SECRETION AND TRAFFICKING MOLECULES

Abstract: The invention provides human secretion and trafficking molecules (SAT) and polynucleotides which identify and encode SAT. The invetion also provides expression vectors, host cells, antibodies, agonists and antagonists. The invention also provides methods for diagnosing, treating, or preventing disorders associated with aberrant expression of SAT.

Description: SECRETION AND TRAFFICKING MOLECULES TECHNICAL FIELD This invention relates to nucleic acid and amino acid sequences of secretion and trafficking molecules and to the use of these sequences in the diagnosis, treatment, and prevention of vesicle trafficking, transport, neurological, autoimmune/inflammatory, and cell proliferative disorders, and in the assessment of the effects of exogenous compounds on the expression of nucleic acid and amino acid sequences of secretion and trafficking molecules. BACKGROUND OF THE INVENTION Eukaryotic cells are bound by a lipid bilayer membrane and subdivided into functionally distinct, membrane-bound compartments. The membranes maintain the essential differences between the cytosol, the extracellular environment, and the lumenal space of each intracellular organelle. Eukaryotic proteins including integral membrane proteins, secreted proteins, and proteins destined for the lumen of organelles are synthesized within the endoplasmic reticulum (ER), delivered to the Golgi complex for post-translational processing and sorting, and then transported to specific intracellular and extracellular destinations. Material is internalized from the extracellular environment by endocytosis, a process essential for transmission of neuronal, metabolic, and proliferative signals; uptake of many essential nutrients; and defense against invading organisms. This intracellular and extracellular movement of protein molecules is termed vesicle trafficking. Trafficking is accomplished by the packaging of protein molecules into specialized vesicles which bud from the donor organelle membrane and fuse to the target membrane (Rothman, J.E and Wieland, F.T. (1996) Science 272:227-234). The transport of proteins across the ER membrane involves a process that is similar in bacteria, yeast, and mammals (Gorlich, D. et al. (1992) Cell 71: 489-503). In mammalian systems, transport is initiated by the action of a cytoplasmic signal recognition particle (SRP) which recognizes a signal sequence on a growing, nascent polypeptide and binds the polypeptide and its ribosome complex to the ER membrane through an SRP receptor located on the ER membrane. The signal peptide is cleaved and the ribosome complex, together with the attached polypeptide, becomes membrane bound. The polypeptide is subsequently translocated across the ER membrane and into a vesicle (Blobel, G. and B. Dobberstein (1975) J. CeU Biol. 67:852-862). Proteins implicated in the translocation of polypeptides across the ER membrane in yeast include SEC61p, SEC62p, and SEC63p. Mutations in the genes encoding these proteins lead to defects in the translocation process. SEC61 may be of particular importance since certain mutations in the gene for this protein inhibit the translocation of many proteins (Gorlich, supra). Mammalian homologs of yeast SEC61 (mSEC61) have been identified in dog and rat (Gorlich, supra). Mammalian SEC61 is also structurally similar to SECYp, the bacterial cytoplasmic membrane translocation protein. mSEC61 is found in tight association with membrane-bound ribosomes. This association is induced by membrane-targeting of nascent polypeptide chains and is weakened by dissociation of the ribosomes into their constituent subunits. mSECδl is postulated to be a component of a putative protein-conducting channel, located in the ER membrane, to which nascent polypeptides are transferred following the completion of translation by ribosomes (Gorlich, supra). Several steps in the transit of material along the secretory and endocytic pathways require the formation of transport vesicles. Specifically, vesicles form at the transitional endoplasmic reticulum (tER), the rim of Golgi cisternae, the face of the Trans-Golgi Network (TGN), the plasma membrane (PM), and tubular extensions of the endosomes. Vesicle formation occurs when a region of membrane buds off from the donor organelle. The membrane-bound vesicle contains proteins to be transported and is surrounded by a proteinaceous coat, the components of which are recruited from the cytosol. The initial budding and coating processes are controlled by a cytosolic ras-like GTP-binding protein, ADP-ribosylating factor (Art), and adapter proteins (AP). Cytosolic GTP-bound Arf is also incorporated into the vesicle as it forms. Different isoforms of both Arf and AP are involved at different sites of budding. For example, Arfs 1, 3, and 5 are required for Golgi budding, Arf4 for endosomal budding, and Arf6 for plasma membrane budding. Two different classes of coat protein have also been identified. Clathrin coats form on vesicles derived from the TGN and PM, whereas coatomer (COP) coats form on vesicles derived from the ER and Golgi (Mellman, I. (1996) Annu. Rev. Cell Dev. Biol. 12:575-625). In clathrin-based vesicle formation, APs bring vesicle cargo and coat proteins together at the surface of the budding membrane. APs are heterotetrameric complexes composed of two large chains: one chain comprised of an α, γ, δ, or ε chain with a β chain, a medium chain (μ), and a small chain (σ). Clathrin binds to APs via the carboxy-terminal appendage domain of the β-adaptin subunit (Le Bourgne, R. and Hoflack, B. (1998) Curr. Opin. CeU. Biol. 10:499-503). AP-1 functions in protein sorting from the TGN and endosomes to compartments of the endosomal/lysosomal system. AP-2 functions in clathrin-mediated endocytosis at the plasma membrane, while AP-3 is associated with endosomes and/or the TGN and recruits integral membrane proteins for transport to lysosomes and lysosome-related organeUes. The recently isolated AP-4 complex localizes to the TGN or a neighboring compartment and may play a role in sorting events thought to take place in post-Golgi compartments (DeU'AngeHca, E. C. et al. (1999) J. Biol. Chem. 274:7278-7285). CytosoUc GTP- bound Arf is also incorporated into the vesicle as it forms. Another GTP-binding protein, dynamin, forms a ring complex around the neck of the forming vesicle and provides the mechanochemical force required to release the vesicle from the donor membrane. The coated vesicle complex is then transported through the cytosol. During the transport process, Arf-bound GTP is hydrolyzed to GDP and the coat dissociates from the transport vesicle (West, M.A. et al. (1997) J. CeU Biol. 138:1239- 1254). Coatomer (COP) coats, a second class of coat proteins, form on vesicles derived from the ER and Golgi. COP coats can further be classified as COPI, involved in retrograde traffic through the Golgi and from the Golgi to the ER, and COPII, involved in anterograde traffic from the ER to the Golgi (Mellman, supra). The COP coat consists of two major components, a GTP-binding protein (Arf or Sar) and coat protomer (coatomer). Coatomer is an equimolar complex of seven proteins, termed α-, β-, β'-, γ-, Δ-, ε- and Z-COP. The coatomer complex binds to dilysine motifs contained on the cytoplasmic tails of integral membrane proteins. These include the dilysine-containing retrieval motif of membrane proteins of the ER and dibasic/diphenylamine motifs of members of the p24 family. The p24 family of type I membrane proteins represents the major membrane proteins of COPI vesicles. (Harter, C. and Wieland, F.T. (1998) Proc. Natl. Acad. Sci. USA 95:11649-11654.) Vesicles can undergo homotypic,fusing with a same type vesicle, or heterotypic, fusing with a different type vesicle, fusion. Molecules required for appropriate targeting and fusion of vesicles include proteins in the vesicle membrane, the target membrane, and proteins recruited from the cytosol. During budding of the vesicle from the donor compartment, an integral membrane protein, VAMP (vesicle-associated membrane protein) is incorporated into the vesicle. Soon after the vesicle uncoats, a cytosoUc prenylated GTP-binding protein, Rab, is inserted into the vesicle membrane. The amino acid sequence of Rab proteins reveals conserved GTP-binding domains characteristic of Ras superfamily members. In the vesicle membrane, GTP-bound Rab interacts with VAMP. Once the vesicle reaches the target membrane, a GTPase activating protein (GAP) in the target membrane converts the Rab protein to the GDP-bound form. A cytosoUc protein, guanine-nucleotide dissociation inhibitor (GDI) then removes GDP-bound Rab from the vesicle membrane. Several Rab isoforms have been identified and appear to associate with specific compartments within the ceU. For example, Rabs 4, 5, and 11 are associated with the early endosome, whereas Rabs 7 and 9 associate with the late endosome. These differences may provide selectivity in the association between vesicles and their target membranes. (Novick, P., and Zerial, M. (1997) Cur. Opin. CeU Biol. 9:496-504.) Docking of the transport vesicle with the target membrane involves the formation of a complex between the vesicle SNAP receptor (v-SNARE), target membrane (t-) SNAREs, and certain other membrane and cytosoUc proteins. Many of these other proteins have been identified although their exact functions in the docking complex remain uncertain (TeUam, J.T. et al. (1995) J. Biol. Chem. 270:5857-5863; Hata, Y. and Sudhof, T.C. (1995) J. Biol. Chem. 270:13022-13028). • N-ethylmaleimide sensitive factor (NSF) and soluble NSF-attachment protein (α-SNAP and β-SNAP) are two such proteins that are conserved from yeast to man and function in most intraceUular membrane fusion reactions. Seel represents a family of yeast proteins that function at many different stages in the secretory pathway including membrane fusion. Recently, mammaUan homologs of Seel , caUed Munc-18 proteins, have been identified (Katagiri, H. et al. (1995) J. Biol. Chem. 270:4963-4966; Hata et al. supra). The SNARE complex involves three SNARE molecules, one in the vesicular membrane and two in the target membrane. Together they form a rod-shaped complex of four α-heUcal coiled-coils. The membrane anchoring domains of aU three SNAREs project from one end of the rod. This complex is similar to the rod-Uke structures formed by fusion proteins characteristic of the enveloped viruses, such as myxovirus, influenza, filovirus (Ebola), and the HIV and SIV retroviruses (Skehel, J.J., and Wiley, D.C. (1998) CeU 95:871-874). It has been proposed that the SNARE complex is sufficient for membrane fusion, suggesting that the proteins which associate with the complex provide regulation over the fusion event (Weber, T. et al. (1998) CeU 92:759-772). For example, in neurons, which exhibit regulated exocytosis, docked vesicles do not fuse with the presynaptic membrane until depolarization, which leads to an influx of calcium (Bennett, M.K., and ScheUer, R.H. (1994) Annu. Rev. Biochem. 63:63-100). Synaptotagmin, an integral membrane protein in the synaptic vesicle, associates with the t-SNARE syntaxin in the docking complex. Synaptotagmin binds calcium in a complex with negatively charged phosphoUpids, which aUows the cytosoUc SNAP protein to displace synaptotagmin from syntaxin and fusion to occur. Thus, synaptotagmin is a negative regulator of fusion in the neuron. (Littleton, J.T. et al. (1993) CeU 74:1125-1134.) The most abundant membrane protein of synaptic vesicles appears to be the glycoprotein synaptophysin, a 38 kDa protein with four transmembrane domains and two intravesicular loops. Synaptophysin monomers associate into homopolymers which form channels in the synaptic vesicle membrane. Synaptophysin' s calcium-binding abiUty, tyrosine phosphorylation, and widespread distribution in neural tissues suggest a potential role in neurosecretion (Bennett, supra.). The transport of proteins into and out of vesicles reUes on interactions between ceU membranes and a supporting membrane cytoskeleton consisting of spectrin and other proteins. A large family of related proteins caUed ankyrins participate in the transport process by binding to the membrane skeleton protein spectrin and to a protein in the ceU membrane caUed band 3, a component of an anion channel in the ceU membrane. Ankyrins therefore function as a critical Unk between the cytoskeleton and the ceU membrane. OriginaUy found in association with erythroid ceUs, ankyrins are also found in other tissues as weU (Birkenmeier, C.S. et al. (1993) J. Biol. Chem. 268:9533-9540). Ankyrins are large proteins (-1800 amino acids) containing an N-terminal, 89 kDa domain that binds the ceU membrane proteins band 3 and tubuUn, a central 62 kDa domain that binds the cytoskeletal proteins spectrin and vimentin, and a C-terminal, 55 kDa regulatory domain that functions as a modifier of the binding activities of the other two domains. Individual genes for ankyrin are able to produce multiple ankyrin isoforms by various insertions and deletions. These isoforms are of nearly identical size but may have different functions. In addition, smaUer transcripts are produced which are missing large regions of the coding sequences from the N-terminal (band 3 binding), and central (spectrin binding) domains. The existence of such a large family of ankyrin proteins and the observation that more than one type of ankyrin may be expressed in the same ceU type suggests that ankyrins may have more speciaUzed functions than simply binding the membrane skeleton to the plasma membrane (Birkenmeier, supra). In humans, two isoforms of ankyrin are expressed, alternatively, in developing erythroids and mature erythroids, respectively (Lambert, S. et. al. (1990) Proc. Natl. Acad. Sci. USA 87:1730-1734). A deficiency in erythroid spectrin and ankyrin has been associated with the hemolytic anemia, hereditary spherocytosis (Coetzer, T.L. et al. (1988) New Engl. J. Med. 318:230-234). Correct trafficking of proteins is of particular importance for the proper function of epitheUal ceUs, which are polarized into distinct apical and basolateral domains containing different ceU membrane components such as Upids and membrane-associated proteins. Certain proteins are flexible and may be sorted to the basolateral or apical side depending upon ceU type or growth conditions. For example, the kidney anion exchanger (kAEl) can be retargeted from the apical to the basolateral domain if ceUs are cultured at higher density. The protein kanadaptin was isolated as a protein which binds to the cytoplasmic domain of kAEl . It also coloca zes with kAEl in vesicles, but not in the membrane, suggesting that kanadaptin' s function is to guide kAEl -containing vesicles to the basolateral target membrane (Chen, J. et al. (1998) J. Biol. Chem. 273:1038-1043). Vesicle trafficking is crucial in the process of neurotransmissiOn. Synaptic vesicles carry neurotransmitter molecules from the cytoplasm of a neuron to the synapse. Rab3's are a family of GTP-binding proteins located on synaptic vesicles. The RIM family of proteins are thought to be effectors for Rab3's (Wang, Y. et al. (2000) J. Biol. Chem. 275:20033-20044). RabphiUn-3 is a synaptic vesicle protein. GranuphiUns are proteins with homology to rabphiUns, and may have a unique role in exocytosis (Wang, J. et al. (1999) J. Biol. Chem. 274:28542-28548). The etiology of numerous human diseases and disorders can be attributed to defects in the trafficking of proteins to organeUes or the ceU surface. Defects in the trafficking of membrane-bound receptors and ion channels are associated with cystic fibrosis (cystic fibrosis transmembrane conductance regulator; CFTR), glucose-galactose malabsorption syndrome (Na + /glucose cotransporter), hypercholesterolemia (low-density Upoprotein (LDL) receptor), and forms of diabetes meUirus (insuUn receptor). Abnormal hormonal secretion is Unked to disorders including diabetes insipidus (vasopressin), hyper- and hypoglycemia (insuUn, glucagon), Grave's disease and goiter (thyroid hormone), and Cushing's and Addison's diseases (adrenocorticotropic hormone; ACTH). Cancer ceUs secrete excessive amounts of hormones or other biologicaUy active peptides. Disorders related to excessive secretion of biologicaUy active peptides by tumor ceUs include: fasting hypoglycemia due to increased insuUn secretion from insuUnoma-islet ceU tumors; hypertension due to increased epinephrine and norepinephrine secreted from pheochromocytomas of the adrenal meduUa and sympathetic paragangUa; and carcinoid syndrome, which includes abdominal cramps, diarrhea, and valvular heart disease, caused by excessive amounts of vasoactive substances (serotonin, bradykinin, histamine, prostaglandins, and polypeptide hormones) secreted from intestinal tumors. Ectopic synthesis and secretion of biologicaUy active peptides (peptides not expected from a tumor) includes ACTH and vasopressin in lung and pancreatic cancers; parathyroid hormone in lung and bladder cancers; calcitonin in lung and breast cancers; and thyroid-stimulating hormone in meduUary thyroid carcinoma. Various human pathogens alter host cell protein trafficking pathways to their own advantage. For example, the HTV protein Nef down-regulates cell surface expression of CD4 molecules by accelerating their endocytosis through clathrin coated pits. This function of Nef is important for the spread of fflV from the infected ceU (Harris, M. (1999) Curr. Biol. 9:R449-R461). A recently identified human protein, Nef-associated factor 1 (Nafl), a protein with four extended coiled-coil domains, has been found to associate with Nef. Overexpression of Nafl increased cell surface expression of CD4, an effect which could be suppressed by Nef (Fukushi, M. et al. (1999) FEBS Lett. 442:83-88). The discovery of new secretion and trafficking molecules and the polynucleotides encoding them satisfies a need in the art by providing new compositions which are useful in the diagnosis, prevention, and treatment of vesicle trafficking, transport, neurological, autoimmune/inflammatory, and cell proUferative disorders, and in the assessment of the effects of exogenous compounds on the expression of nucleic acid and amino acid sequences of secretion and trafficking molecules. SUMMARY OF THE INVENTION The invention features purified polypeptides, secretion and trafficking molecules, referred to coUectively as "SAT" and individuaUy as "SAT-1," "SAT-2," "SAT-3," "SAT-4," "SAT-5," "SAT-6," "SAT-7," "SAT-8," and "SAT-9." In one aspect, the invention provides an isolated polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO:l-9, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9, c) a biologicaUy active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO:l-9. In one alternative, the invention provides an isolated polypeptide comprising the amino acid sequence of SEQ ID NO:l-9. The invention further provides an isolated polynucleotide encoding a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO:l-9, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ED NO:l- 9, c) a biologicaUy active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO:l-9. En one alternative, the polynucleotide encodes a polypeptide selected from the group consisting of SEQ ED NO: 1-9. In another alternative, the polynucleotide is selected from the group consisting of SEQ ID NO: 10-18. AdditionaUy, the invention provides a recombinant polynucleotide comprising a promoter sequence operably Unked to a polynucleotide encoding a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NO : 1 -9, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO:l-9, c) a biologicaUy active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO:l-9. In one alternative, the invention provides a ceU transformed with the recombinant polynucleotide. In another alternative, the invention provides a transgenic organism comprising the recombinant polynucleotide. The invention also provides a method for producing a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ED NO:l-9, c) a biologicaUy active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO:l-9. The method comprises a) culturing a ceU under conditions suitable for expression of the polypeptide, wherein said ceU is transformed with a recombinant polynucleotide comprising a promoter sequence operably Unked to a polynucleotide encoding the polypeptide, and b) recovering the polypeptide so expressed. AdditionaUy, the invention provides an isolated antibody which specificaUy binds to a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NO: 1 -9, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, c) a biologicaUy active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO:l-9. The invention further provides an isolated polynucleotide selected from the group consisting of a) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ED NO: 10-18, b) a polynucleotide comprising a naturaUy occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ED NO:10-18, c) a polynucleotide complementary to the polynucleotide of a), d) a polynucleotide complementary to the polynucleotide of b), and e) an RNA equivalent of a)-d). In one alternative, the polynucleotide comprises at least 60 contiguous nucleotides. Additionally, the invention provides a method for detecting a target polynucleotide in a sample, said target polynucleotide having a sequence of a polynucleotide selected from the group consisting of a) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ED NO: 10-18, b) a polynucleotide comprising a naturaUy occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ED NO:10-18, c) a polynucleotide complementary to the polynucleotide of a), d) a polynucleotide complementary to the polynucleotide of b), and e) an RNA equivalent of a)-d). The method comprises a) hybridizing the sample with a probe comprising at least 20 contiguous nucleotides comprising a sequence complementary to said target polynucleotide in the sample, and which probe specificaUy hybridizes to said target polynucleotide, under conditions whereby a hybridization complex is formed between said probe and said target polynucleotide or fragments thereof, and b) detecting the presence or absence of said hybridization complex, and optionally, if present, the amount thereof. In one alternative, the probe comprises at least 60 contiguous nucleotides. The invention further provides a method for detecting a target polynucleotide in a sample, said target polynucleotide having a sequence of a polynucleotide selected from the group consisting of a) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ED NO:10-18, b) a polynucleotide comprising a naturaUy occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ED NO: 10-18, c) a polynucleotide complementary to the polynucleotide of a), d) a polynucleotide complementary to the polynucleotide of b), and e) an RNA equivalent of a)-d). The method comprises a) ampUfying said target polynucleotide or fragment thereof using polymerase chain reaction ampUfication, and b) detecting the presence or absence of said ampUfied target polynucleotide or fragment thereof, and, optionaUy, if present, the amount thereof. The invention further provides a composition comprising an effective amount of a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9, c) a biologicaUy active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, and a pharmaceuticaUy acceptable excipient. In one embodiment, the composition comprises an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9. The invention additionaUy provides a method of treating a disease or condition associated with decreased expression of functional SAT, comprising administering to a patient in need of such treatment the composition. The invention also provides a method for screening a compound for effectiveness as an agonist of a polypeptide selected from the group consisting of a) a polypeptide comprising an amino . acid sequence selected from the group consisting of SEQ ID NO:l-9, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO:l-9, c) a biologicaUy active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO:l-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO:l-9. The method comprises a) exposing a sample comprising the polypeptide to a compound, and b) detecting agonist activity in the sample. Ln one alternative, the invention provides a composition comprising an agonist compound identified by the method and a pharmaceutically acceptable excipient. In another alternative, the invention provides a method of treating a disease or condition associated with decreased expression of functional SAT, comprising administering to a patient in need of such treatment the composition. AdditionaUy, the invention provides a method for screening a compound for effectiveness as an antagonist of a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9, c) a biologicaUy active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO:l-9. The method comprises a) exposing a sample comprising the polypeptide to a compound, and b) detecting antagonist activity in the sample. En one alternative, the invention provides a composition comprising an antagonist compound identified by the method and a pharmaceuticaUy acceptable excipient. In another alternative, the invention provides a method of treating a disease or condition associated with overexpression of functional SAT, comprising administering to a patient in need of such treatment the composition. The invention further provides a method of screening for a compound that specificaUy binds to a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO:l-9, c) a biologicaUy active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO:l-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9. The method comprises a) combining the polypeptide with at least one test compound under suitable conditions, and b) detecting binding of the polypeptide to the test compound, thereby identifying a compound that specifically binds to the polypeptide. The invention further provides a method of screening for a compound that modulates the activity of a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO.l -9, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected ' from the group consisting of SEQ D NO: 1-9, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO:l-9. The method comprises a) combining the polypeptide with at least one test compound under conditions permissive for the activity of the polypeptide, b) assessing the activity of the polypeptide in the presence of the test compound, and c) comparing the activity of the polypeptide in the presence of the test compound with the activity of the polypeptide in the absence of the test compound, wherein a change in the activity of the polypeptide in the presence of the test compound is indicative of a compound that modulates the activity of the polypeptide. The invention further provides a method for screening a compound for effectiveness in altering expression of a target polynucleotide, wherein said target polynucleotide comprises a sequence selected from the group consisting of SEQ ED NO: 10-18, the method comprising a) exposing a sample comprising the target polynucleotide to a compound, and b) detecting altered expression of the target polynucleotide. The invention further provides a method for assessing toxicity of a test compound, said method comprising a) treating a biological sample containing nucleic acids with the test compound; b) hybridizing the nucleic acids of the treated biological sample with a probe comprising at least 20 contiguous nucleotides of a polynucleotide selected from the group consisting of i) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ED NO:10-18, U) a polynucleotide comprising a naturally occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ED NO:10-18, in) a polynucleotide having a sequence complementary to i), iv) a polynucleotide complementary to the polynucleotide of u), and v) an RNA equivalent of i)-iv). Hybridization occurs under conditions whereby a specific hybridization complex is formed between said probe and a target polynucleotide in the biological sample, said target polynucleotide selected from the group consisting of i) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ED NO: 10-18, U) a polynucleotide comprising a naturaUy occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ED NO:10-18, in) a polynucleotide complementary to the polynucleotide of i), iv) a polynucleotide complementary to the polynucleotide of n), and v) an RNA equivalent of i)-iv). Alternatively, the target polynucleotide comprises a fragment of a polynucleotide sequence selected from the group consisting of i)-v) above; c) quantifying the amount of hybridization complex; and d) comparing the amount of hybridization complex in the treated biological sample with the amount of hybridization complex in an untreated biological sample, wherein a difference in the amount of hybridization complex in the treated biological sample is indicative of toxicity of the test compound. BRIEF DESCRIPTION OF THE TABLES Table 1 summarizes the nomenclature for the fuU length polynucleotide and polypeptide sequences of the present invention. Table 2 shows the GenBank identification number and annotation of the nearest GenBank homolog for polypeptides of the invention. The probabiUty score for the match between each polypeptide and its GenBank homolog is also shown. Table 3 shows structural features of polypeptide sequences of the invention, including predicted motifs and domains, along with the methods, algorithms, and searchable databases used for analysis of the polypeptides. Table 4 Usts the cDNA and/or genomic DNA fragments which were used to assemble polynucleotide sequences of the invention, along with selected fragments of the polynucleotide sequences. Table 5 shows the representative cDNA Ubrary for polynucleotides of the invention. Table 6 provides an appendix which describes the tissues and vectors used for construction of the cDNA Ubraries shown in Table 5. Table 7 shows the tools, programs, and algorithms used to analyze the polynucleotides and polypeptides of the invention, along with appUcable descriptions, references, and threshold parameters. DESCRIPTION OF THE INVENTION Before the present proteins, nucleotide sequences, and methods are described, it is understood that this invention is not Umited to the particular machines, materials and methods described, as these may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to Umit the scope of the present invention which wiU be Umited only by the appended claims. It must be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to "a host ceU" includes a pluraUty of such host cells, and a reference to "an antibody" is a reference to one or more antibodies and equivalents thereof known to those skilled in the art, and so forth. Unless defined otherwise, aU technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skiU in the art to which this invention belongs. Although any machines, materials, and methods similar or equivalent to those described herein can be used to practice or test the present invention, the preferred machines, materials and methods are now described. AU pubUcations mentioned herein are cited for the pmpose of describing and disclosing the ceU Unes, protocols, reagents and vectors which are reported in the pubUcations and which might be used in connection with the invention. