25869, A NOVEL HUMAN CARBOXYLESTERASE AND USES THEREOF

Abstract: The invention provides isolated nucleic acid molecules, designated COE-1 nucleic acid molecules, which encode novel carboxylesterase family members. The invention also provides antisense nucleic acid molecules, recombinant expression vectors containing COE-1 nucleic acid molecules, host cells into which the expression vectors have been introduced, and nonhuman transgenic animals in which a COE-1 gene has been introduced or disrupted. The invention still further provides isolated COE-1 proteins, fusion proteins, antigenic peptides and anti-COE-1 antibodies. Diagnostic methods utilizing compositions of the invention are also provided.

Description: 25865*, A NOVEL HUMAN CARBOXYLESTERASE AND USES THEREOF Related Applications This application claims the benefit of U.S. Provisional Application Serial No. 60/215,370, filed June 29, 2000, the entire contents of which are incorporated herein by this reference. Background of the Invention Carboxylesterases comprise a family of enzymes which catalyze the hydrolysis of a variety of ester-, thioester-, and amide-containing chemicals, as well as drugs (including prodrugs) to their respective free acids. These enzymes are involved in the detoxification or metabolic activation of various drugs, environmental toxins, and carcinogens. Carboxylesterases also catalyze the hydrolysis of endogenous compounds such as short- and long-chain acyl-glycerols, long-chain acylcarnitine, and long-chain acyl-CoA esters (Satoh, T. and Hosokawa, M. (1998) Annu. Rev. Pharmacol. Toxicol. 38:257-88). The general enzymatic reaction that carboxylesterases catalyze is: a carboxylic ester + H 2 O <=> an alcohol + a carboxylic anion The hydrolytic activity of carboxylesterases is dependent on the presence of a "catalytic triad" of amino acid residues that are non-contiguous in the primary sequence but adjacent in the tertiary structure (Ollis, D.L. et al. (1992) Protein Eng. 5:197-211; Cygler, M. et al. (1993) Protein Sci. 2:366-382). In carboxylesterases, the catalytic triad residues are Ser/His/Glu (Satoh and Hosokawa (1998) supra; Oakeshott, J.G. et al. (1999) Bioessays 21:1031-1042). The first step of the hydrolysis reaction catalyzed by carboxylesterases liberates the alcohol moiety of the substrate and forms a covalent linkage between the remaining acid moiety of the substrate and the serine residue of the catalytic triad. The second step cleaves this linkage and liberates the acid moiety of the substrate, largely through the action of the histidine residue of the catalytic triad (Oakeshott et al. (1999) supra). While many well-studied carboxylesterases have catalytic triads, several members of the carboxy 1/cholinesterase multigene family have been reported to lack a functional catalytic triad (Hortsch, M. et al. (1990) Development 110:1327-1340; Auld, V.J. (1995) Cell 81:757-767; Ichtchenko, K. et al. (1995) Cell 81 :435-443; Oakeshott, J.G. et al. (1995) Trends. Ecol. Evol. 10:103-110) and, thus, to lack carboxylesterase activity. However, some of these enzymes have ligand-binding functions involved in signal transduction. Carboxylesterases are responsible for the hydrolysis of many exogenous compounds, resulting in both the inactivation of drugs and the activation of pro-drugs (Satoh, T. (1987) Reviews in Biochem. Toxicol. 8:155-81; Heymann, E. (1980) Enzymatic Basis of Detoxification 2:291-323; Heymann, E. (1982) Metabolic Basis of Detoxification 1 :229-45; Leinweber, F.-J. (1987) Drug. Metab. Rev. 18:379-439). Human liver and plasma carboxylesterase converts lovastatin to its active form (Tang, B.K. and Kalow, W. (1995) Eur. J. Clin. Pharmacol 47:449-51) and converts an inactive prodrug form of prostaglandin F2α to its active metabolite (Cheng-Bennett, A. et al. (1994) Br. J. Ophthalmol 78:560-67). A significant number of drags and endogenous compounds are substrates of carboxylesterases, including dipivefrin hydrochloride (Nakamura, M. et al. (1993) Ophthalmic Res. 25:46-51), carbonates (McCracken, N.W. et al. (1993) Biochem. Pharmacol. 45:31-36; Huang, TX. et al. (1993) Pharmacol Res. 10:639-48), cocaine (Dean, R.A. (1995) J Pharmacol. Exp. Ther. (1995) 275:965-71; Brzezinski, M.R. et al. (1994) Biochem. Pharmacol. 48:1747- 55), salicylates (White, K.N. et al. (1994) Biochem. Soc. Trans. 22:220S), capsaicin (Park, Y.H. and Lee, S.S. (1994) Biochem. Mol. Biol. Int. 34:351-60), palmitoyl- coenzyme A (Hosokawa, M. et al. (1987) Mol. Pharmacol. 31 :579-84; Hosokawa, M. et al. (1990) Arch. Biochem. Biophys. 277:219-27; Tsujita, T. and Okuda, H. (1993) J Lipid. Res. 34:1773-81; Mentlein, R. et al. (1984) Arch. Biochem. Biophys. 234:612-21), haloperidol (Nambu, K. et al. (1987) Biochem. Pharmacol. 36:1715-22), imidapril (Yamada, Y. et al. (1992) Arzneimittel Forsch. 42:507-12), pyrrolizidine alkaloids (Dueker, S.R. et al. (1992) Toxicol. Appl Pharmacol. 117:116-21; Dueker, S.R. et al. (1995) Arch. Toxicol. 69:725-28; Dueker, S.R. et al. (1992) Drug. Metab. Dispos. 20:275-80), and steroids (Lund-Pero, M. et al. (1994) Clin. Chim. Acta. 224:9-20). In insects, carboxylesterases contribute to the development of resistance to ester and amide insecticides (Hammock, B. et al. (1975) Mol. Cell. Endocrinol 3:167-84; Hanzlik, T.N. et al. (1989) J. Biol. Chem. 264:12419-25; McCutchen, B.F. et al. (1993) Arch. Biochem. Biophys. 307:231-41; Jones, G. et al. (1994) Biochem. J. 302:827-35). Summary of the Invention The present invention is based, at least in part, on the discovery of novel carboxylesterase family members, referred to herein as "Carboxylesterase- 1" or "COE- 1" nucleic acid and protein molecules. The COE-1 nucleic acid and protein molecules of the present invention are members of the lipase subfamily of carboxylesterases, show significant homology to mouse and rat Upases, and are upregulated in marmoset monkeys treated with cholestyramine, a cholesterol and/or lipid lowering drug. The COE-1 nucleic acid and protein molecules of the present invention are useful as modulating agents in regulating a variety of cellular processes, e.g., hydrolysis of endogenous and/or exogenous compounds (e.g., hydrolysis of triglycerides); detoxification and/or activation of drugs, pro-drugs, toxins, and/or carcinogens; lipid homeostasis; intra- or inter-cellular signaling; gene expression; and/or cellular growth and/or differentiation. Accordingly, in one aspect, this invention provides isolated nucleic acid molecules encoding COE-1 proteins or biologically active portions thereof, as well as nucleic acid fragments suitable as primers or hybridization probes for the detection of COE-1 -encoding nucleic acids. In one embodiment, the invention features an isolated nucleic acid molecule that includes the nucleotide sequence set forth in SEQ ID NOT or SEQ ID NO:3. In another embodiment, the invention features an isolated nucleic acid molecule that encodes a polypeptide including the amino acid sequence set forth in SEQ ID NO:2. In another embodiment, the invention features an isolated nucleic acid molecule that includes the nucleotide sequence contained in the plasmid deposited with ATCC® as Accession Number . In still other embodiments, the invention features isolated nucleic acid molecules including nucleotide sequences that are substantially identical (e.g., 60%, 65%, 70%, 75%, 80%, 85%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical) to the nucleotide sequence set forth as SEQ ID NOT or SEQ ID NO:3. The invention further features isolated nucleic acid molecules including at least 30 contiguous nucleotides of the nucleotide sequence set forth as SEQ ID NOT or SEQ ID NO:3. In another embodiment, the invention features isolated nucleic acid molecules which encode a polypeptide including an amino acid sequence that is substantially identical (e.g., 60%, 65%, 70%, 75%, 80%, 85%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical) to the amino acid sequence set forth as SEQ ID NO:2. Also featured are nucleic acid molecules which encode allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:2. In addition to isolated nucleic acid molecules encoding full-length polypeptides, the present invention also features nucleic acid molecules which encode fragments, for example, biologically active or antigenic fragments, of the full-length polypeptides of the present invention (e.g., fragments including at least 10, 15, 20, 25, 30, 35, 40, 45, or 50 contiguous amino acid residues of the amino acid sequence of SEQ ID NO:2). In still other embodiments, the invention features nucleic acid molecules that are complementary to, antisense to, or hybridize under stringent conditions to the isolated nucleic acid molecules described herein. In a related aspect, the invention provides vectors including the isolated nucleic acid molecules described herein (e.g., COE-1 -encoding nucleic acid molecules). Such vectors can optionally include nucleotide sequences encoding heterologous polypeptides. Also featured are host cells including such vectors (e.g., host cells including vectors suitable for producing COE-1 nucleic acid molecules and polypeptides). In another aspect, the invention features isolated COE-1 polypeptides and/or biologically active or antigenic fragments thereof. Exemplary embodiments feature a polypeptide including the amino acid sequence set forth as SEQ ID NO:2, a polypeptide including an amino acid sequence at least 60%, 65%, 70%, 75%, 80%, 85%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical to the amino acid sequence set forth as SEQ ID NO:2, a polypeptide encoded by a nucleic acid molecule including a nucleotide sequence at least 60%, 65%, 70%, 75%, 80%, 85%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identical to the nucleotide sequence set forth as SEQ ID NO:l or SEQ ID NO:3. Also featured are fragments of the full-length polypeptides described herein (e.g., fragments including at least 10 contiguous amino acid residues of the sequence set forth as SEQ ID NO:2) as well as allelic variants of the polypeptide having the amino acid sequence set forth as SEQ ID NO:2. The COE-1 polypeptides and/or biologically active or antigenic fragments thereof, are useful, for example, as reagents or targets in assays applicable to treatment and/or diagnosis of carboxylesterase-associated disorders. In one embodiment, a COE-1 polypeptide or fragment thereof has a COE-1 activity. In another embodiment, a COE-1 polypeptide or fragment thereof has at least one or more of the following domains, motifs, and/or amino acid residues: a carboxylesterase domain, a catalytic triad, a catalytic serine, a catalytic histidine, a catalytic serine motif, a carboxylesterases type-B serine active site, and/or an ER retention signal, and optionally, has a COE-1 activity. In a related aspect, the invention features antibodies (e.g., antibodies which specifically bind to any one of the polypeptides, as described herein) as well as fusion polypeptides including all or a fragment of a polypeptide described herein. The present invention further features methods for detecting COE-1 polypeptides and/or COE-1 nucleic acid molecules, such methods featuring, for example, a probe, primer or antibody described herein. Also featured are kits for the detection of COE-1 polypeptides and/or COE-1 nucleic acid molecules. In a related aspect, the invention features methods for identifying compounds which bind to and/or modulate the activity of a COE-1 polypeptide or COE-1 nucleic acid molecule described herein. Also featured are methods for modulating a COE-1 activity. In other embodiments, the invention provides methods for identifying a subject having a carboxylesterase-associated disorder, e.g., a lipid homeostasis disorder, or at risk for developing a carboxylesterase-associated disorder; methods for identifying a compound capable of treating a carboxylesterase-associated disorder characterized by aberrant COE-1 nucleic acid expression or COE-1 polypeptide activity; and methods for treating a subject having a carboxylesterase-associated disorder characterized by aberrant COE-1 polypeptide activity or aberrant COE-1 nucleic acid expression Other features and advantages of the invention will be apparent from the following detailed description and claims. Brief Description of the Drawings Figures 1A-1B depict the nucleotide sequence of human COE-1 cDNA and the corresponding amino acid sequence. The nucleotide sequence corresponds to nucleic acids 1 to 2087 of SEQ ID NOT. The amino acid sequence corresponds to amino acids 1 to 547 of SEQ ID NO:2. The coding region without the 5' or 3' untranslated regions of the human COE-1 gene is shown in SEQ ID NO:3. Figures 2A-2B depict the results of a search in the HMM database, using the amino acid sequence of human COE-1. The search resulted in the identification of a carboxylesterase domain in the amino acid sequence of COE-1 (SEQ ID NO:2). Figure 3 depicts a Clustal W (1.74) alignment of the amino acid sequences of human COE-1 and mouse liver carboxylesterase precursor (mLIVERcarb; GenBank Accession No. Q63880). Identical amino acid residues are indicated by stars. The active site serine and histidine residues are circled. Figure 4 depicts an alignment of the human COE-1 amino acid sequence ("Fbh25869FL.aa; SEQ ID NO:2) with the mouse liver carboxylesterase precursor amino acid sequence ("Q63880.aa"; SEQ ID NO:4) using the GAP program in the GCG software package (Blosum 62 matrix) and a gap weight of 12 and a length weight of 4. As shown in the alignment, the human COE-1 and mouse liver carboxylesterase precursor amino acid sequences are about 61.219% identical. The catalytic (i.e., active site) serine and histidine residues and the ER retention signal are shown in bold. Figure 5 depicts an alignment of the human COE-1 amino acid sequence ("Fbh25869FL.aa; SEQ ID NO:2) with the rat liver carboxylesterase 10 (ES-10) precursor amino acid sequence ("P16303.aa"; SEQ ID NO:5) using the GAP program in the GCG software package (Blosum 62 matrix) and a gap weight of 12 and a length weight of 4. As shown in the alignment, the human COE-1 and rat liver carboxylesterase 10 precursor amino acid sequences are about 46% identical. The catalytic (i. e., active site) serine motif and histidine residue and the ER retention signal are shown in bold. Figure 6 depicts a structural, hydrophobicity, and antigenicity analysis of the human COE-1 protein. Figure 7 depicts the expression levels of human "COE-1 mRNA in various human cell types and tissues, as determined by Taqman analysis. Samples: (1) normal artery; (2) normal vein; (3) aortic smooth muscle cells - early; (4) coronary smooth muscle cells; (5) human umbilical vein endothelial cells (HUVECs) - static; (6) human umbilical vein endothelial cells (HUVECs) - shear; (7) normal heart; (8) heart - congestive heart failure (CHF); (9) kidney; (10) skeletal muscle; (11) normal adipose tissue; (12) pancreas; (13) primary osteoblasts; (14) differentiated osteoclasts; (15) normal skin; (16) normal spinal cord; (17) normal brain cortex; (18) brain - hypothalamus; (19) nerve; (20) dorsal root ganglion (DRG); (21) glial cells (astrocytes); (22) glioblastoma; (23) normal breast; (24) breast tumor; (25) normal ovary; (26) ovary tumor; (27) normal prostate; (28) prostate tumor; (29) epithelial cells (prostate); (30) normal colon; (31) colon tumor; (32) normal lung; (33) lung tumor; (34) lung - chronic obstructive pulmonary disease (COPD); (35) colon - inflammatory bowel disease (IBD); (36) normal liver; (37) liver - fibrosis; (38) dermal cells - fibroblasts; (39) normal spleen; (40) normal tonsil; (41) lymph node; (42) small intestine; (43) skin - decubitus; (44) synovium; (45) bone marrow mononuclear cells (BM-MNC); (46) activated peripheral blood mononuclear cells (PBMCs). Detailed Description of the Invention The present invention is based, at least in part, on the discovery of novel carboxylesterase family members, referred to herein as "Carboxylesterase" or "COE-1" nucleic acid and protein molecules. These novel molecules are capable of hydrolyzing ester-, thioester-, and amide-containing compounds (e.g., triglycerides) to their respective free acids, are upregulated in marmoset monkeys treated with cholestyramine, a cholesterol and/or lipid lowering drag, and play a role in or function in a variety of cellular processes, including lipid homeostasis, hydrolysis of endogenous and/or exogenous compounds; detoxification and/or activation of drugs, pro-drags, toxins, and/or carcinogens; intra- or inter-cellular signaling; gene expression; and/or cellular growth and/or differentiation. The novel COE-1 molecules of the instant invention are members of the lipase subfamily of carboxylesterases and show significant homology to mouse and rat upases. Analysis of the activity of a recently characterized hepatic microsomal lipase, ES-10, showed that increased expression of ES-10 in hepatic cell lines resulted in an increase in the rate of depletion of intracellular triacylglycerol stores, indicating that ES-10 is capable of hydrolysis of stored triacylglycerol. In addition, hepatocytes expressing ES- 10 exhibited increased levels of apo-B 100 in the VLDL fraction (Lehner, R. and Vance, D.E. (1999) Biochem. J. 343:1-10; Robbi, M. et al. (1990) Biochem. J. 269:451-458). Because the COE-1 molecules of the instant invention show significant homology to ES-10, COE-1 may function as an intracellular lipase, the activity of which may contribute to the mobilization of intracellular triacylglycerol stores, which can be used for lipoprotein assembly. Accordingly, modulation of COE-1 activity may result in the modulation of serum lipoprotein and/or triglyceride levels. For example, inhibition of COE-1 activity may have positive effects on serum lipoprotein and triglyceride profiles. In view of the foregoing activities, the COE-1 molecules of the present invention provide novel diagnostic targets and therapeutic agents to control carboxylesterase-associated disorders. As used herein, a "carboxylesterase-associated disorder" includes a disorder, disease or condition which is caused or characterized by a misregulation (e.g., downregulation or upregulation) of carboxylesterase activity. Carboxylesterase- associated disorders can detrimentally affect cellular functions such as lipid homeostasis; cellular proliferation, growth, differentiation, or migration; inter- or intra- cellular communication; tissue function, such as cardiac function or musculoskeletal function; systemic responses in an organism, such as nervous system responses, hormonal responses (e.g., insulin response), or immune responses; and protection of cells from toxic compounds (e.g., carcinogens, toxins, or mutagens). In a preferred embodiment, a carboxylesterase-associated disorder is a "lipid homeostasis disorder". As used herein, a "lipid homeostasis disorder" includes a disorder, disease, or condition associated with, caused by, and/or linked to abnormal regulation (e.g., upregulation or downregulation) of lipid metabolism. Lipid homeostasis disorders may be caused by or associated with aberrant lipolysis, aberrant lipid uptake, aberrant lipid synthesis and/or secretion, aberrant intracellular lipid release and/or turnover, aberrant intracellular triglyceride release aήd/or turnover, aberrant intracellular lipid and/or triglyceride mass, and/or aberrant secreted lipid and/or triglyceride mass within or from a cell, e.g., a liver cell. Lipid homeostasis disorders include, but are not limited to, atherosclerosis, obesity, diabetes, insulin resistance, hyperlipidemia, hypolipidemia, dyslipidemia, hypercholesterolemia, hypocholesterolemia, triglyceride storage disease, cardiovascular disease, coronary artery disease, hypertension, stroke, overweight, anorexia, cachexia, hyperlipoproteinemia, hypolipoproteinemia, Niemann Pick disease, hypertriglyceridemia, hypotriglyceridemia, pancreatitis, diffuse idiopathic skeletal hyperostosis (DISH), atherogenic lipoprotein phenotype (ALP), epilepsy, liver disease, fatty liver, steatohepatitis, and poly cystic ovarian syndrome. Other examples of carboxylesterase-associated disorders include cardiac-related disorders. Cardiovascular system disorders in which the COE-1 molecules of the invention may be directly or indirectly involved include arteriosclerosis, ischemia reperfusion injury, restenosis, arterial inflammation, vascular wall remodeling, ventricular remodeling, rapid ventricular pacing, coronary microembolism, tachycardia, bradycardia, pressure overload, aortic bending, coronary artery ligation, vascular heart disease, atrial fibrilation, Jervell syndrome, Lange-Nielsen syndrome, long-QT syndrome, congestive heart failure, sinus node dysfunction, angina, heart failure, hypertension, atrial fibrillation, atrial flutter, dilated cardiomyopathy, idiopathic cardiomyopathy, myocardial infarction, coronary artery disease, coronary artery spasm, and arrhythmia. COE-1 -mediated or related disorders also include disorders of the musculoskeletal system such as paralysis and muscle weakness, e.g., ataxia, myotonia, and myokymia. Further examples of carboxylesterase-associated disorders include CNS disorders such as cognitive and neurodegenerative disorders, examples of which include, but are not limited to, Alzheimer's disease, dementias related to Alzheimer's disease (such as Pick's disease), Parkinson's and other Lewy diffuse body diseases, senile dementia, Huntington's disease, Gilles de la Tourette's syndrome, multiple sclerosis, amyotrophic lateral sclerosis, progressive supranuclQax palsy, epilepsy, and Jakob-Creutzfieldt disease; autonomic function disorders such as hypertension and sleep disorders, and neuropsychiatric disorders, such as depression, schizophrenia, schizoaffective disorder, korsakoff s psychosis, mania, anxiety disorders, or phobic disorders; learning or memory disorders, e.g., amnesia or age-related memory loss, attention deficit disorder, dysthymic disorder, major depressive disorder, mania, obsessive-compulsive disorder, psychoactive substance use disorders, anxiety, phobias, panic disorder, as well as bipolar affective disorder, e.g., severe bipolar affective (mood) disorder (BP-1), and bipolar affective neurological disorders, e.g., migraine and obesity. Further CNS-related disorders include, for example, those listed in the American Psychiatric Association's Diagnostic and Statistical manual of Mental Disorders (DSM), the most current version of which is incoφorated herein by reference in its entirety. Carboxylesterase disorders also include cellular proliferation, growth, differentiation, or migration disorders. Cellular proliferation, growth, differentiation, or migration disorders include those disorders that affect cell proliferation, growth, differentiation, or migration processes. As used herein, a "cellular proliferation, growth, differentiation, or migration process" is a process by which a cell increases in number, size or content, by which a cell develops a specialized set of characteristics which differ from that of other cells, or by which a cell moves closer to or further from a particular location or stimulus. The COE-1 molecules of the present invention are involved in signal transduction mechanisms, which are known to be involved in cellular growth, differentiation, and migration processes. Thus, the COE-1 molecules may modulate cellular growth, differentiation, or migration, and may play a role in disorders characterized by aberrantly regulated growth, differentiation, or migration. Such disorders include cancer, e.g., carcinoma, sarcoma, or leukemia; tumor angiogenesis and metastasis; skeletal dysplasia; hepatic disorders; and hematopoietic and/or myeloproliferative disorders. COE-1 -associated or related disorders also include hormonal disorders, such as conditions or diseases in which the production and/or regulation of hormones in an organism is aberrant. Examples of such disorders and diseases include type I and type II diabetes mellitus, pituitary disorders (e.g., growth disorders), thyroid disorders (e.g., hypothyroidism or hyperthyroidism), and reproductive or fertility disorders (e.g., disorders which affect the organs of the reproductive system, e.g. , the prostate gland, the uteras, or the vagina; disorders which involve an imbalance in the levels of a reproductive hormone in a subject; disorders affecting the ability of a subject to reproduce; and disorders affecting secondary sex characteristic development, e.g., adrenal hyperplasia). COE-1 -associated or related disorders also include immune disorders, such as autoimmune disorders or immune deficiency disorders, e.g., congenital X-linked infantile hypogammaglobulinemia, transient hypogammaglobulinemia, common variable immunodeficiency, selective IgA deficiency, chronic mucocutaneous candidiasis, or severe combined immunodeficiency. COE-1 -associated or related disorders also include disorders affecting tissues in which COE-1 protein is expressed, e.g., the kidney, colon, liver, brain, small intestine, and skeletal muscle (see Figure 7). The term "family" when referring to the protein and nucleic acid molecules of the invention is intended to mean two or more proteins or nucleic acid molecules having a common structural domain or motif and having sufficient amino acid or nucleotide sequence homology as defined herein. Such family members can be naturally or non- naturally occurring and can be from either the same or different species. For example, a family can contain a first protein of human origin as well as other distinct proteins of human origin or alternatively, can contain homologues of non-human origin, e.g., rat or mouse proteins. Members of a family can also have common functional characteristics. Members of the COE-1 family of proteins, for example, include at least one "carboxylesterase domain" in the protein or corresponding nucleic acid molecule. As used herein, the term "carboxylesterase domain" includes a protein domain having at least about 440-600 amino acid residues and a bit score of at least 440 when compared against a carboxylesterase Hidden Markov Model (HMM), e.g., PFAM Accession Number PF00135. Preferably, a carboxylesterase domain includes a protein having an amino acid sequence of about 460-580, 480-560, 500-540, or more preferably about 519 amino acid residues, and a bit score of at least 470, 480, 490, 500, or more preferably, 516.6. To identify the presence of a carboxylesterase domain in a COE-1 protein, and make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein is searched against a database of known protein domains (e.g., the HMM database). The carboxylesterase domain (HMM) has been assigned the PFAM Accession number PF00135 (see the PFAM website, available online through Washington University in St. Louis). A search was performed against the HMM database resulting in the identification of a carboxylesterase domain in the amino acid sequence of human COE-1 at about residues 5-523 of SEQ ID NO:2. The results of the search are set forth in Figures 2A-2B. A description of the Pfam database can be found in Sonhammer et al. (1997) Proteins 28:405-420, and a detailed description of HMMs can be found, for example, in Gribskov et α/.