domains in the mature amino acid sequence of HST-4 at about amino acid residues 63-81, 93-114, 127-144, 155-179, 187-203, 279-299, 319-338, 373-396, and 403-424 of SEQ ID NO:55.  
      A search of SEQ ID NO:55 was also performed against the ProDom database. The results of this search identified matches against protein domains described as “Polyphosphate IPP Inositol 1-Phosphatase”, “Related Permease Transport Membrane”, “NPT 1(3) Transport Phosphate Cotransporter Renal Na-Dependent Inorganic Glycoprotein Transmembrane”, “GUDP (2) Transmembrane Transport Transporter Permease” and the like.  
      HST-5  
      The amino acid sequence of human HST-5 (SEQ ID NO:58) was analyzed using the program PSORT (www.psort.nibb.ac.jp) to predict the localization of the proteins within the cell. The results of this analysis show that human HST-5 may be localized to the endoplasmic reticulum, vacuoles, mitochondria, Golgi, and cytoplasm.  
      Searches of the amino acid sequence of human HST-5 (SEQ ID NO:58) were performed against the Prosite database. These searches resulted in the identification in the amino acid sequence of human HST-5 of a potential N-glycosylation site, a potential cAMP- and cGMP-dependent protein kinase C phosphorylation site, a number of potential protein kinase C phosphorylation sites, a number of potential casein kinase II phosphorylation sites, a number of potential N-myristoylation sites, a prokaryotic membrane lipoprotein lipid attachment site, and a sugar transport protein signature 2.  
      A search using the polypeptide sequence of SEQ ID NO:58 was performed against the HMM database in PFAM resulting in the identification of a sugar transporter family domain in the amino acid sequence of human HST-5 at about residues 23-429 of SEQ ID NO:58 (score=−139.4), and a monocarboxylate transporter family domain in the amino acid sequence of human HST-5 at about residues 25-416 of SEQ ID NO:58 (score=−200.0).  
      A MEMSAT analysis of the polypeptide sequence of SEQ ID NO:58 was also performed, predicting eleven transmembrane domains in the amino acid sequence of human HST-5 (SEQ ID NO:58) at about amino acid residues 30-51, 62-84, 92-111, 126-143, 154-178, 186-202, 240-260, 276-296, 316-335, 370-393, and 400-421. This protein was also predicted to contain a signal peptide of 43 residues in the amino-terminal end, which would be cleaved off to result in a mature peptide comprising amino acid residues 44-436 of SEQ ID NO:58. A MEMSAT analysis of the presumed mature polypeptide sequence was also performed, predicting ten transmembrane domains in the mature amino acid sequence of HST-5 at about residues 63-85, 93-112, 127-144, 155-179, 187-203, 241-261, 277-297, 317-336, 371-394 and 401-422 of SEQ ID NO:58.  
      A search of SEQ ID NO:58 was also performed against the ProDom database. The results of this search identified matches against protein domains described as “Polyphosphate IPP Inositol 1-Phosphatase”, “Related Permease Transport Membrane”, “NPT 1(3) Transport Phosphate Cotransporter Renal Na-Dependent Inorganic Glycoprotein Transmembrane”, “GUDP (2) Transmembrane Transport Transporter Permease” and the like.  
      Equivalents  
      Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.