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention. DEFINITIONS "SAT" refers to the amino acid sequences of substantiaUy purified SAT obtained from any species, particularly a mammaUan species, including bovine, ovine, porcine, murine, equine, and human, and from any source, whether natural, synthetic, semi-synthetic, or recombinant. The term "agonist" refers to a molecule which intensifies or mimics the biological activity of SAT. Agonists may include proteins, nucleic acids, carbohydrates, smaU molecules, or any other compound or composition which modulates the activity of SAT either by directly interacting with SAT or by acting on components of the biological pathway in which SAT participates. An "aUeUc variant" is an alternative form of the gene encoding SAT. AUeUc variants may result from at least one mutation in the nucleic acid sequence and may result in altered mRNAs or in polypeptides whose structure or function may or may not be altered. A gene may have none, one, or many aUeUc variants of its naturaUy occurring form. Common mutational changes which give rise to aUeUc variants are generaUy ascribed to natural deletions, additions, or substitutions of nucleotides. Each of these types of changes may occur alone, or in combination with the others, one or more times in a given sequence.. "Altered" nucleic acid sequences encoding SAT include those sequences with deletions, insertions, or substitutions of different nucleotides, resulting in a polypeptide the same as SAT or a polypeptide with at least one functional characteristic of SAT. Included within this definition are polymorphisms which may or may not be readily detectable using a particular oUgonucleotide probe of the polynucleotide encoding SAT, and improper or unexpected hybridization to aUeUc variants, with a locus other than the normal chromosomal locus for the polynucleotide sequence encoding SAT. The encoded protein may also be "altered," and may contain deletions, insertions, or substitutions of amino acid residues which produce a silent change and result in a functionally equivalent SAT. DeUberate amino acid substitutions may be made on the basis of similarity in polarity, charge, solubiUty, hydrophobicity, hydrophiUcity, and/or the amphipathic nature of the residues, as long as the biological or immunological activity of SAT is retained. For example, negatively charged amino acids may include aspartic acid and glutamic acid, and positively charged amino acids may include lysine and arginine. Amino acids with uncharged polar side chains having similar hydrophiUcity values may include: asparagine and glutamine; and serine and threonine. Amino acids with uncharged side chains having similar hydrophiUcity values may include: leucine, isoleucine, and vaUne; glycine and alanine; and phenylalanine and tyrosine. The terms "amino acid" and "amino acid sequence" refer to an oUgopeptide, peptide, polypeptide, or protein sequence, or a fragment of any of these, and to naturaUy occurring or synthetic molecules. Where "amino acid sequence" is recited to refer to a sequence of a naturaUy occurring protein molecule, "amino acid sequence" and Uke terms are not meant to Umit the amino acid sequence to the complete native amino acid sequence associated with the recited protein molecule. "AmpUfication" relates to the production of additional copies of a nucleic acid sequence. AmpUfication is generaUy carried out using polymerase chain reaction (PCR) technologies weU known in the art. The term "antagonist" refers to a molecule which inhibits or attenuates the biological activity of SAT. Antagonists may include proteins such as antibodies, nucleic acids, carbohydrates, smaU molecules, or any other compound or composition which modulates the activity of SAT either by directly interacting with SAT or by acting on components of the biological pathway in which SAT participates. The term "antibody" refers to intact immunoglobulin molecules as weU as to fragments thereof, such as Fab, F(ab') 2 , and Fv fragments, which are capable of binding an epitopic determinant. Antibodies that bind SAT polypeptides can be prepared using intact polypeptides or using fragments containing small peptides of interest as the immunizing antigen. The polypeptide or oUgopeptide used to immunize an animal (e.g., a mouse, a rat, or a rabbit) can be derived from the translation of RNA, or synthesized chemicaUy, and can be conjugated to a carrier protein if desired. Commonly used carriers that are chemicaUy coupled to peptides include bovine serum albumin, thyroglobuUn, and keyhole Umpet hemocyanin (KLH). The coupled peptide is then used to immunize the animal. The term "antigenic determinant" refers to that region of a molecule (i.e., an epitope) that makes contact with a particular antibody. When a protein or a fragment of a protein is used to immunize a host animal, numerous regions of the protein may induce the production of antibodies which bind specificaUy to antigenic determinants (particular regions or three-dimensional structures on the protein). An antigenic determinant may compete with the intact antigen (i.e., the immunogen used to eUcit the immune response) for binding to an antibody. The term "antisense" refers to any composition capable of base-pairing with the "sense" (coding) strand of a specific nucleic acid sequence. Antisense compositions may include DNA; RNA; peptide nucleic acid (PNA); oUgonucleotides having modified backbone Unkages such as phosphorothioates, rnethylphosphonates, or benzylphosphonates; oUgonucleotides having modified sugar groups such as 2'-methoxyethyl sugars or 2'-methoxyethoxy sugars; or oUgonucleotides having modified bases such as 5-methyl cytosine, 2'-deoxyuracil, or 7-deaza-2'-deoxyguanosine. Antisense molecules may be produced by any method including chemical synthesis or transcription. Once introduced into a ceU, the complementary antisense molecule base-pairs with a naturally occurring nucleic acid sequence produced by the ceU to form duplexes which block either transcription or translation. The designation "negative" or "minus" can refer to the antisense strand, and the designation "positive" or "plus" can refer to the sense strand of a reference DNA molecule. The term "biologicaUy active" refers to a protein having structural, regulatory, or biochemical functions of a naturaUy occurring molecule. Likewise, "immunologicaUy active" or "immunogenic" refers to the capabiUty of the natural, recombinant, or synthetic SAT, or of any oUgopeptide thereof, to induce a specific immune response in appropriate animals or ceUs and to bind with specific antibodies. "Complementary" describes the relationship between two single-stranded nucleic acid sequences that anneal by base-pairing. For example, 5 -AGT-3' pairs with its complement, 3'-TCA-5'. A "composition comprising a given polynucleotide sequence" and a "composition comprising a given amino acid sequence" refer broadly to any composition containing the given polynucleotide or amino acid sequence. The composition may comprise a dry formulation or an aqueous solution. Compositions comprising polynucleotide sequences encoding SAT or fragments of SAT may be employed as hybridization probes. The probes may be stored in freeze-dried form and may be associated with a stabiUzing agent such as a carbohydrate. Ln hybridizations, the probe may be deployed in an aqueous solution containing salts (e.g., NaCl), detergents (e.g., sodium dodecyl sulfate; SDS), and other components (e.g., Denhardt's solution, dry milk, salmon sperm DNA, etc.). "Consensus sequence" refers to a nucleic acid sequence which has been subjected to repeated DNA sequence analysis to resolve uncaUed bases, extended using the XL-PCR kit (AppUed Biosystems, Foster City CA) in the 5' and/or the 3' direction, and resequenced, or which has been assembled from one or more overlapping cDNA, EST, or genomic DNA fragments using a computer program for fragment assembly, such as the GELVEEW fragment assembly system (GCG, Madison WE) or Phrap (University of Washington, Seattle WA). Some sequences have been both extended and assembled to produce the consensus sequence. "Conservative amino acid substitations" are those substitutions that are predicted to least interfere with the properties of the original protein, i.e., the structure and especiaUy the function of the protein is conserved and not significantly changed by such substitutions. The table below shows amino acids which may be substituted for an original amino acid in a protein and which are regarded as conservative amino acid substitutions. Original Residue Conservative Substitution Ala Gly, Ser Arg His, Lys Asn Asp, Gin, His Asp Asn, Glu Cys Ala, Ser Gin Asn, Glu, His Glu Asp, Gin, His Gly Ala His Asn, Arg, Gin, Glu lie Leu, Val Leu He, Val Lys Arg, Gin, Glu Met Leu, He Phe His, Met, Leu, Trp, Tyr Ser Cys, Thr Thr Ser, Val Trp Phe, Tyr Tyr His, Phe, Trp Val De, Leu, Thr Conservative amino acid substitutions generaUy maintain (a) the structure of the polypeptide backbone in the area of the substitution, for example, as a beta sheet or alpha heUcal conformation, (b) the charge or hydrophobicity of the molecule at the site of the substitution, and/or (c) the bulk of the side chain. A "deletion" refers to a change in the amino acid or nucleotide sequence that results in the absence of one or more amino acid residues or nucleotides. The term "derivative" refers to a chemicaUy modified polynucleotide or polypeptide. Chemical modifications of a polynucleotide can include, for example, replacement of hydrogen by an alkyl, acyl, hydroxyl, or amino group. A derivative polynucleotide encodes a polypeptide which retains at least one biological or immunological function of the natural molecule. A derivative polypeptide is one modified by glycosylation, pegylation, or any similar process that retains at least one biological or immunological function of the polypeptide from which it was derived. A "detectable label" refers to a reporter molecule or enzyme that is capable of generating a measurable signal and is covalently or noncovalently joined to a polynucleotide or polypeptide. "Differential expression" refers to increased or upregulated; or decreased, downregulated, or absent gene or protein expression, determined by comparing at least two different samples. Such comparisons may be carried out between, for example, a treated and an untreated sample, or a diseased and a normal sample. A "fragment" is a unique portion of SAT or the polynucleotide encoding SAT which is identical in sequence to but shorter in length than the parent sequence. A fragment may comprise up to the entire length of the defined sequence, minus one nucleotide/amino acid residue. For example, a fragment may comprise from 5 to 1000 contiguous nucleotides or amino acid residues. A fragment used as a probe, primer, antigen, therapeutic molecule, or for other purposes, may be at least 5, 10, 15, 16, 20, 25, 30, 40, 50, 60, 75, 100, 150, 250 or at least 500 contiguous nucleotides or amino acid residues in length. Fragments may be preferentiaUy selected from certain regions of a molecule. For example, a polypeptide fragment may comprise a certain length of contiguous amino acids selected from the first 250 or 500 amino acids (or first 25% or 50%) of a polypeptide as shown in a certain defined sequence. Clearly these lengths are exemplary, and any length that is supported by the specification, including the Sequence Listing, tables, and figures, may be encompassed by the present embodiments. A fragment of SEQ ED NO : 10- 18 comprises a region of unique polynucleotide sequence that specificaUy identifies SEQ ID NO: 10-18, for example, as distinct from any other sequence in the genome from which the fragment was obtained. A fragment of SEQ ED NO: 10- 18 is useful, for example, in hybridization and ampUfication technologies and in analogous methods that distinguish SEQ ID NO: 10- 18 from related polynucleotide sequences. The precise length of a fragment of SEQ ED NO: 10-18 and the region of SEQ ID NO: 10- 18 to which the fragment corresponds are routinely determinable by one of ordinary skiU in the art based on the intended purpose for the fragment. A fragment of SEQ ED NO:l-9 is encoded by a fragment of SEQ ED NO:10-18. A fragment of SEQ ID NO: 1-9 comprises a region of unique amino acid sequence that specificaUy identifies SEQ ID NO:l-9. For example, a fragment of SEQ ED NO:l-9 is useful as an immunogenic peptide for the development of antibodies that specificaUy recognize SEQ ID NO:l-9. The precise length of a fragment of SEQ ID NO:l-9 and the region of SEQ ID NO:l-9 to which the fragment corresponds are routinely determinable by one of ordinary skill in the art based on the intended purpose for the fragment. A "fuU length" polynucleotide sequence is one containing at least a translation initiation codon (e.g., methionine) foUowed by an open reading frame and a translation termination codon. A "fuU length" polynucleotide sequence encodes a "full length" polypeptide sequence. "Homology" refers to sequence similarity or, interchangeably, sequence identity, between two or more polynucleotide sequences or two or more polypeptide sequences. The terms "percent identity" and "% identity," as appUed to polynucleotide sequences, refer to the percentage of residue matches between at least two polynucleotide sequences aUgned using a standardized algorithm. Such an algorithm may insert, in a standardized and reproducible way, gaps in the sequences being compared in order to optimize aUgnment between two sequences, and therefore achieve a more meaningful comparison of the two sequences. Percent identity between polynucleotide sequences may be determined using the default parameters of the CLUSTAL V algorithm as incorporated into the MEGALIGN version 3.12e sequence aUgnment program. This program is part of the LASERGENE software package, a suite of molecular biological analysis programs (DNASTAR, Madison WT). CLUSTAL V is described in Higgins, D.G. and P.M. Sharp (1989) CABIOS 5:151-153 and in Higgins, D.G. et al. (1992) CABIOS 8:189-191. For pairwise aUgnments of polynucleotide sequences, the default parameters are set as foUows: Ktuple=2, gap penalty=5, window=4, and "diagonals saved"=4. The "weighted" residue weight table is selected as the default. Percent identity is reported by CLUSTAL V as the "percent similarity" between aUgned polynucleotide sequences. Alternatively, a suite of commonly used and freely available sequence comparison algorithms is provided by the National Center for Biotechnology Information (NCBI) Basic LxDcal AUgnment Search Tool (BLAST) (Altschul, S.F. et al. (1990) J. Mol. Biol. 215:403-410), which is available from several sources, including the NCBI, Bethesda, MD, and on the Internet at http://www.ncbi.rilm.nU .gov/BLAST/. The BLAST software suite includes various sequence analysis programs including "blastn," that is used to align a known polynucleotide sequence with other polynucleotide sequences from a variety of databases. Also available is a tool caUed "BLAST 2 Sequences" that is used for direct pairwise comparison of two nucleotide sequences. "BLAST 2 Sequences" can be accessed and used interactively at htφ://www.ncbi.nJjn.nm.gov/gorf/bl2.html. The "BLAST 2 Sequences" tool can be used for both blastn and blastp (discussed below). BLAST programs are commonly used with gap and other parameters set to default settings. For example, to compare two nucleotide sequences, one may use blastn with the "BLAST 2 Sequences" tool Version 2.0.12 (April-21-2000) set at default parameters. Such default parameters may be, for example: Matrix: BLOSUM62 Reward for match: 1 Penalty for mismatch: -2 Open Gap: 5 and Extension Gap: 2 penalties Gap x drop-off: 50 Expect: 10 Word Size: 11 Filter: on Percent identity may be measured over the length of an entire defined sequence, for example, as defined by a particular SEQ ED number, or may be measured over a shorter length, for example, over the length of a fragment taken from a larger, defined sequence, for instance, a fragment of at least 20, at least 30, at least 40, at least 50, at least 70, at least 100, or at least 200 contiguous nucleotides. Such lengths are exemplary only, and it is understood that any fragment length supported by the sequences shown herein, in the tables, figures, or Sequence Listing, may be used to describe a length over which percentage identity may be measured. Nucleic acid sequences that do not show a high degree of identity may nevertheless encode similar amino acid sequences due to the degeneracy of the genetic code. It is understood that changes in a nucleic acid sequence can be made using this degeneracy to produce multiple nucleic acid sequences that aU encode substantiaUy the same protein. The phrases "percent identity" and "% identity," as appUed to polypeptide sequences, refer to the percentage of residue matches between at least two polypeptide sequences aUgned using a standardized algorithm. Methods of polypeptide sequence aUgnment are weU-known. Some aUgnment methods take into account conservative amino acid substitutions. Such conservative substitutions, explained in more detail above, generaUy preserve the charge and ydrophobicity at the site of substitution, thus preserving the structure (and therefore function) of the polypeptide. Percent identity between polypeptide sequences may be determined using the default parameters of the CLUSTAL V algorithm as incorporated into the MEGALIGN version 3.12e sequence aUgnment program (described and referenced above). For pairwise aUgnments of polypeptide sequences using CLUSTAL V, the default parameters are set as foUows: Ktuple=l, gap penalty=3, window=5, and "diagonals saved"=5. The PAM250 matrix is selected as the default residue weight table. As with polynucleotide aUgnments, the percent identity is reported by CLUSTAL V as the "percent similarity" between aUgned polypeptide sequence pairs. Alternatively the NCBI BLAST software suite may be used. For example, for a pairwise comparison of two polypeptide sequences, one may use the "BLAST 2 Sequences" tool Version 2.0.12 (April-21-2000) with blastp set at default parameters. Such default parameters may be, for example: Matrix: BLOSUM62 Open Gap: 11 and Extension Gap: 1 penalties Gap x drop-off: 50 Expect: 10 Word Size: 3 Filter: on Percent identity may be measured over the length of an entire defined polypeptide sequence, for example, as defined by a particular SEQ ID number, or may be measured over a shorter length, for example, over the length of a fragment taken from a larger, defined polypeptide sequence, for instance, a fragment of at least 15, at least 20, at least 30, at least 40, at least 50, at least 70 or at least 150 contiguous residues. Such lengths are exemplary only, and it is understood that any fragment length supported by the sequences shown herein, in the tables, figures or Sequence Listing, may be used to describe a length over which percentage identity may be measured. "Human artificial chromosomes" (HACs) are Unear microchromosomes which may contain DNA sequences of about 6 kb to 10 Mb in size and which contain aU of the elements required for chromosome repUcation, segregation and maintenance. The term "humanized antibody" refers to an antibody molecule in which the amino acid sequence in the non-antigen binding regions has been altered so that the antibody more closely resembles a human antibody, and stiU retains its original binding abiUty. "Hybridization" refers to the process by which a polynucleotide strand anneals with a complementary strand through base pairing under defined hybridization conditions. Specific hybridization is an indication that two nucleic acid sequences share a high degree of complementarity. Specific hybridization complexes form under permissive anneaUng conditions and remain hybridized after the "washing" step(s). The washing step(s) is particularly important in determining the stringency of the hybridization process, with more stringent conditions aUowing less non-specific binding, i.e., binding between pairs of nucleic acid strands that are not perfectly matched. Permissive conditions for anneaUng of nucleic acid sequences are routinely determinable by one of ordinary skiU in the art and may be consistent among hybridization experiments, whereas wash conditions may be varied among experiments to achieve the desired stringency, and therefore hybridization specificity. Permissive anneaUng conditions occur, for example, at 68°C in the presence of about 6 x SSC, about 1% (w/v) SDS, and about 100 μg/ml sheared, denatured salmon sperm DNA. GeneraUy, stringency of hybridization is expressed, in part, with reference to the temperature under which the wash step is carried out. Such wash temperatures are typicaUy selected to be about 5°C to 20°C lower than the thermal melting point (TJ for the specific sequence at a defined ionic strength and pH. The T m is the temperature (under defined ionic strength and pH) at which 50% of the target sequence hybridizes to a perfectly matched probe. An equation for calculating T m and conditions for nucleic acid hybridization are weU known and can be found in Sambrook, J. et al. (1989) Molecular Cloning: A Laboratory Manual, 2 nd ed., vol. 1-3, Cold Spring Harbor Press, Plainview NY; specificaUy see volume 2, chapter 9. High stringency conditions for hybridization between polynucleotides of the present invention include wash conditions of 68°C in the presence of about 0.2 x SSC and about 0.1 % SDS, for 1 hour. Alternatively, temperatures of about 65 °C, 60°C, 55 °C, or 42°C may be used. SSC concentration may be varied from about 0.1 to 2 x SSC, with SDS being present at about 0.1%. TypicaUy, blocking reagents are used to block non-specific hybridization. Such blocking reagents include, for instance, sheared and denatured salmon sperm DNA at about 100-200 μg/ml. Organic solvent, such as formamide at a concentration of about 35-50% v/v, may also be used under particular circumstances, such as for RNA:DNA hybridizations. Useful variations on these wash conditions wiU be readily apparent to those of ordinary skiU in the art. Hybridization, particularly under high stringency conditions, may be suggestive of evolutionary similarity between the nucleotides. Such similarity is strongly indicative of a similar role for the nucleotides and their encoded polypeptides. The term "hybridization complex" refers to a complex formed between two nucleic acid sequences by virtue of the formation of hydrogen bonds between complementary bases. A hybridization complex may be formed in solution (e.g., C 0 t or R 0 t analysis) or formed between one nucleic acid sequence present in solution and another nucleic acid sequence immobilized on a soUd support (e.g., paper, membranes, filters, chips, pins or glass sUdes, or any other appropriate substrate to which ceUs or their nucleic acids have been fixed). The words "insertion" and "addition" refer to changes in an amino acid or nucleotide sequence resulting in the addition of one or more amino acid residues or nucleotides, respectively. "Immune response" can refer to conditions associated with inflammation, trauma, immune disorders, or infectious or genetic disease, etc. These conditions can be characterized by expression of various factors, e.g., cytokines, chemokines, and other signaUng molecules, which may affect ceUular and systemic defense systems. An "immunogenic fragment" is a polypeptide or oUgopeptide fragment of SAT which is capable of eUciting an immune response when introduced into a Uving organism, for example, a mammal. The term "immunogenic fragment" also includes any polypeptide or oUgopeptide fragment of SAT which is useful in any of the antibody production methods disclosed herein or known in the art. The term "microarray" refers to an arrangement of a pluraUty of polynucleotides, polypeptides, or other chemical compounds on a substrate. The terms "element" and "array element" refer to a polynucleotide, polypeptide, or other chemical compound having a unique and defined position on a microarray. The term "modulate" refers to a change in the activity of SAT. For example, modulation may cause an increase or a decrease in protein activity, binding characteristics, or any other biological, functional, or immunological properties of SAT, The phrases "nucleic acid" and "nucleic acid sequence" refer to a nucleotide, oUgonucleotide, polynucleotide, or any fragment thereof. These phrases also refer to DNA or RNA of genomic or synthetic origin which may be single-stranded or double-stranded and may represent the sense or the antisense strand, to peptide nucleic acid (PNA), or to any DNA-Uke or RNA-Uke material. "Operably Unked" refers to the situation in which a first nucleic acid sequence is placed in a functional relationship with a second nucleic acid sequence. For instance, a promoter is operably Unked to a coding sequence if the promoter affects the transcription or expression of the coding sequence. Operably Unked DNA sequences may be in close proximity or contiguous and, where necessary to join two protein coding regions, in the same reading frame. "Peptide nucleic acid" (PNA) refers to an antisense molecule or anti-gene agent which comprises an oUgonucleotide of at least about 5 nucleotides in length Unked to a peptide backbone of amino acid residues ending in lysine. The terminal lysine confers solubiUty to the composition. PNAs preferentiaUy bind complementary single stranded DNA or RNA and stop transcript elongation, and may be pegylated to extend their Ufespan in the ceU. "Post-translational modification" of an SAT may involve Upidation, glycosylation, phosphorylation, acetylation, racemization, proteolytic cleavage, and other modifications known in the art. These processes may occur syntheticaUy or biochemicaUy. Biochemical modifications wiU vary by ceU type depending on the enzymatic milieu of SAT. "Probe" refers to nucleic acid sequences encoding SAT, their complements, or fragments- thereof, which are used to detect identical, aUeUc or related nucleic acid sequences. Probes are isolated oUgonucleotides or polynucleotides attached to a detectable label or reporter molecule. Typical labels include radioactive isotopes, Ugands, chemiluminescent agents, and enzymes. "Primers" are short nucleic acids, usuaUy DNA oUgonucleotides, which may be annealed to a target polynucleotide by complementary base-pairing. The primer may then be extended along the target DNA strand by a DNA polymerase enzyme. Primer pairs can be used for ampUfication (and identification) of a nucleic acid sequence, e.g., by the polymerase chain reaction (PCR). Probes and primers as used in the present invention typically comprise at least 15 contiguous nucleotides of a known sequence. In order to enhance specificity, longer probes and primers may also be employed, such as probes and primers that comprise at least 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, or at least 150 consecutive nucleotides of the disclosed nucleic acid sequences. Probes and primers may be considerably longer than these examples, and it is understood that any length supported by the specification, including the tables, figures, and Sequence Listing, may be used. Methods for preparing and using probes and primers are described in the references, for example Sambrook, J. et al. (1989) Molecular Cloning: A Laboratory Manual, 2 nd ed., vol. 1-3, Cold Spring Harbor Press, Plainview NY; Ausubel, F.M. et al. (1987) Current Protocols in Molecular Biology, Greene Publ. Assoc. & Wiley-Intersciences, New York NY; Innis, M. et al. (1990) PCR Protocols. A Guide to Methods and AppUcations, Academic Press, San Diego CA. PCR primer pairs can be derived from a known sequence, for example, by using computer programs intended for that purpose such as Primer (Version 0.5, 1991, Whitehead Institute for Biomedical Research, Cambridge MA). OUgonucleotides for use as primers are selected using software known in the art for such purpose. For example, OLIGO 4.06 software is useful for the selection of PCR primer pairs of up to 100 nucleotides each, and for the analysis of oUgonucleotides and larger polynucleotides of up to 5,000 nucleotides from an input polynucleotide sequence of up to 32 kilobases. Similar primer selection programs have incorporated additional features for expanded capabilities. For example, the PrimOU primer selection program (available to the pubUc from the Genome Center at University of Texas South West Medical Center, DaUas TX) is capable of choosing specific primers from megabase sequences and is thus useful for designing primers on a genome- wide scope. The Primer3 primer selection program (available to the pubUc from the Whitehead Institate/MET Center for Genome Research, Cambridge MA) aUows the user to input a "mispriming Ubrary," in which sequences to avoid as primer binding sites are user-specified. Primer3 is useful, in particular, for the selection of oUgonucleotides for microarrays. (The source code for the latter two primer selection programs may also be obtained from their respective sources and modified to meet the user's specific needs.) The PrimeGen program (available to the pubUc from the UK Human Genome Mapping Project Resource Centre, Cambridge UK) designs primers based on multiple sequence aUgnments, thereby allowing selection of primers that hybridize to either the most conserved or least conserved regions of aUgned nucleic acid sequences. Hence, this program is useful for identification of both unique and conserved oUgonucleotides and polynucleotide fragments. The oUgonucleotides and polynucleotide fragments identified by any of the above selection methods are useful in hybridization technologies, for example, as PCR or sequencing primers, microarray elements, or specific probes to identify fuUy or partiaUy complementary polynucleotides in a sample of nucleic acids. Methods of oUgonucleotide selection are not Umited to those described above. A "recombinant nucleic acid" is a sequence that is not naturaUy occurring or has a sequence that is made by an artificial combination of two or more otherwise separated segments of sequence. This artificial combination is often accompUshed by chemical synthesis or, more commonly, by the artificial manipulation of isolated segments of nucleic acids, e.g., by genetic engineering techniques such as those described in Sambrook, supra. The term recombinant includes nucleic acids that have been altered solely by addition, substitution, or deletion