(1990) Methods Enzymol. 183:146-159; Gribskov et al. (1987) Proc. Natl. Acad. Sci. USA 84:4355-4358; Krogh et α/.(1994) J Mol Biol. 235:1501-1531; and Stultz et α/.(1993) Protein Sci. 2:305-314, the contents of which are incoφorated herein by reference. In another embodiment, a COE-1 family member of the present invention is identified based on the presence of a "catalytic triad" in the protein or corresponding nucleic acid molecule. As used herein, the term "catalytic triad" includes a group of three amino acid residues which are non-contiguous in the primary sequence but which are adjacent in the tertiary stracture of a protein and which actively participate in an enzymatic reaction catalyzed by a carboxylesterase. In the carboxylesterases of the present invention, the catalytic triad residues are typically serine, histidine, and glutamic acid (Satoh and Hosokawa (1998) supra; Oakeshott et al. (1999) supra). The amino acid residues of the catalytic triad may also be referred to herein as the "catalytic residues" (e.g., the "catalytic serine" or "catalytic histidine") or the "active site residues" (e.g., the "active site serine" or "active site histidine"). In a preferred embodiment, the serine residue of a catalytic triad of the COE-1 molecules of the present invention is contained within a catalytic serine motif, as defined herein. In a further preferred embodiment, the serine residue of a catalytic triad of the COE-1 molecules of the present invention is contained within a carboxylesterases type-B serine active site. Based on an alignment with a mouse liver carboxylesterase precursor (GenBank Accession No. Q63880), two of the catalytic triad residues were identified as serine 205 and histidine 426 of human COE-1 (SEQ ID NO:2; Figure 3). In another embodiment, a COE-1 family member of the present invention is identified based on the presence of a "catalytic serine motif in the protein or corresponding nucleic acid molecule. As used herein, a "catalytic serine motif includes a group of five amino acid residues having the consensus sequence G-X-S-X-G, wherein X indicates any amino acid residue. Catalytic serine motifs are found in all known upases (Lehner, R. and Vance, D.E. (1999) Biochem. J. 343:1-10). In apreferred embodiment, a catalytic serine motif includes a catalytic serine, as defined herein. In a further preferred embodiment, a catalytic serine motif is contained within a carboxylesterases type-B serine active site. Based on an alignment with a mouse liver carboxylesterase precursor (GenBank Accession No. Q63880; SEQ ID NO:4; Figure 4), a catalytic serine motif was identified at about residues 203-207 of human COE-1 (SEQ ID NO:2). In another embodiment, a COE-1 protein of the present invention is identified based on the presence of a "carboxylesterases type-B serine active site" in the protein or corresponding nucleic acid molecule. A carboxylesterases type-B serine active site functions as part of the catalytic active site of a carboxylesterase. The carboxylesterases type-B serine active site has been assigned ProSite Accession Number PS00122. To identify the presence of a carboxylesterases type-B serine active site in a COE-1 protein, and to make the determination that a protein of interest has a particular profile, the amino acid sequence of the protein may be searched against a database of known protein domains (e.g., the ProSite database) using the default parameters (available online through the Swiss Institute of Bioinformatics (SIB)). In a preferred embodiment, a carboxylesterases type-B serine active site comprises a catalytic serine motif, which further comprises a catalytic serine. A search was performed against the ProSite database resulting in the identification of a carboxylesterases type-B serine active site in the amino acid sequence of human COE-1 (SEQ ID NO:2) at about residues 192-207. In another embodiment, a COE-1 family member of the present invention is identified based on the presence of an "ER retention signal" in the protein or corresponding nucleic acid molecule. As used herein, an "ER retention signal" includes a group of four amino acid residues located at the C-terminus of a polypeptide sequence which targets a protein to the lumen of the endoplasmic reticulum. Based on homology to other proteins known to have ER retention signals, an ER retention signal was identified in the amino acid sequence of human COE-1 (SEQ ID NO:2) at about residues 544-547. Isolated proteins of the present invention, preferably COE-1 proteins, have an amino acid sequence sufficiently homologous to the amino acid sequence of SEQ ID NO:2, or are encoded by a nucleotide sequence sufficiently homologous to SEQ ID NOT or 3. As used herein, the term "sufficiently homologous" refers to a first amino acid or nucleotide sequence which contains a sufficient or minimum number of identical or equivalent (e.g., an amino acid residue which has a similar side chain) amino acid residues or nucleotides to a second amino acid or nucleotide sequence such that the first and second amino acid or nucleotide sequences share common structural domains or motifs and/or a common functional activity. For example, amino acid or nucleotide sequences which share common structural domains having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 88%, 89%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more homology or identity across the amino acid sequences of the domains and contain at least one and preferably two structural domains or motifs, are defined herein as sufficiently homologous. Furthermore, amino acid or nucleotide sequences which share at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 88%, 89%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more homology or identity and share a common functional activity are defined herein as sufficiently homologous. In a preferred embodiment, a COE-1 protein includes at least one or more of the following domains, motifs, and/or amino acid residues: a carboxylesterase domain, a catalytic triad, a catalytic serine, a catalytic histidine, a catalytic serine motif, a carboxylesterases type-B serine active site, and/or an ER retention signal, and has an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 85%, 88%, 89%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%), 99.1%, 99.8%), 99.9% or more homologous or identical to the amino acid sequence of SEQ ID NO:2, or the amino acid sequence encoded by the DNA insert of the plasmid deposited with ATCC as Accession Number . In yet another preferred embodiment, a COE-1 protein includes at least one or more of the following domains, motifs, and/or amino acid residues: a carboxylesterase domain, a catalytic triad, a catalytic serine, a catalytic histidine, a catalytic serine motif, a carboxylesterases type-B serine active site, and/or an ER retention signal, and is encoded by a nucleic acid molecule having a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:l or 3. In another preferred embodiment, a COE-1 protein includes at least one or more of the following domains, motifs, and/or amino acid residues: a carboxylesterase domain, a catalytic triad, a catalytic serine, a catalytic histidine, a catalytic serine motif, a carboxylesterases type-B serine active site, and/or an ER retention signal, and has a COE-1 activity. As used interchangeably herein, a "COE-1 activity", "biological activity of COE-1" or "functional activity of COE-1", includes an activity exerted or mediated by a COE-1 protein, polypeptide or nucleic acid molecule on a COE-1 responsive cell or on a COE-1 substrate, as determined in vivo or in vitro, according to standard techniques. In one embodiment, a COE-1 activity is a direct activity, such as an association with a COE-1 target molecule. As used herein, a "target molecule" or "binding partner" is a molecule with which a COE-1 protein binds or interacts in nature, such that COE-1 - mediated function is achieved. A COE-1 target molecule can be a non-COE-1 molecule or a COE-1 protein or polypeptide of the present invention. In an exemplary embodiment, a COE-1 target molecule is a COE-1 substrate or ligand, e.g., a triglyceride. A COE-1 activity can also be an indirect activity, such as a cellular signaling activity mediated by interaction of the COE-1 protein with a COE-1 substrate or ligand. In a preferred embodiment, a COE-1 activity is at least one of the following activities: (i) interaction with a COE-1 substrate or target molecule (e.g., a triglyceride); (ii) conversion of a COE-1 substrate or target molecule to a product (e.g., hydrolysis of an ester linkage and/or liberation of the free acid form of the substrate, e.g., hydrolysis of a triglyceride and/or liberation of free fatty acid(s) and glycerol); (iii) modulation of lipolysis; (iv) modulation of lipid uptake by a cell (e.g., a liver cell); (v) modulation of lipid synthesis and/or secretion; (vi) modulation of intracellular lipid release and/or turnover; (viϊ) modulation of intracellular lipid and/or triglyceride mass; (viii) modulation of secreted lipid and/or triglyceride mass; (ix) modulation of serum lipid, lipoprotein, and/or triglyceride levels; (x) modulation of lipid homeostasis; (xi) direct or indirect modulation of lipoprotein assembly; (xii) interaction with and/or hydrolysis of a second non-COE-1 protein; (xiii) activation/deactivation of a COE-1 substrate or target molecule (e.g., activation/deactivation of a carcinogen); (xiv) metabolism and/or detoxification of a drug; (xv) modulation of cellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (xvi) modulation of cellular proliferation and/or differentiation. The nucleotide sequence of the isolated human COE-1 cDNA and the predicted amino acid sequence encoded by the COE-1 cDNA are shown in Figures 1 A- IB and in SEQ ID NOT and 2, respectively. A plasmid containing the human COE-1 cDNA was deposited with the American Type Culture Collection (ATCC), 10801 University Boulevard, Manassas, VA 20110-2209, on and assigned Accession Number . This deposit will be maintained under the terms of the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Puφoses of Patent Procedure. This deposit were made merely as a convenience for those of skill in the art and is not an admission that a deposit is required under 35 U.S.C. §112. The human COE-1 gene, which is approximately 2087 nucleotides in length, encodes a protein having a molecular weight of approximately 60.2 kD and which is approximately 547 amino acid residues in length. Various aspects of the invention are described in further detail in the following subsections: I. Isolated Nucleic Acid Molecules One aspect of the invention pertains to isolated nucleic acid molecules that encode COE-1 proteins or biologically active portions thereof, as well as nucleic acid fragments sufficient for use as hybridization probes to identify COE-1 -encoding nucleic acid molecules (e.g., COE-1 mRNA) and fragments for use as PCR primers for the amplification or mutation of COE-1 nucleic acid molecules. As used herein, the term "nucleic acid molecule" is intended to include DNA molecules (e.g., cDNA or genomic DNA) and RNA molecules (e.g., mRNA) and analogs of the DNA or RNA generated using nucleotide analogs. The nucleic acid molecule can be single-stranded or double- stranded, but preferably is double-stranded DNA. The term "isolated nucleic acid molecule" includes nucleic acid molecules which are separated from other nucleic acid molecules which are present in the natural source of the nucleic acid. For example, with regards to genomic DNA, the term "isolated" includes nucleic acid molecules which are separated from the chromosome with which the genomic DNA is naturally associated. Preferably, an "isolated" nucleic acid is free of sequences which naturally flank the nucleic acid (i.e., sequences located at the 5' and 3' ends of the nucleic acid) in the genomic DNA of the organism from which the nucleic acid is derived. For example, in various embodiments, the isolated COE-1 nucleic acid molecule can contain less than about 5 kb, 4kb, 3kb, 2kb, 1 kb, 0.5 kb or 0.1 kb of nucleotide sequences which naturally flank the nucleic acid molecule in genomic DNA of the cell from which the nucleic acid is derived. Moreover, an "isolated" nucleic acid molecule, such as a cDNA molecule, can be substantially free of other cellular material, or culture medium when produced by recombinant techniques, or substantially free of chemical precursors or other chemicals when chemically synthesized. A nucleic acid molecule of the present invention, e.g., a nucleic acid molecule having the nucleotide sequence of SEQ ID NO:l or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , or a portion thereof, can be isolated using standard molecular biology techniques and the sequence information provided herein. Using all or a portion of the nucleic acid sequence of SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , as hybridization probes, COE-1 nucleic acid molecules can be isolated using standard hybridization and cloning techniques (e.g., as described in Sambrook, J., Fritsh, E.F., and Maniatis, T. Molecidαr Cloning: A Laboratory Manual 2nd, ed., Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1989). Moreover, a nucleic acid molecule encompassing all or a portion of SEQ ID NO:l or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number can be isolated by the polymerase chain reaction (PCR) using synthetic oligonucleotide primers designed based upon the sequence of SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the'plasmid deposited with ATCC as Accession Number . A nucleic acid of the invention can be amplified using cDNA, mRNA or alternatively, genomic DNA, as a template and appropriate oligonucleotide primers according to standard PCR amplification techniques. The nucleic acid so amplified can be cloned into an appropriate vector and characterized by DNA sequence analysis. Furthermore, oligonucleotides corresponding to COE-1 nucleotide sequences can be prepared by standard synthetic techniques, e.g., using an automated DNA synthesizer. In one embodiment, an isolated nucleic acid molecule of, the invention comprises the nucleotide sequence shown in SEQ ID NOT or 3. This cDNA may comprise sequences encoding the human COE-1 protein (e.g., the "coding region", from nucleotides 222-1862), as well as 5' untranslated sequence (nucleotides 1-221) and 3' untranslated sequences (nucleotides 1863-2087) of SEQ ID NO:l. Alternatively, the nucleic acid molecule can comprise only the coding region of SEQ ID NOT (e.g., nucleotides 222-1862, corresponding to SEQ ID NO:3). Accordingly, in another embodiment, an isolated nucleic acid molecule of the invention comprises SEQ ID NO:3 and nucleotides 1-221 of SEQ ID NO: 1. In yet another embodiment, the isolated nucleic acid molecule comprises SEQ ID NO:3 and nucleotides 1863-2087 of SEQ ID NOT. In yet another embodiment, the nucleic acid molecule consists of the nucleotide sequence set forth as SEQ ID NOT or SEQ ID NO:3. In still another embodiment, the nucleic acid molecule can comprise the coding region of SEQ ID NOT (e.g., nucleotides 222- 1862, corresponding to SEQ ID NO:3), as well as a stop codon (e.g., nucleotides 1863- 1865 of SEQ ID NO: 1). In another embodiment, an isolated nucleic acid molecule comprises nucleotides 1 -229 of SEQ ID NO . In another embodiment, an isolated nucleic acid molecule comprises nucleotides 2073-2087 of SEQ ID NO: 1. In further embodiments, an isolated nucleic acid molecule comprises nucleotides 229-2072 of SEQ ID NOT or nucleotides 230-2073 of SEQ ID NOT. ' In still another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule which is a complement of the nucleotide sequence shown in SEQ ID NO:l or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , or a portion of any of these nucleotide sequences. A nucleic acid molecule which is complementary to the nucleotide sequence shown in SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , is one which is sufficiently complementary to the nucleotide sequence shown in SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , such that it can hybridize to the nucleotide sequence shown in SEQ ID NO or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , thereby forming a stable duplex. In still another embodiment, an isolated nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 88%, 89%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to the nucleotide sequence shown in SEQ ID NOT or 3 (e.g., to the entire length of the nucleotide sequence), or to the nucleotide sequence (e.g., the entire length of the nucleotide sequence) of the DNA insert of the plasmid deposited with ATCC as Accession Number , or a portion or complement of any of these nucleotide sequences. In one embodiment, a nucleic acid molecule of the present invention comprises a nucleotide sequence which is at least (or no greater than) 50, 100, 150, 200, 229, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1844, 1850, 1900, 1950, 2000, 2050 or more nucleotides in length and hybridizes under stringent hybridization conditions to a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:l or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number . Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , for example, a fragment which can be used as a probe or primer or a fragment encoding a portion of a COE-1 protein, e.g., a biologically active portion of a COE-1 protein. The nucleotide sequence determined from the cloning of the COE-1 gene allows for the generation of probes and primers designed for use in identifying and/or cloning other COE-1 family members, as well as COE-1 homologues from other species. The probe/primer (e.g., oligonucleotide) typically comprises substantially purified oligonucleotide. The oligonucleotide typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12 or 15, preferably about 20 or 25, more preferably about 30, 35, 40, 45, 50, 55, 60, 65, or 75 consecutive nucleotides of a sense sequence of SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , of an anti-sense sequence of SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , or of a naturally occurring allelic variant or mutant of SEQ ID NO:l or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number . Exemplary probes or primers are at least (or no greater than) 12 or 15, 20 or 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or more nucleotides in length and or comprise consecutive nucleotides of an isolated nucleic acid molecule described herein. Also included within the scope of the present invention are probes or primers comprising contiguous or consecutive nucleotides of an isolated nucleic acid molecule described herein, but for the difference of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 bases within the probe or primer sequence. Probes based on the COE-1 nucleotide sequences can be used to detect (e.g., specifically detect) transcripts or genomic sequences encoding the same or homologous proteins. In preferred embodiments, the probe further comprises a label group attached thereto, e.g. , the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor. In another embodiment a set of primers is provided, e.g., primers suitable for use in a PCR, which can be used to amplify a selected region of a COE-1 sequence, e.g., a domain, region, site or other sequence described herein. The primers should be at least 5, 10, or 50 base pairs in length and less than 100, or less than 200, base pairs in length. The primers should be identical, or differ by no greater than 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 bases when compared to a sequence disclosed herein or to the sequence of a naturally occurring variant. Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress a COE-1 protein, such as by measuring a level of a COE-1 -encoding nucleic acid in a sample of cells from a subject, e.g., detecting COE-1 mRNA levels or determining whether a genomic COE-1 gene has been mutated or deleted. A nucleic acid fragment encoding a "biologically active portion of a COE-1 protein" can be prepared by isolating a portion of the nucleotide sequence of SEQ ID NO:l or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , which encodes a polypeptide having a COE-1 biological activity (the biological activities of the COE-1 proteins are described herein), expressing the encoded portion of the COE-1 protein (e.g., by recombinant expression in vitro) and assessing the activity of the encoded portion of the COE-1 protein. In an exemplary embodiment, the nucleic acid molecule is at least 50-100, 100-150, 150-200, 200-229, 229-250, 250-300, 300-350, 350-400, 400-450, 450-500, 500-550, 550-600, 600-650, 650-700, 700-750, 750-800, 800-850, 850-900, 900-950, 950-1000, 1000- 1050, 1050-1100, 1100-1150, 1150-1200, 1200-1250, 1250-1300, 1300-1350, 1350- 1400, 1400-1450, 1450-1500, 1500-1550, 1550-1600, 1600-1650, 1650-1700, 1700- 1750, 1750-1800, 1800-1844, 1844-1850, 1850-1900, 1900-1950, 1950-2000, 2000- 2050 or more nucleotides in length and encodes a protein having a COE-1 activity (as described herein). The invention further encompasses nucleic acid molecules that differ from the nucleotide sequence shown in SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , due to degeneracy of the genetic code and thus encode the same COE-1 proteins as those encoded by the nucleotide sequence shown in SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number . In another embodiment,' an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a protein having an amino acid sequence which differs by at least 1, but no greater than 5, 10, 20, 50 or 100 amino acid residues from the amino acid sequence shown in SEQ ID NO:2, or the amino acid sequence encoded by the DNA insert of the plasmid deposited with the ATCC as Accession Number . In yet another embodiment, the nucleic acid molecule encodes the amino acid sequence of human COE-1. If an alignment is needed for this comparison, the sequences should be aligned for maximum homology. Nucleic acid variants can be naturally occurring, such as allelic variants (same locus), homologues (different locus), and orthologues (different organism) or can be non naturally occurring. Non-naturally occurring variants can be made by mutagenesis techniques, including those applied to polynucleotides, cells, or organisms. The variants can contain nucleotide substitutions, deletions, inversions and insertions. Variation can occur in either or both the coding and non-coding regions. The variations can produce both conservative and non-conservative amino acid substitutions (as compared in the encoded product). Allelic variants result, for example, from DNA sequence polymoφhisms within a population (e.g., the human population) that lead to changes in the amino acid sequences of the COE-1 proteins. Such genetic polymoφhism in the COE-1 genes may exist among individuals within a population due to natural allelic variation. As used herein, the terms "gene" and "recombinant gene" refer to nucleic acid molecules which include an open reading frame encoding a COE-1 protein, preferably a mammalian COE-1 protein, and can further include non-coding regulatory sequences, and introns. Accordingly, in one embodiment, the invention features isolated nucleic acid molecules which encode a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO:2, or an amino acid sequence encoded by the DNA insert of the plasmid deposited with ATCC as Accession Number , wherein the nucleic acid molecule hybridizes to a complement of a nucleic acid molecule comprising SEQ ID NO:l or 3, for example, under stringent hybridization conditions. Allelic variants of COE-1, e.g., human COE-1 include both functional and nonfunctional COE-1 proteins. Functional allelic variants are naturally occurring amino acid sequence variants of the COE-1 protein that maintain the ability to bind a COE-1 substrate or ligand, hydrolyze a COE-1 substrate, and/or modulate cellular signaling. Functional allelic variants will typically contain only conservative substitution of one or more amino acids of SEQ ID NO:2, or substitution, deletion or insertion of non-critical residues in non-critical regions of the protein. Non-functional allelic variants are naturally occurring amino acid sequence variants of the COE-1 protein, e.g., human COE-1, that do not have the ability to either bind a COE-1 substrate or ligand, hydrolyze a COE-1 substrate, or modulate cellular signaling. Non-functional allelic variants will typically contain a non-conservative substitution, a deletion, or insertion, or premature truncation of the amino acid sequence of SEQ ID NO:2, or a substitution, insertion, or deletion in critical residues or critical regions of the protein. The present invention further provides non-human orthologues (e.g. , non-human orthologues of the human COE-1 protein). Orthologues of the human COE-1 protein are proteins that are isolated from non-human organisms and possess the same COE-1 substrate or ligand binding mechanisms, carboxylesterase activity, and/or modulation of cellular signaling mechanisms of the human COE-1 protein. Orthologues of the human COE-1 protein can readily be identified as comprising an amino acid sequence that is substantially homologous to SEQ ID NO:2. Moreover, nucleic acid molecules encoding other COE-1 family members and, thus, which have a nucleotide sequence which differs from the COE-1 sequences of SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number are intended to be within the scope of the invention. For example, another COE-1 cDNA can be identified based on the nucleotide sequence of human COE-1. Moreover, nucleic acid molecules encoding COE-1 proteins from different species, and which, thus, have a nucleotide sequence which differs from the COE-1 sequences of SEQ ID NO:l or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number are intended to be within the scope of the invention. For example, a mouse or monkey COE-1 cDNA can be identified based on the nucleotide sequence of a human COE-1. Nucleic acid molecules corresponding to natural allelic variants and homologues of the COE-1 cDNAs of the invention can be isolated based on their homology to the COE-1 nucleic acids disclosed herein using the cDNAs disclosed herein, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions. Nucleic acid molecules corresponding to natural allelic variants and homologues of the COE-1 cDNAs of the invention can further be isolated by mapping to the same chromosome or locus as the COE-1 gene. Orthologues, homologues and allelic variants can be identified using methods known in the art (e.g., by hybridization to an isolated nucleic acid molecule of the present invention, for example, under stringent hybridization conditions). In one embodiment, an isolated nucleic acid molecule of the invention is at least 15, 