of a portion of the nucleic acid. Frequently, a recombinant nucleic acid may include a nucleic acid sequence operably Unked to a promoter sequence. Such a recombinant nucleic acid may be part of a vector that is used, for example, to transform a ceU. Alternatively, such recombinant nucleic acids may be part of a viral vector, e.g., based on a vaccinia virus, that could be use to vaccinate a mammal wherein the recombinant nucleic acid is expressed, inducing a protective immunological response in the mammal. A "regulatory element" refers to a nucleic acid sequence usually derived from untranslated regions of a gene and includes enhancers, promoters, introns, and 5' and 3' untranslated regions (UTRs). Regulatory elements interact with host or viral proteins which control transcription, translation, or RNA stability. "Reporter molecules" are chemical or biochemical moieties used for labeUng a nucleic acid, amino acid, or antibody. Reporter molecules include radionucUdes; enzymes; fluorescent, chemiluminescent, or chromogenic agents; substrates; cofactors; inhibitors; magnetic particles; and other moieties known in the art. An "RNA equivalent," in reference to a DNA sequence, is composed of the same Unear sequence of nucleotides as the reference DNA sequence with the exception that aU occurrences of the nitrogenous base thymine are replaced withuracil, and the sugar backbone is composed of ribose instead of deoxyribose. The term "sample" is used in its broadest sense. A sample suspected of containing SAT, nucleic acids encoding SAT, or fragments thereof may comprise a bodily fluid; an extract from a ceU, chromosome, organeUe, or membrane isolated from a ceU; a ceU; genomic DNA, RNA, or cDNA, in solution or bound to a substrate; a tissue; a tissue print; etc. The terms "specific binding" and "specificaUy binding" refer to that interaction between a protein or peptide and an agonist, an antibody, an antagonist, a smaU molecule, or any natural or synthetic binding composition. The interaction is dependent upon the presence of a particular structure of the protein, e.g., the antigenic determinant or epitope, recognized by the binding molecule. For example, if an antibody is specific for epitope "A," the presence of a polypeptide comprising the epitope A, or the presence of free unlabeled A, in a reaction containing free labeled A and the antibody wiU reduce the amount of labeled A that binds to the antibody. The term "substantiaUy purified" refers to nucleic acid or amino acid sequences that are removed from their natural environment and are isolated or separated, and are at least 60% free, preferably at least 75% free, and most preferably at least 90% free from other components with which they are naturally associated. A "substitution" refers to the replacement of one or more amino acid residues or nucleotides by different amino acid residues or nucleotides, respectively. "Substrate" refers to any suitable rigid or semi-rigid support including membranes, filters, chips, sUdes, wafers, fibers, magnetic or nonmagnetic beads, gels, tubing, plates, polymers, microparticles and capiUaries. The substrate can have a variety of surface forms, such as weUs, trenches, pins, channels and pores, to which polynucleotides or polypeptides are bound. A "transcript image" refers to the coUective pattern of gene expression by a particular ceU type or tissue under given conditions at a given time. "Transformation" describes a process by which exogenous DNA is introduced into a recipient ceU. Transformation may occur under natural or artificial conditions according to various methods weU known in the art, and may rely on any known method for the insertion of foreign nucleic acid sequences into a prokaryotic or eukaryotic host ceU. The method for transformation is selected based on the type of host ceU being transformed and may include, but is not Umited to, bacteriophage or viral infection, electroporation, heat shock, Upofection, and particle bombardment. The term "transformed ceUs" includes stably transformed ceUs in which the inserted DNA is capable of repUcation either as an autonomously repUcating plasmid or as part of the host chromosome, as weU as transiently transformed ceUs which express the inserted DNA or RNA for Umited periods of time. A "fransgenic organism," as used herein, is any organism, including but not Umited to animals and plants, in which one or more of the ceUs of the organism contains heterologous nucleic acid introduced by way of human intervention, such as by fransgenic techniques weU known in the art. The nucleic acid is introduced into the ceU, directly or indirectly by introduction into a precursor of the ceU, by way of deUberate genetic manipulation, such as by microinjection or by infection with a recombinant virus. The term genetic manipulation does not include classical cross-breeding, or in vitro fertilization, but rather is directed to the introduction of a recombinant DNA molecule. The fransgenic organisms contemplated in accordance with the present invention include bacteria, cyanobacteria, fungi, plants and animals. The isolated DNA of the present invention can be introduced into the host by methods known in the art, for example infection, transfection, transformation or transconjugation. Techniques for transferring the DNA of the present invention into such organisms are widely known and provided in references such as Sambrook et al. (1989), supra. A "variant" of a particular nucleic acid sequence is defined as a nucleic acid sequence having at least 40% sequence identity to the particular nucleic acid sequence over a certain length of one of the nucleic acid sequences using blastn with the "BLAST 2 Sequences" tool Version 2.0.9 (May-07- 1999) set at default parameters. Such a pair of nucleic acids may show, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% or greater sequence identity over a certain defined length. A variant may be described as, for example, an "aUeUc" (as defined above), "spUce," "species," or "polymorphic" variant. A spUce variant may have significant identity to a reference molecule, but wiU generally have a greater or lesser number of polynucleotides due to alternative spUcing of exons during mRNA processing. The corresponding polypeptide may possess additional functional domains or lack domains that are present in the reference molecule. Species variants are polynucleotide sequences that vary from one species to another. The resulting polypeptides wiU generally have significant amino acid identity relative to each other. A polymorphic variant is a variation in the polynucleotide sequence of a particular gene between individuals of a given species. Polymorphic variants also may encompass "single nucleotide polymorphisms" (SNPs) in which the polynucleotide sequence varies by one nucleotide base. The presence of SNPs may be indicative of, for example, a certain population, a disease state, or a propensity for a disease state. A "variant" of a particular polypeptide sequence is defined as a polypeptide sequence having at least 40% sequence identity to the particular polypeptide sequence over a certain length of one of the polypeptide sequences using blastp with the "BLAST 2 Sequences" tool Version 2.0.9 (May-07- 1999) set at default parameters. Such a pair of polypeptides may show, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% or greater sequence identity over a certain defined length of one of the polypeptides. THE INVENTION The invention is based on the discovery of new human secretion and trafficking molecules (SAT), the polynucleotides encoding SAT, and the use of these compositions for the diagnosis, treatment, or prevention of vesicle trafficking, transport, neurological, autoimmune/inflammatory, and ceU proUferative disorders. Table 1 summarizes the nomenclature for the fuU length polynucleotide and polypeptide sequences of the invention. Each polynucleotide and its corresponding polypeptide are correlated to a single Incyte project identification number (Incyte Project ED). Each polypeptide sequence is denoted by both a polypeptide sequence identification number (Polypeptide SEQ ED NO:) and an Incyte polypeptide sequence number (Incyte Polypeptide ED) as shown. Each polynucleotide sequence is denoted by both a polynucleotide sequence identification number (Polynucleotide SEQ ED NO:) and an Incyte polynucleotide consensus sequence number (Incyte Polynucleotide ED) as shown. Table 2 shows sequences with homology to the polypeptides of the invention as identified by BLAST analysis against the GenBank protein (genpept) database. Columns 1 and 2 show the polypeptide sequence identification number (Polypeptide SEQ ED NO:) and the corresponding Incyte polypeptide sequence number (Incyte Polypeptide ED) for polypeptides of the invention. Column 3 shows the GenBank identification number (Genbank ED NO:) of the nearest GenBank homolog. Column 4 shows the probabiUty score for the match between each polypeptide and its GenBank homolog. Column 5 shows the annotation of the GenBank homolog along with relevant citations where appUcable, aU of which are expressly incorporated by reference herein. Table 3 shows various structural features of the polypeptides of the invention. Columns 1 and 2 show the polypeptide sequence identification number (SEQ ED NO:) and the corresponding Incyte polypeptide sequence number (Incyte Polypeptide ED) for each polypeptide of the invention. Column 3 shows the number of amino acid residues in each polypeptide. Column 4 shows potential phosphorylation sites, and column 5 shows potential glycosylation sites, as determined by the MOTIFS program of the GCG sequence analysis software package (Genetics Computer Group, Madison WI). Column 6 shows amino acid residues comprising signature sequences, domains, and motifs. Column 7 shows analytical methods for protein structure/function analysis and in some cases, searchable databases to which the analytical methods were appUed. Together, Tables 2 and 3 summarize the properties of polypeptides of the invention, and these properties estabUsh that the claimed polypeptides are secretion and trafficking molecules. For example, SEQ ED NO:2 is 93% identical to mitsugumin29 (GenBank ED g3077703), a synaptophysin family member, as determined by the Basic Local AUgnment Search Tool (BLAST). (See Table 2.) The BLAST probabiUty score is 2.9e-136, which indicates the probabiUty of obtaining the observed polypeptide sequence aUgnment by chance. SEQ ED NO:2 also contains a synaptophysin/synaptoporin domain as determined by searching for statisticaUy significant matches in the hidden Markov model (HMM)-based PFAM database of conserved protein family domains. (See Table 3.) Data from BLIMPS and PROFELESCAN analyses, and BLAST comparisons to protein signature sequences in the DOMO and PRODOM databases provide further corroborative evidence that SEQ ED NO:2 is a synaptophysin family member. SEQ ID NO:3 is 72% identical to rat apical endosomal glycoprotein (GenBank ED g777776) with a BLAST probabiUty score of 0.0. Data from BLAST analyses against the PRODOM database provide further corroborative evidence that SEQ ED NO:3 is an apical endosomal glycoprotein. SEQ ID NO:8 is 95% identical to Rattus norvegicus synaptotagmin HI (GenBank ED g484296) with a BLAST probabiUty score of 0.0. SEQ ID NO:8 also contains a C2 domain as determined by searching for statisticaUy significant matches in the hidden Markov model (HMM)-based PFAM database of conserved protein family domains. (See Table 3.) Data from BLIMPS, MOTIFS, and PROFILESCAN analyses provide further corroborative evidence that SEQ ID NO:8 is a C2 domain-containing protein, most Ukely a member of the synaptotagmin family. SEQ ID NO:l, SEQ ED NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, and SEQ ED NO:9 were analyzed and annotated in a similar manner. The algorithms and parameters for the analysis of SEQ ED NO:l-9 are described in Table 7. As shown in Table 4, the full length polynucleotide sequences of the present invention were assembled using cDNA sequences or coding (exon) sequences derived from genomic DNA, or any combination of these two types of sequences. Columns 1 and 2 Ust the polynucleotide sequence identification number (Polynucleotide SEQ ED NO:) and the corresponding Incyte polynucleotide consensus sequence number (Incyte Polynucleotide ED) for each polynucleotide of the invention. Column 3 shows the length of each polynucleotide sequence in basepairs. Column 4 Usts fragments of the polynucleotide sequences which are useful, for example, in hybridization or ampUfication technologies that identify SEQ ED NO:10-18 or that distinguish between SEQ ID NO:10-18 and related polynucleotide sequences. Column 5 shows identification numbers corresponding to cDNA sequences, coding sequences (exons) predicted from genomic DNA, and/or sequence assemblages comprised of both cDNA and genomic DNA. These sequences were used to assemble the fuU length polynucleotide sequences of the invention. Columns 6 and 7 of Table 4 show the nucleotide start (5') and stop (3') positions of the cDNA and/or genomic sequences in column 5 relative to their respective fuU length sequences. The identification numbers in Column 5of Table 4 may refer specificaUy, for example, to Incyte cDNAs along with their corresponding cDNA Ubraries. For example, 1438701F1 is the identification number of an Incyte cDNA sequence, and PANCNOT02 is the cDNA Ubrary from which it is derived. Incyte cDNAs for which cDNA Ubraries are not indicated were derived from pooled cDNA Ubraries (e.g., 707 7606V1). Alternatively, the identification numbers in column 5 may refer to GenBank cDNAs or ESTs (e.g., g5810426) which contributed to the assembly of the fuU length polynucleotide sequences. In addition, the identification numbers in column 5 may identify sequences derived from the ENSEMBL (The S anger Centre, Cambridge, UK) database (i.e., those sequences including the designation "ENST"). Alternatively, the identification numbers in column 5 may be derived from the NCBI RefSeq Nucleotide Sequence Records Database (i. e. , those sequences including the designation "NM" or "NT") or the NCBI RefSeq Protein Sequence Records (i.e., those sequences including the designation "NP"). Alternatively, the identification numbers in column 5 may refer to assemblages of both cDNA and Genscan-predicted exons brought together by an "exon stitching" algorithm. For example, V XXXXXJ^ 1 Jf 2 Jf¥YYYJ^ 3 Jr 4 represents a "stitched" sequence in which XXXXXX is the identification number of the cluster of sequences to which the algorithm was appUed, and YYYYY is the number of the prediction generated by the algorithm, and N 1Λ3... , if present, represent specific exons that may have been manuaUy edited during analysis (See Example V). Alternatively, the identification numbers in column 5 may refer to assemblages of exons brought together by an "exon-stretching" algorithm. For example, ¥ XXXXXX_gAAAAA_gBBBBB_l_N is the identification number of a "stretched" sequence, with XXXXXX being the Incyte project identification number, gAAAAA being the GenBank identification number of the human genomic sequence to which the "exon-stretching" algorithm was appUed, gBBBBB being the GenBank identification number or NCBI RefSeq identification number of the nearest GenBank protein homolog, and N referring to specific exons (See Example V). In instances where a RefSeq sequence was used as a protein homolog for the "exon-stretching" algorithm, a RefSeq identifier (denoted by "NM," "NP," or "NT") may be used in place of the GenBank identifier (i.e., gBBBBB). Alternatively, a prefix identifies component sequences that were hand-edited, predicted from genomic DNA sequences, or derived from a combination of sequence analysis methods. The foUowing Table Usts examples of component sequence prefixes and corresponding sequence analysis methods associated with the prefixes (see Example IV and Example V). Prefix Type of analysis and/or examples of programs In some cases, Incyte cDNA coverage redundant with the sequence coverage shown in column 5 was obtained to confirm the final consensus polynucleotide sequence, but the relevant Incyte cDNA identification numbers are not shown. Table 5 shows the representative cDNA Ubraries for those full length polynucleotide sequences which were assembled using Incyte cDNA sequences. The representative cDNA Ubrary is the Incyte cDNA Ubrary which is most frequently represented by the Incyte cDNA sequences which were used to assemble and confirm the above polynucleotide sequences. The tissues and vectors which were used to construct the cDNA Ubraries shown in Table 5 are described in Table 6. The invention also encompasses SAT variants. A preferred SAT variant is one which has at least about 80%, or alternatively at least about 90%, or even at least about 95% amino acid sequence identity to the SAT amino acid sequence, and which contains at least one functional or structural characteristic of SAT. The invention also encompasses polynucleotides which encode SAT. In a particular embodiment, the invention encompasses a polynucleotide sequence comprising a sequence selected from the group consisting of SEQ ED NO:10-18, which encodes SAT. The polynucleotide sequences of SEQ ID NO:10-18, as presented in the Sequence Listing, embrace the equivalent RNA sequences, wherein occurrences of the nitrogenous base thymine are replaced with uracil, and the sugar backbone is composed of ribose instead of deoxyribose. The invention also encompasses a variant of a polynucleotide sequence encoding SAT. In particular, such a variant polynucleotide sequence wiU have at least about 70%, or alternatively at least about 85%, or even at least about 95% polynucleotide sequence identity to the polynucleotide sequence encoding SAT. A particular aspect of the invention encompasses a variant of a polynucleotide sequence comprising a sequence selected from the group consisting of SEQ ED NO: 10- 18 which has at least about 70%, or alternatively at least about 85%, or even at least about 95% polynucleotide sequence identity to a nucleic acid sequence selected from the group consisting of SEQ ID NO: 10-18. Any one of the polynucleotide variants described above can encode an amino acid sequence which contains at least one functional or structural characteristic of SAT. It wiU be appreciated by those skiUed in the art that as a result of the degeneracy of the genetic code, a multitude of polynucleotide sequences encoding SAT, some bearing minimal similarity to the polynucleotide sequences of any known and naturaUy occurring gene, may be produced. Thus, the invention contemplates each and every possible variation of polynucleotide sequence that could be made by selecting combinations based on possible codon choices. These combinations are made in accordance with the standard triplet genetic code as appUed to the polynucleotide sequence of naturaUy occurring SAT, and aU such variations are to be considered as being specificaUy disclosed. Although nucleotide sequences which encode SAT and its variants are generaUy capable of hybridizing to the nucleotide sequence of the naturaUy occurring SAT under appropriately selected conditions of stringency, it may be advantageous to produce nucleotide sequences encoding SAT or its derivatives possessing a substantially different codon usage, e.g., inclusion of non-naturaUy occurring codons. Codons may be selected to increase the rate at which expression of the peptide occurs in a particular prokaryotic or eukaryotic host in accordance with the frequency with which particular codons are utiUzed by the host. Other reasons for substantiaUy altering the nucleotide sequence encoding SAT and its derivatives without altering the encoded amino acid sequences include the production of RNA transcripts having more desirable properties, such as a greater half-Ufe, than transcripts produced from the naturaUy occurring sequence. The invention also encompasses production of DNA sequences which encode SAT and SAT derivatives, or fragments thereof, entirely by synthetic chemistry. After production, the synthetic sequence may be inserted into any of the many available expression vectors and cell systems using reagents weU known in the art. Moreover, synthetic chemistry may be used to introduce mutations into a sequence encoding SAT or any fragment thereof. Also encompassed by the invention are polynucleotide sequences that are capable of hybridizing to the claimed polynucleotide sequences, and, in particular, to those shown in SEQ ID NO:10-18 and fragments thereof under various conditions of stringency. (See, e.g., Wahl, G.M. and S.L. Berger (1987) Methods Enzymol. 152:399-407; Kimmel, A.R. (1987) Methods Enzymol. 152:507- 511.) Hybridization conditions, including anneaUng and wash conditions, are described in "Definitions." Methods for DNA sequencing are weU known in the art and may be used to practice any of the embodiments of the invention. The methods may employ such enzymes as the Klenow fragment of DNA polymerase I, SEQUENASE (US Biochemical, Cleveland OH), Taq polymerase (AppUed Biosystems), thermostable T7 polymerase (Amersham Pharmacia Biotech, Piscataway NJ), or combinations of polymerases and proofreading exonucleases such as those found in the ELONGASE ampUfication system (Life Technologies, Gaithersburg MD). Preferably, sequence preparation is automated with machines such as the MICROLAB 2200 Uquid transfer system (Hamilton, Reno NV), PTC200 thermal cycler (MJ Research, Watertown MA) and ABI CATALYST 800 thermal cycler (AppUed Biosystems). Sequencing is then carried out using either the ABI 373 or 377 DNA sequencing system (AppUed Biosystems), the MEGABACE 1000 DNA sequencing system (Molecular Dynamics, Sunnyvale CA), or other systems known in the art. The resulting sequences are analyzed using a variety of algorithms which are weU known in the art. (See, e.g., Ausubel, F.M. (1997) Short Protocols in Molecular Biology, John Wiley & Sons, New York NY, unit 7.7 ; Meyers, R.A. (1995) Molecular Biology and Biotechnology, Wiley VCH, New York NY, pp. 856-853.) The nucleic acid sequences encoding SAT may be extended utiUzing a partial nucleotide sequence and employing various PCR-based methods known in the art to detect upstream sequences, such as promoters and regulatory elements. For example, one method which may be employed, restriction-site PCR, uses universal and nested primers to ampUty unknown sequence from genomic DNA within a cloning vector. (See, e.g., Sarkar, G. (1993) PCR Methods AppUc. 2:318-322.) Another method, inverse PCR, uses primers that extend in divergent directions to ampUfy unknown sequence from a circularized template. The template is derived from restriction fragments comprising a known genomic locus and surrounding sequences. (See, e.g., TrigUa, T. et al. (1988) Nucleic Acids Res. 16:8186.) A third method, capture PCR, involves PCR ampUfication of DNA fragments adjacent to known sequences in human and yeast artificial chromosome DNA. (See, e.g., Lagerstrom, M. et al. (1991) PCR Methods AppUc. 1:111-119.) In this method, multiple restriction enzyme digestions and Ugations may be used to insert an engineered double-stranded sequence into a region of unknown sequence before performing PCR. Other methods which may be used to retrieve unknown sequences are known in the art. (See, e.g., Parker, J.D. et al. (1991) Nucleic Acids Res. 19:3055-3060). AdditionaUy, one may use PCR, nested primers, and PROMOTERFTNDER Ubraries (Clontech, Palo Alto CA) to walk genomic DNA. This procedure avoids the need to screen Ubraries and is useful in finding intron/exon junctions. For aU PCR-based methods, primers may be designed using commerciaUy available software, such as OLIGO 4.06 primer analysis software (National Biosciences, Plymouth MN) or another appropriate program, to be about 22 to 30 nucleotides in length, to have a GC content of about 50% or more, and to anneal to the template at temperatures of about 68°C to 72°C. When screening for fuU length cDNAs, it is preferable to use Ubraries that have been size-selected to include larger cDNAs. In addition, random-primed Ubraries, which often include sequences containing the 5' regions of genes, are preferable for situations in which an oUgo d(T) Ubrary does not yield a fuU-length cDNA. Genomic Ubraries may be useful for extension of sequence into 5' non-transcribed regulatory regions. CapiUary electrophoresis systems which are commerciaUy available may be used to analyze the size or confirm the nucleotide sequence of sequencing or PCR products. In particular, capiUary sequencing may employ flowable polymers for electrophoretic separation, four different nucleotide- specific, laser-stimulated fluorescent dyes, and a charge coupled device camera for detection of the emitted wavelengths. Output/light intensity may be converted to electrical signal using appropriate software (e.g., GENOTYPER and SEQUENCE NAVIGATOR, AppUed Biosystems), and the entire process from loading of samples to computer analysis and electronic data display may be computer controUed. CapiUary electrophoresis is especiaUy preferable for sequencing smaU DNA fragments which may be present in Umited amounts in a particular sample. In another embodiment of the invention, polynucleotide sequences or fragments thereof which encode SAT may be cloned in recombinant DNA molecules that direct expression of SAT, or fragments or functional equivalents thereof, in appropriate host ceUs. Due to the inherent degeneracy of the genetic code, other DNA sequences which encode substantiaUy the same or a functionaUy equivalent amino acid sequence may be produced and used to express SAT. The nucleotide sequences of the present invention can be engineered using methods generaUy known in the art in order to alter SAT-encoding sequences for a variety of purposes including, but not Umited to, modification of the cloning, processing, and/or expression of the gene product. DNA shuffling by random fragmentation and PCR reassembly of gene fragments and synthetic oUgonucleotides may be used to engineer the nucleotide sequences. For example, oUgonucleotide- mediated site-directed mutagenesis may be used to introduce mutations that create new restriction sites, alter glycosylation patterns, change codon preference, produce spUce variants, and so forth. The nucleotides of the present invention may be subjected to DNA shuffling techniques such as MOLECULARBREEDING (Maxygen Inc., Santa Clara CA; described in U.S. Patent Number 5,837,458; Chang, C.-C. et al. (1999) Nat. Biotechnol. 17:793-797; Christians, F.C. et al. (1999) Nat. Biotechnol. 17:259-264; and Crameri, A. et al. (1996) Nat. Biotechnol. 14:315-319) to alter or improve the biological properties of SAT, such as its biological or enzymatic activity or its abiUty to bind to other molecules or compounds. DNA shuffling is a process by which a Ubrary of gene variants is produced using PCR-mediated recombination of gene fragments. The Ubrary is then subjected to selection or screening procedures that identify those gene variants with the desired properties. These preferred Variants may then be pooled and further subjected to recursive rounds of DNA shuffling and selection/screening. Thus, genetic diversity is created through "artificial" breeding and rapid molecular evolution. For example, fragments of a single gene containing random point mutations may be recombined, screened, and then reshuffled until the desired properties are optimized. Alternatively, fragments of a given gene may be recombined with fragments of homologous genes in the same gene family, either from the same or different species, thereby maximizing the genetic diversity of multiple naturaUy occurring genes in a directed and controUable manner. In another embodiment, sequences encoding SAT may be synthesized, in whole or in part, using chemical methods weU known in the art. (See, e.g., Caruthers, M.H. et al. (1980) Nucleic Acids Symp. Ser. 7:215-223; and Horn, T. et al. (1980) Nucleic Acids Symp. Ser. 7:225-232.) Alternatively, SAT itself or a fragment thereof may be synthesized using chemical methods. For example, peptide synthesis can be performed using various solution-phase or soUd-phase techniques. (See, e.g., Creighton, T. (1984) Proteins, Structures and Molecular Properties. WH Freeman, New York NY, pp. 55-60; and Roberge, J.Y. et al. (1995) Science 269:202-204.) Automated synthesis maybe achieved using the ABI 431 A peptide synthesizer (AppUed Biosystems). Additionally, the amino acid sequence of SAT, or any part thereof, may be altered during direct synthesis and/or combined with sequences from other proteins, or any part thereof, to produce a variant polypeptide or a polypeptide having a sequence of a naturally occurring polypeptide. The peptide may be substantiaUy purified by preparative high performance Uquid chromatography. (See, e.g., Chiez, R.M. and F.Z. Regnier (1990) Methods Enzymol. 182:392-421.) The composition of the synthetic peptides may be confirmed by amino acid analysis or by sequencing. (See, e.g., Creighton, supra, pp. 28-53.) In order to express a biologicaUy active SAT, the nucleotide sequences encoding SAT or derivatives thereof may be inserted into an appropriate expression vector, i.e., a vector which contains the necessary elements for transcriptional and translational control of the inserted coding sequence in a suitable host. These elements include regulatory sequences, such as enhancers, constitutive and inducible promoters, and 5' and 3' untranslated regions in the vector and in polynucleotide sequences encoding SAT. Such elements may vary in their strength and specificity. Specific initiation signals may also be used to achieve more efficient translation of sequences encoding SAT. Such signals include the ATG initiation codon and adjacent sequences, e.g. the Kozak sequence. In cases where sequences encoding SAT and its initiation codon and upstream regulatory sequences are inserted into the appropriate expression vector, no additional transcriptional or translational control signals may be needed. However, in cases where only coding sequence, or a fragment thereof, is inserted, exogenous translational control signals including an in-frame ATG initiation codon should be provided by the vector. Exogenous translational elements and initiation codons may be of various origins, both natural and synthetic. The efficiency of expression may be enhanced by the inclusion of enhancers appropriate for the particular host ceU system used. (See, e.g., Scharf, D. et al. (1994) Results Probl. CeU Differ. 