20, 25, 30 or more nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number . In other embodiment, the nucleic acid is at least 50-100, 100-150, 150-200, 200-229, 229-250, 250-300, 300-350, 350-400, 400-450, 450-500, 500-550, 550-600, 600-650, 650-700, 700-750, 750-800, 800-850, 850-900, 900-950, 950-1000, 1000-1050, 1050-1100, 1100-1150, 1150-1200, 1200-1250, 1250-1300, 1300-1350, 1350-1400, 1400-1450, 1450-1500, 1500-1550, 1550-1600, 1600-1650, 1650-1700, 1700-1750, 1750-1800, 1800-1844, 1844-1850, 1850-1900, 1900-1950, 1950-2000, 2000-2050 or more nucleotides in length. As used herein, the term "hybridizes under stringent conditions" is intended to describe conditions for hybridization and washing under which nucleotide sequences . that are significantly identical or homologous to each other remain hybridized to each other. Preferably, the conditions are such that sequences at least about 70%, more preferably at least about 80%, even more preferably at least about 85% or 90% identical to each other remain hybridized to each other. Such stringent conditions are known to those skilled in the art and can be found in Current Protocols in Molecular Biology, Ausubel et al, eds., John Wiley & Sons, Inc. (1995), sections 2, 4 and 6. Additional stringent conditions can be found in Molecular Cloning: A Laboratory Manual, Sambrook et al, Cold Spring Harbor Press, Cold Spring Harbor, NY (1989), chapters 7, 9 and 11. A preferred, non-limiting example of stringent hybridization conditions includes hybridization in 4X or 6X sodium chloride/sodium citrate (SSC), at about 65- 70°C (or hybridization in 4X SSC plus 50% formamide at about 42-50°C) followed by one or more washes in IX SSC, at about 65-70°C. A further preferred, non-limiting example of stringent hybridization conditions includes hybridization at 6X SSC at 45°C, followed by one or more washes in 0.2X SSC, 0.1%) SDS at 65°C. A preferred, non- limiting example of highly stringent hybridization conditions includes hybridization in IX SSC, at about 65-70°C (or hybridization in IX SSC plus 50% formamide at about 42-50°C) followed by one or more washes in 0.3X SSC, at about 65-70°C. A preferred, non-limiting example of reduced stringency hybridization conditions includes hybridization in 4X or 6X SSC, at about 50-60°C (or alternatively hybridization in 6X SSC plus 50%) formamide at about 40-45°C) followed by one or more washes in 2X SSC, at about 50-60°C. Ranges intermediate to the above-recited values, e.g., at 65-70° C or at 42-50°C are also intended to be encompassed by the present invention. SSPE (lxSSPE is 0.15MNaCl, 10mMNaH 2 PO 4 , and 1.25mM EDTA, pH 7.4) can be substituted for SSC (lxSSC is 0T5M NaCl and 15mM sodium citrate) in the hybridization and wash buffers; washes are performed for 15 minutes each after hybridization is complete. The hybridization temperature for hybrids anticipated to be less than 50 base pairs in length should be 5-10°C less than the melting temperature (T m ) of the hybrid, where T m is determined according to the following equations. For hybrids less than 18 base pairs in length, T m (°C) = 2(# of A + T bases) + 4(# of G + C bases). For hybrids between 18 and 49 base pairs in length, T m (°C) = 81.5 + 16.6(log 10 [Na + ]) + 0.41 (%G+C) - (600/N), where N is the number of bases in the hybrid, and [Na "1" ] is the concentration of sodium ions in the hybridization buffer ([Na + ] for lxSSC = 0.165 M). It will also be recognized by the skilled practitioner that additional reagents may be added to hybridization and/or wash buffers to decrease non-specific hybridization of nucleic acid molecules to membranes, for example, nitrocellulose or nylon membranes, including but not limited to blocking agents (e.g., BSA or salmon or herring sperm carrier DNA), detergents (e.g., SDS), chelating agents (e.g., EDTA), Ficoll, PVP and the like. When using nylon membranes, in particular, an additional preferred, non-limiting example of stringent hybridization conditions is hybridization in 0.25-0.5M NaH 2 PO 4 , 7% SDS at about 65°C, followed by one or more washes at 0.02M NaH 2 PO 4 , 1% SDS at 65°C, see e.g., Church and Gilbert (1984) Proc. Natl. Acad. Sci. USA 81:1991-1995, (or alternatively 0.2X SSC, 1% SDS). Preferably, an isolated nucleic acid molecule of the invention that hybridizes under stringent conditions to the sequence of SEQ ID NOT or 3 corresponds to a naturally-occurring nucleic acid molecule. As used herein, a "naturally-occurring" nucleic acid molecule refers to an RNA or DNA molecule having a nucleotide sequence that occurs in nature (e.g., encodes a natural protein). In addition to naturally-occurring allelic variants of the COE-1 sequences that may exist in the population, the skilled artisan will further appreciate that changes can be introduced by mutation into the nucleotide sequences of SEQ ID NO: 1 or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , thereby leading to changes in the amino acid sequence of the encoded COE-1 proteins, without altering the functional ability of the COE-1 proteins. For example, nucleotide substitutions leading to amino acid substitutions at "non- essential" amino acid residues can be made in the sequence of SEQ ID NO: 1 or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number . A "non-essential" amino acid residue is a residue that can be altered from the wild-type sequence of COE-1 (e.g., the sequence of SEQ ID NO:2) without altering the biological activity, whereas an "essential" amino acid residue is required for biological activity. For example, amino acid residues that are conserved among the COE-1 proteins of the present invention, e.g., those present in a carboxylesterase domain, a catalytic triad, a catalytic serine, a catalytic histidine, a catalytic serine motif, a carboxylesterases type-B serine active site, and/or an ER retention signal, are predicted to be particularly unamenable to alteration. Furthermore, additional amino acid residues that are conserved between the COE-1 proteins of the present invention and other members of the carboxylesterase family are not likely to be amenable to alteration. Accordingly, another aspect of the invention pertains to nucleic acid molecules encoding COE-1 proteins that contain changes in amino acid residues that are not essential for activity. Such COE-1 proteins differ in amino acid sequence from SEQ ID NO:2, yet retain biological activity. In one embodiment, the isolated nucleic acid molecule comprises a nucleotide sequence encoding a protein, wherein the protein comprises an amino acid sequence at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 88%, 89%, 90%, 95%, 96%, 91%, 98% 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more homologous to SEQ ID NO:2, e.g., to the entire length of SEQ ID NO:2. An isolated nucleic acid molecule encoding a COE-1 protein homologous to the protein of SEQ ID NO:2 can be created by introducing one or more nucleotide substitutions, additions or deletions into the nucleotide sequence of SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , such that one or more amino acid substitutions, additions or deletions are introduced into the encoded protein. Mutations can be introduced into SEQ ID NOT or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number by standard techniques, such as site- directed mutagenesis and PCR-mediated mutagenesis. Preferably, conservative amino acid substitutions are made at one or more predicted non-essential amino acid residues. A "conservative amino acid substitution" is one in which the amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine, tryptophan), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Thus, a predicted nonessential amino acid residue in a COE-1 protein is preferably replaced with another amino acid residue from the same side chain family. Alternatively, in another embodiment, mutations can be introduced randomly along all or part of a COE-1 coding sequence, such as by saturation mutagenesis, and the resultant mutants can be screened for COE-1 biological activity to identify mutants that retain activity. Following mutagenesis of SEQ ID NO or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number , the encoded protein can be expressed recombinantly and the activity of the protein can be determined. In a preferred embodiment, a mutant COE-1 protein can be assayed for the ability to (i) interact with a COE-1 substrate or target molecule (e.g., a triglyceride); (ii) convert a COE-1 substrate or target molecule to a product (e.g. , hydrolyze an ester linkage and/or liberate the free acid form of the substrate, e.g., hydrolyze a triglyceride and/or liberate free fatty acid(s) and glycerol); (iii) modulate lipolysis; (iv) modulate lipid uptake by a cell (e.g., a liver cell); (v) modulate lipid synthesis and/or secretion; (vi) modulate intracellular lipid release and/or turnover; (vii) modulate intracellular lipid and/or triglyceride mass; (viii) modulate secreted lipid and/or triglyceride mass; (ix) modulate serum lipid, lipoprotein, and/or triglyceride levels; (x) modulate lipid homeostasis; (xi) direct or indirect modulation of lipoprotein assembly; (xii) interaction with and/or hydrolysis of a second non-COE-1 protein; (xiii) activation/deactivation of a COE-1 substrate or target molecule (e.g., activation/deactivation of a carcinogen); (xiv) metabolism and/or detoxification of a drag; (xv) modulation of cellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or (xvi) modulation of cellular proliferation and/or differentiation. In addition to the nucleic acid molecules encoding COE-1 proteins described above, another aspect of the invention pertains to isolated nucleic acid molecules which are antisense thereto. In an exemplary embodiment, the invention provides an isolated nucleic acid molecule which is antisense to a COE-1 nucleic acid molecule (e.g. , is antisense to the coding strand of a COE-1 nucleic acid molecule). An "antisense" nucleic acid comprises a nucleotide sequence which is complementary to a "sense" nucleic acid encoding a protein, e.g., complementary to the coding strand of a double- stranded cDNA molecule or complementary to an mRNA sequence. Accordingly, an antisense nucleic acid can hydrogen bond to a sense nucleic acid. The antisense nucleic acid can be complementary to an entire COE-1 coding strand, or to only a portion thereof. In one embodiment, an antisense nucleic acid molecule is antisense to "coding region sequences" of the coding strand of a nucleotide sequence encoding COE-1. The term "coding region sequences" refers to the region of the nucleotide sequence comprising codons which are translated into amino acid residues (e.g., the coding region sequences of human COE-1 corresponding to SEQ ID NO:3). In another embodiment, the antisense nucleic acid molecule is antisense to a "noncoding region" of the coding strand of a nucleotide sequence encoding COE-1. The term "noncoding region" refers to 5' and/or 3' sequences which flank the coding region sequences that are not translated into amino acids (also referred to as 5' and 3' untranslated regions). Given the coding strand sequences encoding COE-1 disclosed herein (e.g., SEQ ID NO:3), antisense nucleic acids of the invention can be designed according to the rules of Watson and Crick base pairing. The antisense nucleic acid molecule can be complementary to coding region sequences of COE-1 mRNA, but more preferably is an oligonucleotide which is antisense to only a portion of the COE-1 mRNA. An antisense oligonucleotide can be, for example, about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or more nucleotides in length. An antisense nucleic acid of the invention can be constracted using chemical synthesis and enzymatic ligation reactions using procedures known in the art. For example, an antisense nucleic acid (e.g., an antisense oligonucleotide) can be chemically synthesized using naturally occurring nucleotides or variously modified nucleotides designed to increase the biological stability of the molecules or to increase the physical stability of the duplex formed between the antisense and sense nucleic acids, e.g., phosphorothioate derivatives and acridine substituted nucleotides can be used. Examples of modified nucleotides which can be used to generate the antisense nucleic acid include 5-fluorouracil, 5-bromouracil, 5- chlorouracil, 5-iodouracil, hypoxanthine, xantine, 4-acetylcytosine, 5- (carboxyhydroxylmethyl) uracil, 5-carboxymethylaminomethyl-2-thiouridine, 5- carboxymethylaminomethyluracil, dihydrouracil, beta-D-galactosylqueosine, inosine, N6-isopentenyladenine, 1-methylguanine, 1-methylinosine, 2,2-dimethylguanine, 2- methyladenine, 2-methylguanine, 3-methylcytosine, 5-methylcytosine, N6-adenine, 7- methylguanine, 5-methylaminomethyluracil, 5-methoxyaminomethyl-2-thiouracil, beta- D-mannosylqueosine, 5 '-methoxycarboxymethyluracil, 5-methoxyuracil, 2-methylthio- N6-isopentenyladenine, uracil-5-oxyacetic acid (v), wybutoxosine, pseudouracil, queosine, 2-thiocytosine, 5-methyl-2-thiouracil, 2-thiouracil, 4-thiouracil, 5- methyluracil, uracil-5- oxyacetic acid methylester, uracil-5-oxyacetic acid (v), 5-methyl- 2-thiouracil, 3-(3-amino-3-N-2-carboxypropyl) uracil, (acp3)w, and 2,6-diaminopurine. Alternatively, the antisense nucleic acid can be produced biologically using an expression vector into which a nucleic acid has been subcloned in an antisense orientation (i.e., RNA transcribed from the inserted nucleic acid will be of an antisense orientation to a target nucleic acid of interest, described further in the following subsection). The antisense nucleic acid molecules of the invention are typically administered to a subject or generated in situ such that they hybridize with or bind to cellular mRNA and/or genomic DNA encoding a COE-1 protein to thereby inhibit expression of the protein, e.g., by inhibiting transcription and/or translation. The hybridization can be by conventional nucleotide complementarity to form a stable duplex, or, for example, in the case of an antisense nucleic acid molecule which binds to DNA duplexes, through specific interactions in the major groove of the double helix. An example of a route of administration of antisense nucleic acid molecules of the invention include direct injection at a tissue site. Alternatively, antisense nucleic acid molecules can be modified to target selected cells and then administered systemically. For example, for systemic administration, antisense molecules can be modified such that they specifically bind to receptors or antigens expressed on a selected cell surface, e.g., by linking the antisense nucleic acid molecules to peptides or antibodies which bind to cell surface receptors or antigens. The antisense nucleic acid molecules can also be delivered to cells using the vectors described herein. To achieve sufficient intracellular concentrations of the antisense molecules, vector constructs in which the antisense nucleic acid molecule is placed under the control of a strong pol II or pol III promoter are preferred. In yet another embodiment, the antisense nucleic acid molecule of the invention is an -anomeric nucleic acid molecule. An α-anomeric nucleic acid molecule forms specific double-stranded hybrids with complementary RNA in which, contrary to the usual β-units, the strands ran parallel to each other (Gaultier et al. (1987) Nucleic Acids Res. 15:6625-6641). The antisense nucleic acid molecule can also comprise a 2'-o- methylribonucleotide (Inoue et al. (1987) Nucleic Acids Res. 15:6131-6148) or a chimeric RNA-DNA analogue (Inoue et al. (1987) FEBSLett. 215:327-330). In still another embodiment, an antisense nucleic acid of the invention is a ribozyme. Ribozymes are catalytic RNA molecules with ribonuclease activity which are capable of cleaving a single-stranded nucleic acid, such as an mRNA, to which they have a complementary region. Thus, ribozymes (e.g., hammerhead ribozymes (described in Haseloff and Gerlach (1988) Nature 334:585-591)) can be used to catalytically cleave COE-1 mRNA transcripts to thereby inhibit translation of COE-1 mRNA. A ribozyme having specificity for a COE-1 -encoding nucleic acid can be designed based upon the nucleotide sequence of a COE-1 cDNA disclosed herein (i.e., SEQ ID NO or 3, or the nucleotide sequence of the DNA insert of the plasmid deposited with ATCC as Accession Number ). For example, a derivative of a Tetrahymena L-19 IVS RNA can be constracted in which the nucleotide sequence of the active site is complementary to the nucleotide sequence to be cleaved in a COE-1 - encoding mRNA. See, e.g. , Cech et al, U.S. Patent No. 4,987,071 ; and Cech et al, U.S. Patent No. 5,116,742. Alternatively, COE-1 mRNA can be used to select a catalytic RNA having a specific ribonuclease activity from a pool of RNA molecules. See, e.g., Bartel, D. and Szostak, J.W. (1993) Science 261:1411-1418. Alternatively, COE-1 gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the COE-1 (e.g., the COE-1 promoter and/or enhancers; e.g., nucleotides 1-221 of SEQ ID NOT) to form triple helical structures that prevent transcription of the COE-1 gene in target cells. See generally, Helene, C. (1991) Anticancer Drug Des. 6(6):569-84; Helene, C. et al. (1992) Ann. NY. Acad. Sci. 660:27-36; and Maher, L.J. (1992) Bioessays 14(12):807-15. In yet another embodiment, the COE-1 nucleic acid molecules of the present invention can be modified at the base moiety, sugar moiety or phosphate backbone to improve, e.g., the stability, hybridization, or solubility of the molecule. For example, the deoxyribose phosphate backbone of the nucleic acid molecules can be modified to generate peptide nucleic acids (see Hyrap, B. and Nielsen, P. E. (1996) Bioorg. Med. Chem. 4(l):5-23). As used herein, the terms "peptide nucleic acids" or "PNAs" refer to nucleic acid mimics, e.g., DNA mimics, in which the deoxyribose phosphate backbone is replaced by a pseudopeptide backbone and only the four natural nucleobases are retained. The neutral backbone of PNAs has been shown to allow for specific hybridization to DNA and RNA under conditions of low ionic strength. The synthesis of PNA oligomers can be performed using standard solid phase peptide synthesis protocols as described in Hyrap and Nielsen (1996) supra; Perry-O'Keefe et al. (1996) Proc. Natl. Acad. Sci. USA 93:14670-675. PNAs of COE-1 nucleic acid molecules can be used in therapeutic and diagnostic applications. For example, PNAs can be used as antisense or antigene agents for sequence-specific modulation of gene expression by, for example, inducing transcription or translation arrest or inhibiting replication. PNAs of COE-1 nucleic acid molecules can also be used in the analysis of single base pair mutations in a gene (e.g., by PNA-directed PCR clamping); as 'artificial restriction enzymes' when used in combination with other enzymes (e.g., SI nucleases (Hyrap and Nielsen (1996) supra)); or as probes or primers for DNA sequencing or hybridization (Hyrap and Nielsen (1996) supra; Perry-O'Keefe et al. (1996) supra). In another embodiment, PNAs of COE-1 can be modified (e.g., to enhance their stability or cellular uptake), by attaching lipophilic or other helper groups to PNA, by the formation of PNA-DNA chimeras, or by the use of liposomes or other techniques of drug delivery known in the art. For example, PNA-DNA chimeras of COE-1 nucleic acid molecules can be generated which may combine the advantageous properties of PNA and DNA. Such chimeras allow DNA recognition enzymes (e.g. , RNase H and DNA polymerases) to interact with the DNA portion while the PNA portion would - provide high binding affinity and specificity. PNA-DNA chimeras can be linked using linkers of appropriate lengths selected in terms of base stacking, number of bonds between the nucleobases, and orientation (Hyrap and Nielsen (1996) supra). The synthesis of PNA-DNA chimeras can be performed as described in Hyrap and Nielsen (1996) supra and Finn, P.J. et al. (1996) Nucleic Acids Res. 24 (17):3357-63. For example, a DNA chain can be synthesized on a solid support using standard phosphoramidite coupling chemistry and modified nucleoside analogs, e.g., 5 '-(4- methoxytrityl)amino-5'-deoxy-thymidine phosphoramidite, can be used as a between the PNA and the 5' end of DNA (Mag, M. et al. (1989) Nucleic Acids Res. 17:5973-88). PNA monomers are then coupled in a stepwise manner to produce a chimeric molecule with a 5' PNA segment and a 3' DNA segment (Finn, P.J. et al. (1996) supra). Alternatively, chimeric molecules can be synthesized with a 5' DNA segment and a 3' PNA segment (Peterser, K.H. et al. (1975) Bioorganic Med. Chem. Lett. 5:1119-11124). In other embodiments, the oligonucleotide may include other appended groups such as peptides (e.g., for targeting host cell receptors in vivo), or agents facilitating transport across the cell membrane (see, e.g., Letsinger et al. (1989) Proc. Natl. Acad. Sci. USA 86:6553-6556; Lemaitre et al. (1987) Proc. Natl. Acad. Sci. USA 84:648-652; PCT Publication No. WO 88/09810) or the blood-brain barrier (see, e.g. , PCT Publication No. WO 89/10134). In addition, oligonucleotides can be modified with hybridization-triggered cleavage agents (See, e.g., Krol et al. (1988) f Bio-Techniques 6:958-976) or intercalating agents (See, e.g., Zon (1988) Pharm. Res. 5:539-549). To this end, the oligonucleotide may be conjugated to another molecule (e.g., a peptide, hybridization triggered cross-linking agent, transport agent, or hybridization-triggered cleavage agent). II. Isolated COE-1 Proteins and Anti-COE-1 Antibodies One aspect of the invention pertains to isolated or recombinant COE-1 proteins and polypeptides, and biologically active portions thereof, as well as polypeptide fragments suitable for use as immunogens to raise anti-COE-1 antibodies. In one embodiment, native COE-1 proteins can be isolated from cells or tissue sources by an appropriate purification scheme using standard protein purification techniques. In another embodiment, COE-1 proteins are produced by recombinant DNA techniques. Alternative to recombinant expression, a COE-1 protein or polypeptide can be synthesized chemically using standard peptide synthesis techniques. An "isolated" or "purified" protein or biologically active portion thereof is substantially free of cellular material or other contaminating proteins from the cell or tissue source from which the COE-1 protein is derived, or substantially free from chemical precursors or other chemicals when chemically synthesized. The language "substantially free of cellular material" includes preparations of COE-1 protein in which the protein is separated from cellular components of the cells from which it is isolated or recombinantly produced. In one embodiment, the language 1 "substantially free of cellular material" includes preparations of COE-1 protein having less than about 30% (by dry weight) of non-COE-1 protein (also referred to herein as a "contaminating protein"), more preferably less than about 20%> of non-COE-1 protein, still more preferably less than about 10% of non-COE-1 protein, and most preferably less than about 5% non-COE-1 protein. When the COE-1 protein or biologically active portion thereof is recombinantly produced, it is also preferably substantially free of culture medium, i.e., culture medium represents less than about 20%, more preferably less than about 10%, and most preferably less than about 5%> of the volume of the protein preparation. The language "substantially free of chemical precursors or other chemicals" includes preparations of COE-1 protein in which the protein is separated from chemical precursors or other chemicals which are involved in the synthesis of the protein. In one embodiment, the language "substantially free of chemical precursors or other chemicals" includes preparations of COE-1 protein having less than about 30% (by dry weight) of chemical precursors or non-COE-1 chemicals, more preferably less than about 20%> chemical precursors or non-COE-1 chemicals, still more preferably less than about 10%> chemical precursors or non-COE-1 chemicals, and most preferably less than about 5%> chemical precursors or non-COE-1 chemicals. As used herein, a "biologically active portion" of a COE-1 protein includes a fragment of a COE-1 protein which participates in an interaction between a COE-1 molecule and a non-COE-1 molecule (e.g., a COE-1 substrate). Biologically active portions of a COE-1 protein include peptides comprising amino acid sequences sufficiently homologous to or derived from the COE-1 amino acid sequences, e.g., the amino acid sequences shown in SEQ ID NO:2, which include sufficient amino acid residues to exhibit at least one activity of a COE-1 protein. Typically, biologically active portions comprise a domain or motif with at least one activity of the COE-1 protein, e.g., carboxylesterase activity, lipolytic activity, and/or modulation of lipid homeostasis. A biologically active portion of a COE-1 protein can be a polypeptide which is, for example, 10, 25, 50, 75, 100, 125, 150, 175, 200, 250, 300, 350, 400, 450, 500 or more amino acids in length. Biologically active portions of a COE-1 protein can be used as targets for developing agents which modulate a COE-1 mediated activity, e.g., carboxylesterase activity, lipolytic activity, and/or modulation of lipid homeostasis. In one embodiment, a biologically active portion of a COE-1 protein comprises at least one or more of the following domains, motifs, and/or amino acid residues: a carboxylesterase domain, a catalytic triad, a catalytic serine, a catalytic histidine, a catalytic serine motif, a carboxylesterases type-B serine active site, and/or an ER retention signal. Moreover, other biologically active portions, in which other regions of the protein are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native COE-1 protein. Another aspect of the invention features fragments of the protein having the amino acid sequence of SEQ ID NO:2, for example, for use as immunogens. In one embodiment, a fragment comprises at least 5 amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:2, or an amino acid sequence encoded by the DNA insert of the plasmid deposited with the ATCC as Accession Number . In another embodiment, a fragment comprises at least 10, 15, 20, 25, 30, 35, 40, 45, 50 or more amino acids (e.g., contiguous or consecutive amino acids) of the amino acid sequence of SEQ ID NO:2, or an amino acid sequence encoded by the DNA insert of the plasmid deposited with the ATCC as Accession Number In a preferred embodiment, a COE-1 protein has an amino acid sequence shown in SEQ ID NO:2. In other embodiments, the COE-1 protein is substantially identical to SEQ ID NO:2, and retains the functional activity of the protein of SEQ ID NO:2, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail in subsection I above. In another embodiment, the COE-1 protein is a protein which comprises an amino acid sequence at least about 50%), 55%), 60%>, 65%o, 70%, 75%, 80%, 85%, 88%, 89%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to SEQ ID NO:2. In another embodiment, the invention features a COE-1 protein which is encoded by a nucleic acid molecule consisting of a nucleotide sequence at least about 50%>, 55%», 60%, 65%, 70%, 75%, 80%, 85%, 88%, 89%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or more identical to a nucleotide sequence of SEQ ID NO: 1 or 3, or a complement thereof. This invention further features a COE-1 protein which is encoded by a nucleic acid molecule consisting of a nucleotide sequence which hybridizes under stringent hybridization conditions to a complement of a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NOT or 3, or a complement thereof. To determine the percent identity of two amino acid sequences or of two nucleic acid sequences, the sequences are aligned for optimal comparison puφoses (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-homologous sequences can be disregarded for comparison puφoses). In a preferred embodiment, the length of a reference sequence aligned for comparison puφoses is at least 30%>, preferably at least 40%, more preferably at least 50%>, even more preferably at least 60%>, and even more preferably at least 70%, 80%>, or 90% of the length of the reference sequence (e.g., when aligning a second sequence to the COE-1 amino acid sequence of SEQ ID NO:2 having 547 amino acid residues, at least 274, preferably at least 329, more preferably at least 383, even more preferably at least 438, and even more preferably at least 493, 520 or 542 amino acid residues are aligned). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid "identity" is equivalent to amino acid or nucleic acid "homology"). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences. The comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm. In a preferred embodiment, the percent identity between two amino acid sequences is determined using the Needleman and Wunsch (J Mol. Biol. (48):444-453 (1970)) algorithm which has been incoφorated into the GAP program in the GCG software package (available online through the Genetics Computer Group), using either a Blossum 62 matrix or a PAM250 matrix, and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5, or 6. In yet another preferred embodiment, the percent identity between two nucleotide sequences is determined using the GAP program in the GCG software package (available online through the Genetics Computer Group), using a NWSgapdna.CMP matrix and a gap weight of 40, 50, 60, 70, or 80 and a length weight of 1, 2, 3, 4, 5, or 6. A preferred, non-limiting example of parameters to be used in conjunction with the GAP program include a Blosum 62 scoring matrix with a gap penalty of 12, a gap extend penalty of 4, and a frameshift gap penalty of 5. In another embodiment, the percent identity between two amino acid or nucleotide sequences is determined using the algorithm of Meyers and Miller (Comput. Appl Biosci. 4:11-17 (1988)) which has been incoφorated into the ALIGN program (version 2.0 or version 2.0U), using a PAM120 weight residue table, a gap length penalty of 12 and a gap penalty of 4. The nucleic acid and protein sequences of the present invention can further be used as a "query sequence" to perform a search against public databases to, for example, identify other family members or related sequences. Such searches can be performed using the NBLAST and XBLAST programs (version 2.0) of Altschul et al. (1990) J Mol. Biol 215:403-10. BLAST nucleotide searches can be performed with the NBLAST program, score = 100, wordlength = 12 to obtain nucleotide sequences homologous to COE-1 nucleic acid molecules of the invention. BLAST protein searches can be performed with the XBLAST program, score = 50, wordlength = 3 to obtain amino acid sequences homologous to COE-1 protein molecules of the invention. To obtain gapped alignments for comparison puφoses, Gapped BLAST can be utilized as described in Altschul et al. (1997) Nucleic Acids Res. 25(17):3389-3402. When utilizing BLAST and Gapped BLAST programs, the default parameters of the respective programs (e.g. , XBLAST and NBLAST) can be used. See the internet website for the National Center for Biotechnology Information. The invention also provides COE-1 chimeric or fusion proteins. As used herein, a COE-1 "chimeric protem" or "fusion protem" comprises a COE-1 polypeptide operatively linked to a non-COE-1 polypeptide. A "COE-1 polypeptide" refers to a polypeptide having an amino acid sequence corresponding to COE-1, whereas a "non- COE-1 polypeptide" refers to a polypeptide having an amino acid sequence corresponding to a protein which is not substantially homologous to the COE-1 protein, e.g., a protein which is different from the COE-1 protein and which is derived from the same or a different organism. Within a COE-1 fusion protein the COE-1 polypeptide can correspond to all or a portion of a COE-1 protein. In a preferred embodiment, a COE-1 fusion protein comprises at least one biologically active portion of a COE-1 protein. In another preferred embodiment, a COE-1 fusion protein comprises at least two biologically active portions of a COE-1 protein. Within the fusion protein, the term "operatively linked" is intended to indicate that the COE-1 polypeptide and the non- COE-1 polypeptide are fused in-frame to each other. The non-COE-1 polypeptide can be fused to the N-terminus or C-terminus of the COE-1 polypeptide. For example, in one embodiment, the fusion protein is a GST-COE-1 fusion protein in which the COE-1 sequences are fused to the C-terminus of the GST sequences. Such fusion proteins can facilitate the purification of recombinant COE-1. In another embodiment, the fusion protein is a COE-1 protem containing a heterologous signal sequence at its N-terminus. In certain host cells (e.g. , mammalian host cells), expression and/or secretion of COE-1 can be increased through use of a heterologous signal sequence. The COE-1 fusion proteins of the invention can be incoφorated into pharmaceutical compositions and administered to a subject in vivo. The COE-1 fusion proteins can be used to affect the bioavailability of a COE-1 substrate. Use of COE-1 fusion proteins may be useful therapeutically for the treatment of disorders caused by, for example, (i) aberrant modification or mutation of a gene encoding a COE-1 protein; (ii) mis-regulation of the COE-1 gene; and (iii) aberrant post-translational modification of a COE- 1 protein. Moreover, the COE-1 -fusion proteins of the invention can be used as immunogens to produce anti-COE-1 antibodies in a subject, to purify COE-1 ligands, and in screening assays to identify molecules which inhibit the interaction of COE-1 with a COE-1 substrate. Preferably, a COE-1 chimeric or fusion protein of the invention is produced by standard recombinant DNA techniques. For example, DNA fragments coding for the different polypeptide sequences are ligated together in-frame in accordance with conventional techniques, for example by employing blunt-ended or stagger-ended termini for ligation, restriction enzyme digestion to provide for appropriate termini, filling-in of cohesive ends as appropriate, alkaline phosphatase treatment to avoid undesirable joining, and enzymatic ligation. In another embodiment, the fusion gene can be synthesized by conventional techniques including automated DNA synthesizers. Alternatively, PCR amplification of gene fragments can be carried out using anchor primers which give rise to complementary overhangs between two consecutive gene fragments which can subsequently be annealed and reamplified to generate a chimeric gene sequence (see, for example, Current Protocols in Molecular Biology, eds. Ausubel et al. John Wiley & Sons:1992). Moreover, many expression vectors are commercially available that already encode a fusion moiety (e.g., a GST polypeptide). A COE-1 - encoding nucleic acid can be cloned into such an expression vector such that the fusion moiety is linked in-frame to the COE-1 protein. The present invention also pertains to variants of the COE-1 proteins which function as either COE-1 agonists (mimetics) or as COE-1 antagonists. Variants of the COE-1 proteins can be generated by mutagenesis, e.g., discrete point mutation or truncation of a COE-1 protein. An agonist of the COE-1 proteins can retain substantially the same, or a subset, of the biological activities of the naturally occurring form of a COE-1 protein. An antagonist of a COE-1 protein can inhibit one or more of the activities of the naturally occurring form of the COE-1 protein by, for example, competitively modulating a COE-1 -mediated activity of a COE-1 protein. Thus, specific biological effects can be elicited by treatment with a variant of limited function. In one embodiment, treatment of a subject with a variant having a subset of the biological activities of the naturally occurring form of the protein has fewer side effects in a subject relative to treatment with the naturally occurring form of the COE-1 protein. In one embodiment, variants of a COE-1 protein which function as either COE-1 agonists (mimetics) or as COE-1 antagonists can be identified by screening combinatorial libraries of mutants, e.g., trancation mutants, of a COE-1 protein for COE-1 protein agonist or antagonist activity. In one embodiment, a variegated library of COE-1 variants is generated by combinatorial mutagenesis at the nucleic acid level and is encoded by a variegated gene library. A variegated library of COE-1 variants can be produced by, for example, enzymatically ligating a mixture of synthetic oligonucleotides into gene sequences such that a degenerate set of potential COE-1 sequences is expressible as individual polypeptides, or alternatively, as a set of larger fusion proteins (e.g., for phage display) containing the set of COE-1 sequences therein. There are a variety of methods which can be used to produce libraries of potential COE- 1 variants from a degenerate oligonucleotide sequence. Chemical synthesis of a degenerate gene sequence can be performed in an automatic DNA synthesizer, and the synthetic gene then ligated into an appropriate expression vector. Use of a degenerate set of genes allows for the provision, in one mixture, of all of the sequences encoding the desired set of potential COE-1 sequences. Methods for synthesizing degenerate oligonucleotides are known in the art (see, e.g., Narang, S.A. (1983) Tetrahedron 39:3; Itakura et al. (1984) Annu. Rev. Biochem. 53:323; Itakura et al. (1984) Science 198:1056; Ike et al. (1983) Nucleic Acids Res. 11:477. In addition, libraries of fragments of a COE-1 protein coding sequence can be used to generate a variegated population of COE-1 fragments for screening and subsequent selection of variants of a COE-1 protein. In one embodiment, a library of coding sequence fragments can be generated by treating a double stranded PCR fragment of a COE-1 coding sequence with a nuclease under conditions wherein nicking occurs only about once per molecule, denaturing the double stranded DNA, renaturing the DNA to form double stranded DNA which can include sense/antisense pairs from different nicked products, removing single stranded portions from refoπned duplexes by treatment with SI nuclease, and ligating the resulting fragment library into an expression vector. By this method, an expression library can be derived which encodes N-terminal, C-terminal and internal fragments of various sizes of the COE-1 protein. Several techniques are known in the art for screening gene products of combinatorial libraries made by point mutations or truncation, and for screening cDNA libraries for gene products having a selected property. Such techniques are adaptable for rapid screening of the gene libraries generated by the combinatorial mutagenesis of COE-1 proteins. The most widely used techniques, which are amenable to high through-put analysis, for screening large gene libraries typically include cloning the gene library into replicable expression vectors, transforming appropriate cells with the resulting library of vectors, and expressing the combinatorial genes under conditions in which detection of a desired activity facilitates isolation of the vector encoding the gene whose product was detected. Recursive ensemble mutagenesis (REM), a new technique which enhances the frequency of functional mutants in the libraries, can be used in combination with the screening assays to identify COE-1 variants (Arkin and Youvan (1992) Proc. Natl. Acad. Sci. USA 89:7811-7815; Delagrave et al. (1993) Protein Eng. 6(3):327-331). In one embodiment, cell based assays can be exploited to analyze a variegated COE-1 library. For example, a library of expression vectors can be transfected into a cell line, e.g., a liver cell line, which ordinarily responds to COE-1 in a particular COE-1 substrate-dependent manner. The transfected cells are then contacted with COE-1 and the effect of the expression of the mutant on signaling by the COE-1 substrate can be detected, e.g., by measuring levels of triglyceride and/or free fatty acid(s), gene transcription, and/or cell growth and differentiation. Plasmid DNA can then be recovered from the cells which score for inhibition, or alternatively, potentiation of signaling by the COE-1 substrate, and the individual clones further characterized. An isolated COE-1 protein, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind COE-1 using standard techniques for polyclonal and monoclonal antibody preparation. A full-length COE-1 protein can be used or, alternatively, the invention provides antigenic peptide fragments of COE-1 for use as immunogens. The antigenic peptide of COE-1 comprises at least 8 amino acid residues of the amino acid sequence shown in SEQ ID NO:2 and encompasses an epitope of COE-1 such that an antibody raised against the peptide forms a specific immune complex with COE-1. Preferably, the antigenic peptide comprises at least 10 amino acid residues, more preferably at least 15 amino acid residues, even more preferably at least 20 amino acid residues, and most preferably at least 30 amino acid residues. Preferred epitopes encompassed by the antigenic peptide are regions of COE-1 that are located on the surface of the protein, e.g., hydrophilic regions, as well as regions with high antigenicity (see, for example, Figure 6). A COE-1 immunogen typically is used to prepare antibodies by immunizing a suitable subject (e.g., rabbit, goat, mouse, or other mammal) with the immunogen. An appropriate immunogenic preparation can contain, for example, recombinantly expressed COE-1 protein or a chemically-synthesized COE-1 polypeptide. The preparation can further include an adjuvant, such as Freund's complete or incomplete adjuvant, or similar immunostimulatory agent. Immunization of a suitable subject with an immunogenic COE-1 preparation induces a polyclonal anti-COE-1 antibody response. Accordingly, another aspect of the invention pertains to anti-COE-1 antibodies. The term "antibody" as used herein refers to immunoglobulin molecules and immunologically active portions of immunoglobulin molecules, i.e., molecules that contain an antigen binding site which specifically binds (immunoreacts with) an antigen, such as COE-1. Examples of immunologically active portions of immunoglobulin molecules include F(ab) and F(ab')2 fragments which can be generated by treating the antibody with an enzyme such as pepsin. The invention provides polyclonal and monoclonal antibodies that bind COE-1. The term "monoclonal antibody" or "monoclonal antibody composition", as used herein, refers to a population of antibody molecules that contain only one species of an antigen binding site capable of immunoreacting with a particular epitope of COE-1. A monoclonal antibody composition thus typically displays a single binding affinity for a particular COE-1 protein with which it immunoreacts. Polyclonal anti-COE-1 antibodies can be prepared as described above by immunizing a suitable subject with a COE-1 immunogen. The anti-COE-1 antibody titer in the immunized subject can be monitored over time by standard techniques, such as with an enzyme linked immunosorbent assay (ELISA) using immobilized COE-1. If desired, the antibody molecules directed against COE-1 can be isolated from the mammal (e.g., from the blood) and further purified by well known techniques, such as protein A chromatography to obtain the IgG fraction. At an appropriate time after immunization, e.g., when the anti-COE-1 antibody titers are highest, antibody-producing cells can be obtained from the subject and used to prepare monoclonal antibodies by standard techniques, such as the hybridoma technique originally described by Kohler and Milstein (1975) Nature 256:495-497 (see also Brown et al. (1981) J Immunol. 127:539-46; Brown et al. (1980) J. Biol Chem. 255:4980-83; Yeh et al. (1976) Proc. Natl. Acad. Sci. USA 76:2927-31; and Yeh et al. (1982) Int. J. Cancer 29:269-75), the more recent human B cell hybridoma technique (Kozbor et al. (1983) Immunol. Today 4:72), the EBV-hybridoma technique (Cole et al. (1985), Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, Inc., pp. 77-96) or trioma techniques. The technology for producing monoclonal antibody hybridomas is well known (see generally Kenneth, R.H. in Monoclonal Antibodies: A New Dimension In Biological Analyses, Plenum Publishing Coφ., New York, New York (1980); Lerner, E.A. (1981) Yale J. Biol. Med. 54:387-402; Gefter, M.L. et al. (1977) Somatic Cell Genet. 3:231-36). Briefly, an immortal cell line (typically a myeloma) is fused to lymphocytes (typically splenocytes) from a mammal immunized with a COE-1 immunogen as described above, and the culture supernatants of the resulting hybridoma cells are screened to identify a hybridoma producing a monoclonal antibody that binds COE-1. Any of the many well known protocols used for fusing lymphocytes and immortalized cell lines can be applied for the puφose of generating an anti-COE-1 monoclonal antibody (see, e.g., Galfre, G. et al. (1977) Nature 266:55052; Gefter et al. (1977) supra; Lerner (1981) supra; Kenneth (1980) supra). Moreover, the ordinarily skilled worker will appreciate that there are many variations of such methods which also would be useful. Typically, the immortal cell line (e.g., a myeloma cell line) is derived from the same mammalian species as the lymphocytes. For example, murine hybridomas can be made by fusing lymphocytes from a mouse immunized with an immunogenic preparation of the present invention with an immortalized mouse cell line. Preferred immortal cell lines are mouse myeloma cell lines that are sensitive to culture medium containing hypoxanthine, aminopterin and thymidine ("HAT medium"). Any of a number of myeloma cell lines can be used as a fusion partner according to standard techniques, e.g. , the P3-NS 1/1 -Ag4-1 , P3-x63-Ag8.653 or Sp2/O-Agl4 myeloma lines. These myeloma lines are available from ATCC. Typically, HAT-sensitive mouse myeloma cells are fused to mouse splenocytes using polyethylene glycol ("PEG"). Hybridoma cells resulting from the fusion are then selected using HAT medium, which kills unfused and unproductively fused myeloma cells (unfused splenocytes die after several days because they are not transformed). Hybridoma cells producing a monoclonal antibody of the invention are detected by screening the hybridoma culture supernatants for antibodies that bind COE-1, e.g., using a standard ELISA assay. Alternative to preparing monoclonal antibody-secreting hybridomas, a monoclonal anti-COE-1 antibody can be identified and isolated by screening a recombinant combinatorial immunoglobulin library (e.g. , an antibody phage display library) with COE-1 to thereby isolate immunoglobulin library members that bind COE- 1. Kits for generating and screening phage display libraries are commercially available (e.g., the Pharmacia Recombinant Phage Antibody System, Catalog No. 27-9400-01 ; and the Stratagene SurfZAP™ Phage Display Kit, Catalog No. 240612). Additionally, examples of methods and reagents particularly amenable for use in generating and screening antibody display library can be found in, for example, Ladner et al., U.S. Patent No. 5,223,409; Kang et al, PCT International Publication No. WO 92/18619; Dower et al, PCT International Publication No. WO 91/17271; Winter et al, PCT International Publication WO 92/20791; Markland et al, PCT International Publication No. WO 92/15679; Breitling et al, PCT International Publication WO 93/01288; McCafferty et al., PCT International Publication No. WO 92/01047; Garrard et al, PCT International Publication No. WO 92/09690; Ladner et al, PCT International Publication No. WO 90/02809; Fuchs et al. (1991) Biotechnology (NY) 9:1369-1372; Hay et al. (1992) Hum. Antibod. Hybridomas 3:81-85; Huse et al. (1989) Science 246:1275-1281; Griffiths et al. (1993) EMBO J. 12:725-734; Hawkins et al. (1992) J Mol. Biol 226:889-896; Clackson et al. (1991) Nature 352:624-628; Gram et al. (1992) Proc. Natl. Acad. Sci. USA 89:3576-3580; Garrard et al. (1991) Biotechnology (NY) 9:1373-1377; Hoogenboom et al. (1991) Nucleic Acids Res. 19:4133-4137; Barbas et al. (1991) Proc. Natl. Acad. Sci. USA 88:7978-7982; and McCafferty et al. (1990) Nature 348:552-554. Additionally, recombinant anti-COE-1 antibodies, such as chimeric and humanized monoclonal antibodies, comprising both human and non-human portions, which can be made using standard recombinant DNA techniques, are within the scope of the invention. Such chimeric and humanized monoclonal antibodies can be produced by recombinant DNA techniques known in the art, for example using methods described in Robinson et al, International Application No. PCT/US86/02269; Akira et al., European Patent Application 184,187; Taniguchi, M., European Patent Application 171,496; Morrison et al., European Patent Application 173,494; Neuberger et al, PCT International Publication No. WO 86/01533; Cabilly et al., U.S. Patent No. 4,816,567; Cabilly et al., European Patent Application 125,023; Better et al. (1988) Science 240:1041-1043; Liu et al. (1987) Proc. Natl. Acad. Sci. USA 84:3439-3443; Liu et al. (1987) J. Immunol 139:3521-3526; Sun et al. (1987) Proc. Natl. Acad. Sci. USA 84:214-218; Nishimura et al. (1987) Cancer Res. 47:999-1005; Wood et al. (1985) Nature 314:446-449; and Shaw et α/. (19S8) J. Natl Cancer Inst. 80:1553-1559); Morrison, S.L. (1985) Science 229:1202-1207; Oi et al. (1986) Biotechniques 4:214; Winter, U.S. Patent 5,225,539; Jones et al. (1986) Nature 321:552-525; Verhoeyen et al. (1988) Science 239:1534; and Beidler et al. (1988) J. Immunol. 141 :4053-4060. An anti-COE-1 antibody (e.g. , monoclonal antibody) can be used to isolate COE-1 by standard techniques, such as affinity chromatography or immunoprecipitation. An anti-COE-1 antibody can facilitate the purification of natural COE-1 from cells and of recombinantly produced COE-1 expressed in host cells. Moreover, an anti-COE-1 antibody can be used to detect COE-1 protein (e.g., in a cellular lysate or cell supernatant) in order to evaluate the abundance and pattern of expression of the COE-1 protein. Anti-COE-1 antibodies can be used diagnostically to monitor protein levels in tissue as part of a clinical testing procedure, e.g., to, for example, determine the efficacy of a given treatment regimen. Detection can be facilitated by coupling (i.e., physically linking) the antibody to a detectable substance. Examples of detectable substances include various enzymes, prosthetic groups, fluorescent materials, luminescent materials, bioluminescent materials, and radioactive materials. Examples of suitable enzymes include horseradish peroxidase, alkaline phosphatase, β-galactosidase, or acetylcholinesterase; examples of suitable prosthetic group complexes include streptavidin/biotin and avidin/biotin; examples of suitable fluorescent materials include umbelliferone, fluorescein, fluorescein isothiocyanate, ■ rhodamine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; an example of a luminescent material includes luminol; examples of bioluminescent materials include luciferase, luciferin, and aequorin, and examples of suitable 175 1 ^1 35 ^ radioactive material include I, I, S or H. III. Recombinant Expression Vectors and Host Cells Another aspect of the invention pertains to vectors, for example recombinant expression vectors, containing a COE-1 nucleic acid molecule or vectors containing a nucleic acid molecule which encodes a COE-1 protein (or a portion thereof). As used herein, the term "vector" refers to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. One type of vector is a "plasmid", which refers to a circular double stranded DNA loop into which additional DNA segments can be ligated. Another type of vector is a viral vector, wherein additional DNA segments can be ligated into the viral genome. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (e.g., non-episomal mammalian vectors) are integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. Moreover, certain vectors are capable of directing the expression of genes to which they are operatively linked. Such vectors are referred to herein as "expression vectors". In general, expression vectors of utility in recombinant DNA techniques are often in the form of plasmids. In the present specification, "plasmid" and "vector" can be used interchangeably as the plasmid is the most commonly used form of vector. However, the invention is intended to include such other forms of expression vectors, such as viral vectors (e.g., replication defective retro viruses, adeno viruses and adeno- associated viruses), which serve equivalent functions. The recombinant expression vectors of the invention comprise a nucleic acid of the invention in a form suitable for expression of the nucleic acid in a host cell, which means that the recombinant expression vectors include one or more regulatory sequences, selected on the basis of the host cells to be used for expression, which is operatively linked to the nucleic acid sequence to be expressed. Within a recombinant expression vector, "operably linked" is intended to mean that the nucleotide sequence of interest is linked to the regulatory sequence(s) in a manner which allows for expression of the nucleotide sequence (e.g., in an in vitro transcription/translation system or in a host cell when the vector is introduced into the host cell). The term "regulatory sequence" is intended to include promoters, enhancers and other expression control elements (e.g., polyadenylation signals). Such regulatory sequences are described, for example, in Goeddel (1990) Methods Enzymol. 