20:125-162.) Methods which are weU known to those skiUed in the art may be used to construct expression vectors containing sequences encoding SAT and appropriate transcriptional and translational control elements. These methods include in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination. (See, e.g., Sambrook, J. et al. (1989) Molecular Cloning, A Laboratory Manual, Cold Spring Harbor Press, Plainview NY, ch. 4, 8, and 16-17; Ausubel, F.M. et al. (1995) Current Protocols in Molecular Biology. John Wiley & Sons, New York NY, ch. 9, 13, and 16.) A variety of expression vector/host systems may be utilized to contain and express sequences encoding SAT. These include, but are not Umited to, microorganisms such as bacteria transformed with recombinant bacteriophage, plasmid, or cosmid DNA expression vectors; yeast transformed with yeast expression vectors; insect ceU systems infected with viral expression vectors (e.g., baculovirus); plant ceU systems transformed with viral expression vectors (e.g., cauUflower mosaic virus, CaMV, or tobacco mosaic virus, TMV) or with bacterial expression vectors (e.g., Ti or pBR322 plasmids); or animal ceU systems. (See, e.g., Sambrook, supra; Ausubel, supra; Van Heeke, G. and S.M. Schuster (1989) J. Biol. Chem. 264:5503-5509; Engelhard, E.K. et al. (1994) Proc. Natl. Acad. Sci. USA 91:3224-3227; Sandig, V. et al. (1996) Hum. Gene Ther. 7:1937-1945; Takamatsu, N. (1987) EMBO J. 6:307-311 : The McGraw HiU Yearbook of Science and Technology (1992) McGraw Hill, New YorkNY, pp. 191-196; Logan, J. and T. Shenk (1984) Proc. Natl. Acad. Sci. USA 81:3655-3659; and Harrington, J.J. et al. (1997) Nat. Genet. 15:345-355.) Expression vectors derived from retroviruses, adenoviruses, or herpes or vaccinia vimses, or from various bacterial plasmids, may be used for deUvery of nucleotide sequences to the targeted organ, tissue, or cell population. (See, e.g., Di Nicola, M. et al. (1998) Cancer Gen. Ther. 5(6):350-356; Yu, M. et al. (1993) Proc. Natl. Acad. Sci. USA 90(13):6340-6344; BuUer, R.M. et al. (1985) Nature 317(6040):813-815; McGregor, D.P. et al. (1994) Mol. Immunol. 31(3):219-226; and Verma, EM. and N. Somia (1997) Nature 389:239-242.) The invention is not Umited by the host cell employed. In bacterial systems, a number of cloning and expression vectors may be selected depending upon the use intended for polynucleotide sequences encoding SAT. For example, routine cloning, subcloning, and propagation of polynucleotide sequences encoding SAT can be achieved using a multifunctional E. coU vector such as PBLUESCREPT (Stratagene, La JoUa CA) or PSPORT1 plasmid (Life Technologies). Ligation of sequences encoding SAT into the vector's multiple cloning site disrupts the lacL gene, aUowing a colorimetric screening procedure for identification of transformed bacteria containing recombinant molecules. In addition, these vectors may be useful for in vitro transcription, dideoxy sequencing, single strand rescue with helper phage, and creation of nested deletions in the cloned sequence. (See, e.g., Van Heeke, G. and S.M. Schuster (1989) J. Biol. Chem. 264:5503-5509.) When large quantities of SAT are needed, e.g. for the production of antibodies, vectors which direct high level expression of SAT may be used. For example, vectors containing the strong, inducible SP6 or T7 bacteriophage promoter may be used. Yeast expression systems may be used for production of SAT. A number of vectors containing constitutive or inducible promoters, such as alpha factor, alcohol oxidase, and PGH promoters, may be used in the yeast Saccharomvces cerevisiae or Pichia pastoris. In addition, such vectors direct either the secretion or intraceUular retention of expressed proteins and enable integration of foreign sequences into the host genome for stable propagation. (See, e.g., Ausubel, 1995, supra; 5 Bitter, G.A. et al. (1987) Methods Enzymol. 153:516-544; and Scorer, CA. et al. (1994) Bio/Technology 12:181-184.) Plant systems may also be used for expression of SAT. Transcription of sequences encoding SAT may be driven by viral promoters, e.g., the 35S and 1 S promoters of CaMV used alone or in combination with the omega leader sequence from TMV (Takamatsu, N. (1987) EMBO J. 10 6:307-311). Alternatively, plant promoters such as the smaU subunit of RUBISCO or heat shock promoters may be used. (See, e.g., Coruzzi, G. et al. (1984) EMBO J. 3:1671-1680; BrogUe, R. et al. (1984) Science 224:838-843; and Winter, J. et al. (1991) Results Probl. CeU Differ. 17:85-105.) These constructs can be introduced into plant ceUs by direct DNA transformation or pathogen-mediated transfection. (See, e.g., The McGraw Hill Yearbook of Science and Technology (1992) McGraw HiU, 15 New YorkNY, pp. 191-196.) En mammaUan ceUs, a number of viral-based expression systems may be utiUzed. In cases where an adenovirus is used as an expression vector, sequences encoding SAT may be Ugated into an adeno virus transcription/translation complex consisting of the late promoter and tripartite leader sequence. Insertion in a non-essential El or E3 region of the viral genome may be used to obtain 20 infective virus which expresses SAT in host ceUs. (See, e.g., Logan, J. and T. Shenk (1984) Proc. Natl. Acad. Sci. USA 81:3655-3659.) In addition, transcription enhancers, such as the Rous sarcoma virus (RSV) enhancer, may be used to increase expression in mammaUan host ceUs. SV40 or EBV- based vectors may also be used for high-level protein expression. Human artificial chromosomes (HACs) may also be employed to deUver larger fragments of •25 DNA than can be contained in and expressed from a plasmid. HACs of about 6 kb to 10 Mb are constructed and deUvered via conventional deUvery methods (Uposomes, polycationic amino polymers, or vesicles) for therapeutic purposes. (See, e.g., Harrington, J.J. et al. (1997) Nat. Genet. 15:345- 355.) , For long term production of recombinant proteins in mammaUan systems, stable expression of 30 SAT in ceU Unes is preferred. For example, sequences encoding SAT can be transformed into ceU Unes using expression vectors which may contain viral origins of repUcation and/or endogenous expression elements and a selectable marker gene on the same or on a separate vector. FoUowing the introduction of the vector, ceUs may be aUowed to grow for about 1 to 2 days in enriched media before being switched to selective media. The purpose of the selectable marker is to confer resistance to a selective agent, and its presence aUows growth and recovery of ceUs which successfuUy express the introduced sequences. Resistant clones of stably transformed ceUs may be propagated using tissue culture techniques appropriate to the ceU type. Any number of selection systems may be used to recover transformed ceU Unes. These include, but are not Umited to, the herpes simplex vims thymidine kinase and adenine phosphoribosyltransferase genes, for use in tk and apr ceUs, respectively. (See, e.g., Wigler, M. et al. (1977) Cell 11:223-232; Lowy, I. et al. (1980) CeU 22:817-823.) Also, antimetaboUte, antibiotic, or herbicide resistance can be used as the basis for selection. For example, dhfr confers resistance to methotrexate; neo confers resistance to the aminoglycosides neomycin and G-418; and als and pat confer resistance to chlorsuUuron and phosphinotricin acetyltransferase, respectively. (See, e.g., Wigler, M. et al. (1980) Proc. Natl. Acad. Sci. USA 77:3567-3570; Colbere-Garapin, F. et al. (1981) J. Mol. Biol. 150:1-14.) Additional selectable genes have been described, e.g., trpB and hisD, which alter ceUular requirements for metaboUtes. (See, e.g., Hartman, S.C. and R.C. MuUigan (1988) Proc. Natl. Acad. Sci. USA 85:8047-8051.) Visible markers, e.g., anthocyanins, green fluorescent proteins (GFP; Clontech), β glucuronidase and its substrate β-glucuronide, or luciferase and its substrate luciferin may be used. These markers can be used not only to identify transformants, but also to quantify the amount of transient or stable protein expression attributable to a specific vector system. (See, e.g., Rhodes, C.A. (1995) Methods Mol. Biol. 55:121-131.) Although the presence/absence of marker gene expression suggests that the gene of interest is also present, the presence and expression of the gene may need to be confirmed. For example, if the sequence encoding SAT is inserted within a marker gene sequence, transformed ceUs containing sequences encoding SAT can be identified by the absence of marker gene function. Alternatively, a marker gene can be placed in tandem with a sequence encoding SAT under the control of a single promoter. Expression of the marker gene in response to induction or selection usuaUy indicates expression of the tandem gene as weU. hi general, host ceUs that contain the nucleic acid sequence encoding SAT and that express SAT may be identified by a variety of procedures known to those of skill in the art. These procedures include, but are not Umited to, DNA-DNA or DNA-RNA hybridizations, PCR ampUfication, and protein bioassay or immunoassay techniques which include membrane, solution, or chip based technologies for the detection and/or quantification of nucleic acid or protein sequences. Immunological methods for detecting and measuring the expression of SAT using either specific polyclonal or monoclonal antibodies are known in the art. Examples of such techniques include enzyme-Unked immunosorbent assays (ELISAs), radioimmunoassays (RIAs), and fluorescence activated ceU sorting (FACS). A two-site, monoclonal-based immunoassay utiUzing monoclonal antibodies reactive to two non-interfering epitopes on SAT is preferred, but a competitive binding assay may be employed. These and other assays are weU known in the art. (See, e.g., Hampton, R. et al. (1990) Serological Methods, a Laboratory Manual, APS Press, St. Paul MN, Sect. EV; CoUgan, J.E. et al. (1997) Current Protocols in Immunology, Greene Pub. Associates and Wiley- Interscience, New York NY; and Pound, J.D. (1998) Lmmunochemical Protocols, Humana Press, Totowa NJ.) A wide variety of labels and conjugation techniques are known by those skiUed in the art and may be used in various nucleic acid and amino acid assays. Means for producing labeled hybridization or PCR probes for detecting sequences related to polynucleotides encoding SAT include oUgolabeUng, nick translation, end-labeUng, or PCR ampUfication using a labeled nucleotide. Alternatively, the sequences encoding SAT, or any fragments thereof, may be cloned into a vector for the production of an mRNA probe. Such vectors are known in the art, are commercially available, and may be used to synthesize RNA probes in vitro by addition of an appropriate RNA polymerase such as T7, T3, or SP6 and labeled nucleotides. These procedures may be conducted using a variety of commerciaUy available kits, such as those provided by Amersham Pharmacia Biotech, Promega (Madison WT), and US Biochemical. Suitable reporter molecules or labels which may be used for ease of detection include radionucUdes, enzymes, fluorescent, chemiluminescent, or chromogenic agents, as well as substrates, cofactors, inhibitors, magnetic particles, and the Uke. Host ceUs transformed with nucleotide sequences encoding SAT may be cultured under conditions suitable for the expression and recovery of the protein from ceU culture. The protein produced by a transformed cell may be secreted or retained intraceUularly depending on the sequence and/or the vector used. As wiU be understood by those of skiU in the art, expression vectors containing polynucleotides which encode SAT may be designed to contain signal sequences which direct secretion of SAT through a prokaryotic or eukaryotic ceU membrane. In addition, a host ceU strain may be chosen for its abiUty to modulate expression of the inserted sequences or to process the expressed protein in the desired fashion. Such modifications of the polypeptide include, but are not Umited to, acetylation, carboxylation, glycosylation, phosphorylation, Upidation, and acylation. Post-translational processing which cleaves a "prepro" or "pro" form of the protein may also be used to specify protein targeting, folding, and/or activity. Different host ceUs which have specific ceUular machinery and characteristic mechanisms for post-translational activities (e.g., CHO, HeLa, MDCK, HEK293, and WI38) are available from the American Type Culture CoUection (ATCC, Manassas VA) and may be chosen to ensure the correct modification and processing of the foreign protein. In another embodiment of the invention, natural, modified, or recombinant nucleic acid sequences encoding SAT may be Ugated to a heterologous sequence resulting in translation of a fusion protein in any of the aforementioned host systems. For example, a chimeric SAT protein containing a heterologous moiety that can be recognized by a commerciaUy available antibody may faciUtate the screening of peptide Ubraries for inhibitors of SAT activity. Heterologous protein and peptide moieties may also faciUtate purification of fusion proteins using commerciaUy available affinity matrices. Such moieties include, but are not Umited to, glutathione S-transferase (GST), maltose binding protein (MBP), thioredoxin (Trx), calmoduUn binding peptide (CBP), 6-His, FLAG, c-myc, and hemagglutinin (HA). GST, MBP, Trx, CBP, and 6-His enable purification of their cognate fusion proteins on immobiUzed glutathione, maltose, phenylarsine oxide, calmoduUn, and metal-chelate resins, respectively. FLAG, c-myc, and hemagglutinin (HA) enable immunoaffinity purification of fusion proteins using commerciaUy available monoclonal and polyclonal antibodies that specifically recognize these epitope tags. A fusion protein may also be engineered to contain a proteolytic cleavage site located between the SAT encoding sequence and the heterologous protein sequence, so that SAT may be cleaved away from the heterologous moiety foUowing purification. Methods for fusion protein expression and purification are discussed in Ausubel (1995, supra, ch. 10). A variety of commerciaUy available kits may also be used to faciUtate expression and purification of fusion proteins. In a further embodiment of the invention, synthesis of radiolabeled SAT may be achieved in vitro using the TNT rabbit reticulocyte lysate or wheat germ extract system (Promega). These systems couple transcription and translation of protein-coding sequences operably associated with the T7, T3, or SP6 promoters. Translation takes place in the presence of a radiolabeled amino acid precursor, for example, 35 S -methionine. SAT of the present invention or fragments thereof may be used to screen for compounds that specificaUy bind to SAT. At least one and up to a pluraUty of test compounds may be screened for specific binding to SAT. Examples of test compounds include antibodies, oUgonucleotides, proteins (e.g., receptors), or smaU molecules. In one embodiment, the compound thus identified is closely related to the natural Ugand of SAT, e.g., a Ugand or fragment thereof, a natural substrate, a structural or functional mimetic, or a natural binding partner. (See, e.g., CoUgan, J.E. et al. (1991) Current Protocols in Immunology 1(2): Chapter 5.) Similarly, the compound can be closely related to the natural receptor to which SAT binds, or to at least a fragment of the receptor, e.g., the Ugand binding site. In either case, the compound can be rationaUy designed using known techniques. En one embodiment, screening for these compounds involves producing appropriate ceUs which express SAT, either as a secreted protein or on the ceU membrane. Preferred ceUs include ceUs from mammals, yeast, Drosophila, or E. coU. CeUs expressing SAT or ceU membrane fractions which contain SAT are then contacted with a test compound and binding, stimulation, or inhibition of activity of either SAT or the compound is analyzed. An assay may simply test binding of a test compound to the polypeptide, wherein binding is detected by a fluorophore, radioisotope, enzyme conjugate, or other detectable label. For example, the assay may comprise the steps of combining at least one test compound with SAT, either in solution or affixed to a soUd support, and detecting the binding of SAT to the compound. Alternatively, the assay may detect or measure binding of a test compound in the presence of a labeled competitor. AdditionaUy, the assay may be carried out using ceU-free preparations, chemical Ubraries, or natural product mixtures, and the test compound(s) may be free in solution or affixed to a soUd support. SAT of the present invention or fragments thereof may be used to screen for compounds that modulate the activity of SAT. Such compounds may include agonists, antagonists, or partial or inverse agonists. In one embodiment, an assay is performed under conditions permissive for SAT activity, wherein SAT is combined with at least one test compound, and the activity of SAT in the presence of a test compound is compared with the activity of SAT in the absence of the test compound. A change in the activity of SAT in the presence of the test compound is indicative of a compound that modulates the activity of SAT. Alternatively, a test compound is combined with an in vitro or ceU-free system comprising SAT under conditions suitable for SAT activity, and the assay is performed. In either of these assays, a test compound which modulates the activity of SAT may do so indirectly and need not come in direct contact with the test compound. At least one and up to a pluraUty of test compounds may be screened. In another embodiment, polynucleotides encoding SAT or their mammaUan homologs may be "knocked out" in an animal model system using homologous recombination in embryonic stem (ES) cells. Such techniques are weU known in the art and are useful for the generation of animal models of human disease. (See, e.g., U.S. Patent Number 5,175,383 and U.S. Patent Number 5,767,337.) For example, mouse ES ceUs, such as the mouse 129/SvJ ceU Une, are derived from the early mouse embryo and grown in culture. The ES ceUs are transformed with a vector containing the gene of interest dismpted by a marker gene, e.g., the neomycin phosphotransferase gene (neo; Capecchi, M.R. (1989) Science 244:1288-1292). The vector integrates into the corresponding region of the host genome by homologous recombination. Alternatively, homologous recombination takes place using the Cre-loxP system to knockout a gene of interest in a tissue- or developmental stage-specific manner (Marth, J.D. (1996) CUn. Invest. 97:1999-2002; Wagner, K.U. et al. (1997) Nucleic Acids Res. 25:4323-4330). Transformed ES ceUs are identified and microinjected into mouse ceU blastocysts such as those from the C57BL/6 mouse strain. The blastocysts are surgicaUy transferred to pseudopregnant dams, and the resulting chimeric progeny are genotyped and bred to produce heterozygous or homozygous strains. Transgenic animals thus generated may be tested with potential therapeutic or toxic agents. Polynucleotides encoding SAT may also be manipulated in vitro in ES ceUs derived from human blastocysts. Human ES ceUs have the potential to differentiate into at least eight separate ceU Uneages including endoderm, mesoderm, and ectodermal ceU types. These ceU Uneages differentiate into, for example, neural ceUs, hematopoietic Uneages, and cardiomyocytes (Thomson, J.A. et al. (1998) Science 282:1145-1147). Polynucleotides encoding SAT can also be used to create "knockin" humanized animals (pigs) or transgenic animals (mice or rats) to model human disease. With knockin technology, a region of a polynucleotide encoding SAT is injected into animal ES ceUs, and the injected sequence integrates into the animal ceU genome. Transformed cells are injected into blastalae, and the blastalae are implanted as described above. Transgenic progeny or inbred Unes are studied and treated with potential pharmaceutical agents to obtain information on treatment of a human disease. Alternatively, a mammal inbred to overexpress SAT, e.g., by secreting SAT in its milk, may also serve as a convenient source of that protein (Jaime, J. et al. (1998) Biotechnol. Annu. Rev. 4:55-74). THERAPEUTICS Chemical and structural similarity, e.g., in the context of sequences and motifs, exists between regions of SAT and secretion and trafficking molecules. In addition, the expression of SAT is closely associated with brain, spinal cord, lymphatic, and reproductive tissues. Therefore, SAT appeal's to play a role in vesicle trafficking, transport, neurological, autoimmune/inflammatory, and cell proUferative disorders. In the treatment of disorders associated with increased SAT expression or activity, it is desirable to decrease the expression or activity of SAT. In the treatment of disorders associated with decreased SAT expression or activity, it is desirable to increase the expression or activity of SAT. Therefore, in one embodiment, SAT or a fragment or derivative thereof may be administered to a subject to treat or prevent a disorder associated with decreased expression or activity of SAT. Examples of such disorders include, but are not Umited to, a vesicle trafficking disorder such as cystic fibrosis, glucose-galactose malabsorption syndrome, hypercholesterolemia, diabetes meUitas, diabetes insipidus, hyper- and hypoglycemia, Grave's disease, goiter, Cushing's disease, and Addison's disease; gastrointestinal disorders including ulcerative coUtis, gastric and duodenal ulcers; other conditions associated with abnormal vesicle trafficking, including acquired immunodeficiency syndrome (AIDS); aUergies including hay fever, asthma, and urticaria (hives); autoimmune hemolytic anemia; proUferative glomerulonephritis; inflammatory bowel disease; multiple sclerosis; myasthenia gravis; rheumatoid and osteoarthritis; scleroderma; Chediak-Higashi and Sjogren's syndromes; systemic lupus erythematosus; toxic shock syndrome; traumatic tissue damage; and viral, bacterial, fungal, helminthic, and protozoal infections; a transport disorder such as akinesia, amyotrophic lateral sclerosis, ataxia telangiectasia, cystic fibrosis, Becker's muscular dystrophy, BeU's palsy, Charcot-Marie Tooth disease, diabetes meUitus, diabetes insipidus, diabetic neuropathy, Duchenne muscular dystrophy, hyperkalemic periodic paralysis, normokalemic periodic paralysis, Parkinson's disease, maUgnant hyperthermia, multidrug resistance, myasthenia gravis, myotonic dystrophy, catatonia, tardive dyskinesia, dystonias, peripheral neuropathy, cerebral neoplasms, prostate cancer; cardiac disorders associated with transport, e.g., angina, bradyarrythmia, tachyarrythmia, hypertension, Ex>ng QT syndrome, myocarditis, cardiomyopathy, nemaUne myopathy, centronuclear myopathy, Upid myopathy, mitochondrial myopathy, thyrotoxic myopathy, ethanol myopathy, dermatomyositis, inclusion body myositis, infectious myositis, polymyositis; neurological disorders associated with transport, e.g., Alzheimer's disease, amnesia, bipolar disorder, dementia, depression, epilepsy, Tourette's disorder, paranoid psychoses, and schizophrenia; and other disorders associated with transport, e.g., neurofibromatosis, postherpetic neuralgia, trigeminal neuropathy, sarcoidosis, sickle ceU anemia, Wilson's disease, cataracts, infertility, pulmonary artery stenosis, sensorineural autosomal deafness, hyperglycemia, hypoglycemia, Grave's disease, goiter, Cushing's disease, Addison's disease, glucose-galactose malabsorption syndrome, hypercholesterolemia, adrenoleukodystrophy, ZeUweger syndrome, Menkes disease, occipital horn syndrome, von Gierke disease, cystinuria, iminoglycinuria, Hartup disease, and Fanconi disease; a neurological disorder such as epilepsy, ischemic cerebrovascular disease, stroke, cerebral neoplasms, Alzheimer's disease, Pick's disease, Huntington's disease, dementia, Parkinson's disease and other extiapyramidal disorders, amyotrophic lateral sclerosis and other motor neuron disorders, progressive neural muscular atrophy, retinitis pigmentosa, hereditary ataxias, multiple sclerosis and other demyeUnating diseases, bacterial and viral meningitis, brain abscess, subdural empyema, epidural abscess, suppurative intracranial thrombophlebitis, myeUtis and radicuUtis, viral central nervous system disease, prion diseases including kuru, Creutzfeldt- Jakob disease, and Gerstmann-Straussler-Scheinker syndrome, fatal famiUal insomnia, nutritional and metaboUc diseases of the nervous system, neurofibromatosis, tuberous sclerosis, cerebeUoretinal hemangioblastomatosis, encephalotrigeminal syndrome, mental retardation and other developmental disorders of the central nervous system including Down syndrome, cerebral palsy, neuroskeletal disorders, autonomic nervous system disorders, cranial nerve disorders, spinal cord diseases, muscular dystrophy and other neuromuscular disorders, peripheral nervous system disorders, dermatomyositis and polymyositis, inherited, metaboUc, endocrine, and toxic myopathies, myasthenia gravis, periodic paralysis, mental disorders including mood, anxiety, and schizophrenic disorders, seasonal affective disorder (SAD), akathesia, amnesia, catatonia, diabetic neuropathy, tardive dyskinesia, dystonias, paranoid psychoses, postherpetic neuralgia, Tourette's disorder, progressive supranuclear palsy, corticobasal degeneration, and familial frontotemporal dementia; an autoimmune/inflammatory disorder such as such as acquired immunodeficiency syndrome (AFDS), Addison's disease, adult respiratory distress syndrome, aUergies, ankylosing spondyUtis, amyloidosis, anemia, asthma, atherosclerosis, autoimmune hemolytic anemia, autoimmune thyroiditis, autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), bronchitis, cholecystitis, contact dermatitis, Crohn's disease, atopic dermatitis, dermatomyositis, diabetes mellitas, emphysema, episodic lymphopenia with lymphocytotoxins, erythroblastosis fetaUs, erythema nodosum, atrophic gastritis, glomerulonephritis, Goodpasture's syndrome, gout, Graves' disease, Hashimoto's thyroiditis, hypereosinophiUa, irritable bowel syndrome, multiple sclerosis, myasthenia gravis, myocardial or pericardial inflammation, osteoarthritis, osteoporosis, pancreatitis, polymyositis, psoriasis, Reiter' s syndrome, rheumatoid arthritis, scleroderma, Sjogren's syndrome, systemic anaphylaxis, systemic lupus erythematosus, systemic sclerosis, thrombocytopenic purpura, ulcerative coUtis, uveitis, Werner syndrome, compUcations of cancer, hemodialysis, and extracorporeal circulation, viral, bacterial, fungal, parasitic, protozoal, and helminthic infections, and trauma; and a ceU proUferative disorder such as actinic keratosis, arteriosclerosis, atherosclerosis, bursitis, cirrhosis, hepatitis, mixed connective tissue disease (MCTD), myelofibrosis, paroxysmal nocturnal hemoglobinuria, polycythemia vera, psoriasis, primary thrombocythemia, and cancers including adenocarcinoma, leukemia, lymphoma, melanoma, myeloma, sarcoma, teratocarcinoma, and, in particular, cancers of the adrenal gland, bladder, bone, bone marrow, brain, breast, cervix, gaU bladder, gangUa, gastrointestinal tract, heart, kidney, Uver, lung, muscle, ovary, pancreas, parathyroid, penis, prostate, saUvary glands, skin, spleen, testis, thymus, thyroid, and uterus. In another embodiment, a vector capable of expressing SAT or a fragment or derivative thereof may be administered to a subject to treat or prevent a disorder associated with decreased expression or activity of SAT including, but not Umited to, those described above. In a further embodiment, a composition comprising a substantially purified SAT in conjunction with a suitable pharmaceutical carrier may be administered to a subject to treat or prevent a disorder associated with decreased expression or activity of SAT including, but not Umited to, those provided above. In stiU another embodiment, an agonist which modulates the activity of SAT may be administered to a subject to treat or prevent a disorder associated with decreased expression or activity of SAT including, but not Umited to, those Usted above. In a further embodiment, an antagonist of SAT may be administered to a subject to treat or prevent a disorder associated with increased expression or activity of SAT. Examples of such disorders include, but are not Umited to, those vesicle trafficking, transport, neurological, autoimmune/inflammatory, and ceU proUferative disorders described above. En one aspect, an antibody which specificaUy binds SAT may be used directly as an antagonist or indirectly as a targeting or deUvery mechanism for bringing a pharmaceutical agent to ceUs or tissues which express SAT. In an additional embodiment, a vector expressing the complement of the polynucleotide encoding SAT may be administered to a subject to treat or prevent a disorder associated with increased expression or activity of SAT including, but not Umited to, those described above. In other embodiments, any of the proteins, antagonists, antibodies, agonists, complementary sequences, or vectors of the invention may be administered in combination with other appropriate therapeutic agents. Selection of the appropriate agents for use in combination therapy may be made by one of ordinary skiU in the art, according to conventional pharmaceutical principles. The combination of therapeutic agents may act synergisticaUy to effect the treatment or prevention of the various disorders described above. Using this approach, one may be able to achieve therapeutic efficacy with lower dosages of each agent, thus reducing the potential for adverse side effects. An antagonist of SAT may be produced using methods which are generally known in the art. In particular, purified SAT may be used to produce antibodies or to screen Ubraries of pharmaceutical agents to identify those which specificaUy bind SAT. Antibodies to SAT may also be generated using methods that are weU known in the art. Such antibodies may include, but are not Umited to, polyclonal, monoclonal, chimeric, and single chain antibodies, Fab fragments, and fragments produced by a Fab expression Ubrary. NeutraUzing antibodies (i.e., those which inhibit dimer formation) are generally preferred for therapeutic use. For the production of antibodies, various hosts including goats, rabbits, rats, mice, humans, and others may be immunized by injection with SAT or with any fragment or oUgopeptide thereof which has immunogenic properties. Depending on the host species, various adjuvants may be used to increase immunological response. Such adjuvants include, but are not Umited to, Freund's, mineral gels such as aluminum hydroxide, and surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, KLH, and dinifrophenol. Among adjuvants used in humans, BCG (bacilli Calmette-Guerin) and Corynebacterium parvum are especiaUy preferable. It is preferred that the oUgopeptides, peptides, or fragments used to induce antibodies to SAT have an amino acid sequence consisting of at least about 5 amino acids, and generaUy wiU consist of at least about 10 amino acids. It is also preferable that these oUgopeptides, peptides, or fragments are identical to a portion of the amino acid sequence of the natural protein. Short stretches of SAT amino acids may be fused with those of another protein, such as KLH, and antibodies to the chimeric molecule may be produced. Monoclonal antibodies to SAT may be prepared using any technique which provides for