185:3-7. Regulatory sequences include those which direct constitutive expression of a nucleotide sequence in many types of host cells and those which direct expression of the nucleotide sequence only in certain host cells (e.g., tissue-specific regulatory sequences). It will be appreciated by those skilled in the art that the design of the expression vector can depend on such factors as the choice of the host cell to be transformed, the level of expression of protein desired, and the like. The expression vectors of the invention can be introduced into host cells to thereby produce proteins or peptides, including fusion proteins or peptides, encoded by nucleic acids as described herein (e.g., COE-1 proteins, mutant forms of COE-1 proteins, fusion proteins, and the like). Accordingly, an exemplary embodiment provides a method for producing a protein, preferably a COE-1 protein, by culturing in a suitable medium a host cell of the invention (e.g., a mammalian host cell such as a non-human mammalian cell) containing a recombinant expression vector, such that the protein is produced. The recombinant expression vectors of the invention can be designed for expression of COE-1 proteins in prokaryotic or eukaryotic cells. For example, COE-1 proteins can be expressed in bacterial cells such as E. coli, insect cells (using baculoviras expression vectors) yeast cells or mammalian cells. Suitable host cells are discussed further in Goeddel (1990) supra. Alternatively, the recombinant expression vector can be transcribed and translated in vitro, for example using T7 promoter regulatory sequences and T7 polymerase. Expression of proteins in prokaryotes is most often carried out in E. coli with vectors containing constitutive or inducible promoters directing the expression of either fusion or non-fusion proteins. Fusion vectors add a number of amino acids to a protein encoded therein, usually to the amino terminus of the recombinant protein. Such fusion vectors typically serve three puφoses: 1) to increase expression of recombinant protein; 2) to increase the solubility of the recombinant protein; and 3) to aid in the purification of the recombinant protein by acting as a ligand in affinity purification. Often, in fusion expression vectors, a proteolytic cleavage site is introduced at the junction of the fusion moiety and the recombinant protein to enable separation of the recombinant protein from the fusion moiety subsequent to purification of the fusion protein. Such enzymes, and their cognate recognition sequences, include Factor Xa, thrombin and enterokinase. Typical fusion expression vectors include pGEX (Pharmacia Biotech lnc; Smith, D.B. and Johnson, K.S. (1988) Gene 67:31-40), pMAL (New England Biolabs, Beverly, MA) and pRIT5 (Pharmacia, Piscataway, NJ) which fuse glutathione S-transferase (GST), maltose E binding protein, or protein A, respectively, to the target recombinant protein. Purified fusion proteins can be utilized in COE-1 activity assays (e.g., direct assays or competitive assays described in detail below), or to generate antibodies specific for COE-1 proteins, for example. In a preferred embodiment, a COE-1 fusion protein expressed in a retro viral expression vector of the present invention can be utilized to infect bone marrow cells, which are subsequently transplanted into irradiated recipients. The pathology of the subject recipient is then examined after sufficient time has passed (e.g., six (6) weeks). Examples of suitable inducible non-fusion E. coli expression vectors include pTrc (Amann et al. (1988) Gene 69:301-315) and pET 1 Id (Studier et al. (1990) Methods Enzymol 185:60-89). Target gene expression from the pTrc vector relies on host RNA polymerase transcription from a hybrid tφ-lac fusion promoter. Target gene expression from the pET l id vector relies on transcription from a T7 gnlO-lac fusion promoter mediated by a coexpressed viral RNA polymerase (T7 gnl). This viral polymerase is supplied by host strains BL21(DE3) or HMS174(DE3) from a resident prophage harboring a T7 gnl gene under the transcriptional control of the lacUV 5 promoter. One strategy to maximize recombinant protein expression in E. coli is to express the protein in a host bacteria with an impaired capacity to proteolytically cleave the recombinant protein (Gottesman, S. (1990) Methods Enzymol. 185:119-128). Another strategy is to alter the nucleic acid sequence of the nucleic acid to be inserted into an expression vector so that the individual codons for each amino acid are those preferentially utilized in E. coli (Wada et al. (1992) Nucleic Acids Res. 20:2111-2118). Such alteration of nucleic acid sequences of the invention can be carried out by standard DNA synthesis techniques. In another embodiment, the COE-1 expression vector is a yeast expression vector. Examples of vectors for expression in yeast S. cerivisae include pYepSecl (Baldari et al. (1987) EMBOJ. 6:229-234), pMFa (Kurjan and Herskowitz (1982) Cell 30:933-943), pJRY88 (Schultz et al. (1987) Gene 54:113-123), pYES2 (Invitrogen Coφoration, San Diego, CA), and picZ (Invitrogen Coφ., San Diego, CA). Alternatively, COE-1 proteins can be expressed in insect cells using baculoviras expression vectors. Baculoviras vectors available for expression of proteins in cultured insect cells (e.g., Sf 9 cells) include the pAc series (Smith et al. (1983) Mol. Cell Biol. 3:2156-2165) and the pVL series (Lucklow and Summers (1989) Virology 170:31-39). In yet another embodiment, a nucleic acid of the invention is expressed in mammalian cells using a mammalian expression vector. Examples of mammalian expression vectors include pCDM8 (Seed, B. (1987) Nature 329:840) and pMT2PC (Kaufman et al. (1987) EMBO J. 6:187-195). When used in mammalian cells, the expression vector's control functions are often provided by viral regulatory elements. For example, commonly used promoters are derived from polyoma, Adenovirus 2, cytomegalovirus and Simian Virus 40. For other suitable expression systems for both prokaryotic and eukaryotic cells see chapters 16 and 17 of Sambrook, J. et al. Molecular Cloning: A Laboratory Manual. 2nd, ed., Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1989. In another embodiment, the recombinant mammalian expression vector is capable of directing expression of the nucleic acid preferentially in a particular cell type (e.g., tissue-specific regulatory elements are used to express the nucleic acid). Tissue- specific regulatory elements are known in the art. Non-limiting examples of suitable tissue-specific promoters include the albumin promoter (liver-specific; Pinkert et al. (1987) Genes Dev. 1:268-277), lymphoid-specific promoters (Calame and Eaton (1988) Adv. Immunol. 43:235-275), in particular promoters of T cell receptors (Winoto and Baltimore (1989) EMBOJ. 8:729-733) and immunoglobulins (Banerji et al. (1983) Cell 33:729-740; Queen and Baltimore (1983) Cell 33:741-748), neuron-specific promoters (e.g., the neurofilament promoter; Byrne and Ruddle (1989) Proc. Natl. Acad. Sci. USA 86:5473-5477), pancreas-specific promoters (Edlund et al. (1985) Science 230:912-916), and mammary gland-specific promoters (e.g., milk whey promoter; U.S. Patent No. 4,873,316 and European Application Publication No. 264,166). Developmentally- regulated promoters are also encompassed, for example the murine hox promoters (Kessel and Grass (1990) Science 249:374-379) and the -fetoprotein promoter (Campes and Tilghman (1989) Genes Dev. 3:537-546). The invention further provides a recombinant expression vector comprising a DNA molecule of the invention cloned into the expression vector in an antisense orientation. That is, the DNA molecule is operatively linked to a regulatory sequence in a manner which allows for expression (by transcription of the DNA molecule) of an RNA molecule which is antisense to COE-1 mRNA. Regulatory sequences operatively linked to a nucleic acid cloned in the antisense orientation can be chosen which direct the continuous expression of the antisense RNA molecule in a variety of cell types, for instance viral promoters and/or enhancers, or regulatory sequences can be chosen which direct constitutive, tissue specific or cell type specific expression of antisense RNA. The antisense expression vector can be in the form of a recombinant plasmid, phagemid or attenuated virus in which antisense nucleic acids are produced under the control of a high efficiency regulatory region, the activity of which can be determined by the cell type into which the vector is introduced. For a discussion of the regulation of gene expression using antisense genes see Weintraub, H. et al. "Antisense RNA as a molecular tool for genetic analysis", Reviews - Trends in Genetics, Vol. 1(1) 1986. Another aspect of the invention pertains to host cells into which a COE-1 nucleic acid molecule of the invention is introduced, e.g., a COE-1 nucleic acid molecule within a vector (e.g. , a recombinant expression vector) or a COE-1 nucleic acid molecule containing sequences which allow it to homologously recombine into a specific site of the host cell's genome. The terms "host cell" and "recombinant host cell" are used interchangeably herein. It is understood that such terms refer not only to the particular subject cell but to the progeny or potential progeny of such a cell. Because certain modifications may occur in succeeding generations due to either mutation or environmental influences, such progeny may not, in fact, be identical to the parent cell, but are still included within the scope of the term as used herein. A host cell can be any prokaryotic or eukaryotic cell. For example, a COE-1 protein can be expressed in bacterial cells such as E. coli, insect cells, yeast or mammalian cells (such as Chinese hamster ovary cells (CHO) or COS cells). A preferred host cell is a primary hepatocyte or a cell from a liver cell line (e.g., a HepG2 cell or a McArdle RH7777 cell). Other suitable host cells are known to those skilled in the art. Vector DNA can be introduced into prokaryotic or eukaryotic cells via conventional transformation or transfection techniques. As used herein, the terms "transformation" and "transfection" are intended to refer to a variety of art-recognized techniques for introducing foreign nucleic acid (e.g., DNA) into a host cell, including calcium phosphate or calcium chloride co-precipitation, DEAE-dextran-mediated transfection, lipofection, or electroporation. Suitable methods for transforming or transfecting host cells can be found in Sambrook et al. (Molecular Cloning: A Laboratory Manual. 2nd, ed, Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1989), and other laboratory manuals. For stable transfection of mammalian cells, it is known that, depending upon the expression vector and transfection technique used, only a small fraction of cells may integrate the foreign DNA into their genome. In order to identify and select these integrants, a gene that encodes a selectable marker (e.g., resistance to antibiotics) is generally introduced into the host cells along with the gene of interest. Preferred selectable markers include those which confer resistance to drugs, such as G418, hygromycin and methotrexate. Nucleic acid encoding a selectable marker can be introduced into a host cell on the same vector as that encoding a COE-1 protein or can be introduced on a separate vector. Cells stably transfected with the introduced nucleic acid can be identified by drug selection (e.g. , cells that have incoφorated the selectable marker gene will survive, while the other cells die). A host cell of the invention, such as a prokaryotic or eukaryotic host cell in culture, can be used to produce (i.e., express) a COE-1 protein. Accordingly, the invention further provides methods for producing a COE-1 protein using the host cells of the invention. In one embodiment, the method comprises culturing the host cell of the invention (into which a recombinant expression vector encoding a COE-1 protein has been introduced) in a suitable medium such that a COE-1 protein is produced. In another embodiment, the method further comprises isolating a COE-1 protein from the medium or the host cell. The host cells of the invention can also be used to produce non-human transgenic animals. For example, in one embodiment, a host cell of the invention is a fertilized oocyte or an embryonic stem cell into which COE-1 -coding sequences have been introduced. Such host cells can then be used to create non-human transgenic animals in which exogenous COE-1 sequences have been introduced into their genome or homologous recombinant animals in which endogenous COE-1 sequences have been altered. Such animals are useful for studying the function and/or activity of a COE-1 protein and for identifying and/or evaluating modulators of COE-1 activity. As used herein, a "transgenic animal" is a non-human animal, preferably a mammal, more preferably a rodent such as a rat or mouse, in which one or more of the cells of the animal includes a transgene. Other examples of transgenic animals include non-human primates, sheep, dogs, cows, goats, chickens, amphibians, and the like. A transgene is exogenous DNA which is integrated into the genome of a cell from which a transgenic animal develops and which remains in the genome of the mature animal, thereby directing the expression of an encoded gene product in one or more cell types or tissues of the transgenic animal. As used herein, a "homologous recombinant animal" is a non- human animal, preferably a mammal, more preferably a mouse, in which an endogenous COE-1 gene has been altered by homologous recombination between the endogenous gene and an exogenous DNA molecule introduced into a cell of the animal, e.g., an embryonic cell of the animal, prior to development of the animal. A transgenic animal of the invention can be created by introducing a COE-1 - encoding nucleic acid into the male pronuclei of a fertilized oocyte, e.g., by microinjection or retro viral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal. The COE-1 cDNA sequence of SEQ ID NO:l can be introduced as a transgene into the genome of a non-human animal. Alternatively, a non-human homologue of a human COE-1 gene, such as a rat or mouse COE-1 gene, can be used as a transgene. Alternatively, a COE-1 gene homologue, such as another COE-1 family member, can be isolated based on hybridization to the COE-1 cDNA sequences of SEQ ID NO: 1 or 3, or the DNA insert of the plasmid deposited with ATCC as Accession Number (described further in subsection I above) and used as a transgene. Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene. A tissue-specific regulatory sequence(s) can be operably linked to a COE-1 transgene to direct expression of a COE-1 protein to particular cells. Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U.S. Patent Nos. 4,736,866 and 4,870,009, both by Leder et al, U.S. Patent No. 4,873,191 by Wagner et al. and in Hogan, B., Manipulating the Mouse Embryo (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Similar methods are used for production of other transgenic animals. A transgenic founder animal can be identified based upon the presence of a COE-1 transgene in its genome and/or expression of COE-1 mRNA in tissues or cells of the animals. A transgenic founder animal can then be used to breed additional animals carrying the transgene. Moreover, transgenic animals carrying a transgene encoding a COE-1 protein can further be bred to other transgenic animals carrying other transgenes. To create a homologous recombinant animal, a vector is prepared which contains at least a portion of a COE-1 gene into which a deletion, addition or substitution has been introduced to thereby alter, e.g., functionally disrupt, the COE-1 gene. The COE-1 gene can be a human gene (e.g. , the cDNA of SEQ ID NO:3), but more preferably, is a non-human homologue of a human COE-1 gene (e.g., a cDNA isolated by stringent hybridization with the nucleotide sequence of SEQ ID NOT), For example, a mouse COE-1 gene can be used to construct a homologous recombination nucleic acid molecule, e.g., a vector, suitable for altering an endogenous COE-1 gene in the mouse genome. In a preferred embodiment, the homologous recombination nucleic acid molecule is designed such that, upon homologous recombination, the endogenous COE- 1 gene is functionally disrupted (i.e., no longer encodes a functional protein; also referred to as a "knock out" vector). Alternatively, the homologous recombination nucleic acid molecule can be designed such that, upon homologous recombination, the endogenous COE-1 gene is mutated or otherwise altered but still encodes functional protein (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous COE-1 protein). In the homologous recombination nucleic acid molecule, the altered portion of the COE-1 gene is flanked at its 5' and 3' ends by additional nucleic acid sequence of the COE-1 gene to allow for homologous recombination to occur between the exogenous COE-1 gene carried by the homologous recombination nucleic acid molecule and an endogenous COE-1 gene in a cell, e.g., an embryonic stem cell. The additional flanking COE-1 nucleic acid sequence is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5' and 3' ends) are included in the homologous recombination nucleic acid molecule (see, e.g., Thomas, K.R. and Capecchi, M.R. (1987) Cell 51 :503 for a description of homologous recombination vectors). The homologous recombination nucleic acid molecule is introduced into a cell, e.g. , an embryonic stem cell line (e.g. , by electroporation) and cells in which the introduced COE-1 gene has homologously recombined with the endogenous COE-1 gene are selected (see e.g., Li, E. et al. (1992) Cell 69:915). The selected cells can then be injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras (see e.g., Bradley, A. in Teratocarcinomas and Embryonic Stem Cells: A Practical Approach, Robertson, E.J. ed. (IRL, Oxford, 1987) pp. 113-152). A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to term. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination nucleic acid molecules, e.g., vectors, or homologous recombinant animals are described further in Bradley, A. (1991) Current Opinion in Biotechnology 2:823-829 and in PCT International Publication Nos.: WO 90/11354 by Le Mouellec et al; WO 91/01140 by Smithies et al.; WO 92/0968 by Zijlstra et al; and WO 93/04169 by Berns et al. In another embodiment, transgenic non-humans animals can be produced which contain selected systems which allow for regulated expression of the transgene. One example of such a system is the cre/loxP recombinase system of bacteriophage PI. For a description of the cre/loxP recombinase system, see, e. g. , Lakso et al. ( 1992) Proc. Natl. Acad. Sci. USA 89:6232-6236. Another example of a recombinase system is the FLP recombinase system of Saccharomyces cerevisiae (O'Gorman et al. (1991) Science 251:1351-1355). If a cre/loxP recombinase system is used to regulate expression of the transgene, animals containing transgenes encoding both the Cre recombinase and a selected protein are required. Such animals can be provided through the constraction of "double" transgenic animals, e.g., by mating two transgenic animals, one containing a transgene encoding a selected protein and the other containing a transgene encoding a recombinase. Clones of the non-human transgenic animals described herein can also be produced according to the methods described in Wilmut, I. et al. (1997) Nature 385:810-813 and PCT International Publication Nos. WO 97/07668 and WO 97/07669. In brief, a cell, e.g., a somatic cell, from the transgenic animal can be isolated and induced to exit the growth cycle and enter G 0 phase. The quiescent cell can then be fused, e.g., through the use of electrical pulses, to an enucleated oocyte from an animal of the same species from which the quiescent cell is isolated. The reconstracted oocyte is then cultured such that it develops to morula or blastocyte and then transferred to pseudopregnant female foster animal. The offspring borne of this female foster animal will be a clone of the animal from which the cell, e.g., the somatic cell, is isolated. IV. Pharmaceutical Compositions The COE-1 nucleic acid molecules, of COE-1 proteins, fragments thereof, anti- COE-1 antibodies, and COE-1 modulators (also referred to herein as "active compounds") of the invention can be incoφorated into pharmaceutical compositions suitable for administration. Such compositions typically comprise the nucleic acid molecule, protein, or antibody and a pharmaceutically acceptable carrier. As used herein the language "pharmaceutically acceptable carrier" is intended to include any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absoφtion delaying agents, and the like, compatible with pharmaceutical administration. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active compound, use thereof in the compositions is contemplated. Supplementary active compounds can also be incoφorated into the compositions. A pharmaceutical composition of the invention is formulated to be compatible with its intended route of administration. Examples of routes of administration include parenteral, e.g., intravenous, intradermal, subcutaneous, oral (e.g., inhalation), transdermal (topical), transmucosal, and rectal administration. Solutions or suspensions used for parenteral, intradermal, or subcutaneous application can include the following components: a sterile diluent such as water for injection, saline solution, fixed oils, polyethylene glycols, glycerine, propylene glycol or other synthetic solvents; antibacterial agents such as benzyl alcohol or methyl parabens; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates and agents for the adjustment of tonicity such as sodium chloride or dextrose. pH can be adjusted with acids or bases, such as hydrochloric acid or sodium hydroxide. The parenteral preparation can be enclosed in ampoules, disposable syringes or multiple dose vials made of glass or plastic. Pharmaceutical compositions suitable for injectable use include sterile aqueous solutions (where water soluble) or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersion. For intravenous administration, suitable carriers include physiological saline, bacteriostatic water, Cremophor EL™ (BASF, Parsippany, NJ) or phosphate buffered saline (PBS). In all cases, the composition must be sterile and should be fluid to the extent that easy syringeability exists. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyetheylene glycol, and the like), and suitable mixtures thereof. The proper fluidity can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. Prevention of the action of microorganisms can be achieved by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, ascorbic acid, thimerosal, and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars, polyalcohols such as manitol, sorbitol, sodium chloride in the composition. Prolonged absoφtion of the injectable compositions can be brought about by including in the composition an agent which delays absoφtion, for example, aluminum monostearate and gelatin. Sterile injectable solutions can be prepared by incoφorating the active compound (e.g., a fragment of a COE-1 protein or an anti-COE-1 antibody) in the required amount in an appropriate solvent with one or a combination of ingredients enumerated above, as required, followed by filtered sterilization. Generally, dispersions are prepared by incoφorating the active compound into a sterile vehicle which contains a basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum drying and freeze-drying which yields a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof. Oral compositions generally include an inert diluent or an edible carrier. They can be enclosed in gelatin capsules or compressed into tablets. For the puφose of oral therapeutic administration, the active compound can be incoφorated with excipients and used in the form of tablets, troches, or capsules. Oral compositions can also be prepared using a fluid carrier for use as a mouthwash, wherein the compound in the fluid carrier is applied orally and swished and expectorated or swallowed. Pharmaceutically compatible binding agents, and/or adjuvant materials can be included as part of the composition. The tablets, pills, capsules, troches and the like can contain any of the following ingredients, or compounds of a similar nature: a binder such as microcrystalline cellulose, gum tragacanth or gelatin; an excipient such as starch or lactose, a disintegrating agent such as alginic acid, Primogel, or corn starch; a lubricant such as magnesium stearate or Sterotes; a glidant such as colloidal silicon dioxide; a sweetening agent such as sucrose or saccharin; or a flavoring agent such as peppermint, methyl salicylate, or orange flavoring. For administration by inhalation, the compounds are delivered in the form of an aerosol spray from pressured container or dispenser which contains a suitable propellant, e.g., a gas such as carbon dioxide, or a nebulizer. Systemic administration can also be by transmucosal or transdermal means. For transmucosal or transdermal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art, and include, for example, for transmucosal administration, detergents, bile salts, and fusidic acid derivatives. Transmucosal administration can be accomplished through the use of nasal sprays or suppositories. For transdermal administration, the active compounds are formulated into ointments, salves, gels, or creams as generally known in the art. The compounds can also be prepared in the form of suppositories (e.g., with conventional suppository bases such as cocoa butter and other glycerides) or retention enemas for rectal delivery. In one embodiment, the active compounds are prepared with carriers that will protect the compound against rapid elimination from the body, such as a controlled release formulation, including implants and microencapsulated delivery systems. Biodegradable, biocompatible polymers can be used, such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Methods for preparation of such formulations will be apparent to those skilled in the art. The materials can also be obtained commercially from Alza Coφoration and Nova Pharmaceuticals, Inc. Liposomal suspensions (including liposomes targeted to infected cells with monoclonal antibodies to viral antigens) can also be used as pharmaceutically acceptable carriers. These can be prepared according to methods known to those skilled in the art, for example, as described in U.S. Patent No. 4,522,811. It is especially advantageous to formulate oral or parenteral compositions in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used herein refers to physically discrete units suited as unitary dosages for the subject to be treated; each unit containing a predetermined quantity of active compound calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. The specification for the dosage unit forms of the invention are dictated by and directly dependent on the unique characteristics of the active compound and the particular therapeutic effect to be achieved, and the limitations inherent in the art of compounding such an active compound for the treatment of individuals. Toxicity and therapeutic efficacy of such compounds can be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD50 (the dose lethal to 50% of the population) and the ED50 (the dose therapeutically effective in 50%> of the population). The dose ratio between toxic and therapeutic effects is the therapeutic index and it can be expressed as the ratio LD50/ED50. Compounds which exhibit large therapeutic indices are preferred. While compounds that exhibit toxic side effects may be used, care should be taken to design a delivery system that targets such compounds to the site of affected tissue in order to minimize potential damage to uninfected cells and, thereby, reduce side effects. The data obtained from the cell culture assays and animal studies can be used in formulating a range of dosage for use in humans. The dosage of such compounds lies preferably within a range of circulating concentrations that include the ED50 with little or no toxicity. The dosage may vary within this range depending upon the dosage form employed and the route of administration utilized. For any compound used in the method of the invention, the therapeutically effective dose can be estimated initially from cell culture assays. A dose may be formulated in animal models to achieve a circulating plasma concentration range that includes the IC50 (i.e., the concentration of the test compound which achieves a half-maximal inhibition of symptoms) as determined in cell culture. Such information can be used to more accurately determine useful doses in humans. Levels in plasma may be measured, for example, by high performance liquid chromatography. As defined herein, a therapeutically effective amount of protein or polypeptide ( . e. , an effective dosage) ranges from about 0.001 to 30 mg/kg body weight, preferably about 0.01 to 25 mg/kg body weight, more preferably about 0.1 to 20 mg/kg body weight, and even more preferably about 1 to 10 mg/kg, 2 to 9 mg/kg, 3 to 8 mg/kg, 4 to 7 mg kg, or 5 to 6 mg/kg body weight. The skilled artisan will appreciate that certain factors may influence the dosage required to effectively treat a subject, including but not limited to the severity of the disease or disorder, previous treatments, the general health and/or age of the subject, and other diseases present. Moreover, treatment of a subject with a therapeutically effective amount of a protein, polypeptide, or antibody can include a single treatment or, preferably, can include a series of treatments. In a preferred example, a subject is treated with antibody, protein, or polypeptide in the range of between about 0.1 to 20 mg/kg body weight, one time per week for between about 1 to 10 weeks, preferably between 2 to 8 weeks, more preferably between about 3 to 7 weeks, and even more preferably for about 4, 5, or 6 weeks. It will also be appreciated that the effective dosage of antibody, protein, or polypeptide used for treatment may increase or decrease over the course of a particular treatment. Changes in dosage may result and become apparent from the results of diagnostic assays as described herein. The present invention encompasses agents which modulate expression or activity. An agent may, for example, be a small molecule. For example, such small molecules include, but are not limited to, peptides, peptidomimetics, amino acids, amino acid analogs, polynucleotides, polynucleotide analogs, nucleotides, nucleotide analogs, organic or inorganic compounds (i.e., including heteroorganic and organometallic compounds) having a molecular weight less than about 10,000 grams per mole, organic or inorganic compounds having a molecular weight less than about 5,000 grams per mole, organic or inorganic compounds having a molecular weight less than about 1,000 grams per mole, organic or inorganic compounds having a molecular weight less than about 500 grams per mole, and salts, esters, and other pharmaceutically acceptable forms of such compounds. It is understood that appropriate doses of small molecule agents depends upon a number of factors within the ken of the ordinarily skilled physician, veterinarian, or researcher. The dose(s) of the small molecule will vary, for example, depending upon the identity, size, and condition of the subject or sample being treated, further depending upon the route by which the composition is to be administered, if applicable, and the effect which the practitioner desires the small molecule to have upon the nucleic acid or polypeptide of the invention. Exemplary doses include milligram or microgram amounts of the small molecule per kilogram of subject or sample weight (e.g., about 1 microgram per kilogram to about 500 milligrams per kilogram, about 100 micrograms per kilogram to about 5 milligrams per kilogram, or about 1 microgram per kilogram to about 50 micrograms per kilogram. It is furthermore understood that appropriate doses of a small molecule depend upon the potency of the small molecule with respect to the expression or activity to be modulated. Such appropriate doses may be determined using the assays described herein. When one or more of these small molecules is to be administered to an animal (e.g., a human) in order to modulate expression or activity of a polypeptide or nucleic acid of the invention, a physician, veterinarian, or researcher may, for example, prescribe a relatively low dose at first, subsequently increasing the dose until an appropriate response is obtained. In addition, it is understood that the specific dose level for any particular animal subject will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, general health, gender, and diet of the subj ect, the time of administration, the route of administration, the rate of excretion, any drug combination, and the degree of expression or activity to be modulated. In certain embodiments of the invention, a modulator of COE-1 activity is administered in combination with other agent(s) (e.g., small molecule(s)), or in conjunction with another, complementary treatment regime. For example, in one embodiment, a modulator of COE-1 activity is used to treat a COE-1 associated disorder, e.g., a lipid homeostasis disorder. Accordingly, modulation of COE-1 activity may be used in conjunction with, for example, another agent used to treat the disorder such as cholestyramine, a statin (e.g., pravastatin, simvastatin, lovastatin, atorvastatin, cerivastatin, or fluvastatin), a thiazoladinedione (e.g., troglitazone, pioglitazone, or rosiglitizone), a fibrate (e.g., clofibrate, gemfibrozil, fenofibrate, bezafibrate, simfibrate, ronifibrate, ciprofibrate, etofibrate, or clofibride), metformin, insulin, aspirin, niacin, cholestipol, or neomycin. Further, an antibody (or fragment thereof) may be conjugated to a therapeutic moiety such as a cytotoxin, a therapeutic agent or a radioactive metal ion. A cytotoxin or cytotoxic agent includes any agent that is detrimental to cells. Examples include taxol, cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, and puromycin and analogs or homologs thereof. Therapeutic agents include, but are not limited to, antimetabolites (e.g., methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, 5-fluorouracil decarbazine), alkylating agents (e.g., mechlorethamine, thioepa chlorambucil, melphalan, carmustine (BSNU) and lomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol, streptozotocin, mitomycin C, and cis-dichlorodiamine platinum (II) (DDP) cisplatin), anthracyclines (e.g., daunorubicin (formerly daunomycin) and doxorabicin), antibiotics (e.g., dactinomycin (formerly actinomycin), bleomycin, mithramycin, and anthramycin (AMC)), and anti-mitotic agents (e.g., vincristine and vinblastine). The conjugates of the invention can be used for modifying a given biological response, the drug moiety is not to be construed as limited to classical chemical therapeutic agents. For example, the drag moiety may be a protein or polypeptide possessing a desired biological activity. Such proteins may include, for example, a toxin such as abrin, ricin A, pseudomonas exotoxin, or diphtheria toxin; a protein such as tumor necrosis factor, alpha-interferon, beta-interferon, nerve growth factor, platelet derived growth factor, tissue plasminogen activator; or, biological response modifiers such as, for example, lymphokines, interleukin-1 ("IL-1"), interleukin-2 ("IL-2"), interleukin-6 ("IL-6"), granulocyte macrophage colony stimulating factor ("GM-CSF"), granulocyte colony stimulating factor ("G-CSF"), or other growth factors. Techniques for conjugating such therapeutic moiety to antibodies are well known, see, e.g., Arnon et al. "Monoclonal Antibodies For Immunotargeting Of Drugs In Cancer Therapy" in Monoclonal Antibodies And Cancer Therapy, Reisfeld et al (eds.), pp. 243-56 (Alan R. Liss, Inc. 1985); Hellstrom et al "Antibodies For Drug Delivery" in Controlled Drug Delivery (2nd Ed.), Robinson et al. (eds.), pp. 623-53 (Marcel Dekker, Inc. 1987); Thoφe "Antibody Carriers Of Cytotoxic Agents In Cancer Therapy: A Review" in Monoclonal Antibodies '84: Biological And Clinical Applications, Pinchera et al (eds.), pp. 475-506 (1985); "Analysis, Results, And Future Prospective Of The Therapeutic Use Of Radiolabeled Antibody In Cancer Therapy" in Monoclonal Antibodies For Cancer Detection And Therapy, Baldwin et al. (eds.), pp. 303-16 (Academic Press 1985); and Thoφe et al. "The Preparation And Cytotoxic Properties Of Antibody-Toxin Conjugates" Immunol. Rev. 62:119-58 (1982). Alternatively, an antibody can be conjugated to a second antibody to form an antibody heteroconjugate as described by Segal in U.S. Patent No. 4,676,980. The nucleic acid molecules of the invention can be inserted into vectors and used as gene therapy vectors. Gene therapy vectors can be delivered to a subject by, for example, intravenous injection, local administration (see U.S. Patent 5,328,470) or by stereotactic injection (see e.g., Chen et al. (1994) Proc. Natl. Acad. Sci. USA 91:3054- 3057). The pharmaceutical preparation of the gene therapy vector can include the gene therapy vector in an acceptable diluent, or can comprise a slow release matrix in which the gene delivery vehicle is imbedded. Alternatively, where the complete gene delivery vector can be produced intact from recombinant cells, e.g., retro viral vectors, the pharmaceutical preparation can include one or more cells which produce the gene delivery system. The pharmaceutical compositions can be included in a container, pack, or dispenser together with instractions for administration. V. Uses and Methods of the Invention The nucleic acid molecules, proteins, protein homologues, and antibodies described herein can be used in one or more of the following methods: a) screening assays; b) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenetics); and c) methods of treatment (e.g., therapeutic and prophylactic). As described herein, a COE-1 protein of the invention has one or more of the following activities: (i) interaction with a COE-1 substrate or target molecule (e.g., a triglyceride); (ii) conversion of a COE-1 substrate or target molecule to a product (e.g., hydrolysis of an ester linkage and/or liberation of the free acid form of the substrate, e.g., hydrolysis of a triglyceride and/or liberation of free fatty acid(s) and glycerol); (iii) modulation of lipolysis; (iv) modulation of lipid uptake by a cell (e.g., a liver cell); (v) modulation of lipid synthesis and/or secretion; (vi) modulation of intracellular lipid release and/or turnover; (vii) modulation of intracellular lipid and/or triglyceride mass; (viii) modulation of secreted lipid and/or triglyceride mass; (ix) modulation of serum lipid, lipoprotein, and/or triglyceride levels; (x) modulation of lipid homeostasis; (xi) direct or indirect modulation of lipoprotein assembly; (xii) interaction with and/or hydrolysis of a second non-COE-1 protein; (xiii) activation/deactivation of a COE-1 substrate or target molecule (e.g., activation/deactivation of a carcinogen); (xiv) metabolism and/or detoxification of a drag; (xv) modulation of cellular signaling and/or gene transcription (e.g. , either directly or indirectly); and/or (xvi) modulation of cellular proliferation and/or differentiation. The isolated nucleic acid molecules of the invention can be used, for example, to express COE-1 protein (e.g., via a recombinant expression vector in a host cell in gene therapy applications), to detect COE-1 mRNA (e.g., in a biological sample) or a genetic alteration in a COE-1 gene, and to modulate COE-1 activity, as described further below. The COE-1 proteins can be used to treat disorders characterized by insufficient or excessive production of a COE-1 substrate or production of COE-1 inhibitors. In addition, the COE-1 proteins can be used to screen for naturally occurring COE-1 substrates, to screen for drugs or compounds which modulate COE-1 activity, as well as to treat disorders characterized by insufficient or excessive production of COE-1 protein or production of COE-1 protein forms which have decreased, aberrant or unwanted activity compared to COE-1 wild type protein (e.g., a COE-1 -associated disorder). Moreover, the anti-COE-1 antibodies of the invention can be used to detect and isolate COE-1 proteins, regulate the bioavailability of COE-1 proteins, and modulate COE-1 activity. A. Screening Assays: The invention provides a method (also referred to herein as a "screening assay") for identifying modulators, i.e., candidate or test compounds or agents (e.g., peptides, peptidomimetics, small molecules or other drags) which bind to COE-} proteins, have a stimulatory or inhibitory effect on, for example, COE-1 expression or COE-1 activity, or have a stimulatory or inhibitory effect on, for example, the expression or activity of a COE-1 substrate. In one embodiment, the invention provides assays for screening candidate or test compounds which are substrates of a COE-1 protein or polypeptide or biologically active portion thereof. In another embodiment, the invention provides assays for screening candidate or test compounds which bind to or modulate the activity of a COE- 1 protein or polypeptide or biologically active portion thereof. The test compounds of the present invention can be obtained using any of the numerous approaches in combinatorial library methods known in the art, including: biological libraries; spatially addressable parallel solid phase or solution phase libraries; synthetic library methods requiring deconvolution; the 'one-bead one-compound' library method; and synthetic library methods using affinity chromatography selection. The biological library approach is limited to peptide libraries, while the other four approaches are applicable to peptide, non-peptide oligomer or small molecule libraries of compounds (Lam, K.S. (1997) Anticancer Drug Des. 12:45). Examples of methods for the synthesis of molecular libraries can be found in the art, for example, in: DeWitt et al. (1993) Proc. Natl Acad. Sci. USA 90:6909; Erb et al (1994) Proc. Natl. Acad. Sci. USA 91 :11422; Zuckermann et al. (1994) J Med. Chem. 37:2678; Cho et al. (1993) Science 261:1303; Carrell et al (1994) Angew. Chem. Int. Ed. Engl 33:2059; Carell et al (1994) Angew. Chem. Int. Ed. Engl 33:2061; and Gallop et al. (1994) J. Med. Chem. 37:1233. Libraries of compounds may be presented in solution (e.g., Houghten (1992) Biotechniques 13:412-421), or on beads (Lam (1991) Nature 354:82-84), chips (Fodor (1993) Nature 364:555-556), bacteria (Ladner USP 5,223,409), spores (Ladner USP '409), plasmids (Cull et al. (1992) Proc. Natl Acad. Sci. USA 89:1865-1869) or on phage (Scott and Smith (1990) Science 249:386-390); (Devlin (1990) Science 249:404- 406); (Cwirla et al. (1990) Proc. Natl. Acad. Sci. USA 87:6378-6382); (Felici (1991) J. Mol. Biol. 222:301-310); (Ladner supra.). In one embodiment, an assay is a cell-based assay in which a cell which expresses a COE-1 protein or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate COE-1 activity is determined. Determining the ability of the test compound to modulate COE-1 activity can be accomplished by monitoring, for example, COE-1 interaction with a substrate or target molecule (e.g., a triglyceride); conversion of a COE-1 substrate or target molecule to a product (e.g., hydrolysis of an ester linkage and/or liberation of the free acid form of the substrate, e.g., hydrolysis of a triglyceride and/or liberation of free fatty acid(s) and glycerol); modulation of lipolysis; modulation of lipid uptake by a cell (e.g., a liver cell); modulation of lipid synthesis and/or secretion; modulation of intracellular lipid release and/or turnover; modulation of intracellular lipid and/or triglyceride mass; modulation of secreted lipid and/or triglyceride mass; modulation of serum lipid, lipoprotein, and/or triglyceride levels; modulation of lipid homeostasis; direct or indirect modulation of lipoprotein assembly; interaction with and/or hydrolysis of a second non- COE-1 protein; activation/deactivation of a COE-1 substrate or target molecule (e.g., activation/deactivation of a carcinogen); metabolism and/or detoxification of a drug; modulation of cellular signaling and/or gene transcription (e.g., either directly or indirectly); and/or modulation of cellular proliferation and/or differentiation. Exemplary methods for determining COE-1 activity are further described in Example 4 and in Lehner, R. and Vance, D.E. (1999) Biochem. J. 343:1-10, the contents of which are incoφorated herein by reference. The cell, for example, can be of a mammalian origin (e.g., a liver cell such as a primary liver cell, a HepG2 cell, or a McArdle RH7777 cell). The ability of the test compound to modulate COE-1 binding to a substrate (e.g., a triglyceride) or to bind to COE-1 can also be determined. Determining the ability of the test compound to modulate COE-1 binding to a substrate can be accomplished, for example, by coupling the COE-1 substrate with a radioisotope or enzymatic label such that binding of the COE-1 substrate to COE-1 can be determined by detecting the labeled COE-1 substrate in a complex. Alternatively, COE-1 could be coupled with a radioisotope or enzymatic label to monitor the ability of a test compound to modulate COE-1 binding to a COE-1 substrate in a complex. Determining the ability of the test compound to bind COE-1 can be accomplished, for example, by coupling the compound with a radioisotope or enzymatic label such that binding of the compound to COE-1 can be determined by detecting the labeled COE-1 compound in a complex. For example, compounds (e.g., COE-1 substrates) can be labeled with 125L, 35S, ^C, or ^H, either directly or indirectly, and the radioisotope detected by direct counting of radioemission or by scintillation counting. Alternatively, compounds can be enzymatically labeled with, for example, horseradish peroxidase, alkaline phosphatase, or luciferase, and the enzymatic label detected by determination of conversion of an appropriate substrate to product. It is also within the scope of this invention to determine the ability of a compound (e.g., a COE-1 substrate) to interact with COE-1 without the labeling of any of the interactants. For example, a microphysiometer can be used to detect the interaction of a compound with COE-1 without the labeling of either the compound or the COE-1. McConnell, H.M. et αl (1992) Science 257:1906-1912. As used herein, a "microphysiometer" (e.g., Cytosensor) is an analytical instrument that measures the rate at which a cell acidifies its environment using a light-addressable potentiometric sensor (LAPS). Changes in this acidification rate can be used as an indicator of the interaction between a compound and COE-1. In another embodiment, an assay is a cell-based assay comprising contacting a cell expressing a COE-1 target molecule (e.g., a COE-1 substrate or hydrolysis product) with a test compound and determining the ability of the test compound to modulate (e.g., stimulate or inhibit) the activity of the COE-1 target molecule or product. Determining the ability of the test compound to modulate the activity of a COE-1 target molecule or product can be accomplished, for example, by determining the ability of the COE-1 protein to bind to or interact with the COE-1 target molecule, or by determining the amount (e.g., the mass) of the COE-1 target molecule or hydrolysis product. Determining the ability of the COE-1 protein or a biologically active fragment thereof, to bind to or interact with a COE-1 target molecule can be accomplished by one of the methods described above for determining direct binding. In a preferred embodiment, determining the ability of the COE-1 protein to bind to or interact with a COE-1 target molecule can be accomplished by determining the activity of the target molecule. For example, the activity of the target molecule can be determined by detecting the amount of the target molecule or induction of a hydro lytic product of the target molecule (e.g., intracellular or secreted free fatty acids, intracellular alcohols or carboxylic anions), detecting catalytic/enzymatic activity of the target molecule upon an appropriate substrate, detecting the induction of a reporter gene (comprising a target- responsive regulatory element operatively linked to a nucleic acid encoding a detectable marker, e.g., luciferase), or detecting a target-regulated cellular response (e.g., cell growth or differentiation). In yet another embodiment, an assay of the present invention is a cell-free assay in which a COE-1 protein or biologically active portion thereof is contacted with a test compound and the ability of the test compound to bind to the COE-1 protein or biologically active portion thereof is determined. Preferred biologically active portions of the COE-1 proteins to be used in assays of the present invention include fragments which participate in interactions with non-COE-1 molecules, e.g., fragments with high surface probability scores (see, for example, Figure 6). Binding of the test compound to the COE-1 protein can be determined either directly or indirectly as described above. In a preferred embodiment, the assay includes contacting the COE-1 protein or biologically active portion thereof with a known compound which binds COE-1 to form an assay mixture, contacting the assay mixture with a test compound, and determining the ability of the test compound to interact with a COE-1 protein, wherein determining the ability of the test compound to interact with a COE-1 protein comprises determining the ability of the test compound to preferentially bind to COE-1 or biologically active portion thereof as compared to the known compound. In another embodiment, the assay is a cell-free assay in which a COE-1 protein or biologically active portion thereof is contacted with a test compound and the ability of the test compound to modulate (e.g., stimulate or inhibit) the activity of the COE-1 protein or biologically active portion thereof is determined. Determining the ability of the test compound to modulate the activity of a COE-1 protein can be accomplished, for example, by determining the ability of the COE-1 protein to bind to a COE-1 target molecule by one of the methods described above for determining direct binding. Determining the ability of the COE-1 protein to bind to a COE-1 target molecule can also be accomplished using a technology such as real-time Biomolecular Interaction Analysis (BIA). Sjolander, S. and Urbaniczky, C. (1991) Anal Chem. 63:2338-2345 and Szabo et al (1995) Curr. Opin. Struct. Biol. 5:699-705. As used herein, "BIA" is a technology for studying biospecific interactions in real time, without labeling any of the interactants (e.g., BIAcore). Changes in the optical phenomenon of surface plasmon resonance (SPR) can be used as an indication of real-time reactions between biological molecules. In an alternative embodiment, determining the ability of the test compound to modulate the activity of a COE-1 protein can be accomplished by determining the ability of the COE-1 protein to further modulate the activity of a downstream effector of a COE-1 target molecule. For example, the activity of the effector molecule on an appropriate target can be determined or the binding of the effector to an appropriate target can be determined as previously described. In yet another embodiment, the cell-free assay involves contacting a COE-1 protein or biologically active portion thereof with a known compound which binds the COE-1 protein to form an assay mixture, contacting the assay mixture with a test compound, and determining the ability of the test compound to interact with the COE-1 protein, wherein determining the ability of the test compound to interact with the COE-1 protein comprises determining the ability of the COE-1 protein to preferentially bind to or modulate the activity of a COE-1 target molecule. The cell-free assays of the present invention are amenable to use of both soluble and/or membrane-bound forms of isolated proteins (e.g., COE-1 proteins or biologically active portions thereof). In the case of cell-free assays in which a membrane-bound form of an isolated protein is used it may be desirable to utilize a solubilizing agent such that the membrane-bound form of the isolated protein is maintained in solution. Examples of such solubilizing agents include non-ionic detergents such as n- octylglucoside, n-dodecylglucoside, n-dodecylmaltoside, octanoyl-N-methylglucamide, decanoyl-N-methylglucamide, Triton® X-100, Triton® X-114, Thesit®, Isotridecypoly(ethylene glycol ether) n , 3-[(3-cholamidopropyl)dimethylamminio]-l- propane sulfonate (CHAPS), 3-[(3-cholamidopropyl)dimethylamminio]-2-hydroxy-l- propane sulfonate (CHAPSO), or N-dodecyl=N,N-dimethyl-3-ammonio-l -propane sulfonate. In more than one embodiment of the above assay methods of the present invention, it may be desirable to immobilize either COE-1 or its target molecule to facilitate separation of complexed from uncomplexed forms of one or both of the proteins, as well as to accommodate automation of the assay. Binding of a test compound to a COE-1 protein, or interaction of a COE-1 protein with a target molecule in the presence and absence of a candidate compound, can be accomplished in any vessel suitable for containing the reactants. Examples of such vessels include microtiter plates, test tubes, and micro-centrifuge tubes. In one embodiment, a fusion protein can be provided which adds a domain that allows one or both of the proteins to be bound to a n atrix. For example, glutathione-S-transferase/COE-1 fusion proteins or glutathione- S-transferase/target fusion proteins can be adsorbed onto glutathione sepharose beads (Sigma Chemical, St. Louis, MO) or glutathione derivatized micrometer plates, which are then combined with the test compound or the test compound and either the non- adsorbed target protein or COE-1 protein, and the mixture incubated under conditions conducive to complex formation (e.g., at physiological conditions for salt and pH). Following incubation, the beads or microtiter plate wells are washed to remove any unbound components, the matrix immobilized in the case of beads, complex determined either directly or indirectly, for example, as