the production of antibody molecules by continuous ceU Unes in culture. These include, but are not Umited to, the hybridoma technique, the human B-ceU hybridoma technique, and the EBV-hybridoma technique. (See, e.g., Kohler, G. et al. (1975) Nature 256:495-497; Kozbor, D. et al. (1985) J. Immunol. Methods 81:31-42; Cote, R.J. et al. (1983) Proc. Natl. Acad. Sci. USA 80:2026-2030; and Cole, S.P. et al. (1984) Mol. CeU Biol. 62:109-120.) In addition, techniques developed for the production of "chimeric antibodies," such as the spUcing of mouse antibody genes to human antibody genes to obtain a molecule with appropriate antigen specificity and biological activity, can be used. (See, e.g., Morrison, S.L. et al. (1984) Proc. Natl. Acad. Sci. USA 81:6851-6855; Neuberger, M.S. et al. (1984) Nature 312:604-608; and Takeda, S. et al. (1985) Nature 314:452-454.) Alternatively, techniques described for the production of single chain antibodies may be adapted, using methods known in the art, to produce SAT-specific single chain antibodies. Antibodies with related specificity, but of distinct idiotypic composition, may be generated by chain shuffling from random combinatorial immunoglobuUn Ubraries. (See, e.g., Burton, D.R. (1991) Proc. Natl. Acad. Sci. USA 88:10134-10137.) Antibodies may also be produced by inducing in vivo production in the lymphocyte population or by screening immunoglobuUn Ubraries or panels of highly specific binding reagents as disclosed in the Uterature. (See, e.g., Orlandi, R. et al. (1989) Proc. Natl. Acad. Sci. USA 86:3833-3837; Winter, G. et al. (1991) Nature 349:293-299.) Antibody fragments which contain specific binding sites for SAT may also be generated. For example, such fragments include, but are not Umited to, F(ab') 2 fragments produced by pepsin digestion of the antibody molecule and Fab fragments generated by reducing the disulfide bridges of the F(ab')2 fragments. Alternatively, Fab expression Ubraries may be constructed to aUow rapid and easy identification of monoclonal Fab fragments with the desired specificity. (See, e.g., Huse, W.D. et al. (1989) Science 246:1275-1281.) Various immunoassays may be used for screening to identify antibodies having the desired specificity. Numerous protocols for competitive binding or immunoradiometric assays using either polyclonal or monoclonal antibodies with estabUshed specificities are weU known in the art. Such immunoassays typicaUy involve the measurement of complex formation between SAT and its specific antibody. A two-site, monoclonal-based immunoassay utilizing monoclonal antibodies reactive to two non-interfering SAT epitopes is generally used, but a competitive binding assay may also be employed (Pound, supra). Various methods such as Scatchard analysis in conjunction with radioimmunoassay techniques may be used to assess the affinity of antibodies for SAT. Affinity is expressed as an association constant, K ^ , which is defined as the molar concentration of SAT-antibody complex divided by the molar concentrations of free antigen and free antibody under equiUbrium conditions. The K ^ determined for a preparation of polyclonal antibodies, which are heterogeneous in their affinities for multiple SAT epitopes, represents the average affinity, or avidity, of the antibodies for SAT. The K^ determined for a preparation of monoclonal antibodies, which are monospecific for a particular SAT epitope, represents a true measure of affinity. High-affinity antibody preparations with K^ ranging from about 10 9 to 10 12 L/mole are preferred for use in immunoassays in which the SAT-antibody complex must withstand rigorous manipulations. Low-affinity antibody preparations with I ranging from about 10 6 to 10 7 L/mole are preferred for use in immunopurification and similar procedures which ultimately require dissociation of SAT, preferably in active form, from the antibody (Catty, D. (1988) Antibodies, Volume I: A Practical Approach, ERL Press, Washington DC; LiddeU, J.E. and A. Cryer (1991) A Practical Guide to Monoclonal Antibodies, John Wiley & Sons, New York NY). The titer and avidity of polyclonal antibody preparations may be further evaluated to determine the quaUty and suitability of such preparations for certain downstream appUcations. For example, a polyclonal antibody preparation containing at least 1-2 mg specific antibody/ml, preferably 5-10 mg specific antibody/ml, is generaUy employed in procedures requiring precipitation of SAT-antibody complexes. Procedures for evaluating antibody specificity, titer, and avidity, and guideUnes for antibody quaUty and usage in various appUcations, are generaUy available. (See, e.g., Catty, supra, and CoUgan et al. supra.) In another embodiment of the invention, the polynucleotides encoding SAT, or any fragment or complement thereof, may be used for therapeutic purposes. In one aspect, modifications of gene expression can be achieved by designing complementary sequences or antisense molecules (DNA, RNA, PNA, or modified oUgonucleotides) to the coding or regulatory regions of the gene encoding SAT. Such technology is weU known in the art, and antisense oUgonucleotides or larger fragments can be designed from various locations along the coding or control regions of sequences encoding SAT. (See, e.g., Agrawal, S., ed. (1996) Antisense Therapeutics, Humana Press Inc., Totawa NJ.) In therapeutic use, any gene deUvery system suitable for introduction of the antisense sequences into appropriate target ceUs can be used. Antisense sequences can be deUvered intracellularly in the form of an expression plasmid which, upon transcription, produces a sequence complementary to at least a portion of the ceUular sequence encoding the target protein. (See, e.g., Slater, J.E. et al. (1998) J. AUergy CUn. Immunol. 102(3):469-475; and Scanlon, KJ. et al. (1995) 9(13):1288-1296.) Antisense sequences can also be introduced intiaceUularly through the use of viral vectors, such as retrovirus and adeno-associated virus vectors. (See, e.g., MiUer, A.D. (1990) Blood 76:271; Ausubel, supra: Uckert, W. and W. Walther (1994) Pharmacol. Ther. 63(3):323-347.) Other gene deUvery mechanisms include Uposome-derived systems, artificial viral envelopes, and other systems known in the art. (See, e.g., Rossi, J.J. (1995) Br. Med. BuU. 51(l):217-225; Boado, R.J. et al. (1998) J. Pharm. Sci. 87(11):1308-1315; and Morris, M.C. et al. (1997) Nucleic Acids Res. 25(14):2730-2736.) In another embodiment of the invention, polynucleotides encoding SAT may be used for somatic or germUne gene therapy. Gene therapy may be performed to (i) correct a genetic deficiency (e.g., in the cases of severe combined immunodeficiency (SCED)-Xl disease characterized by X- Unked inheritance (Cavazzana-Calvo, M. et al. (2000) Science 288:669-672), severe combined immunodeficiency syndrome associated with an inherited adenosine deaminase (ADA) deficiency (Blaese, R.M. et al. (1995) Science 270:475-480; Bordignon, C. et al. (1995) Science 270:470-475), cystic fibrosis (Zabner, J. et al. (1993) CeU 75:207-216; Crystal, R.G. et al. (1995) Hum. Gene Therapy 6:643-666; Crystal, R.G. et al. (1995) Hum. Gene Therapy 6:667-703), thalassamias, famiUal hypercholesterolemia, and hemophiUa resulting from Factor VEEI or Factor EX deficiencies (Crystal, R.G. (1995) Science 270:404-410; Verma, M. and N. Somia (1997) Nature 389:239-242)), (n) express a conditionaUy lethal gene product (e.g., in the case of cancers which result from unregulated ceU proUferation), or (Ui) express a protein which affords protection against intraceUular parasites (e.g., against human retroviruses, such as human immunodeficiency virus (HEV) (Baltimore, D. (1988) Nature 335:395-396; Poeschla, E. et al. (1996) Proc. Natl. Acad. Sci. USA. 93:11395-11399), hepatitis B or C virus (HBN HCV); fungal parasites, such as Candida albicans and Paracoccidioides brasiUensis; and protozoan parasites such as Plasmodium falciparum and Trypanosoma cruzi). In the case where a genetic deficiency in SAT expression or regulation causes disease, the expression of SAT from an appropriate population of transduced ceUs may aUeviate the cUnical manifestations caused by the genetic deficiency. In a further embodiment of the invention, diseases or disorders caused by deficiencies in SAT are treated by constructing mammaUan expression vectors encoding SAT and introducing these vectors by mechanical means into SAT-deficient ceUs. Mechanical transfer technologies for use with ceUs in vivo or ex vitro include (i) direct DNA microinjection into individual ceUs, (U) balUstic gold particle deUvery, (ui) Uposome-mediated tiansfection, (iv) receptor-mediated gene transfer, and (v) the use of DNA transposons (Morgan, R.A. and W.F. Anderson (1993) Annu. Rev. Biochem. 62:191- 217; Ivies, Z. (1997) CeU 91:501-510; Boulay, J-L. and H. Recipon (1998) Curr. Opin. Biotechnol. 9:445-450). Expression vectors that may be effective for the expression of SAT include, but are not Umited to, the PCDNA 3.1, EPFTAG, PRCCMV2, PREP, PVAX vectors (Lnvitrogen, Carlsbad CA), PCMV-SCREPT, PCMV-TAG, PEGSH PERV (Stratagene, La JoUa CA), and PTET-OFF, PTET-ON, PTRE2, PTRE2-LUC, PTK-HYG (Clontech, Palo Alto CA). SAT may be expressed using (i) a constitutively active promoter, (e.g., from cytomegalovirus (CMV), Rous sarcoma virus (RSV), SV40 vims, thymidine kinase (TK), or β-actin genes), (U) an inducible promoter (e.g., the tetracycUne-regulated promoter (Gossen, M. and H. Bujard (1992) Proc. Natl. Acad. Sci. USA 89:5547-5551; Gossen, M. et al. (1995) Science 268:1766-1769; Rossi, F.M.V. and H.M. Blau (1998) Curr. Opin. Biotechnol. 9:451-456), commerciaUy available in the T-REX plasmid (Invitrogen)); the ecdysone-inducible promoter (available in the plasmids PVGRXR and PEND; Invitrogen); the FK506/rapamycin inducible promoter; or the RU486/mifepristone inducible promoter (Rossi, F.M.V. and Blau, H.M. supra)), or (in) a tissue-specific promoter or the native promoter of the endogenous gene encoding SAT from a normal individual. CommerciaUy available Uposome transformation kits (e.g., the PERFECT LEPED TRANSFECTION KIT, available from Invitrogen) allow one with ordinary skill in the art to deUver polynucleotides to target ceUs in culture and require minimal effort to optimize experimental parameters. In the alternative, transformation is performed using the calcium phosphate method (Graham, F.L. and A.J. Eb (1973) Virology 52:456-467), or by electroporation (Neumann, E. et al. (1982) EMBO J. 1 :841-845)'. The introduction of DNA to primary ceUs requires modification of these standardized mammaUan transfection protocols. In another embodiment of the invention, diseases or disorders caused by genetic defects with respect to SAT expression are treated by constructing a retroviras vector consisting of (i) the polynucleotide encoding SAT under the control of an independent promoter or the retrovirus long terminal repeat (LTR) promoter, (U) appropriate RNA packaging signals, and (iii) a Rev-responsive element (RRE) along with additional retrovirus cis-aciag RNA sequences and coding sequences required for efficient vector propagation. Retrovirus vectors (e.g., PFB and PFBNEO) are commerciaUy available (Stratagene) and are based on pubUshed data (Riviere, I. et al. (1995) Proc. Natl. Acad. Sci. USA 92:6733-6737), incorporated by reference herein. The vector is propagated in an appropriate vector producing ceU Une (VPCL) that expresses an envelope gene with a tropism for receptors on the target ceUs or a promiscuous envelope protein such as VSVg (Armentano, D. et al. (1987) J. Virol. 61:1647-1650; Bender, M.A. et al. (1987) J. Virol. 61:1639-1646; Adam, M.A. and A.D. MiUer (1988) J. Virol. 62:3802-3806; DuU, T. et al. (1998) J. Virol. 72:8463-8471; Zufferey, R. et al. (1998) J. Virol. 72:9873-9880). U.S. Patent Number 5,910,434 to Rigg ("Method for obtaining retroviras packaging ceU Unes producing high transducing efficiency retroviral supernatant") discloses a method for obtaining retroviras packaging ceU Unes and is hereby incorporated by reference. Propagation of retroviras vectors, transduction of a population of ceUs (e.g., CD4 + T-ceUs), and the return of transduced ceUs to a patient are procedures weU known to persons skilled in the art of gene therapy and have been weU documented (Ranga, U. et al. (1997) J. Virol. 71:7020-7029; Bauer, G. et al. (1997) Blood 89:2259-2267; Bonyhadi, M.L. (1997) J. Virol. 71:4707-4716; Ranga, U. et al. (1998) Proc. Natl. Acad. Sci. USA 95:1201-1206; Su, L. (1997) Blood 89:2283-2290). In the alternative, an adenovirus-based gene therapy deUvery system is used to deUver polynucleotides encoding SAT to ceUs which have one or more genetic abnormaUties with respect to the expression of SAT. The construction and packaging of adenovirus-based vectors are weU known to those with ordinary skill in the art. RepUcation defective adenoviras vectors have proven to be versatile for importing genes encoding immunoregulatory proteins into intact islets in the pancreas (Csete, M.E. et al. (1995) Transplantation 27:263-268). PotentiaUy useful adenoviral vectors are described in U.S. Patent Number 5,707,618 to Armentano ("Adenoviras vectors for gene therapy"), hereby incorporated by reference. For adenoviral vectors, see also Antinozzi, P. A. et al. (1999) Annu. Rev. Nufr. 19:511-544 and Veπna, EM. and N. Somia (1997) Nature 18:389:239-242, both incorporated by reference herein. In another alternative, a herpes-based, gene therapy deUvery system is used to deUver polynucleotides encoding SAT to target ceUs which have one or more genetic abnormaUties with respect to the expression of SAT. The use of herpes simplex virus (HSV)-based vectors may be especiaUy valuable for introducing SAT to ceUs of the central nervous system, for which HSV has a tropism. The construction and packaging of herpes-based vectors are weU known to those with ordinary skiU in the art. A repUcation-competent herpes simplex virus (HSV) type 1 -based vector has been used to deUver a reporter gene to the eyes of primates (Liu, X. et al. (1999) Exp. Eye Res. 169:385-395). The construction of a HSV-1 virus vector has also been disclosed in detail in U.S. Patent Number 5,804,413 to DeLuca ("Herpes simplex virus strains for gene transfer"), which is hereby incorporated by reference. U.S. Patent Number 5,804,413 teaches the use of recombinant HSV d92 which consists of a genome containing at least one exogenous gene to be transferred to a ceU under the control of the appropriate promoter for purposes including human gene therapy. Also taught by this patent are the construction and use of recombinant HSV strains deleted for ICP4, ICP27 and ICP22. For HSV vectors, see also Goins, W.F. et al. (1999) J. Virol. 73:519-532 and Xu, H. et al. (1994) Dev. Biol. 163:152-161, hereby incorporated by reference. The manipulation of cloned herpesvirus sequences, the generation of recombinant virus foUowing the tiansfection of multiple plasmids containing different segments of the large herpesvirus genomes, the growth and propagation of herpesvirus, and the infection of ceUs with herpesvirus are techniques weU known to those of ordinary skiU in the art. In another alternative, an alphavirus (positive, single-stranded RNA virus) vector is used to deUver polynucleotides encoding SAT to target ceUs. The biology of the prototypic alphavirus, SernUki Forest Virus (SFV), has been studied extensively and gene transfer vectors have been based on the SFV genome (Garoff, H. and K.-J. Li (1998) Curr. Opin. Biotechnol. 9:464-469). During alphavirus RNA repUcation, a subgenomic RNA is generated that normaUy encodes the viral capsid proteins. This subgenomic RNA repUcates to higher levels than the fuU length genomic RNA, resulting in the overproduction of capsid proteins relative to the viral proteins with enzymatic activity (e.g., protease and polymerase). Similarly, inserting the coding sequence for SAT into the alphavirus genome in place of the capsid-coding region results in the production of a large number of SAT-coding RNAs and the synthesis of high levels of SAT in vector transduced ceUs. While alphavirus infection is typicaUy associated with ceU lysis within a few days, the abiUty to estabUsh a persistent infection in hamster normal kidney ceUs (BHK-21) with a variant of Sindbis virus (SEN) indicates that the lytic repUcation of alphavirases can be altered to suit the needs of the gene therapy appUcation (Dryga, S.A. et al. (1997) Virology 228:74-83). The wide host range of alphavirases will allow the introduction of SAT into a variety of ceU types. The specific transduction of a subset of cells in a population may require the sorting of ceUs prior to transduction. The methods of manipulating infectious cDNA clones of alphavirases, performing alphavirus cDNA and RNA transfections, and performing alphavirus infections, are weU known to those with ordinary skill in the art. OUgonucleotides derived from the transcription initiation site, e.g., between about positions -10 and +10 from the start site, may also be employed to inhibit gene expression. Similarly, inhibition can be achieved using triple heUx base-pairing methodology. Triple heUx pairing is useful because it causes inhibition of the abiUty of the double heUx to open sufficiently for the binding of polymerases, transcription factors, or regulatory molecules. Recent therapeutic advances using triplex DNA have been described in the Uterature. (See, e.g., Gee, J.E. et al. (1994) in Huber, B.E. and B.I. Carr, Molecular and Immunologic Approaches, Futura PubUsbing, Mt. Kisco NY, pp. 163-177.) A complementary sequence or antisense molecule may also be designed to block translation of mRNA by preventing the transcript from binding to ribosomes. Ribozymes, enzymatic RNA molecules, may also be used to catalyze the specific cleavage of RNA. The mechanism of ribozyme action involves sequence-specific hybridization of the ribozyme molecule to complementary target RNA, foUowed by endonucleolytic cleavage. For example, engineered hammerhead motif ribozyme molecules may specificaUy and efficiently catalyze endonucleolytic cleavage of sequences encoding SAT. Specific ribozyme cleavage sites within any potential RNA target are initiaUy identified by scanning the target molecule for ribozyme cleavage sites, including the foUowing sequences: GUA, GUU, and GUC Once identified, short RNA sequences of between 15 and 20 ribonucleotides, corresponding to the region of the target gene containing the cleavage site, may be evaluated for secondary structural features which may render the oUgonucleotide inoperable. The suitabiUty of candidate targets may also be evaluated by testing accessibiUty to hybridization with complementary oUgonucleotides using ribonuclease protection assays. Complementary ribonucleic acid molecules and ribozymes of the invention may be prepared by any method known in the art for the synthesis of nucleic acid molecules. These include techniques for chemicaUy synthesizing oUgonucleotides such as soUd phase phosphoramidite chemical synthesis. Alternatively, RNA molecules may be generated by in vitro and in vivo transcription of DNA sequences encoding SAT. Such DNA sequences may be incorporated into a wide variety of vectors with suitable RNA polymerase promoters such as T7 or SP6. Alternatively, these cDNA constructs that synthesize complementary RNA, constitatively or inducibly, can be infroduced into ceU Unes, ceUs, or tissues. RNA molecules may be modified to increase intraceUular stabiUty and half-Ufe. Possible modifications include, but are not Umited to, the addition of flanking sequences at the 5 ' and/or 3 ' ends of the molecule, or the use of phosphorothioate or 2' O-methyl rather than phosphodiesterase Unkages within the backbone of the molecule. This concept is inherent in the production of PNAs and can be extended in aU of these molecules by the inclusion of nontraditional bases such as inosine, queosine, and wybutosine, as weU as acetyl-, methyl-, thio-, and similarly modified forms of adenine, cytidine, guanine, thymine, and uridine which are not as easily recognized by endogenous endonucleases. An additional embodiment of the invention encompasses a method for screening for a compound which is effective in altering expression of a polynucleotide encoding SAT. Compounds which may be effective in altering expression of a specific polynucleotide may include, but are not Umited to, oUgonucleotides, antisense oUgonucleotides, triple heUx-forming oUgonucleotides, transcription factors and other polypeptide transcriptional regulators, and non-macromolecular chemical entities which are capable of interacting with specific polynucleotide sequences. Effective compounds may alter polynucleotide expression by acting as either inhibitors or promoters of polynucleotide expression. Thus, in the treatment of disorders associated with increased SAT expression or activity, a compound which specificaUy inhibits expression of the polynucleotide encoding SAT may be therapeutically useful, and in the treatment of disorders associated with decreased SAT expression or activity, a compound which specificaUy promotes expression of the polynucleotide encoding SAT may be therapeuticaUy useful. At least one, and up to a pluraUty, of test compounds may be screened for effectiveness in altering expression of a specific polynucleotide. A test compound may be obtained by any method commonly known in the art, including chemical modification of a compound known to be effective in altering polynucleotide expression; selection from an existing, commerciaUy-available or proprietary Ubrary of naturaUy-occurring or non-natural chemical compounds; rational design of a compound based on chemical and/or structural properties of the target polynucleotide; and selection from a Ubrary of chemical compounds created combinatoriaUy or randomly. A sample comprising a polynucleotide encoding SAT is exposed to at least one test compound thus obtained. The sample may comprise, for example, an intact or permeabiUzed ceU, or an in vitro ceU-free or reconstituted biochemical system. Alterations in the expression of a polynucleotide encoding SAT are assayed by any method commonly known in the art. TypicaUy, the expression of a specific nucleotide is detected by hybridization with a probe having a nucleotide sequence complementary to the sequence of the polynucleotide encoding SAT. The amount of hybridization may be quantified, thus forming the basis for a comparison of the expression of the polynucleotide both with and without exposure to one or more test compounds. Detection of a change in the expression of a polynucleotide exposed to a test compound indicates that the test compound is effective in altering the expression of the polynucleotide. A screen for a compound effective in altering expression of a specific polynucleotide can be carried out, for example, using a Schizosaccharomyces pombe gene expression system (Atkins, D. et al. (1999) U.S. Patent No. 5,932,435; Arndt, CM. et al. (2000) Nucleic Acids Res. 28:E15) or a human cell Une such as HeLa ceU (Clarke, MX. et al. (2000) Biochem. Biophys. Res. Commun. 268:8-13). A particular embodiment of the present invention involves screening a combinatorial Ubrary of oUgonucleotides (such as deoxyribonucleotides, ribonucleotides, peptide nucleic acids, and modified oUgonucleotides) for antisense activity against a specific polynucleotide sequence (Braice, T.W. et al. (1997) U.S. Patent No. 5,686,242; Braice, T.W. et al. (2000) U.S. Patent No. 6,022,691). Many methods for introducing vectors into ceUs or tissues are available and equaUy suitable for use in vivo, in vitro, and ex vivo. For ex vivo therapy, vectors may be introduced into stem cells taken from the patient and clonaUy propagated for autologous transplant back into that same patient. DeUvery by tiansfection, by Uposome injections, or by polycationic amino polymers may be achieved using methods which are weU known in the art. (See, e.g., Goldman, C.K. et al. (1997) Nat. Biotechnol. 15:462-466.) Any of the therapeutic methods described above may be appUed to any subject in need of such therapy, including, for example, mammals such as humans, dogs, cats, cows, horses, rabbits, and monkeys. An additional embodiment of the invention relates to the administration of a composition which generaUy comprises an active ingredient formulated with a pharmaceuticaUy acceptable excipient. Excipients may include, for example, sugars, starches, ceUuloses, gums, and proteins. Various formulations are commonly known and are thoroughly discussed in the latest edition of Remington's Pharmaceutical Sciences (Maack PubUsbing, Easton PA). Such compositions may consist of SAT, antibodies to SAT, and mimetics, agonists, antagonists, or inhibitors of SAT. The compositions utiUzed in this invention may be administered by any number of routes including, but not Umited to, oral, intravenous, intramuscular, infra-arterial, intrameduUary, infrathecal, intiaventricular, pulmonary, fransdermal, subcutaneous, intraperitoneal, intranasal, enteral, topical, subUngual, or rectal means. Compositions for pulmonary administiation may be prepared in Uquid or dry powder form. These compositions are generaUy aerosoUzed immediately prior to inhalation by the patient. In the case of smaU molecules (e.g. traditional low molecular weight organic drugs), aerosol deUvery of fast- acting formulations is well-known in the art. En the case of macromolecules (e.g. larger peptides and proteins), recent developments in the field of pulmonary deUvery via the alveolar region of the lung have enabled the practical deUvery of drags such as insuUn to blood circulation (see, e.g., Patton, J.S. et al, U.S. Patent No. 5,997,848). Pulmonary deUvery has the advantage of administration without needle injection, and obviates the need for potentially toxic penetration enhancers. Compositions suitable for use in the invention include compositions wherein the active ingredients are contained in an effective amount to achieve the intended pmpose. The determination of an effective dose is weU within the capability of those skilled in the art. SpeciaUzed forms of compositions may be prepared for direct intraceUular deUvery of macromolecules comprising SAT or fragments thereof. For example, Uposome preparations, containing a cell-impermeable macromolecule may promote ceU fusion and intracellular deUvery of the macromolecule. Alternatively, SAT or a fragment thereof may be joined to a short cationic N- terminal portion from the H V Tat-1 protein. Fusion proteins thus generated have been found to transduce into the ceUs of aU tissues, including the brain, in a mouse model system (Schwarze, S.R. et al. (1999) Science 285:1569-1572). For any compound, the therapeuticaUy effective dose can be estimated initiaUy either in ceU culture assays, e.g., of neoplastic ceUs, or in animal models such as mice, rats, rabbits, dogs, monkeys, or pigs. An animal model may also be used to determine the appropriate concentration range and route of administration. Such information can then be used to determine useful doses and routes for administration in humans. A therapeuticaUy effective dose refers to that amount of active ingredient, for example SAT or fragments thereof, antibodies of SAT, and agonists, antagonists or inhibitors of SAT, which ameUorates the symptoms or condition. Therapeutic efficacy and toxicity may be determined by standard pharmaceutical procedures in ceU cultures or with experimental animals, such as by calculating the ED 50 (the dose therapeuticaUy effective in 50% of the population) or LD 50 (the dose lethal to 50% of the population) statistics. The dose ratio of toxic to therapeutic effects is the therapeutic index, which can be expressed as the LD 50 /ED 50 ratio. Compositions which exhibit large therapeutic indices are preferred. The data obtained from ceU culture assays and animal studies are used to formulate a range of dosage for human use. The dosage contained in such compositions is preferably within a range of circulating concentrations that includes the ED 50 with Uttle or no toxicity. The dosage varies within this range depending upon the dosage form employed, the sensitivity of the patient, and the route of administiation. The exact dosage wiU be determined by the practitioner, in Ught of factors related to the subject requiring treatment. Dosage and administration are adjusted to provide sufficient levels of the active moiety or to maintain the desired effect. Factors which may be taken into account include the severity of the disease state, the general health of the subject, the age, weight, and gender of the subject, time and frequency of administiation, drag combination(s), reaction sensitivities, and response to therapy. Long-acting compositions may be administered every 3 to 4 days, every week, or biweekly depending on the half-Ufe and clearance rate of the particular formulation. Normal dosage amounts may vary from about 0.1 μg to 100,000 μg, up to a total dose of about 1 gram, depending upon the route of administration. Guidance as to particular dosages and methods of deUvery is provided in the Uterature and generaUy available to practitioners in the art. Those skiUed in the art will employ different formulations for nucleotides than for proteins or their inhibitors. Similarly, deUvery of polynucleotides or polypeptides wiU be specific to particular ceUs, conditions, locations, etc. DIAGNOSTICS In another embodiment, antibodies which specifically bind SAT may be used for the diagnosis of disorders characterized by expression of SAT, or in assays to monitor patients being treated with SAT or agonists, antagonists, or inhibitors of SAT. Antibodies useful for diagnostic purposes may be prepared in the same manner as described above for therapeutics. Diagnostic assays for SAT include methods which utiUze the antibody and a label to detect SAT in human body fluids or in extracts of ceUs or tissues. The antibodies may be used with or without modification, and may be labeled by covalent or non-covalent attachment of a reporter molecule. A wide variety of reporter molecules, several of which are described above, are known in the art and may be used. A variety of protocols for measuring SAT, including ELISAs, RLAs, and FACS, are known in the art and provide a basis for diagnosing altered or abnormal levels of SAT expression. Normal or standard values for SAT expression are estabUshed by combining body fluids or ceU extracts taken from normal mammaUan subjects, for example, human subjects, with antibodies to SAT under conditions suitable for complex formation. The amount of standard complex formation may be quantitated by various methods, such as photometric means. Quantities of SAT expressed in subject, control, and disease samples from biopsied tissues are compared with the standard values. Deviation between standard and subject values estabUshes the parameters for diagnosing disease. In another embodiment of the invention, the polynucleotides encoding SAT may be used for diagnostic purposes. The polynucleotides which may be used include oUgonucleotide sequences, complementary RNA and DNA molecules, and PNAs. The polynucleotides may be used to detect and quantify gene expression in biopsied tissues in which expression of SAT may be correlated with disease. The diagnostic assay may be used to determine absence, presence, and excess expression of SAT, and to monitor regulation of SAT levels during therapeutic intervention. In one aspect, hybridization with PCR probes which are capable of detecting polynucleotide sequences, including genomic sequences, encoding SAT or closely related molecules may be used to identify nucleic acid sequences which encode SAT. The specificity of the probe, whether it is made from a highly specific region, e.g., the 5' regulatory region, or from a less specific region, e.g., a conserved motif, and the stringency of the hybridization or ampUfication will determine whether the probe identifies only naturaUy occurring sequences encoding SAT, aUeUc variants, or related sequences. Probes may also be used for the detection of related sequences, and may have at least 50% sequence identity to any of the SAT encoding sequences. The hybridization probes of the subject invention may be DNA or RNA and may be derived from the sequence of SEQ ED NO: 10- 18 or from genomic sequences including promoters, enhancers, and introns of the SAT gene. Means for producing specific hybridization probes for DNAs encoding SAT include the cloning of polynucleotide sequences encoding SAT or SAT derivatives into vectors for the production of mRNA probes. Such vectors are known in the art, are commerciaUy available, and may be used to synthesize RNA probes in vitro by means of the addition of the appropriate RNA polymerases and the appropriate labeled nucleotides. Hybridization probes may be labeled by a variety of reporter groups, for example, by radionucUdes such as 32 P or 35 S, or by enzymatic labels, such as alkaUne phosphatase coupled to the probe via avidin/biotin coupUng systems, and the Uke. Polynucleotide sequences encoding SAT may be used for the diagnosis of disorders associated with expression of SAT. Examples of such disorders include, but are not Umited to, a vesicle trafficking disorder such as cystic fibrosis, glucose-galactose malabsorption syndrome, hypercholesterolemia, diabetes meUitas, diabetes insipidus, hyper- and hypoglycemia, Grave's disease, goiter, Cushing's disease, and Addison's disease; gastrointestinal disorders including ulcerative coUtis, gastric and duodenal ulcers; other conditions associated with abnormal vesicle trafficking, including acquired immunodeficiency syndrome (AEDS); aUergies including hay fever, asthma, and urticaria (hives); autoimmune hemolytic anemia; proUferative glomerulonephritis; inflammatory bowel disease; multiple sclerosis; myasthenia gravis; rheumatoid and osteoarthritis; scleroderma; Chediak-Higashi and Sjogren's syndromes; systemic lupus erythematosus; toxic shock syndrome; traumatic tissue damage; and viral, bacterial, fungal, helminthic, and protozoal infections; a transport disorder such as akinesia, amyotrophic lateral sclerosis, ataxia telangiectasia, cystic fibrosis, Becker's muscular dystrophy, BeU's palsy, Charcot-Marie Tooth disease, diabetes meUitas, diabetes insipidus, diabetic neuropathy, Duchenne muscular dystrophy, hyperkalemic periodic paralysis, normokalemic periodic paralysis, Parkinson's disease, maUgnant hyperthermia, multidrag resistance, myasthenia gravis, myotonic dystrophy, catatonia, tardive dyskinesia, dystonias, peripheral neuropathy, cerebral neoplasms, prostate cancer; cardiac disorders associated with transport, e.g., angina, bradyariythmia, tachyarrythmia, hypertension, Lxing QT syndrome, myocarditis, cardiomyopathy, nemaUne myopathy, centionuclear myopathy, Upid myopathy, mitochondrial myopathy, thyrotoxic myopathy, ethanol myopathy, dermatomyositis, inclusion body myositis, infectious myositis, polymyositis; neurological disorders associated with transport, e.g., Alzheimer's disease, amnesia, bipolar disorder, dementia, depression, epilepsy, Tourette's disorder, paranoid psychoses, and schizophrenia; and other disorders associated with transport, e.g., neurofibromatosis, postherpetic neuralgia, trigeminal neuropathy, sarcoidosis, sickle cell anemia, Wilson's disease, cataracts, infertiUty, pulmonary artery stenosis, sensorineural autosomal deafness, hyperglycemia, hypoglycemia, Grave's disease, goiter, Cushing's disease, Addison's disease, glucose-galactose malabsorption syndrome, hypercholesterolemia, adrenoleukodystrophy, Zellweger syndrome, Menkes disease, occipital horn syndrome, von Gierke disease, cystinuria, iminoglycinuria, Hartap disease, and Fanconi disease; a neurological disorder such as epilepsy, ischemic cerebro vascular disease, stroke, cerebral neoplasms, Alzheimer's disease, Pick's disease, Huntington' s disease, dementia, Parkinson's disease and other extrapyramidal disorders, amyotiophic lateral sclerosis and other motor neuron disorders, progressive neural muscular atrophy, retinitis pigmentosa, hereditary ataxias, multiple sclerosis and other demyeUnating diseases, bacterial and viral meningitis, brain abscess, subdural empyema, epidural abscess, suppurative intracranial thrombophlebitis, myeUtis and radicuUtis, viral central nervous system disease, prion diseases including kura, Creutzfeldt-Jakob disease, and Gerstmann-Straussler-Scheinker syndrome, fatal famiUal insomnia, nutritional and metaboUc diseases of the nervous system, neurofibromatosis, tuberous sclerosis, cerebeUoretinal hemangioblastomatosis, encephalotrigeminal syndrome, mental retardation and other developmental disorders of the central nervous system including Down syndrome, cerebral palsy, neuroskeletal disorders, autonomic nervous system disorders, cranial nerve disorders, spinal cord diseases, muscular dystrophy and other neuromuscular disorders, peripheral nervous system disorders, dermatomyositis and polymyositis, inherited, metaboUc, endocrine, and toxic myopathies, myasthenia gravis, periodic paralysis, mental disorders including mood, anxiety, and schizophrenic disorders, seasonal affective disorder (SAD), akathesia, amnesia, catatonia, diabetic neuropathy, tardive dyskinesia, dystonias, paranoid psychoses, postherpetic neuralgia, Tourette's disorder, progressive supranuclear palsy, corticobasal degeneration, and famiUal frontotemporal dementia; an autoimmune/inflammatory disorder such as such as acquired immunodeficiency syndrome (AEDS), Addison's disease, adult respiratory distress syndrome, aUergies, ankylosing spondyUtis, amyloidosis, anemia, asthma, atherosclerosis, autoimmune hemolytic anemia, autoimmune thyroiditis, autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), bronchitis, cholecystitis, contact dermatitis, Crohn's disease, atopic dermatitis, dermatomyositis, diabetes meUitas, emphysema, episodic lymphopenia with lymphocytotoxins, erythroblastosis fetaUs, erythema nodosum, atrophic gastritis, glomeralonephritis, Goodpasture's syndrome, gout, Graves' disease, Hashimoto's thyroiditis, hypereosinophiUa, irritable bowel syndrome, multiple sclerosis, myasthenia gravis, myocardial or pericardial inflammation, osteoarthritis, osteoporosis, pancreatitis, polymyositis, psoriasis, Reiter' s syndrome, rheumatoid arthritis, scleroderma, Sjogren's syndrome, systemic anaphylaxis, systemic lupus erythematosus, systemic sclerosis, thrombocytopenic purpura, ulcerative coUtis, uveitis, Werner syndrome, compUcations of cancer, hemodialysis, and extracorporeal circulation, viral, bacterial, fungal, parasitic, protozoal, and helminthic infections, and trauma; and a ceU proUferative disorder such as actinic keratosis, arteriosclerosis, atherosclerosis, bursitis, cirrhosis, hepatitis, mixed connective tissue disease (MCTD), myelofibrosis, paroxysmal nocturnal hemoglobinuria, polycythemia vera, psoriasis, primary thrombocythemia, and cancers including adenocarcinoma, leukemia, lymphoma, melanoma, myeloma, sarcoma, teratocarcinoma, and, in particular, cancers of the adrenal gland, bladder, bone, bone marrow, brain, breast, cervix, gall bladder, gangUa, gastrointestinal tract, heart, kidney, Uver, lung, muscle, ovary, pancreas, parathyiOid, penis, prostate, saUvary glands, skin, spleen, testis, thymus, thyroid, and uterus. The polynucleotide sequences encoding SAT may be used in Southern or northern analysis, dot blot, or other membrane-based technologies; in PCR technologies; in dipstick, pin, and multiformat ELISA-Uke assays; and in microarrays utiUzing fluids or tissues from patients to detect altered SAT expression. Such quaUtative or quantitative methods are weU known in the art. In a particular aspect, the nucleotide sequences encoding SAT may be useful in assays that detect the presence of associated disorders, particularly those mentioned above. The nucleotide sequences encoding SAT may be labeled by standard methods and added to a fluid or tissue sample from a patient under conditions suitable for the formation of hybridization complexes. After a suitable incubation period, the sample is washed and the signal is quantified and compared with a standard value. If the amount of signal in the patient sample is significantly altered in comparison to a control sample then the presence of altered levels of nucleotide sequences encoding SAT in the sample indicates the presence of the associated disorder. Such assays may also be used to evaluate the efficacy of a particular therapeutic treatment regimen in animal studies, in cUnical trials, or to monitor the treatment of an individual patient. In order to provide a basis for the diagnosis of a disorder associated with expression of SAT, a normal or standard profile for expression is estabUshed. This may be accompUshed by combining body fluids or ceU extracts taken from normal subjects, either animal or human, with a sequence, or a fragment thereof, encoding SAT, under conditions suitable for hybridization or ampUfication. Standard hybridization may be quantified by comparing the values obtained from normal subjects with values from an experiment in which a known amount of a substantiaUy purified polynucleotide is used. Standard values obtained in this manner may be compared with values obtained from samples from patients who are symptomatic for a disorder. Deviation from standard values is used to estabUsh the presence of a disorder. Once the presence of a disorder is estabUshed and a treatment protocol is initiated, hybridization assays may be repeated on a regular basis to determine if the level of expression in the patient begins to approximate that which is observed in the normal subject. The results obtained from successive assays may be used to show the efficacy of treatment over a period ranging from several days to months. With respect to cancer, the presence of an abnormal amount of transcript (either under- or overexpressed) in biopsied tissue from an individual may indicate a predisposition for the development of the disease,, or may provide a means for detecting the disease prior to the appearance of actual cUnical symptoms. A more definitive diagnosis of this type may aUow health professionals to employ preventative measures or aggressive treatment earUer thereby preventing the development or further progression of the cancer. Additional diagnostic uses for oUgonucleotides designed from the sequences encoding SAT may involve the use of PCR. These oUgomers may be chemicaUy synthesized, generated enzymaticaUy, or produced in vitro. OUgomers wiU preferably contain a fragment of a polynucleotide encoding SAT, or a fragment of a polynucleotide complementary to the polynucleotide encoding SAT, and wiU be employed under optimized conditions for identification of a specific gene or condition. OUgomers may also be employed under less stringent conditions for detection or quantification of closely related DNA or RNA sequences. In a particular aspect, oUgonucleotide primers derived from the polynucleotide sequences encoding SAT may be used to detect single nucleotide polymorphisms (SNPs). SNPs are substitations, insertions and deletions that are a frequent cause of inherited or acquired genetic disease in humans. Methods of SNP detection include, but are not Umited to, single-stranded conformation polymorphism (SSCP) and fluorescent SSCP (fSSCP) methods. En SSCP, oUgonucleotide primers derived from the polynucleotide sequences encoding SAT are used to ampUfy DNA using the polymerase chain reaction (PCR). The DNA may be derived, for example, from diseased or normal tissue, biopsy samples, bodily fluids, and the Uke. SNPs in the DNA cause differences in the secondary and tertiary structures of PCR products in single-stranded form, and these differences are detectable using gel electrophoresis in non-denaturing gels. In fSCCP, the oUgonucleotide primers are fluorescently labeled, which aUows detection of the ampUmers in high-throughput equipment such as DNA sequencing machines. AdditionaUy, sequence database analysis methods, termed in siUco SNP (isSNP), are capable of identifying polymorphisms by comparing the sequence of individual overlapping DNA fragments which assemble into a common consensus sequence. These computer- based methods filter out sequence variations due to laboratory preparation of DNA and sequencing errors using statistical models and automated analyses of DNA sequence chromatograms. In the alternative, SNPs may be detected and characterized by mass spectrometry using, for example, the high throughput MASSARRAY system (Sequenom, Inc., San Diego CA). Methods which may also be used to quantify the expression of SAT include radiolabeUng or biotinylating nucleotides, coampUfication of a control nucleic acid, and interpolating results from standard curves. (See, e.g., Melby, P.C. et al. (1993) J. Immunol. Methods 159:235-244; Duplaa, C. et al. (1993) Anal. Biochem. 212:229-236.) The speed of quantitation of multiple samples maybe accelerated by running the assay in a high-throughput format where the oUgomer or polynucleotide of interest is presented in various dilutions and a spectrophotometric or colorimetric response gives rapid quantitation. In further embodiments, oUgonucleotides or longer fragments derived from any of the polynucleotide sequences described herein may be used as elements on a microarray. The microarray can be used in transcript imaging techniques which monitor the relative expression levels of large numbers of genes simultaneously as described below. The microarray may also be used to identify genetic variants, mutations, and polymorphisms. This information may be used to determine gene function, to understand the genetic basis of a disorder, to diagnose a disorder, to monitor progression/regression of disease as a function of gene expression, and to develop and monitor the activities of therapeutic agents in the treatment of disease. In particular, this information may be used to develop a pharmacogenomic profile of a patient in order to select the most appropriate and effective treatment regimen for that patient. For example, therapeutic agents which are highly effective and display the fewest side effects may be selected for a patient based on his/her pharmacogenomic profile. In another embodiment, SAT, fragments of SAT, or antibodies specific for SAT may be used as elements on a microarray. The microarray may be used to monitor or measure protein-protein interactions, drug-target interactions, and gene expression profiles, as described above. A particular embodiment relates to the use of the polynucleotides of the present invention to generate a transcript image of a tissue or ceU type. A transcript image represents the global pattern of gene expression by a particular tissue or ceU type. Global gene expression patterns are analyzed by quantifying the number of expressed genes and their relative abundance under given conditions and at a given time. (See SeiUiamer et al., "Comparative Gene Transcript Analysis," U.S. Patent Number 5,840,484, expressly incorporated by reference herein.) Thus a transcript image may be generated by hybridizing the polynucleotides of the present invention or their complements to the totaUty of transcripts or reverse transcripts of a particular tissue or ceU type. In one embodiment, the hybridization takes place in high-throughput format, wherein the polynucleotides of the present invention or their complements comprise a subset of a pluraUty of elements on a microarray. The resultant transcript image would provide a profile of gene activity. Transcript images may be generated using transcripts isolated from tissues, ceU Unes, biopsies, or other biological samples. The transcript image may thus reflect gene expression in vivo, as in the case of a tissue or biopsy sample, or in vitro, as in the case of a ceU Une. Transcript images which profile the expression of the polynucleotides of the present invention may also be used in conjunction with in vitro model systems and precUnical evaluation of pharmaceuticals, as weU as toxicological testing of industrial and naturaUy-occurring environmental compounds. AU compounds induce characteristic gene expression patterns, frequently termed molecular fingerprints or toxicant signatures, which are indicative of mechanisms of action and toxicity (Nuwaysir, E.F. et al. (1999) Mol. Carcinog. 24:153-159; Steiner, S. and N.L. Anderson (2000) Toxicol. Lett. 112- 113 :467-471 , expressly incorporated by reference herein) . If a test compound has a signature similar to that of a compound with known toxicity, it is Ukely to share those toxic properties. These fingerprints or signatures are most useful and refined when they contain expression information from a large number of genes and gene famiUes. IdeaUy, a genome-wide measurement of expression provides the highest quaUty signature. Even genes whose expression is not altered by any tested compounds are important as weU, as the levels of expression of these genes are used to normaUze the rest of the expression data. The normaUzation procedure is useful for comparison of expression data after treatment with different compounds. While the assignment of gene function to elements of a toxicant signature aids in interpretation of toxicity mechanisms, knowledge of gene function is not necessary for the statistical matching of signatures which leads to prediction of toxicity. (See, for example, Press Release 00-02 from the National Institute of Environmental Health Sciences, released February 29, 2000, available at http://www.niehs.nih.gov/oc/news/toxchip.htm.) Therefore, it is important and desirable in toxicological screening using toxicant signatures to include aU expressed gene sequences. In one embodiment, the toxicity of a test compound is assessed by treating a biological sample containing nucleic acids with the test compound. Nucleic acids that are expressed in the treated biological sample are hybridized with one or more probes specific to the polynucleotides of the present invention, so that transcript levels corresponding to the polynucleotides of the present invention may be quantified. The transcript levels in the treated biological sample are compared with levels in an untreated biological sample. Differences in the transcript levels between the two samples are indicative of a toxic response caused by the test compound in the treated sample. Another particular embodiment relates to the use of the polypeptide sequences of the present invention to analyze the proteome of a tissue or ceU type. The term proteome refers to the global pattern of protein expression in a particular tissue or ceU type. Each protein component of a proteome can be subjected individuaUy to further analysis. Proteome expression patterns, or profiles, are analyzed by quantifying the number of expressed proteins and their relative abundance under given conditions and at a given time. A profile of a cell's proteome may thus be generated by separating and analyzing the polypeptides of a particular tissue or ceU type. In one embodiment, the separation is achieved using two-dimensional gel electiophoresis, in which proteins from a sample are separated by isoelectric focusing in the first dimension, and then according to molecular weight by sodium dodecyl sulfate slab gel electiophoresis in the second dimension (Steiner and Anderson, supra). The proteins are visuaUzed in the gel as discrete and uniquely positioned spots, typicaUy by staining the gel with an agent such as Coomassie Blue or silver or fluorescent stains. The optical density of each protein spot is generaUy proportional to the level of the protein in the sample. The optical densities of equivalently positioned protein spots from different samples, for example, from biological samples either treated or untreated with a test compound or therapeutic agent, are compared to identify any changes in protein spot density related to the treatment. The proteins in the spots are partiaUy sequenced using, for example, standard methods employing chemical or enzymatic cleavage foUowed by mass spectrometry. The identity of the protein in a spot may be determined by comparing its partial sequence, preferably of at least 5 contiguous amino acid residues, to the polypeptide sequences of the present invention. In some cases, further sequence data may be obtained for definitive protein identification. A proteomic profile may also be generated using antibodies specific for SAT to quantify the levels of SAT expression. In one embodiment, the antibodies are used as elements on a microarray, and protein expression levels are quantified by exposing the microarray to the sample and detecting the levels of protein bound to each array element (Lueking, A. et al. (1999) Anal. Biochem. 270:103- 111; Mendoze, L.G. et al. (1999) Biotechniques 27:778-788). Detection may be performed by a variety of methods known in the art, for example, by reacting the proteins in the sample with a thiol- or amino-reactive fluorescent compound and detecting the amount of fluorescence bound at each array element. Toxicant signatures at the proteome level are also useful for toxicological screening, and should be analyzed in paraUel with toxicant signatures at the transcript level. There is a poor correlation between transcript and protein abundances for some proteins in some tissues (Anderson, N.L. and J. SeiUiamer (1997) Electiophoresis 18:533-537), so proteome toxicant signatures maybe useful in the analysis of compounds which do not significantly affect the transcript image, but which alter the proteomic profile. En addition, the analysis of transcripts in body fluids is difficult, due to rapid degradation of mRNA, so proteomic profiUng may be more reUable and informative in such cases. In another embodiment, the toxicity of a test compound is assessed by treating a biological sample containing proteins with the test compound. Proteins that are expressed in the treated biological sample are separated so that the amount of each protein can be quantified. The amount of each protein is compared to the amount of the corresponding protein in an untreated biological sample. A difference in the amount of protein between the two samples is indicative of a toxic response to the test compound in the treated sample. Individual proteins are identified by sequencing the amino acid residues of the individual proteins and comparing these partial sequences to the polypeptides of the present invention. In another embodiment, the toxicity of a test compound is assessed by treating a biological sample containing proteins with the test compound. Proteins from the biological sample are incubated with antibodies specific to the polypeptides of the present invention. The amount of protein recognized by the antibodies is quantified. The amount of protein in the treated biological sample is compared with the amount in an untreated biological sample. A difference in the amount of protein between the two samples is indicative of a toxic response to the test compound in the treated sample. Microarrays may be prepared, used, and analyzed using methods known in the art. (See, e.g., Brennan, T.M. et al. (1995) U.S. Patent No. 5,474,796; Schena, M. et al. (1996) Proc. Natl. Acad. Sci. USA 93:10614-10619; Baldeschweiler et al. (1995) PCT appUcation W095/251116; Shalon, D. et al. (1995) PCT appUcation WO95/35505; HeUer, R.A. et al. (1997) Proc. Natl. Acad. Sci. USA 94:2150-2155; and HeUer, M.J. et al. (1997) U.S. Patent No. 5,605,662.) Various types of microarrays are weU known and thoroughly described in DNA Microarrays: A Practical Approach. M. Schena, ed. (1999) Oxford University Press, London, hereby expressly incorporated by reference. In another embodiment of the invention, nucleic acid sequences encoding SAT may be used to generate hybridization probes useful in mapping the naturaUy occurring genomic sequence. Either coding or noncoding sequences may be used, and in some instances, noncoding sequences may be preferable over coding sequences. For example, conservation of a coding sequence among members of a multi-gene family may potentiaUy cause undesired cross hybridization during chromosomal mapping. The sequences may be mapped to a particular chromosome, to a specific region of a chromosome, or to artificial chromosome constructions, e.g., human artificial chromosomes (HACs), yeast artificial chromosomes (YACs), bacterial artificial chromosomes (BACs), bacterial PI constructions, or single chromosome cDNA Ubraries. (See, e.g., Harrington, J.J. et al. (1997) Nat. Genet. 15:345-355; Price, CM. (1993) Blood Rev. 7:127-134; and Trask, B.J. (1991) Trends Genet. 7:149-154.) Once mapped, the nucleic acid sequences of the invention may be used to develop genetic Unkage maps, for example, which correlate the inheritance of a disease state with the inheritance of a particular chromosome region or restriction fragment length polymorphism (RFLP). (See, for example, Lander, E.S. and D. Botstein (1986) Proc. Natl. Acad. Sci. USA 83:7353-7357.) Fluorescent in situ hybridization (FISH) may be correlated with other physical and genetic map data. (See, e.g., Heinz-Ukich, et al. (1995) in Meyers, supra, pp. 965-968.) Examples of genetic map data can be found in various scientific journals or at the Online MendeUan Inheritance in Man (OMEM) World Wide Web site. Correlation between the location of the gene encoding SAT on a physical map and a specific disorder, or a predisposition to a specific disorder, may help define the region of DNA associated with that disorder and thus may further positional cloning efforts. In situ hybridization of chromosomal preparations and physical mapping techniques, such as Unkage analysis using estabUshed chromosomal markers, may be used for extending genetic maps. Often the placement of a gene on the chromosome of another mammaUan species, such as mouse, may reveal associated markers even if the exact chromosomal locus is not known. This information is valuable to investigators searching for disease genes using positional cloning or other gene discovery techniques. Once the gene or genes responsible for a disease or syndrome have been crudely locaUzed by genetic Unkage to a particular genomic region, e.g., ataxia-telangiectasia to 1 lq22-23, any sequences mapping to that area may represent associated or regulatory genes for further investigation. (See, e.g., Gatti, R.A. et al. (1988) Nature 336:577-580.) The nucleotide sequence of the instant invention may also be used to detect differences in the chromosomal location due to translocation, inversion, etc., among normal, carrier, or affected individuals. , In another embodiment of the invention, SAT, its catalytic or immunogenic fragments, or oUgopeptides thereof can be used for screening Ubraries of compounds in any of a variety of drug screening techniques. The fragment employed in such screening may be free in solution, affixed to a soUd support, borne on a ceU surface, or located intiaceUularly. The formation of binding complexes between SAT and the agent being tested may be measured. Another technique for drag screening provides for high throughput screening of compounds having suitable binding affinity to the protein of interest. (See, e.g., Geysen, et al. (1984) PCT appUcation WO84/03564.) In this method, large numbers of different smaU test compounds are synthesized on a soUd substrate. The test compounds are reacted with SAT, or fragments thereof, and washed. Bound SAT is then detected by methods weU known in the art. Purified SAT can also be coated directly onto plates for use in the aforementioned drag screening techniques. Alternatively, non-neutraUzing antibodies can be used to capture the peptide and immobiUze it on a soUd support. In another embodiment, one may use competitive drag screening assays in which neutraUzing antibodies capable of binding SAT specificaUy compete with a test compound for binding SAT. In this manner, antibodies can be used to detect the presence of any peptide which shares one or more antigenic determinants with SAT. In additional embodiments, the nucleotide sequences which encode SAT may be used in any molecular biology techniques that have yet to be developed, provided the new techniques rely on properties of nucleotide sequences that are currently known, including, but not Umited to, such properties as the triplet genetic code and specific base pair interactions. Without further elaboration, it is beUeved that one skilled in the art can, using the preceding description, utiUze the present invention to its fuUest extent. The following embodiments are, therefore, to be construed as merely illustrative, and not Umitative of the remainder of the disclosure in any way whatsoever. The disclosures of all patents, appUcations, and pubUcations mentioned above and below, including U.S. Ser. No. 60/215,465, U.S. Ser. No. 60/239,384, and U.S. Ser. No. 60/253,639, are hereby expressly incorporated by reference. EXAMPLES I. Construction of cDNA Libraries Incyte cDNAs were derived from cDNA Ubraries described in the LEFESEQ GOLD database (Incyte Genomics, Palo Alto CA) and shown in Table 4, column 5. Some tissues were homogenized and lysed in guanidinium isothiocyanate, while others were homogenized and lysed in phenol or in a suitable mixture of denatarants, such as TRIZOL (Life Technologies), a monophasic solution of phenol and guanidine isothiocyanate. The resulting lysates were centiifuged over CsCl cushions or extracted with chloroform. RNA was precipitated from the lysates with either isopropanol or sodium acetate and ethanol, or by other routine methods. Phenol extraction and precipitation of RNA were repeated as necessary to increase RNA purity. In some cases, RNA was treated with DNase. For most Ubraries, poly(A)+ RNA was isolated using oUgo d(T)-coupled paramagnetic particles (Promega), OLIGOTEX latex particles (QIAGEN, Chatsworth CA), or an OLIGOTEX mRNA purification kit (QIAGEN). Alternatively, RNA was isolated directly from tissue lysates using other RNA isolation kits, e.g., the POLY(A)PURE mRNA purification kit (Ambion, Austin TX). In some cases, Stratagene was provided with RNA and constructed the corresponding cDNA Ubraries. Otherwise, cDNA was synthesized and cDNA Ubraries were constructed with the UNIZAP vector system (Stratagene) or SUPERSCRIPT plasmid system (Life Technologies), using the recommended procedures or similar methods known in the art. (See, e.g., Ausubel, 1997, supra, units 5.1-6.6.) Reverse transcription was initiated using oUgo d(T) or random primers. Synthetic oUgonucleotide adapters were Ugated to double stranded cDNA, and the cDNA was digested with the appropriate restriction enzyme or enzymes. For most Ubraries, the cDNA was size-selected (300- 1000 bp) using SEPHACRYL S1000, SEPHAROSE CL2B, or SEPHAROSE CL4B column chromatography (Amersham Pharmacia Biotech) or preparative agarose gel electiophoresis. cDNAs were Ugated into compatible restriction enzyme sites of the polyUnker of a suitable plasmid, e.g., PBLUESCRIPT plasmid (Stratagene), PSPORT1 plasmid (Life Technologies), PCDNA2.1 plasmid (Invitrogen, Carlsbad CA), PBK-CMV plasmid (Stratagene), or pINCY (Incyte Genomics, Palo Alto CA), or derivatives thereof. Recombinant plasmids were transformed into competent E. coh ceUs including XLl-Blue, XLl-BlueMRF, or SOLR from Stratagene or DH5α, DH10B, or ElectroMAX DH10B from Life Technologies. II. Isolation of cDNA Clones Plasmids obtained as described in Example I were recovered from host ceUs by in vivo excision using the UN ZAP vector system (Stratagene) or by ceU lysis. Plasmids were purified using at least one of the foUowing: a Magic or WIZARD Minipreps DNA purification system (Promega); an AGTC Miniprep purification kit (Edge Biosystems, Gaithersburg MD); and QIAWELL 8 Plasmid, QIAWELL 8 Plus Plasmid, QIAWELL 8 Ultra Plasmid purification systems or the R.E.A.L. PREP 96 plasmid purification kit from QIAGEN. FoUowing precipitation, plasmids were resuspended in 0.1 ml of distiUed water and stored, with or without lyophiUzation, at 4°C Alternatively, plasmid DNA was ampUfied from host ceU lysates using direct Unk PCR in a high-throughput format (Rao, V.B. (1994) Anal. Biochem. 