described above. Alternatively, the complexes can be dissociated from the matrix, and the level of COE-1 binding or activity determined using standard techniques. Other techniques for immobilizing proteins on matrices can also be used in the screening assays of the invention. For example, either a COE-1 protein or a COE-1 target molecule can be immobilized utilizing conjugation of biotin and streptavidin. Biotinylated COE-1 protein or target molecules can be prepared from biotin-NHS (N- hydroxy-succinimide) using techniques known in the art (e.g., biotinylation kit, Pierce Chemicals, Rockford, IL), and immobilized in the wells of streptavidin-coated 96 well plates (Pierce Chemical). Alternatively, antibodies reactive with COE-1 protein or target molecules but which do not interfere with binding of the COE-1 protein to its target molecule can be derivatized to the wells of the plate, and unbound target or COE- 1 protein trapped in the wells by antibody conjugation. Methods for detecting such complexes, in addition to those described above for the GST-immobilized complexes, include immunodetection of complexes using antibodies reactive with the COE-1 protein or target molecule, as well as enzyme-linked assays which rely on detecting an enzymatic activity associated with the COE-1 protein or target molecule. In another embodiment, modulators of COE-1 expression are identified in a method wherein a cell is contacted with a candidate compound and the expression of COE-1 mRNA or protein in the cell is determined. The level of expression of COE-1 mRNA or protein in the presence of the candidate compound is compared to the level of expression of COE-1 mRNA or protein in the absence of the candidate compound. The candidate compound can then be identified as a modulator of COE-1 expression based on this comparison. For example, when expression of COE-1 mRNA or protein is greater (statistically significantly greater) in the presence of the candidate compound than in its absence, the candidate compound is identified as a stimulator of COE-1 mRNA or protein expression. Alternatively, when expression of COE-1 mRNA or protein is less (statistically significantly less) in the presence of the candidate compound than in its absence, the candidate compound is identified as an inhibitor of COE-1 mRNA or protein expression. The level of COE-1 mRNA or protein expression in the cells can be determined by methods described herein for detecting COE-1 mRNA or protein. In yet another aspect of the invention, the COE-1 proteins can be used as "bait proteins" in a two-hybrid assay or three-hybrid assay (see, e.g. , U.S. Patent No. 5,283,317; Zervos et al. (1993) Cell 72:223-232; Madura et al (1993) J Biol. Chem. 268:12046-12054; Bartel et al (1993) Biotechniques 14:920-924; Iwabuchi et al (1993) Oncogene 8:1693-1696; and Brent WO94/10300), to identify other proteins, which bind to or interact with COE-1 ("COE-1 -binding proteins" or "COE-l-bp") and are involved in COE-1 activity. Such COE-1 -binding proteins are also likely to be involved in the propagation of signals by the COE-1 proteins or COE-1 targets as, for example, downstream elements of a COE-1 -mediated signaling pathway. Alternatively, such COE-1 -binding proteins may be COE-1 inhibitors. The two-hybrid system is based on the modular nature of most transcription factors, which consist of separable DNA-binding and activation domains. Briefly, the assay utilizes two different DNA constructs. In one construct, the gene that codes for a COE-1 protem is fused to a gene encoding the DNA binding domain of a known transcription factor (e.g., GAL-4). In the other construct, a DNA sequence, from a library of DNA sequences, that encodes an unidentified protein ("prey" or "sample") is fused to a gene that codes for the activation domain of the known transcription factor. If the "bait" and the "prey" proteins are able to interact, in vivo, forming a COE-1- dependent complex, the DNA-binding and activation domains of the transcription factor are brought into close proximity. This proximity allows transcription of a reporter gene (e.g., LacZ) which is operably linked to a transcriptional regulatory site responsive to the transcription factor. Expression of the reporter gene can be detected and cell colonies containing the functional transcription factor can be isolated and used to obtain the cloned gene which encodes the protein which interacts with the COE-1 protein. In another aspect, the invention pertains to a combination of two or more of the assays described herein. For example, a modulating agent can be identified using a cell- based or a cell free assay, and the ability of the agent to modulate the activity of a COE- 1 protein can be confirmed in vivo, e.g., in a COE-1 knockout or transgenic animal (e.g., a mouse), or in an animal such as an animal model for a lipid homeostasis disorder, for drag sensitivity, or for cellular transformation and/or tumorigenesis. For example, the following animal models may be used in the methods of the invention: the hypertensive transgenic mouse model that lacks fat and has lipoatrophic diabetes (Reitmann, M. L. et al. (1999) Ann. N. Y Acad. Sci. 192:289-96; Moitra J. et al ( 998) Genes Dev. 12:3168-81 ); a VEGF transgenic animal model for atherosclerosis and angiogenesis (Sueishi, K. et al. (1997) Ann. N. Y. Acad. Sci. 811:311-324); guinea pigs, which are used as models for cholesterol and lipoprotein metabolism, as well as early atherosclerosis development (Fernandez, M.L. (2001) J. Nutr. 131(1): 10-20); the macrophage scavenger receptor class A (SR-A) transgenic mouse, which shows reduced atherosclerosis (De Winther, M.P. et al (2000) Int. J. Tissue React. 22(2-3):85-91); the St. Thomas' Hospital rabbit strain, an animal model with genetically elevated plasma levels of VLDL, IDL, and low-density lipoprotein (LDL) (Nordestgaard, B.G. et al (1992) Eur. J. Epidemiol. 8 Suppl 1:92-8); the Watanabe heritable hyperlipidemic (WHHL) rabbit, the animal model for familial hypercholesterolemia (Buja, L.M. et al. (1990) Eur. Heart J. 11 Suppl E:41-52); atherosclerosis induced in Cynomolgus macaque monkeys by feeding cholesterol (Weingand, K.W. (1989) Exp. Mol. Pathol 50(1):1-15); atherosclerosis induced by infection with Marek's disease heφesvirus in chickens (1999) Am. Heart J. 138(5 Pt 2):S465-8); genetically selected lines of Japanese quail, highly susceptible (SUS) and resistant (RES) to atherosclerosis (1987) Atherosclerosis 68(l-2):77-8); the atherosclerotic and hypertensive strain of male broad- breasted white turkeys (BBWT) (Pagnan, A. (1980) Artery 6(4):320-7); diet-induced, apoE deficiency-induced, or LDL receptor-deficiency induced atherosclerosis in mice (Smith, J.D. (1991) J. Intern. Med. 242(2):99-109); the JCRXA-coφulent rat, an experimental model for the obese-diabetic-dyslipidemic syndrome that mimics the human condition and exhibits spontaneous development of atherosclerosis and myocardial lesions (Brindley, D.N. (1995) Metabolism 44(2 Suppl 2):23-7); marmosets or other animals treated with cholestyramine or other cholesterol and/or lipid lowering drags; and numerous other animal models of atherosclerosis (reviewed in Bocan, T.M. (1998) Curr. Pharm. Des. 4(l):37-52; Fekete, S. (1993) Acta Vet. Hung. 41(l-2):3-9). Further examples of animals that can be used include the transgenic mouse described in U.S. Patent No. 5,932,779 that contains a mutation in an endogenous melanocortin-4-receptor (MC4-R) gene; animals having mutations which lead to syndromes that include obesity symptoms (described in, for example, Friedman, J.M. et al. (1991) Mamm. Genome 1 :130-144; Friedman, J.M. and Liebel, R.L. (1992) Cell 69:217-220; Bray, G.A. (1992) Prog. Brain Res. 93:333-341; and Bray, G.A. (1989) Amer. J. Clin. Nutr. 5:891-902); the animals described in Stubdal, H. et al. (2000) Mol. Cell Biol. 20(3):878-82 (the mouse tubby phenotype characterized by maturity-onset obesity); the animals described in Abadie, J.M. et al. (2000) Lipids 35(6):613-20 (the obese Zucker rat (ZR), a genetic model of human youth-onset obesity and type 2 diabetes mellitus); the animals described in Shaughnessy, S. et al. (2000) Diabetes 49(6):904-l 1 (mice null for the adipocyte fatty acid binding protein); or the animals described in Loskutoff, D.J. et al (2000) Ann. NY. Acad. Sci. 902:272-81 (the fat mouse). Other examples of animals that may be used include non-recombinant, non- genetic animal models of obesity such as, for example, rabbit, mouse, or rat models in which the animal has been exposed to long-term over-eating. This invention further pertains to novel agents identified by the above-described screening assays. Accordingly, it is within the scope of this invention to further use an agent identified as described herein in an appropriate animal model. For example, an agent identified as described herein (e.g., a COE-1 modulating agent, an antisense COE- 1 nucleic acid molecule, a COE-1 -specific antibody, or a COE-1 binding partner) can be used in an animal model to determine the efficacy, toxicity, or side effects of treatment with such an agent. Alternatively, an agent identified as described herein can be used in an animal model to determine the mechanism of action of such an agent. Furthermore, this invention pertains to uses of novel agents identified by the above-described screening assays for treatments as described herein. In another aspect, cell-based systems, as described herein, may be used to identify compounds which may act to ameliorate lipid homeostasis disease symptoms. For example, such cell systems may be exposed to a compound, suspected of exhibiting an ability to ameliorate lipid homeostasis disease symptoms, at a sufficient concentration and for a time sufficient to elicit such an amelioration of lipid homeostasis disease symptoms in the exposed cells. After exposure, the cells are examined to determine whether one or more of the lipid homeostasis disease cellular phenotypes has been altered to resemble a more normal or more wild type, non-lipid homeostasis disease phenotype. Cellular phenotypes that are associated with lipid homeostasis disease states include aberrant lipolysis, aberrant lipid uptake, aberrant lipid synthesis and/or secretion, aberrant intracellular lipid release and/or turnover, aberrant intracellular triglyceride release and/or turnover, aberrant intracellular lipid and/or triglyceride mass, and/or aberrant secreted lipid and/or triglyceride mass. In addition, animal-based lipid homeostasis disease systems, such as those described herein, may be used to identify compounds capable of ameliorating lipid homeostasis disease symptoms. Such animal models may be used as test substrates for the identification of drugs, pharmaceuticals, therapies, and interventions which may be effective in treating lipid homeostasis disease. For example, animal models may be exposed to a compound, suspected of exhibiting an ability to ameliorate lipid homeostasis disease symptoms, at a sufficient concentration and for a time sufficient to elicit such an amelioration of lipid homeostasis disease symptoms in the exposed animals. The response of the animals to the exposure may be monitored by assessing the reversal of disorders associated with lipid homeostasis disease, for example, by measuring lipid and/or triglyceride levels (e.g., in the seram or in tissues such as liver), or by measuring the size of arterial atherosclerotic plaques before and after treatment. With regard to intervention, any treatments which reverse any aspect of lipid homeostasis disease symptoms should be considered as candidates for human lipid homeostasis disease therapeutic intervention. Dosages of test agents may be determined by deriving dose-response curves. Additionally, gene expression patterns may be utilized to assess the ability of a compound to ameliorate lipid homeostasis disease symptoms. For example, the expression pattern of one or more genes may form part of a "gene expression profile" or "transcriptional profile" which may be then be used in such an assessment. "Gene expression profile" or "transcriptional profile", as used herein, includes the pattern of mRNA expression obtained for a given tissue or cell type under a given set of conditions. Such conditions may include, but are not limited to, the presence of aberrant serum lipids, lipoprotein, or triglyceride levels, including any of the control or experimental conditions described herein, for example, cholestyramine treated animals. Other conditions may include, for example, atherosclerosis induced by diet or other means. Gene expression profiles may be generated, for example, by utilizing a differential display procedure, Northern analysis and/or RT-PCR. In one embodiment, COE-1 gene sequences may be used as probes and/or PCR primers for the generation and corroboration of such gene expression profiles. Gene expression profiles may be characterized for known states, either lipid homeostasis disease or normal, within the cell- and/or animal-based model systems. Subsequently, these known gene expression profiles may be compared to ascertain the effect a test compound has to modify such gene expression profiles, and to cause the profile to more closely resemble that of a more desirable profile. For example, administration of a compound may cause the gene expression profile of a lipid homeostasis disease model system to more closely resemble the control system. Administration of a compound may, alternatively, cause the gene expression profile of a control system to begin to mimic a lipid homeostasis disease state. Such a compound may, for example, be used in further characterizing the compound of interest, or may be used in the generation of additional animal models. B. Detection Assays Portions or fragments of the cDNA sequences identified herein (and the corresponding complete gene sequences) can be used in numerous ways as polynucleotide reagents. For example, these sequences can be used to: (i) map their respective genes on a chromosome; and, thus, locate gene regions associated with genetic disease; (ii) identify an individual from a minute biological sample (tissue typing); and (iii) aid in forensic identification of a biological sample. These applications are described in the subsections below. 1. Chromosome Mapping Once the sequence (or a portion of the sequence) of a gene has been isolated, this sequence can be used to map the location of the gene on a chromosome. This process is called chromosome mapping. Accordingly, portions or fragments of the COE-1 nucleotide sequences, described herein, can be used to map the location of the COE-1 genes on a chromosome. The mapping of the COE-1 sequences to chromosomes is an important first step in correlating these sequences with genes associated with disease. Briefly, COE-1 genes can be mapped to chromosomes by preparing PCR primers (preferably 15-25 bp in length) from the COE-1 nucleotide sequences. Computer analysis of the COE-1 sequences can be used to predict primers that do not span more than one exon in the genomic DNA, thus complicating the amplification process. These primers can then be used for PCR screening of somatic cell hybrids containing individual human chromosomes. Only those hybrids containing the human gene corresponding to the COE-1 sequences will yield an amplified fragment. Somatic cell hybrids are prepared by fusing somatic cells from different mammals (e.g., human and mouse cells). As hybrids of human and mouse cells grow and divide, they gradually lose human chromosomes in random order, but retain the mouse chromosomes. By using media in which mouse cells cannot grow, because they lack a particular enzyme, but human cells can, the one human chromosome that contains the gene encoding the needed enzyme, will be retained. By using various media, panels of hybrid cell lines can be established. Each cell line in a panel contains either a single human chromosome or a small number of human chromosomes, and a full set of mouse chromosomes, allowing easy mapping of individual genes to specific human chromosomes (D'Eustachio, P. et al (1983) Science 220:919-924). Somatic cell hybrids containing only fragments of human chromosomes can also be produced by using human chromosomes with translocations and deletions. PCR mapping of somatic cell hybrids is a rapid procedure for assigning a particular sequence to a particular chromosome. Three or more sequences can be assigned per day using a single thermal cycler. Using the COE-1 nucleotide sequences to design oligonucleotide primers, sublocalization can be achieved with panels of fragments from specific chromosomes. Other mapping strategies which can similarly be used to map a COE-1 sequence to its chromosome include in situ hybridization (described in Fan, Y. et al. (1990) Proc. Natl. Acad. Sci. USA 87:6223-27), pre- screening with labeled flow-sorted chromosomes, and pre-selection by hybridization to chromosome-specific cDNA libraries. Fluorescence in situ hybridization (FISH) of a DNA sequence to a metaphase chromosomal spread can further be used to provide a precise chromosomal location in one step. Chromosome spreads can be made using cells whose division has been blocked in metaphase by a chemical such as colcemid that disrupts the mitόtic spindle. The chromosomes can be treated briefly with trypsin, and then stained with Giemsa. A pattern of light and dark bands develops on each chromosome, so that the chromosomes can be identified individually. The FISH technique can be used with a DNA sequence as short as 500 or 600 bases. However, clones larger than 1,000 bases have a higher likelihood of binding to a unique chromosomal location with sufficient signal intensity for simple detection. Preferably 1,000 bases, and more preferably 2,000 bases will suffice to get good results at a reasonable amount of time. For a review of this technique, see Verma et al, Human Chromosomes: A Manual of Basic Techniques (Pergamon Press, New York 1988). Reagents for chromosome mapping can be used individually to mark a single chromosome or a single site on that chromosome, or panels of reagents can be used for marking multiple sites and/or multiple chromosomes. Reagents corresponding to noncoding regions of the genes actually are preferred for mapping puφoses. Coding sequences are more likely to be conserved within gene families, thus increasing the chance of cross hybridizations during chromosomal mapping. Once a sequence has been mapped to a precise chromosomal location, the physical position of the sequence on the chromosome can be correlated with genetic map data. (Such data are found, for example, in McKusick, V., Mendelian Inheritance in Man, available on-line through Johns Hopkins University Welch Medical Library.) The relationship between a gene and a disease, mapped to the same chromosomal region, can then be identified through linkage analysis (co-inheritance of physically adjacent genes), described in, for example, Egeland, J. et al (1987) Nature, 325:783- 787. Moreover, differences in the DNA sequences between individuals affected and unaffected with a disease associated with the COE-1 gene, can be determined. If a mutation is observed in some or all of the affected individuals but not in any unaffected individuals, then the mutation is likely to be the causative agent of the particular disease. Comparison of affected and unaffected individuals generally involves first looking for structural alterations in the chromosomes, such as deletions or translocations that are visible from chromosome spreads or detectable using PCR based on that DNA sequence. Ultimately, complete sequencing of genes from several individuals can be performed to confirm the presence of a mutation and to distinguish mutations from polymoφhisms. 2. Tissue Typing The COE-1 sequences of the present invention can also be used to identify individuals from minute biological samples. The United States military, for example, is considering the use of restriction fragment length polymoφhism (RFLP) for identification of its personnel. In this technique, an individual's genomic DNA is digested with one or more restriction enzymes, and probed on a Southern blot to yield unique bands for identification. This method does not suffer from the current limitations of "Dog Tags" which can be lost, switched, or stolen, making positive identification difficult. The sequences of the present invention are useful as additional DNA markers for RFLP (described in U.S. Patent 5,272,057). Furthermore, the sequences of the present invention can be used to provide an alternative technique which determines the actual base-by-base DNA sequence of selected portions of an individual's genome. Thus, the COE-1 nucleotide sequences described herein can be used to prepare two PCR primers from the 5' and 3' ends of the sequences. These primers can then be used to amplify an individual's DNA and subsequently sequence it. Panels of corresponding DNA sequences from individuals, prepared in this manner, can provide unique individual identifications, as each individual will have a unique set of such DNA sequences due to allelic differences. The sequences of the present invention can be used to obtain such identification sequences from individuals and from tissue. The COE-1 nucleotide sequences of the invention uniquely represent portions of the human genome. Allelic variation occurs to some degree in the coding regions of these sequences, and to a greater degree in the noncoding regions. It is estimated that allelic variation between individual humans occurs with a frequency of about once per each 500 bases. Each of the sequences described herein can, to some degree, be used as a standard against which DNA from an individual can be compared for identification puφoses. Because greater numbers of polymoφhisms occur in the noncoding regions, fewer sequences are necessary to differentiate individuals. The noncoding sequences of SEQ ID NOT can comfortably provide positive individual identification with a panel of perhaps 10 to 1,000 primers which each yield a noncoding amplified sequence of 100 bases. If predicted coding sequences, such as those in SEQ ID NO: 3 are used, a more appropriate number of primers for positive individual identification would be 500-2,000. If a panel of reagents from COE-1 nucleotide sequences described herein is used to generate a unique identification database for an individual, those same reagents can later be used to identify tissue from that individual. Using the unique identification database, positive identification of the individual, living or dead, can be made from extremely small tissue samples. 3. Use of Partial COE-1 Sequences in Forensic Biology DNA-based identification techniques can also be used in forensic biology. Forensic biology is a scientific field employing genetic typing of biological evidence found at a crime scene as a means for positively identifying, for example, a perpetrator of a crime. To make such an identification, PCR technology can be used to amplify DNA sequences taken from very small biological samples such as tissues, e.g., hair or skin, or body fluids, e.g., blood, saliva, or semen found at a crime scene. The amplified sequence can then be compared to a standard, thereby allowing identification of the origin of the biological sample. The sequences of the present invention can be used to provide polynucleotide reagents, e.g., PCR primers, targeted to specific loci in the human genome, which can enhance the reliability of DNA-based forensic identifications by, for example, providing another "identification marker" (i.e., another DNA sequence that is unique to a particular individual). As mentioned above, actual base sequence information can be used for identification as an accurate alternative to patterns formed by restriction enzyme generated fragments. Sequences targeted to noncoding regions of SEQ ID NO:l are particularly appropriate for this use as greater numbers of polymoφhisms occur in the noncoding regions, making it easier to differentiate individuals using this technique. Examples of polynucleotide reagents include the COE-1 nucleotide sequences or portions thereof, e.g., fragments derived from the noncoding regions of SEQ ID NOT having a length of at least 20 bases, preferably at least 30 bases. The COE-1 nucleotide sequences described herein can further be used to provide polynucleotide reagents, e.g., labeled or labelable probes which can be used in, for example, an in situ hybridization technique, to identify a specific tissue, e.g., a tissue containing endothelial cells. This can be very useful in cases where a forensic pathologist is presented with a tissue of unknown origin. Panels of such COE-1 probes can be used to identify tissue by species and/or by organ type. In a similar fashion, these reagents, e.g., COE-1 primers or probes can be used to screen tissue culture for contamination (i.e., screen for the presence of a mixture of different types of cells in a culture). C. Predictive Medicine: The present invention also pertains to the field of predictive medicine in which diagnostic assays, prognostic assays, and monitoring clinical trials are used for prognostic (predictive) puφoses to thereby treat an individual prophylactically. Accordingly, one aspect of the present invention relates to diagnostic assays for determining COE-1 protein and/or nucleic acid expression as well as COE-1 activity, in the context of a biological sample (e.g., blood, serum, cells, or tissue) to thereby determine whether an individual is afflicted with a disease or disorder, or is at risk of developing a disorder, associated with aberrant or unwanted COE-1 expression or activity. The invention also provides for prognostic (or predictive) assays for determining whether an individual is at risk of developing a disorder associated with COE-1 protein, nucleic acid expression or activity. For example, mutations in a COE-1 gene can be assayed in a biological sample. Such assays can be used for prognostic or predictive puφose to thereby prophylactically treat an individual prior to the onset of a disorder characterized by or associated with COE-1 protein, nucleic acid expression or activity. Another aspect of the invention pertains to monitoring the influence of agents (e.g., drags, compounds) on the expression or activity of COE-1 in clinical trials. These and other agents are described in further detail in the following sections. 