216:1-14). Host ceU lysis and thermal cycUng steps were carried out in a single reaction mixture. Samples were processed and stored in 384-weU plates, and the concentration of ampUfied plasmid DNA was quantified fluorometiicaUy using PICOGREEN dye (Molecular Probes, Eugene OR) and a FLUOROSKAN II fluorescence scanner (Labsystems Oy, Helsinki, Finland). III. Sequencing and Analysis Incyte cDNA recovered in plasmids as described in Example Et were sequenced as foUows. Sequencing reactions were processed using standard methods or high-throughput instrumentation such as the ABI CATALYST 800 (AppUed Biosystems) thermal cycler or the PTC-200 thermal cycler (MJ Research) in conjunction with the HYDRA microdispenser (Robbins Scientific) or the MICROLAB 2200 (Hamilton) Uquid transfer system. cDNA sequencing reactions were prepared using reagents provided by Amersham Pharmacia Biotech or suppUed in ABI sequencing kits such as the ABI PRISM BIGDYE Terminator cycle sequencing ready reaction kit (AppUed Biosystems). Electrophoretic separation of cDNA sequencing reactions and detection of labeled polynucleotides were carried out using the MEGABACE 1000 DNA sequencing system (Molecular Dynamics); the ABI PRISM 373 or 377 sequencing system (AppUed Biosystems) in conjunction with standard ABI protocols and base calUng software; or other sequence analysis systems known in the art. Reading frames within the cDNA sequences were identified using standard methods (reviewed in Ausubel, 1997, supra, unit 7.7). Some of the cDNA sequences were selected for extension using the techniques disclosed in Example VEH. The polynucleotide sequences derived from Incyte cDNAs were vaUdated by removing vector, Unker, and poly(A) sequences and by masking ambiguous bases, using algorithms and programs based on BLAST, dynamic programming, and dinucleotide nearest neighbor analysis. The Incyte cDNA sequences or translations thereof were then queried against a selection of pubUc databases such as the GenBank primate, rodent, mammaUan, vertebrate, and eukaryote databases, and BLOCKS, PRINTS, DOMO, PRODOM, and hidden Markov model (HMM)-based protein family databases such as PFAM. (HMM is a probabiUstic approach which analyzes consensus primary structures of gene families. See, for example, Eddy, S.R. (1996) Curr. Opin. Stract. Biol. 6:361-365.) The queries were performed using programs based on BLAST, FASTA, BLIMPS, and HMMER. The Incyte cDNA sequences were assembled to produce fuU length polynucleotide sequences. Alternatively, GenBank cDNAs, GenBank ESTs, stitched sequences, stretched sequences, or Genscan-predicted coding sequences (see Examples IV and V) were used to extend Incyte cDNA assemblages to fuU length. Assembly was performed using programs based on Phred, Phrap, and Consed, and cDNA assemblages were screened for open reading frames using programs based on GeneMark, BLAST, and FASTA. The fuU length polynucleotide sequences were translated to derive the corresponding full length polypeptide sequences. Alternatively, a polypeptide of the invention may begin at any of the methionine residues of the fuU length translated polypeptide. FuU length polypeptide sequences were subsequently analyzed by querying against databases such as the GenBank protein databases (genpept), SwissProt, BLOCKS, PRINTS, DOMO, PRODOM, Prosite, and bidden Markov model (HMM)-based protein family databases such as PFAM. FuU length polynucleotide sequences are also analyzed using MACDNASIS PRO software (Hitachi Software Engineering, South San Francisco CA) and LASERGENE software (DNASTAR). Polynucleotide and polypeptide sequence aUgnments are generated using default parameters specified by the CLUSTAL algorithm as incorporated into the MEGALIGN multisequence aUgnment program (DNASTAR), which also calculates the percent identity between aUgned sequences. Table 7 summarizes the tools, programs, and algorithms used for the analysis and assembly of Incyte cDNA and fuU length sequences and provides appUcable descriptions, references, and threshold parameters. The first column of Table 7 shows the tools, programs, and algorithms used, the second column provides brief descriptions thereof, the third column presents appropriate references, aU of which are incorporated by reference herein in their entirety, and the fourth column presents, where appUcable, the scores, probabiUty values, and other parameters used to evaluate the strength of a match between two sequences (the higher the score or the lower the probabiUty value, the greater the identity between two sequences). The programs described above for the assembly and analysis of full length polynucleotide and polypeptide sequences were also used to identify polynucleotide sequence fragments from SEQ ID NO: 10-18. Fragments from about 20 to about 4000 nucleotides which are useful in hybridization and ampUfication technologies are described in Table 4, column 4. IV. Identification and Editing of Coding Sequences from Genomic DNA Putative secretion and trafficking molecules were initially identified by running the Genscan gene identification program against pubUc genomic sequence databases (e.g., gbpri and gbhtg). Genscan is a general-purpose gene identification program which analyzes genomic DNA sequences from a variety of organisms (See Burge, C and S. KarUn (1997) J. Mol. Biol. 268:78-94, and Burge, C and S. KarUn (1998) Curr. Opin. Struct. Biol. 8:346-354). The program concatenates predicted exons to form an assembled cDNA sequence extending from a methionine to a stop codon. The output of Genscan is a FASTA database of polynucleotide and polypeptide sequences. The maximum range of sequence for Genscan to analyze at once was set to 30 kb. To determine which of these Genscan predicted cDNA sequences encode secretion and trafficking molecules, the encoded polypeptides were analyzed by querying against PFAM models for secretion and trafficking molecules. Potential secretion and trafficking molecules were also identified by homology to Incyte cDNA sequences that had been annotated as secretion and trafficking molecules. These selected Genscan-predicted sequences were then compared by BLAST analysis to the genpept and gbpri pubUc databases. Where necessary, the Genscan-predicted sequences were then edited by comparison to the top BLAST hit from genpept to correct errors in the sequence predicted by Genscan, such as extra or omitted exons. BLAST analysis was also used to find any Incyte cDNA or pubUc cDNA coverage of the Genscan-predicted sequences, thus providing evidence for transcription. When Incyte cDNA coverage was available, this information was used to correct or confirm the Genscan predicted sequence. Full length polynucleotide sequences were obtained by assembUng Genscan-predicted coding sequences with Incyte cDNA sequences and/or pubUc cDNA sequences using the assembly process described in Example HI. Alternatively, fuU length polynucleotide sequences were derived entirely from edited or unedited Genscan-predicted coding sequences. V. Assembly of Genomic Sequence Data with cDNA Sequence Data "Stitched" Sequences Partial cDNA sequences were extended with exons predicted by the Genscan gene identification program described in Example IN Partial cDΝAs assembled as described in Example HI were mapped to genomic DΝA and parsed into clusters containing related cDΝAs and Genscan exon predictions from one or more genomic sequences. Each cluster was analyzed using an algorithm based on graph theory and dynamic programming to integrate cDΝA and genomic information, generating possible spUce variants that were subsequently confirmed, edited, or extended to create a full length sequence. Sequence intervals in which the entire length of the interval was present on more than one sequence in the cluster were identified, and intervals thus identified were considered to be equivalent by transitivity. For example, if an interval was present on a cDΝA and two genomic sequences, then all three intervals were considered to be equivalent. This process aUows unrelated but consecutive genomic sequences to be brought together, bridged by cDΝA sequence. Intervals thus identified were then "stitched" together by the stitching algorithm in the order that they appear along their parent sequences to generate the longest possible sequence, as weU as sequence variants. Linkages between intervals which proceed along one type of parent sequence (cDΝA to cDΝA or genomic sequence to genomic sequence) were given preference over Unkages which change parent type (cDΝA to genomic sequence). The resultant stitched sequences were translated and compared by BLAST analysis to the genpept and gbpri pubUc databases. Incorrect exons predicted by Genscan were corrected by comparison to the top BLAST hit from genpept. Sequences were further extended with additional cDΝA sequences, or by inspection of genomic DΝA, when necessary. "Stretched" Sequences Partial DΝA sequences were extended to fuU length with an algorithm based on BLAST analysis. First, partial cDΝAs assembled as described in Example ED[ were queried against pubUc databases such as the GenB ank primate, rodent, mammaUan, vertebrate, and eukaryote databases using the BLAST program. The nearest GenB ank protein homolog was then compared by BLAST analysis to either Incyte cDΝA sequences or GenScan exon predicted sequences described in Example IN A chimeric protein was generated by using the resultant high-scoring segment pairs (HSPs) to map the translated sequences onto the GenB ank protein homolog. Insertions or deletions may occur in the chimeric protein with respect to the original GenBank protein homolog. The GenBank protein homolog, the chimeric protein, or both were used as probes to search for homologous genomic sequences from the pubUc human genome databases. Partial DNA sequences were therefore "stretched" or extended by the addition of homologous genomic sequences. The resultant stretched sequences were examined to determine whether it contained a complete gene. VI. Chromosomal Mapping of SAT Encoding Polynucleotides The sequences which were used to assemble SEQ ED NO: 10- 18 were compared with sequences from the Incyte LEFESEQ database and pubUc domain databases using BLAST and other implementations of the Smith- Waterman algorithm. Sequences from these databases that matched SEQ ID NO: 10- 18 were assembled into clusters of contiguous and overlapping sequences using assembly algorithms such as Phrap (Table 7). Radiation hybrid and genetic mapping data available from pubUc resources such as the Stanford Human Genome Center (SHGC), Whitehead Institute for Genome Research (WIGR), and Genethon were used to determine if any of the clustered sequences had been previously mapped. Inclusion of a mapped sequence in a cluster resulted in the assignment of all sequences of that cluster, including its particular SEQ ED NO:, to that map location. Map locations are represented by ranges, or intervals, of human chromosomes. The map position of an interval, in centiMorgans, is measured relative to the terminus of the chromosome's p- arm. (The centiMorgan (cM) is a unit of measurement based on recombination frequencies between chromosomal markers. On average, 1 cM is roughly equivalent to 1 megabase (Mb) of DNA in humans, although this can vary widely due to hot and cold spots of recombination.) The cM distances are based on genetic markers mapped by Genethon which provide boundaries for radiation hybrid markers whose sequences were included in each of the clusters. Human genome maps and other resources available to the pubUc, such as the NCBI "GeneMap'99" World Wide Web site (http://www.ncbi.nlm.nih.gov/genemap/), can be employed to determine if previously identified disease genes map within or in proximity to the intervals indicated above. VII. Analysis of Polynucleotide Expression Northern analysis is a laboratory technique used to detect the presence of a transcript of a gene and involves the hybridization of a labeled nucleotide sequence to a membrane on which RNAs from a particular ceU type or tissue have been bound. (See, e.g., Sambrook, supra, ch. 7; Ausubel (1995) supra, ch. 4 and 16.) Analogous computer techniques applying BLAST were used to search for identical or related molecules in cDNA databases such as GenBank or LIFESEQ (Incyte Genomics). This analysis is much faster than multiple membrane-based hybridizations. In addition, the sensitivity of the computer search can be modified to determine whether any particular match is categorized as exact or similar. The basis of the search is the product score, which is defined as: BLAST Score x Percent Identity 5 x minimum {length(Seq. 1), length(Seq. 2) } , The product score takes into account both the degree of similarity between two sequences and the length of the sequence match. The product score is a normaUzed value between 0 and 100, and is calculated as foUows: the BLAST score is multipUed by the percent nucleotide identity and the product is divided by (5 times the length of the shorter of the two sequences). The BLAST score is calculated by assigning a score of +5 for eveiy base that matches in a high-scoring segment pair (HSP), and -4 for every mismatch. Two sequences may share more than one HSP (separated by gaps). If there is more than one HSP, then the pair with the highest BLAST score is used to calculate the product score. The product score represents a balance between fractional overlap and quality in a BLAST aUgnment. For example, a product score of 100 is produced only for 100% identity over the entire length of the shorter of the two sequences being compared. A product score of 70 is produced either by 100% identity and 70% overlap at one end, or by 88% identity and 100% overlap at the other. A product score of 50 is produced either by 100% identity and 50% overlap at one end, or 79% identity and 100% overlap. Alternatively, polynucleotide sequences encoding SAT are analyzed with respect to the tissue sources from which they were derived. For example, some fuU length sequences are assembled, at least in part, with overlapping Incyte cDNA sequences (see Example HI). Each cDNA sequence is derived from a cDNA Ubrary constructed from a human tissue. Each human tissue is classified into one of the foUowing organ/tissue categories: cardiovascular system; connective tissue; digestive system; embryonic structures; endocrine system; exocrine glands; genitaUa, female; genitaUa, male; germ ceUs; hemic and immune system; Uver; musculoskeletal system; nervous system; pancreas; respiratory system; sense organs; skin; stomatognathic system; unclassified/mixed; or urinary tract. The number of Ubraries in each category is counted and divided by the total number of Ubraries across aU categories. Similarly, each human tissue is classified into one of the following disease/condition categories: cancer, ceU Une, developmental, inflammation, neurological, trauma, cardiovascular, pooled, and other, and the number of Ubraries in each category is counted and divided by the total number of Ubraries across aU categories. The resulting percentages reflect the tissue- and disease-specific expression of cDNA encoding SAT. cDNA sequences and cDNA Ubrary/tissue information are found in the LEFESEQ GOLD database (Incyte Genomics, Palo Alto CA). VIII. Extension of SAT Encoding Polynucleotides FuU length polynucleotide sequences were also produced by extension of an appropriate fragment of the fuU length molecule using oUgonucleotide primers designed from this fragment. One primer was synthesized to initiate 5' extension of the known fragment, and the other primer was synthesized to initiate 3' extension of the known fragment. The initial primers were designed using OLIGO 4.06 software (National Biosciences), or another appropriate program, to be about 22 to 30 nucleotides in length, to have a GC content of about 50% or more, and to anneal to the target sequence at temperatures of about 68 °C to about 72 °C. Any stretch of nucleotides which would result in hairpin structures and primer-primer dimerizations was avoided. Selected human cDNA Ubraries were used to extend the sequence. If more than one extension was necessary or desired, additional or nested sets of primers were designed. High fideUty ampUfication was obtained by PCR using methods weU known in the art. PCR was performed in 96-weU plates using the PTC-200 thermal cycler (MJ Research, Inc.). The reaction mix contained DNA template, 200 nmol of each primer, reaction buffer containing Mg 2+ , (NH 4 ) 2 S0 4 , and 2-mercaptoethanol, Taq DNA polymerase (Amersham Pharmacia Biotech), ELONGASE enzyme (Life Technologies), and Pfu DNA polymerase (Stratagene), with the foUowing parameters for primer pair PCI A and PCI B: Step 1: 94°C, 3 min; Step 2: 94°C, 15 sec; Step 3: 60° C, 1 min; Step 4: 68 °C, 2 min; Step 5: Steps 2, 3, and 4 repeated 20 times; Step 6: 68 °C, 5 min; Step 7: storage at 4°C. In the alternative, the parameters for primer pair T7 and SK+ were as foUows: Step 1 : 94 °C, 3 min; Step 2: 94°C, 15 sec; Step 3: 57°C, 1 min; Step 4: 68°C, 2 min; Step 5: Steps 2, 3, and 4 repeated 20 times; Step 6: 68 °C, 5 min; Step 7: storage at 4°C The concentration of DNA in each well was determined by dispensing 100 μl PICOGREEN quantitation reagent (0.25% (v/v) PICOGREEN; Molecular Probes, Eugene OR) dissolved in IX TE and 0.5 μl of undiluted PCR product into each weU of an opaque fluorimeter plate (Corning Costar, Acton MA), aUowing the DNA to bind to the reagent. The plate was scanned in a Fluoroskan IT (Labsystems Oy, Helsinki, Finland) to measure the fluorescence of the sample and to quantify the concentration of DNA. A 5 μl to 10 μl aliquot of the reaction mixture was analyzed by electiophoresis on a 1 % agarose gel to determine which reactions were successful in extending the sequence. The extended nucleotides were desalted and concentrated, transferred to 384-weU plates, digested with CviJI cholera virus endonuclease (Molecular Biology Research, Madison WE), and sonicated or sheared prior to reUgation into pUC 18 vector (Amersham Pharmacia Biotech). For shotgun sequencing, the digested nucleotides were separated on low concentration (0.6 to 0.8%) agarose gels, fragments were excised, and agar digested with Agar ACE (Promega). Extended clones were reUgated using T4 Ugase (New England Biolabs, Beverly MA) into pUC 18 vector (Amersham Pharmacia Biotech), treated with Pfu DNA polymerase (Stratagene) to fiU-in restriction site overhangs, and tiansfected into competent E. coU ceUs. Transformed ceUs were selected on antibiotic-containing media, and individual colonies were picked and cultured overnight at 37 °C in 384- weU plates in LB/2x carb Uquid media. The ceUs were lysed, and DNA was ampUfied by PCR using Taq DNA polymerase (Amersham Pharmacia Biotech) and Pfu DNA polymerase (Stratagene) with the foUowing parameters: Step 1: 94°C, 3 min; Step 2: 94°C, 15 sec; Step 3: 60°C, 1 min; Step 4: 72°C, 2 min; Step 5: steps 2, 3, and 4 repeated 29 times; Step 6: 72°C, 5 min; Step 7: storage at 4°C DNA was quantified by PICOGREEN reagent (Molecular Probes) as described above. Samples with low DNA recoveries were reampUfied using the same conditions as described above. Samples were diluted with 20% dimethysulfoxide (1 :2, v/v), and sequenced using DYENAMIC energy transfer sequencing primers and the DYENAMIC DIRECT kit (Amersham Pharmacia Biotech) or the ABI PRISM BIGDYE Terminator cycle sequencing ready reaction kit (AppUed Biosystems). In Uke manner, fuU length polynucleotide sequences are verified using the above procedure or are used to obtain 5 'regulatory sequences using the above procedure along with oUgonucleotides designed for such extension, and an appropriate genomic Ubrary. IX. Labeling and Use of Individual Hybridization Probes Hybridization probes derived from SEQ ED NO: 10- 18 are employed to screen cDNAs, genomic DNAs, or mRNAs. Although the labeUng of oUgonucleotides, consisting of about 20 base pairs, is specifically described, essentially the same procedure is used with larger nucleotide fragments. OUgonucleotides are designed using state-of-the-art software such as OLIGO 4.06 software (National Biosciences) and labeled by combining 50 pmol of each oUgomer, 250 μCi of [γ- 32 P] adenosine triphosphate (Amersham Pharmacia Biotech), and T4 polynucleotide kinase (DuPont NEN, Boston MA). The labeled oUgonucleotides are substantiaUy purified using a SEPHADEX G-25 superfine size exclusion dextran bead column (Amersham Pharmacia Biotech). An aUquot containing 10 7 counts per minute of the labeled probe is used in a typical membrane-based hybridization analysis of human genomic DNA digested with one of the foUowing endonucleases: Ase I, Bgl π, Eco RL Pst I, Xba I, or Pvu π (DuPont NEN). The DNA from each digest is fractionated on a 0.7% agarose gel and transferred to nylon membranes (Nytran Plus, Schleicher & SchueU, Durham NH). Hybridization is carried out for 16 hours at 40 °C To remove nonspecific signals, blots are sequentiaUy washed at room temperature under conditions of up to, for example, 0.1 x saUne sodium citrate and 0.5% sodium dodecyl sulfate. Hybridization patterns are visuaUzed using autoradiography or an alternative imaging means and compared. X. Microarrays The Unkage or synthesis of array elements upon a microarray can be achieved utiUzing photoUthography, piezoelectric printing (ink-jet printing, See, e.g., Baldeschweiler, supra.), mechanical microspotting technologies, and derivatives thereof. The substrate in each of the aforementioned technologies should be uniform and soUd with a non-porous surface (Schena (1999), supra). Suggested substrates include siUcon, siUca, glass sUdes, glass chips, and siUcon wafers. Alternatively, a procedure analogous to a dot or slot blot may also be used to arrange and Unk elements to the surface of a substrate using thermal, UN, chemical, or mechanical bonding procedures. A typical array may be produced using available methods and machines weU known to those of ordinary skill in the art and may contain any appropriate number of elements. (See, e.g., Schena, M. et al. (1995) Science 270:467-470; Shalon, D. et al. (1996) Genome Res. 6:639-645; MarshaU, A. and J. Hodgson (1998) Nat. Biotechnol. 16 :27-31.) Full length cDNAs, Expressed Sequence Tags (ESTs), or fragments or oUgomers thereof may comprise the elements of the microarray. Fragments or oUgomers suitable for hybridization can be selected using software well known in the art such as LASERGENE software (DNASTAR). The array elements are hybridized with polynucleotides in a biological sample. The polynucleotides in the biological sample are conjugated to a fluorescent label or other molecular tag for ease of detection. After hybridization, nonhybridized nucleotides from the biological sample are removed, and a fluorescence scanner is used to detect hybridization at each array element. Alternatively, laser desorbtion and mass spectrometiy may be used for detection of hybridization. The degree of complementarity and the relative abundance of each polynucleotide which hybridizes to an element on the microarray may be assessed. In one embodiment, microarray preparation and usage is described in detail below. Tissue or Cell Sample Preparation Total RNA is isolated from tissue samples using the guanidinium thiocyanate method and poly(A) + RNA is purified using the oUgo-(dT) ceUulose method. Each poly(A) + RNA sample is reverse transcribed using MMLV reverse-transcriptase, 0.05 pg/μl oUgo-(dT) primer (21mer), IX first strand buffer, 0.03 units/μl RNase inhibitor, 500 μM dATP, 500 μM dGTP, 500 μM dTTP, 40 μM dCTP, 40 μM dCTP-Cy3 (BDS) or dCTP-Cy5 (Amersham Pharmacia Biotech). The reverse transcription reaction is performed in a 25 ml volume containing 200 ng poly(A) + RNA with GEMB RIGHT kits (Incyte). Specific control poly(A) + RNAs are synthesized by in vitro transcription from non-coding yeast genomic DNA. After incubation at 37° C for 2 hr, each reaction sample (one with Cy3 and another with Cy5 labeUng) is treated with 2.5 ml of 0.5M sodium hydroxide and incubated for 20 minutes at 85° C to the stop the reaction and degrade the RNA. Samples are purified using two successive CHROMA SPENT 30 gel filtration spin columns (CLONTECH Laboratories, Inc. (CLONTECH), Palo Alto CA) and after combining, both reaction samples are ethanol precipitated using 1 ml of glycogen (1 mg/ml), 60 ml sodium acetate, and 300 ml of 100% ethanol. The sample is then dried to completion using a SpeedVAC (Savant Instruments Inc., Holbrook NY) and resuspended in 14 μl 5X SSC/0.2% SDS. Microarray Preparation Sequences of the present invention are used to generate array elements. Each array element is ampUfied from bacterial ceUs containing vectors with cloned cDNA inserts. PCR ampUfication uses primers complementary to the vector sequences flanking the cDNA insert. Array elements are ampUfied in thirty cycles of PCR from an initial quantity of 1 -2 ng to a final quantity greater than 5 μg. AmpUfied array elements are then purified using SEPHACRYL-400 (Amersham Pharmacia Biotech). Purified array elements are immobiUzed on polymer-coated glass sUdes. Glass microscope sUdes (Corning) are cleaned by ultrasound in 0.1% SDS and acetone, with extensive distilled water washes between and after treatments. Glass sUdes are etched in 4% hydrofluoric acid (VWR Scientific Products Corporation (VWR), West Chester PA), washed extensively in distiUed water, and coated with 0.05% aminopropyl silane (Sigma) in 95% ethanol. Coated sUdes are cmed in a 110°C oven. Array elements are appUed to the coated glass substrate using a procedure described in US Patent No. 5,807,522, incorporated herein by reference. 1 μl of the array element DNA, at an average concentration of 100 ng/μl, is loaded into the open capillary printing element by a high-speed robotic apparatus. The apparatus then deposits about 5 nl of array element sample per sUde. Microarrays are UV-crossUnked using a STRATALINKER UV-crossUnker (Stratagene). Mcroarrays are washed at room temperature once in 0.2% SDS and three times in distiUed water. Non-specific binding sites are blocked by incubation of microarrays in 0.2% casein in phosphate buffered saUne (PBS) (Tropix, Inc., Bedford MA) for 30 minutes at 60° C followed by washes in 0.2% SDS and distiUed water as before. Hybridization Hybridization reactions contain 9 μl of sample mixture consisting of 0.2 μg each of Cy3 and Cy5 labeled cDNA synthesis products in 5X SSC, 0.2% SDS hybridization buffer. The sample mixture is heated to 65° C for 5 minutes and is aUquoted onto the microarray surface and covered with an 1.8 cm 2 coversUp. The arrays are transferred to a wateφroof chamber having a cavity just sUghtly larger than a microscope sUde. The chamber is kept at 100% humidity internaUy by the addition of 140 μl of 5X SSC in a corner of the chamber. The chamber containing the arrays is incubated for about 6.5 hours at 60° C. The arrays are washed for 10 min at 45° C in a first wash buffer (IX SSC, 0.1 % SDS), three times for 10 minutes each at 45° C in a second wash buffer (0.1X SSC), and dried. Detection Reporter-labeled hybridization complexes are detected with a microscope equipped with an Innova 70 mixed gas 10 W laser (Coherent, Inc., Santa Clara CA) capable of generating spectral Unes at 488 nm for excitation of Cy3 and at 632 nm for excitation of Cy5. The excitation laser Ught is focused on the array using a 20X microscope objective (Nikon, Inc., MelviUe NY). The sUde containing the array is placed on a computer-contioUed X-Y stage on the microscope and raster- scanned past the objective. The 1.8 cm x 1.8 cm array used in the present example is scanned with a resolution of 20 micrometers. In two separate scans, a mixed gas multiline laser excites the two fluorophores sequentiaUy. Emitted Ught is spUt, based on wavelength, into two photomultipUer tube detectors (PMT R1477, Hamamatsu Photonics Systems, Bridgewater NJ) corresponding to the two fluorophores. Appropriate filters positioned between the array and the photomultipUer tubes are used to filter the signals. The emission maxima of the fluorophores used are 565 nm for Cy3 and 650 nm for Cy5. Each array is typically scanned twice, one scan per fluorophore using the appropriate filters at the laser source. although the apparatus is capable of recording the spectra from both fluorophores simultaneously. The sensitivity of the scans is typicaUy caUbrated using the signal intensity generated by a cDNA contiol species added to the sample mixture at a known concentration. A specific location on the array contains a complementary DNA sequence, allowing the intensity of the signal at that location to be correlated with a weight ratio of hybridizing species of 1 : 100,000. When two samples from different sources (e.g., representing test and control ceUs), each labeled with a different fluorophore, are hybridized to a single array for the purpose of identifying genes that are differentiaUy expressed, the caUbration is done by labeUng samples of the caUbrating cDNA with the two fluorophores and adding identical amounts of each to the hybridization mixture. The output of the photomultipUer tube is digitized using a 12-bit RTI-835H analog-to-digital (A/D) conversion board (Analog Devices, Inc., Norwood MA) instaUed in an IBM-compatible PC computer. The digitized data are displayed as an image where the signal intensity is mapped using a Unear 20-color transformation to a pseudocolor scale ranging from blue (low signal) to red (high signal). The data is also analyzed quantitatively. Where two different fluorophores are excited and measured simultaneously, the data are first corrected for optical crosstalk (due to overlapping emission spectra) between the fluorophores using each fluorophore's emission spectrum. A grid is superimposed over the fluorescence signal image such that the signal from each spot is centered in each element of the grid. The fluorescence signal within each element is then integrated to obtain a numerical value corresponding to the average intensity of the signal. The software used for signal analysis is the GEMTOOLS gene expression analysis program (Incyte). XL Complementary Polynucleotides Sequences complementary to the SAT-encoding sequences, or any parts thereof, are used to detect, decrease, or inhibit expression of naturaUy occurring SAT. Although use of oUgonucleotides comprising from about 15 to 30 base pairs is described, essentiaUy the same procedure is used with smaUer or with larger sequence fragments. Appropriate oUgonucleotides are designed using OLIGO 4.06 software (National Biosciences) and the coding sequence of SAT. To inhibit transcription, a complementary oUgonucleotide is designed from the most unique 5' sequence and used to prevent promoter binding to the coding sequence. To inhibit translation, a complementary oUgonucleotide is designed to prevent ribosomal binding to the SAT-encoding transcript. XII. Expression of SAT Expression and purification of SAT is achieved using bacterial or virus-based expression systems. For expression of SAT in bacteria, cDNA is subcloned into an appropriate vector containing an antibiotic resistance gene and an inducible promoter that directs high levels of cDNA transcription. Examples of such promoters include, but are not Umited to, the trp-lac (tac) hybrid promoter and the T5 or T7 bacteriophage promoter in conjunction with the lac operator regulatory element. Recombinant vectors are transformed into suitable bacterial hosts, e.g., BL21(DE3). Antibiotic resistant bacteria express SAT upon induction with isopropyl beta-D-thiogalactopyranoside (EPTG). Expression of SAT in eukaryotic ceUs is achieved by infecting insect or mammaUan ceU Unes with recombinant Autographica caUfornica nuclear polyhedrosis virus (AcMNPV), commonly known as baculoviras. The nonessential polyhedrin gene of baculoviras is replaced with cDNA encoding SAT by either homologous recombination or bacterial-mediated transposition involving transfer plasmid intermediates. Viral infectivity is maintained and the strong polyhedrin promoter drives high levels of cDNA transcription. Recombinant baculoviras is used to infect Spodoptera frugiperda (Sf9) insect ceUs in most cases, or human hepatocytes, in some cases. Infection of the latter requires additional genetic modifications to baculoviras. (See Engelhard, E.K. et al. (1994) Proc. Natl. Acad. Sci. USA 91:3224-3227; Sandig, V. et al. (1996) Hum. Gene Ther. 7:1937-1945.) In most expression systems, SAT is synthesized as a fusion protein with, e.g., glutathione S- transferase (GST) or a peptide epitope tag, such as FLAG or 6-His, permitting rapid, single-step, affinity-based purification of recombinant fusion protein from crude ceU lysates. GST, a 26-kilodalton enzyme from Schistosoma iaponicum. enables the purification of fusion proteins on immobiUzed glutathione under conditions that maintain protein activity and antigenicity (Amersham Pharmacia Biotech). FoUowing purification, the GST moiety can be proteolyticaUy cleaved from SAT at specificaUy engineered sites. FLAG, an 8-amino acid peptide, enables immunoaffinity purification using commerciaUy available monoclonal and polyclonal anti-FLAG antibodies (Eastman Kodak). 6- His, a stretch of six consecutive histidine residues, enables purification on metal-chelate resins (QIAGEN). Methods for protein expression and purification are discussed in Ausubel (1995, supra, ch. 10 and 16) . Purified SAT obtained by these methods can be used directly in the assays shown in Examples XVI and XVπ, where appUcable. XIII. Functional Assays SAT function is assessed by expressing the sequences encoding SAT at physiologicaUy elevated levels in mammaUan ceU culture systems. cDNA is subcloned into a mammaUan expression vector containing a strong promoter that drives high levels of cDNA expression. Vectors of choice include PCMV SPORT (Life Technologies) and PCR3.1 (Invitrogen, Carlsbad CA), both of which contain the cytomegaloviras promoter. 5-10 μg of recombinant vector are tiansiently fransfected into a human ceU Une, for example, an endotheUal or hematopoietic ceU Une, using either Uposome formulations or electioporation. 1-2 μg of an additional plasmid containing sequences encoding a marker protein are co-tiansfected. Expression of a marker protein provides a means to distinguish transfected ceUs from nontiansfected ceUs and is a reUable predictor of cDNA expression from the recombinant vector. Marker proteins of choice include, e.g., Green Fluorescent Protein (GFP; Clontech), CD64, or a CD64-GFP fusion protein. Flow cytometry (FCM), an automated, laser optics- based technique, is used to identify transfected cells expressing GFP or CD64-GFP and to evaluate the apoptotic state of the cells and other ceUular properties, FCM detects and quantifies the uptake of fluorescent molecules that diagnose events preceding or coincident with ceU death. These events include changes in nuclear DNA content as measured by staining of DNA with propidium iodide; changes in cell size and granularity as measured by forward Ught scatter and 90 degree side Ught scatter; down-regulation of DNA synthesis as measured by decrease in bromodeoxyuridine uptake; alterations in expression of ceU surface and intraceUular proteins as measured by reactivity with specific antibodies; and alterations in plasma membrane composition as measured by the binding of fluorescein-conjugated Annexin V protein to the ceU surface. Methods in flow cytometry are discussed in Ormerod, M.C (1994) Flow Cytometry, Oxford, New York NY. The influence of SAT on gene expression can be assessed using highly purified populations of ceUs transfected with sequences encoding SAT and either CD64 or CD64-GFP. CD64 and CD64- GFP are expressed on the surface of transfected ceUs and bind to conserved regions of human immunoglobuUn G (IgG). Transfected ceUs are efficiently separated from nontiansfected ceUs using magnetic beads coated with either human IgG or antibody against CD64 (DYNAL, Lake Success NY). mRNA can be purified from the ceUs using methods weU known by those of skiU in the art. Expression of mRNA encoding SAT and other genes of interest can be analyzed by northern analysis or microarray techniques. XIV. Production of SAT Specific Antibodies SAT substantiaUy purified using polyacrylamide gel electiophoresis (PAGE; see, e.g., Harrington, M.G. (1990) Methods Enzymol. 182:488-495), or other purification techniques, is used to immunize rabbits and to produce antibodies using standard protocols. Alternatively, the SAT amino acid sequence is analyzed using LASERGENE software (DNASTAR) to determine regions of high immunogenicity, and a corresponding oUgopeptide is synthesized and used to raise antibodies by means known to those of skiU in the art. Methods for selection of appropriate epitopes, such as those near the C-terminus or in hydrophiUc regions are weU described in the art. (See, e.g., Ausubel, 1995, supra, ch. 11.) TypicaUy, oUgopeptides of about 15 residues in length are synthesized using an ABI 431 A peptide synthesizer (AppUed Biosystems) using FMOC chemistry and coupled to KLH (Sigma- Aldrich, St. Louis MO) by reaction with N-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS) to increase immunogenicity. (See, e.g., Ausubel, 1995, supra.) Rabbits are immunized with the oUgopeptide-KLH complex in complete Freund's adjuvant. Resulting antisera are tested for antipeptide and anti-SAT activity by, for example, binding the peptide or SAT to a substrate, blocking with 1 % BSA, reacting with rabbit antisera, washing, and reacting with radio-iodinated goat anti-rabbit IgG. XV. Purification of Naturally Occurring SAT Using Specific Antibodies Naturally occurring or recombinant SAT is substantiaUy purified by immunoaffinity chromatography using antibodies specific for SAT. An immunoaffinity column is constructed by covalently coupUng anti-SAT antibody to an activated chromatographic resin, such as CNBr-activated SEPHAROSE (Amersham Pharmacia Biotech). After the coupUng, the resin is blocked and washed according to the manufacturer's instructions. Media containing SAT are passed over the immunoaffinity column, and the column is washed under conditions that aUow the preferential absorbance of SAT (e.g., high ionic strength buffers in the presence of detergent). The column is eluted under conditions that disrupt antibody/SAT binding (e.g., a buffer of pH 2 to pH 3, or a high concentration of a chaotiope, such as urea or thiocyanate ion), and SAT is coUected. XVI. Identification of Molecules Which Interact with SAT SAT, or biologicaUy active fragments thereof, are labeled with 125 I Bolton-Hunter reagent. (See, e.g., Bolton A.E. and W.M. Hunter (1973) Biochem. J. 133:529-539.) Candidate molecules previously arrayed in the weUs of a multi-weU plate are incubated with the labeled SAT, washed, and any weUs with labeled SAT complex are assayed. Data obtained using different concentrations of SAT are used to calculate values for the number, affinity, and association of SAT with the candidate molecules. Alternatively, molecules interacting with SAT are analyzed using the yeast two-hybrid system as described in Fields, S. and 0. Song (1989) Nature 340:245-246, or using commerciaUy available kits based on the two-hybrid system, such as the MATCHMAKER system (Clontech). SAT may also be used in the PATHCALLENG process (CuraGen Coφ. , New Haven CT) which employs the yeast two-hybrid system in a high-throughput manner to determine aU interactions between the proteins encoded by two large Ubraries of genes (Nandabalan, K. et al. (2000) U.S. Patent No. 6,057,101). XVII. Demonstration of SAT Activity SAT activity is measured by its inclusion in coated vesicles. SAT can be expressed by transforming a mammaUan cell Une such as COS7, HeLa, or CHO with an eukaryotic expression vector encoding SAT. Eukaryotic expression vectors are commercially available, and the techniques to introduce them into ceUs are weU known to those skiUed in the art. A smaU amount of a second plasmid, which expresses any one of a number of marker genes, such as β-galactosidase, is co- fransformed into the ceUs in order to allow rapid identification of those cells which have taken up and expressed the foreign DNA. The ceUs are incubated for 48-72 hours after transformation under conditions appropriate for the ceU Une to aUow expression and accumulation of SAT and β- galactosidase. Transformed ceUs are coUected and ceU lysates are assayed for vesicle formation. A non- hydrolyzable form of GTP, GTPγS, and an ATP regenerating system are added to the lysate and the mixture is incubated at 37 °C for 10 minutes. Under these conditions, over 90% of the vesicles remain coated (Orci, L. et al. (1989) CeU 56:357-368). Transport vesicles are salt-released from the Golgi membranes, loaded under a sucrose gradient, centrifuged, and fractions are coUected and analyzed by SDS-PAGE. Co-locaUzation of SAT with clathrin or COP coatamer is indicative of SAT activity in » vesicle formation. The contribution of SAT in vesicle formation can be confirmed by incubating lysates with antibodies specific for SAT prior to GTPγS addition. The antibody wiU bind to SAT and interfere with its activity, thus preventing vesicle formation. In the alternative, SAT activity is measured by its abiUty to alter vesicle trafficking pathways. Vesicle tiafficking in ceUs transformed with SAT is examined using fluorescence microscopy. Antibodies specific for vesicle coat proteins or typical vesicle trafficking substrates such as fransferrin or the mannose-6-phosphate receptor are commerciaUy available. Various ceUular components such as ER, Golgi bodies, peroxisomes, endosomes, lysosomes, and the plasmalemma are examined. Alterations in the numbers and locations of vesicles in ceUs transformed with SAT as compared to control ceUs are characteristic of SAT activity. Various modifications and variations of the described methods and systems of the invention wiU be apparent to those skiUed in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with certain embodiments, it should be understood that the invention as claimed should not be unduly Umited to such specific embodiments. Endeed, various modifications of the described modes for carrying out the invention which are obvious to those skiUed in molecular biology or related fields are intended to be within the scope of the foUowing claims. Table 1 oo o Table 2 Table 3 Table 3 (cont.) Table 3 (cont.) Table 3 (cont.) Table 3 (cont.) Table 3 (cont.) Table 4 Table 4 (cont.) Table 4 (cont.) Table 5 VO Table 6 Table 6 (cont.) Table 7 Program Description Reference Parameter Threshold ABI FACTURA A program that removes vector sequences and Applied Biosystems, Foster City, CA. masks ambiguous bases in nucleic acid sequences. ABI/PARACEL FDF A Fast Data Finder useful in comparing and Applied Biosystems, Foster City, CA; Mismatch <50% annotating amino acid or nucleic acid sequences. Paracel Inc., Pasadena, CA. ABI AutoAssembler A program that assembles nucleic acid sequences. Applied Biosystems, Foster City, CA. BLAST A Basic Local Alignment Search Tool useful in Altschul, S.F. et al. (1990) J. Mol. Biol. ESTs: Probability value= 1.0E-8 sequence similarity search for amino acid and 215:403-410; Altschul, S.F. et al. (1997) or less nucleic acid sequences. BLAST includes five Nucleic Acids Res. 25:3389-3402. Full Length sequences: Probability functions: blastp, blastn, blastx, tblastn, and tblastx. value= l.OE-lO or less O FASTA A Pearson and Lipman algorithm that searches for Pearson, W.R. and D.J. Lipman (1988) Proc. ESTs: fasta E value=1.06E-6 ^ similarity between a query sequence and a group of Natl. Acad Sci. USA 85:2444-2448; Pearson, Assembled ESTs: fasta Identity= sequences of the same type. FASTA comprises as W.R. (1990) Methods Enzymol. 183:63-98; 95% or greater and least five functions: fasta, tfasta, fastx, tfastx, and and Smith, T.F. and M.S. Waterman (1981) Match length=200 bases or greater ssearch. Adv. Appl. Math. 2:482-489. fastx E valuer 1.0E-8 or less Full Length sequences: fastx score=100 or greater BLIMPS A BLoc s EvlProved Searcher that matches a Henikoff, S. and J.G. Henikoff (1991) Nucleic Probability value= 1.0E-3 or less sequence against those in BLOCKS, PRINTS, Acids Res. 19:6565-6572; Henikoff, J.G. and DOMO, PRODOM, and PFAM databases to search S. Henikoff (1996) Methods Enzymol. for gene families, sequence homology, and 266:88-105; and Attwood, T.K. et al. (1997) J. structural fingerprint regions. Chem. Inf. Comput. Sci. 37:417-424. HMMER An algorithm for searching a query sequence against Krogh, A. et al. (1994) J. Mol. Biol. PFAM hits: Probability value= hidden Markov model (HMM)-based databases of 235:1501-1531; Sonnhammer, E.L.L. et al. 1.0E-3 or less protein family consensus sequences, such as PFAM. (1988) Nucleic Acids Res. 26:320-322; Signal peptide hits: Score= 0 or Durbin, R. et al. (1998) Our World View, in a greater Nutshell, Cambridge Univ. Press, pp. 1-350. Table 7 (cont.) Program Description Reference Parameter Threshold ProfϊIeScan An algorithm that searches for structural and sequence Gribskov, M. et al. (1988) CABIOS 4:61-66; Normalized quality scores GCG- motifs in protein sequences that match sequence patterns Gribskov, M. et al. (1989) Methods Enzymol. specifled "HIGH" value for that defined in Prosite. 183:146-159; Bairoch, A. et al. (1997) particular Prosite motif. Nucleic Acids Res. 25:217-221. Generally, score= 1.4-2.1. Phred A base-calling algorithm that examines automated Ewing, B. et al. (1998) Genome Res. sequencer traces with high sensitivity and probability. 8:175-185; Ewing, B. and P. Green (1998) Genome Res. 8: 186-194. Phrap A Phils Revised Assembly Program including SWAT and Smith, T.F. and M.S. Waterman (1981) Adv. Score= 120 or greater; CrossMatch, programs based on efficient implementation Appl. Math. 2:482-489; Smith, T.F. and M.S. Match length= 56 or greater of the Smith-Waterman algorithm, useful in searching Waterman (1981) J. Mol. Biol. 147:195-197; sequence homology and assembling DNA sequences. and Green, P., University of Washington, Seattle, WA. Consed A graphical tool for viewing and editing Phrap Gordon, D. et al. (1998) Genome Res. 8:195-202. assemblies. SPScan A weight matrix analysis program that scans protein Nielson, H. et al. (1997) Protein Engineering Score=3.5 or greater sequences for the presence of secretory signal peptides. 10:1-6; Claverie, J.M. and S. Audic (1997) CABIOS 12:431-439. TMAP A program that uses weight matrices to delineate Persson, B. and P. Argos (1994) J. Mol. Biol. transmembrane segments on protein sequences and 237: 182-192; Persson, B. and P. Argos (1996) determine orientation. Protein Sci. 5:363-371. TMHMMER A program that uses a hidden Markov model (HMM) to Sonnhammer, E.L. et al. (1998) Proc. Sixth Intl. delineate transmembrane segments on protein sequences Conf. on Intelligent Systems for Mol. Biol., and determine orientation. Glasgow et al., eds., The Am. Assoc. for Artificial Intelligence Press, Menlo Park, CA, pp. 175-182. Motifs A program that searches amino acid sequences for patterns Bairoch, A. et al. (1997) Nucleic Acids Res. 25:217-221; that matched those defined in Prosite. Wisconsin Package Program Manual, version 9, page M51-59, Genetics Computer Group, Madison, WI.

Claims: What is claimed is: 1. An isolated polypeptide selected from the group consisting of: a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9. 2. An isolated polypeptide of claim 1 selected from the group consisting of SEQ ID NO: 1 -9. 3. An isolated polynucleotide encoding a polypeptide of claim 1. 4. An isolated polynucleotide encoding a polypeptide of claim 2. 5. An isolated polynucleotide of claim 4 selected from the group consisting of SEQ ID NO:10-18. 6. A recombinant polynucleotide comprising a promoter sequence operably linked to a polynucleotide of claim 3. 7. A cell transformed with a recombinant polynucleotide of claim 6. 8. A transgenic organism comprising a recombinant polynucleotide of claim 6. 9. A method for producing a polypeptide of claim 1 , the method comprising: a) culturing a cell under conditions suitable for expression of the polypeptide, wherein said cell is transformed with a recombinant polynucleotide, and said recombinant polynucleotide comprises a promoter sequence operably linked to a polynucleotide encoding the polypeptide of claim 1, and b) recovering the polypeptide so expressed. 10. An isolated antibody which specifically binds to a polypeptide of claim 1. 11. An isolated polynucleotide selected from the group consisting of: a) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ I NO:10-18, b) a polynucleotide comprising a naturally occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ID NO: 10- 18, c) a polynucleotide complementary to a polynucleotide of a), d) a polynucleotide complementary to a polynucleotide of b), and e) an RNA equivalent of a)-d). 12. An isolated polynucleotide comprising at least 60 contiguous nucleotides of a polynucleotide of claim 11. 13. A method for detecting a target polynucleotide in a sample, said target polynucleotide having a sequence of a polynucleotide of claim 11, the method comprising: a) hybridizing the sample with a probe comprising at least 20 contiguous nucleotides comprising a sequence complementary to said target polynucleotide in the sample, and which probe specifically hybridizes to said target polynucleotide, under conditions whereby a hybridization complex is formed between said probe and said target polynucleotide or fragments thereof, and b) detecting the presence or absence of said hybridization complex, and, optionally, if present, the amount thereof. 14. A method of claim 13, wherein the probe comprises at least 60 contiguous nucleotides. 15. A method for detecting a target polynucleotide in a sample, said target polynucleotide having a sequence of a polynucleotide of claim 11, the method comprising: a) amplifying said target polynucleotide or fragment thereof using polymerase chain reaction amplification, and b) detecting the presence or absence of said amplified target polynucleotide or fragment thereof, and, optionally, if present, the amount thereof. 16. A composition comprising a polypeptide of claim 1 and a pharmaceutically acceptable excipient. 17. A composition of claim 16, wherein the polypeptide has an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9. 18. A method for treating a disease or condition associated with decreased expression of functional SAT, comprising administering to a patient in need of such treatment the composition of claim 16. 19. A method for screening a compound for effectiveness as an agonist of a polypeptide of claim 1, the method comprising: a) exposing a sample comprising a polypeptide of claim 1 to a compound, and b) detecting agonist activity in the sample. 20. A composition comprising an agonist compound identified by a method of claim 1 and a pharmaceutically acceptable excipient. 21. A method for treating a disease or condition associated with decreased expression of functional SAT, comprising administering to a patient in need of such treatment a composition of claim 20. 22. A method for screening a compound for effectiveness as an antagonist of a polypeptide of claim 1, the method comprising: a) exposing a sample comprising a polypeptide of claim 1 to a compound, and b) detecting antagonist activity in the sample. 23. A composition comprising an antagonist compound identified by a method of claim 22 and a pharmaceutically acceptable excipient. 24. A method for treating a disease or condition associated with overexpression of functional SAT, comprising administering to a patient in need of such treatment a composition of claim 23. 25. A method of screening for a compound that specifically binds to the polypeptide of claim 1 , said method comprising the steps of: a) combining the polypeptide of claim 1 with at least one test compound under suitable conditions, and b) detecting binding of the polypeptide of claim 1 to the test compound, thereby identifying a compound that specifically binds to the polypeptide of claim 1. 26. A method of screening for a compound that modulates the activity of the polypeptide of claim 1 , said method comprising: a) combining the polypeptide of claim 1 with at least one test compound under conditions permissive for the activity of the polypeptide of claim 1 , b) assessing the activity of the polypeptide of claim 1 in the presence of the test compound, and c) comparing the activity of the polypeptide of claim 1 in the presence of the test compound with the activity of the polypeptide of claim 1 in the absence of the test compound, wherein a change in the activity of the polypeptide of claim 1 in the presence of the test compound is indicative of a compound that modulates the activity of the polypeptide of claim 1. 27. A method for screening a compound for effectiveness in altering expression of a target polynucleotide, wherein said target polynucleotide comprises a sequence of claim 5, the method comprising: a) exposing a sample comprising the target polynucleotide to a compound, under conditions suitable for the expression of the target polynucleotide, b) detecting altered expression of the target polynucleotide, and c) comparing the expression of the target polynucleotide in the presence of varying amounts of the compound and in the absence of the compound. 28. A method for assessing toxicity of a test compound, said method comprising: a) treating a biological sample containing nucleic acids with the test compound; b) hybridizing the nucleic acids of the treated biological sample with a probe comprising at least 20 contiguous nucleotides of a polynucleotide of claim 11 under conditions whereby a specific hybridization complex is formed between said probe and a target polynucleotide in the biological sample, said target polynucleotide comprising a polynucleotide sequence of a polynucleotide of claim 11 or fragment thereof; c) quantifying the amount of hybridization complex; and d) comparing the amount of hybridization complex in the treated biological sample with the amount of hybridization complex in an untreated biological sample, wherein a difference in the amount of hybridization complex in the treated biological sample is indicative of toxicity of the test compound. 29. A diagnostic test for a condition or disease associated with the expression of SAT in a biological sample comprising the steps of: a) combining the biological sample with an antibody of claim 10, under conditions suitable for the antibody to bind the polypeptide and form an antibody:polypeptide complex; and b) detecting the complex, wherein the presence of the complex correlates with the presence of the polypeptide in the biological sample. 30. The antibody of claim 10, wherein the antibody is: a) a chimeric antibody, b) a single chain antibody, c) a Fab fragment, d) a F(ab') 2 fragment, or e) a humanized antibody. 31. A composition comprising an antibody of claim 10 and an acceptable excipient. 32. A method of diagnosing a condition or disease associated with the expression of SAT in a subject, comprising administering to said subject an effective amount of the composition of claim 31. 33. A composition of claim 31, wherein the antibody is labeled. 34. A method of diagnosing a condition or disease associated with the expression of SAT in a subject, comprising administering to said subject an effective amount of the composition of claim 33. 35. A method of preparing a polyclonal antibody with the specificity of the antibody of claim 10 comprising: a) immunizing an animal with a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9, or an immunogenic fragment thereof, under conditions to elicit an antibody response; b) isolating antibodies from said animal; and c) screening the isolated antibodies with the polypeptide, thereby identifying a polyclonal antibody which binds specifically to a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO : 1 -9. 36. An antibody produced by a method of claim 35. 37. A composition comprising the antibody of claim 36 and a suitable carrier. 38. A method of making a monoclonal antibody with the specificity of the antibody of claim 10 comprising: a) immunizing an animal with a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO:l-9, or an immunogenic fragment thereof, under conditions to elicit an antibody response; b) isolating antibody producing cells from the animal; c) fusing the antibody producing cells with immortalized cells to form monoclonal antibody- producing hybridoma cells; d) culturing the hybridoma cells; and e) isolating from the culture monoclonal antibody which binds specifically to a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9. 39. A monoclonal antibody produced by a method of claim 38. 40. A composition comprising the antibody of claim 39 and a suitable carrier. 41. The antibody of claim 10, wherein the antibody is produced by screening a Fab expression library. 42. The antibody of claim 10, wherein the antibody is produced by screening a recombinant immunoglobulin library. 43. A method for detecting a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9 in a sample, comprising the steps of: a) incubating the antibody of claim 10 with a sample under conditions to allow specific binding of the antibody and the polypeptide; and b) detecting specific binding, wherein specific binding indicates the presence of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9 in the sample. 44. A method of purifying a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-9 from a sample, the method comprising: a) incubating the antibody of claim 10 with a sample under conditions to allow specific binding of the antibody and the polypeptide; and b) separating the antibody from the sample and obtaining the purified polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-9. 45. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ID NO:l. 46. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ID NO:2. 47. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ID NO:3. 48. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ID NO:4. 49. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ID NO:5. 50. A polypeptide of claim 1 , comprising the amino acid sequence of SEQ ID NO:6. 51. A polypeptide of claim 1 , comprising the amino acid sequence of SEQ ID NO:7. 52. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ID NO:8. 53. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ID NO:9. 54. A polynucleotide of claim 11 , comprising the polynucleotide sequence of SEQ ID NO: 10. 55. A polynucleotide of claim 11, comprising the polynucleotide sequence of SEQ ID NO:l 1. 56. A polynucleotide of claim 11 , comprising the polynucleotide sequence of SEQ ID NO:l 2. 57. A polynucleotide of claim 11, comprising the polynucleotide sequence of SEQ ID NO: 13. 58. A polynucleotide of claim 11 , comprising the polynucleotide sequence of SEQ ED NO:14. 59. A polynucleotide of claim 11, comprising the polynucleotide sequence of SEQ ID NO: 15. 60. A polynucleotide of claim 11, comprising the polynucleotide sequence of SEQ ID NO: 16. 61. A polynucleotide of claim 11 , comprising the polynucleotide sequence of SEQ ED NO:17. 62. A polynucleotide of claim 11 , comprising the polynucleotide sequence of SEQ ID NO: 18.

Inventors: LEE ERNESTINE A, LU YAN, LEE, ERNESTINE, A., LU, YAN
Applicants: INCYTE GENOMICS INC, LEE ERNESTINE A, LU YAN, INCYTE GENOMICS, INC., LEE, ERNESTINE, A., LU, YAN
Application year: 2001
Main classification: C07K14
IPC codes: A61K38, A61K45, A61P25, A61P29, A61P35, A61P37, A61P43, C07K1, C07K14, C07K16, C12N1, C12N5, C12N15, C12P21, C12Q1, G01N33