1. Diagnostic Assays An exemplary method for detecting the presence or absence of COE-1 protein, polypeptide or nucleic acid in a biological sample involves obtaining a biological sample from a test subject and contacting the biological sample with a compound or an agent capable of detecting COE-1 protem, polypeptide or nucleic acid (e.g., mRNA, genomic DNA) that encodes COE-1 protein such that the presence of COE-1 protein or nucleic acid is detected in the biological sample. In another aspect, the present invention provides a method for detecting the presence of COE-1 activity in a biological sample by contacting the biological sample with an agent capable of detecting an indicator of COE-1 activity such that the presence of COE-1 activity is detected in the biological sample. A preferred agent for detecting COE-1 mRNA or genomic DNA is a labeled nucleic acid probe capable of hybridizing to COE-1 mRNA or genomic DNA. The nucleic acid probe can be, for example, a full-length COE-1 nucleic acid, such as the nucleic acid of SEQ ID NO: 1 or 3, or the DNA insert of the plasmid deposited with ATCC as Accession Number , or a portion thereof, such as an oligonucleotide of at least 15, 30, 50, 100, 250 or 500 nucleotides in length and sufficient to specifically hybridize under stringent conditions to COE-1 mRNA or genomic DNA. Other suitable probes for use in the diagnostic assays of the invention are described herein. A preferred agent for detecting COE-1 protein is an antibody capable of binding to COE-1 protein, preferably an antibody with a detectable label. Antibodies can be polyclonal, or more preferably, monoclonal. An intact antibody, or a fragment thereof (e.g., Fab or F(ab')2) can be used. The term "labeled", with regard to the probe or antibody, is intended to encompass direct labeling of the probe or antibody by coupling (i.e., physically linking) a detectable substance to the probe or antibody, as well as indirect labeling of the probe or antibody by reactivity with another reagent that is directly labeled. Examples of indirect labeling include detection of a primary antibody using a fluorescently labeled secondary antibody and end-labeling of a DNA probe with biotin such that it can be detected with fluorescently labeled streptavidin. The term "biological sample" is intended to include tissues, cells and biological fluids isolated from a subject, as well as tissues, cells and fluids present within a subject. That is, the detection method of the invention can be used to detect COE-1 mRNA, protein, or genomic DNA in a biological sample in vitro as well as in vivo. For example, in vitro techniques for detection of COE-1 mRNA include Northern hybridizations and in situ hybridizations. In vitro techniques for detection of COE-1 protein include enzyme linked immunosorbent assays (ELISAs), Western blots, immunoprecipitations and immunofluorescence. In vitro techniques for detection of COE-1 genomic DNA include Southern hybridizations. Furthermore, in vivo techniques for detection of a COE-1 protein include introducing into a subject a labeled anti-COE-1 antibody. For example, the antibody can be labeled with a radioactive marker whose presence and location in a subject can be detected by standard imaging techniques. The present invention also provides diagnostic assays for identifying the presence or absence of a genetic alteration characterized by at least one of (i) aberrant modification or mutation of a gene encoding a COE-1 protein; (ii) aberrant expression of a gene encoding a COE-1 protein; (iii) mis-regulation of the gene; and (iii) aberrant post-translational modification of a COE-1 protein, wherein a wild-type form of the gene encodes a protein with a COE-1 activity. "Misexpression or aberrant expression", as used herein, refers to a non- wild type pattern of gene expression, at the RNA or protein level. It includes, but is not limited to, expression at non- wild type levels (e.g. , over or under expression); a pattern of expression that differs from wild type in terms of the time or stage at which the gene is expressed (e.g., increased or decreased expression (as compared with wild type) at a predetermined developmental period or stage); a pattern of expression that differs from wild type in terms of decreased expression (as compared with wild type) in a predetermined cell type or tissue type; a pattern of expression that differs from wild type in terms of the splicing size, amino acid sequence, post- transitional modification, or biological activity of the expressed polypeptide; a pattern of expression that differs from wild type in terms of the effect of an environmental stimulus or extracellular stimulus on expression of the gene (e.g., a pattern of increased or decreased expression (as compared with wild type) in the presence of an increase or decrease in the strength of the stimulus). In one embodiment, the biological sample contains protein molecules from the test subject. Alternatively, the biological sample can contain mRNA molecules from the test subject or genomic DNA molecules from the test subject. A preferred biological sample is a seram sample isolated by conventional means from a subject. In another embodiment, the methods further involve obtaining a control biological sample from a control subject, contacting the control sample with a compound or agent capable of detecting COE-1 protein, mRNA, or genomic DNA, such that the presence of COE-1 protein, mRNA or genomic DNA is detected in the biological sample, and comparing the presence of COE-1 protein, mRNA or genomic DNA in the control sample with the presence of COE-1 protein, mRNA or genomic DNA in the test sample. The invention also encompasses kits for detecting the presence of COE-1 in a biological sample. For example, the kit can comprise a labeled compound or agent capable of detecting COE-1 protein or mRNA in a biological sample; means for determining the amount of COE-1 in the sample; and means for comparing the amount of COE-1 in the sample with a standard. The compound or agent can be packaged in a suitable container. The kit can further comprise instructions for using the kit to detect COE-1 protein or nucleic acid. 2. Prognostic Assays The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant or unwanted COE-1 expression or activity. As used herein, the term "aberrant" includes a COE-1 expression or activity which deviates from the wild type COE-1 expression or activity. Aberrant expression or activity includes increased or decreased expression or activity, as well as expression or activity which does not follow the wild type developmental pattern of expression or the subcellular pattern of expression. For example, aberrant COE-1 expression or activity is intended to include the cases in which a mutation in the COE-1 gene causes the COE-1 gene to be under-expressed or over- expressed and situations in which such mutations result in a non-functional COE-1 protein or a protein which does not function in a wild-type fashion, e.g., a protein which does not interact with a COE-1 substrate, or one which interacts with a non-COE-1 substrate. As used herein, the term "unwanted" includes an unwanted phenomenon involved in a biological response such as lipid and/or triglyceride metabolism, pain or deregulated cell proliferation. For example, the term unwanted includes a COE-1 expression or activity which is undesirable in a subject. The assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing a disorder associated with a misregulation in COE-1 protein activity or nucleic acid expression, such as lipid homeostasis disorder, a cell proliferation and/or differentiation disorder. Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disorder associated with a misregulation in COE-1 protein activity or nucleic acid expression, such as lipid homeostasis disorder, a drug or toxin sensitivity disorder or a cell proliferation and/or differentiation disorder. Thus, the present invention provides a method for identifying a disease or disorder associated with aberrant or unwanted COE-1 expression or activity in which a test sample is obtained from a subject and COE-1 protein or nucleic acid (e.g., mRNA or genomic DNA) is detected, wherein the presence of COE-1 protein or nucleic acid is diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant or unwanted COE-1 expression or activity. As used herein, a "test sample" refers to a biological sample obtained from a subject of interest. For example, a test sample can be a biological fluid (e.g., serum or blood), a cell sample, or a tissue sample (e.g., a liver sample). Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drag candidate) to treat a disease or disorder associated with aberrant or unwanted COE-1 expression or activity. For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a lipid homeostasis disorder, a drag or toxin sensitivity disorder or a cell proliferation and/or differentiation disorder. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant or unwanted COE-1 expression or activity in which a test sample is obtained and COE-1 protein or nucleic acid expression or activity is detected (e.g., wherein the abundance of COE-1 protein or nucleic acid expression or activity is diagnostic for a subject that can be administered the agent to treat a disorder associated with aberrant or unwanted COE-1 expression or activity). The methods of the invention can also be used to detect genetic alterations in a COE-1 gene, thereby determining if a subject with the altered gene is at risk for a disorder characterized by misregulation in COE-1 protein activity or nucleic acid expression, such as lipid homeostasis disorder, a drag or toxin sensitivity disorder or a cell proliferation and/or differentiation disorder. In preferred embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic alteration characterized by at least one of an alteration affecting the integrity of a gene encoding a COE-1 -protein, or the mis-expression of the COE-1 gene. For example, such genetic alterations can be detected by ascertaining the existence of at least one of 1) a deletion of one or more nucleotides from a COE-1 gene; 2) an addition of one or more nucleotides to a COE-1 gene; 3) a substitution of one or more nucleotides of a COE-1 gene, 4) a chromosomal rearrangement of a COE-1 gene; 5) an alteration in the level of a messenger RNA transcript of a COE-1 gene, 6) aberrant modification of a COE-1 gene, such as of the methylation pattern of the genomic DNA, 7) the presence of a non- wild type splicing pattern of a messenger RNA transcript of a COE-1 gene, 8) a non- wild type level of a COE-1 -protein, 9) allelic loss of a COE-1 gene, and 10) inappropriate post-translational modification of a COE-1 -protein. As described herein, there are a large number of assays known in the art which can be used for detecting alterations in a COE-1 gene. A preferred biological sample is a tissue or serum sample isolated by conventional means from a subject. In certain embodiments, detection of the alteration involves the use of a probe/primer in a polymerase chain reaction (PCR) (see, e.g., U.S. Patent Nos. 4,683,195 and 4,683,202), such as anchor PCR or RACE PCR, or, alternatively, in a ligation chain reaction (LCR) (see, e.g., Landegran et al. (1988) Science 241 :1077-1080; and Nakazawa et al (1994) Proc. Natl. Acad. Sci. USA 91:360-364), the latter of which can be particularly useful for detecting point mutations in the COE-1 -gene (see Abravaya et al. (1995) Nucleic Acids Res. 23:675-682). This method can include the steps of collecting a sample of cells from a subject, isolating nucleic acid (e.g., genomic, mRNA or both) from the cells of the sample, contacting the nucleic acid sample with one or more primers which specifically hybridize to a COE-1 gene under conditions such that hybridization and amplification of the COE-1 -gene (if • present) occurs, and detecting the presence or absence of an amplification product, or detecting the size of the amplification product and comparing the length to a control sample. It is anticipated that PCR and/or LCR may be desirable to use as a preliminary amplification step in conjunction with any of the techniques used for detecting mutations described herein. Alternative amplification methods include: self sustained sequence replication (Guatelli, J.C. et al (1990) Proc. Natl Acad. Sci. USA 87:1874-1878), transcriptional amplification system (Kwoh, D.Y. et al. (1989) Proc. Natl. Acad. Sci. USA 86:1173- 1177), Q-Beta Replicase (Lizardi, P.M. et al. (1988) Bio-Technology 6:1197), or any other nucleic acid amplification method, followed by the detection of the amplified molecules using techniques well known to those of skill in the art. These detection schemes are especially useful for the detection of nucleic acid molecules if such molecules are present in very low numbers. In an alternative embodiment, mutations in a COE-1 gene from a sample cell can be identified by alterations in restriction enzyme cleavage patterns. For example, sample and control DNA is isolated, amplified (optionally), digested with one or more restriction endonucleases, and fragment length sizes are determined by gel electrophoresis and compared. Differences in fragment length sizes between sample and control DNA indicates mutations in the sample DNA. Moreover, the use of sequence specific ribozymes (see, for example, U.S. Patent No. 5,498,531) can be used to score for the presence of specific mutations by development or loss of a ribozyme cleavage site. In other embodiments, genetic mutations in COE-1 can be identified by hybridizing a sample and control nucleic acids, e.g. , DNA or RNA, to high density arrays containing hundreds or thousands of oligonucleotides probes (Cronin, M.T. et al (1996) Human Mutation 7:244-255; Kozal, M.J. et al. (1996) Nat. Med. 2:753-759). For example, genetic mutations in COE-1 can be identified in two dimensional arrays containing light-generated DNA probes as described in Cronin, M.T. et al (1996) supra. Briefly, a first hybridization array of probes can be used to scan through long stretches of DNA in a sample and control to identify base changes between the sequences by making linear arrays of sequential overlapping probes. This step allows the identification of point mutations. This step is followed by a second hybridization array that allows the characterization of specific mutations by using smaller, specialized probe arrays complementary to all variants or mutations detected. Each mutation array is composed of parallel probe sets, one complementary to the wild-type gene and the other complementary to the mutant gene. In yet another embodiment, any of a variety of sequencing reactions known in the art can be used to directly sequence the COE-1 gene and detect mutations by comparing the sequence of the sample COE-1 with the corresponding wild-type (control) sequence. Examples of sequencing reactions include those based on techniques developed by Maxam and Gilbert ((1977) Proc. Natl. Acad. Sci. USA 74:560) or Sanger ((1977) Proc. Natl. Acad. Sci. USA 74:5463). It is also contemplated that any of a variety of automated sequencing procedures can be utilized when performing the diagnostic assays (Naeve, C.W. (1995) Biotechniques 19:448), including sequencing by mass spectrometry (see, e.g., PCT International Publication No. WO 94/16101; Cohen et al. (1996) Adv. Chromatogr. 36:127-162; and Griffin et al (1993) Appl Biochem. Biotechnol. 38:147-159). Other methods for detecting mutations in the COE-1 gene include methods in which protection from cleavage agents is used to detect mismatched bases in RNA RNA or RNA/DNA heteroduplexes (Myers et al. (1985) Science 230:1242). In general, the art technique of "mismatch cleavage" starts by providing heteroduplexes formed by hybridizing (labeled) RNA or DNA containing the wild-type COE-1 sequence with potentially mutant RNA or DNA obtained from a tissue sample. The double-stranded duplexes are treated with an agent which cleaves single-stranded regions of the duplex such as which will exist due to basepair mismatches between the control and sample strands. For instance, RNA/DNA duplexes can be treated with RNase and DNA DNA hybrids treated with SI nuclease to enzymatically digesting the mismatched regions. In other embodiments, either DNA/DNA or RNA/DNA duplexes can be treated with hydroxylamine or osmium tetroxide and with piperidine in order to digest mismatched regions. After digestion of the mismatched regions, the resulting material is then separated by size on denaturing poly aery lamide gels to determine the site of mutation. See, for example, Cotton et al (1988) Proc. Natl. Acad. Sci. USA 85:4397; Saleeba et al. (1992) Methods Enzymol 217:286-295. In a preferred embodiment, the control DNA or RNA can be labeled for detection. In still another embodiment, the mismatch cleavage reaction employs one or more proteins that recognize mismatched base pairs in double-stranded DNA (so called "DNA mismatch repair" enzymes) in defined systems for detecting and mapping point mutations in COE-1 cDNAs obtained from samples of cells. For example, the mutY enzyme of E. coli cleaves A at G/A mismatches and the thymidine DNA glycosylase from HeLa cells cleaves T at G/T mismatches (Hsu et al. (1994) Carcinogenesis 15:1657-1662). According to an exemplary embodiment, a probe based on a COE-1 sequence, e.g., a wild-type COE-1 sequence, is hybridized to a cDNA or other DNA product from a test cell(s). The duplex is treated with a DNA mismatch repair enzyme, and the cleavage products, if any, can be detected from electrophoresis protocols or the like. See, for example, U.S. Patent No. 5,459,039. In other embodiments, alterations in electrophoretic mobility will be used to identify mutations in COE-1 genes. For example, single strand conformation polymoφhism (SSCP) may be used to detect differences in electrophoretic mobility between mutant and wild type nucleic acids (Orita et al. (1989) Proc Natl. Acad. Sci USA 86:2766, see also Cotton (1993) Mutat. Res. 285:125-144; and Hayashi (1992) Genet. Anal. Tech. Appl 9:73-79). Single-stranded DNA fragments of sample and control COE-1 nucleic acids will be denatured and allowed to renature. The secondary stracture of single-stranded nucleic acids varies according to sequence, the resulting alteration in electrophoretic mobility enables the detection of even a single base change. The DNA fragments may be labeled or detected with labeled probes. The sensitivity of the assay may be enhanced by using RNA (rather than DNA), in which the secondary stracture is more sensitive to a change in sequence. In a preferred embodiment, the subject method utilizes heteroduplex analysis to separate double stranded heteroduplex molecules on the basis of changes in electrophoretic mobility (Keen et al. (1991) Trends Genet. 7:5). In yet another embodiment the movement of mutant or wild-type fragments in polyacrylamide gels containing a gradient of denaturant is assayed using denaturing gradient gel electrophoresis (DGGE) (Myers et al. (1985) Nature 313:495). When DGGE is used as the method of analysis, DNA will be modified to insure that it does not completely denature, for example by adding a GC clamp of approximately 40 bp of high-melting GC-rich DNA by PCR. In a further embodiment, a temperature gradient is used in place of a denaturing gradient to identify differences in the mobility of control and sample DNA (Rosenbaum and Reissner (1987) Biophys Chem 265:12753). Examples of other techniques for detecting point mutations include, but are not limited to, selective oligonucleotide hybridization, selective amplification, or selective primer extension. For example, oligonucleotide primers may be prepared in which the known mutation is placed centrally and then hybridized to target DNA under conditions which permit hybridization only if a perfect match is found (Saiki et al. (1986) Nature 324:163); Saiki et al. (1989) Proc. Natl Acad. Sci. USA 86:6230). Such allele specific oligonucleotides are hybridized to PCR amplified target DNA or a number of different mutations when the oligonucleotides are attached to the hybridizing membrane and hybridized with labeled target DNA. Alternatively, allele specific amplification technology which depends on selective PCR amplification may be used in conjunction with the instant invention. Oligonucleotides used as primers for specific amplification may carry the mutation of interest in the center of the molecule (so that amplification depends on differential hybridization) (Gibbs et al. (1989) Nucleic Acids Res. 17:2437-2448) or at the extreme 3' end of one primer where, under appropriate conditions, mismatch can prevent, or reduce polymerase extension (Prossner (1993) Tibtech 11 :238). In addition it may be desirable to introduce a novel restriction site in the region of the mutation to create cleavage-based detection (Gasparini et al (1992) Mol Cell Probes 6:1). It is anticipated that in certain embodiments amplification may also be performed using Taq ligase for amplification (Barany (1991) Proc. Natl. Acad. Sci USA 88:189). In such cases, ligation will occur only if there is a perfect match at the 3' end of the 5' sequence making it possible to detect the presence of a known mutation at a specific site by looking for the presence or absence of amplification. The methods described herein may be performed, for example, by utilizing prepackaged diagnostic kits comprising at least one probe nucleic acid or antibody reagent described herein, which may be conveniently used, e.g., in clinical settings to diagnose patients exhibiting symptoms or family history of a disease or illness involving a COE-1 ■ g ene - Furthermore, any cell type or tissue in which COE-1 is expressed (e.g., the kidney, colon, liver, brain, small intestine, or skeletal muscle) may be utilized in the prognostic assays described herein. 3. Monitoring of Effects During Clinical Trials Monitoring the influence of agents (e.g. , drags) on the expression or activity of a COE-1 protein (e.g., the modulation of gene expression, and or cell growth and differentiation mechanisms) can be applied not only in basic drag screening, but also in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase COE-1 gene expression, protein levels, or upregulate COE-1 activity, can be monitored in clinical trials of subjects exhibiting decreased COE-1 gene expression, protein levels, or downregulated COE-1 activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease COE-1 gene expression, protein levels, or downregulate COE-1 activity, can be monitored in clinical trials of subjects exhibiting increased COE-1 gene expression, protein levels, or upregulated COE-1 activity. In such clinical trials, the expression or activity of a COE-1 gene, and preferably, other genes that have been implicated in, for example, a COE-1 -associated disorder can be used as a "read out" or markers of the phenotype of a particular cell. For example, and not by way of limitation, genes, including COE-1, that are modulated in cells by treatment with an agent (e.g., compound, drag or small molecule) which modulates COE-1 activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on COE-1 -associated disorders (e.g. , disorders characterized by deregulated lipid homeostasis, gene expression, and/or cell growth and differentiation mechanisms), for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of COE-1 and other genes implicated in the COE-1 -associated disorder, respectively. The levels of gene expression (e.g., a gene expression pattern) can be quantified by northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of protein produced, by one of the methods as described herein, or by measuring the levels of activity of COE-1 or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during treatment of the individual with the agent. In a preferred embodiment, the present invention provides a method for monitoring the effectiveness of treatment of a subject with an agent (e.g., an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drag candidate identified by the screening assays described herein) including the steps of (i) obtaining a pre-administration sample from a subject prior to administration of the agent; (ii) detecting the level of expression of a COE-1 protein, mRNA, or genomic DNA in the preadministration sample; (iii) obtaining one or more post-administration samples from the subject; (iv) detecting the level of expression or activity of the COE-1 protein, mRNA, or genomic DNA in the post-administration samples; (v) comparing the level of expression or activity of the COE-1 protein, mRNA, or genomic DNA in the pre-administration sample with the COE-1 protein, mRNA, or genomic DNA in the post administration sample or samples; and (vi) altering the administration of the agent to the subject accordingly. For example, increased administration of the agent may be desirable to increase the expression or activity of COE-1 to higher levels than detected, i.e., to increase the effectiveness of the agent. Alternatively, decreased administration of the agent may be desirable to decrease expression or activity of COE-1 to lower levels than detected, i.e., to decrease the effectiveness of the agent. According to such an embodiment, COE-1 expression or activity may be used as an indicator of the effectiveness of an agent, even in the absence of an observable phenotypic response. D. Methods of Treatment: The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having a COE-1 -associated disorder, e.g., a disorder associated with aberrant or unwanted COE-1 expression or activity. As used herein, "treatment" of a subject includes the application or administration of a therapeutic agent to a subject, or application or administration of a therapeutic agent to a cell or tissue from a subject, who has a diseases or disorder, has a symptom of a disease or disorder, or is at risk of (or susceptible to) a disease or disorder, with the puφose to cure, heal, alleviate, relieve, alter, remedy, ameliorate, improve, or affect the disease or disorder, the symptom of the disease or disorder, or the risk of (or susceptibility to) the disease or disorder. As used herein, a "therapeutic agent" includes, but is not limited to, small molecules, peptides, polypeptides, antibodies, ribozymes, and antisense oligonucleotides. With regards to both prophylactic and therapeutic methods of treatment, such treatments may be specifically tailored or modified, based on knowledge obtained from the field of pharmacogenomics. "Pharmacogenomics", as used herein, refers to the application of genomics technologies such as gene sequencing, statistical genetics, and gene expression analysis to drags in clinical development and on the market. More specifically, the term refers the study of how a patient's genes determine his or her response to a drug (e.g., a patient's "drag response phenotype", or "drug response genotype"). Thus, another aspect of the invention provides methods for tailoring an individual's prophylactic or therapeutic treatment with either the COE-1 molecules of the present invention or COE-1 modulators according to that individual's drug response genotype. Pharmacogenomics allows a clinician or physician to target prophylactic or therapeutic treatments to patients who will most benefit from the treatment and to avoid treatment of patients who will experience toxic drag-related side effects. 1. Prophylactic Methods In one aspect, the invention provides a method for preventing in a subject, a disease or condition associated with an aberrant or unwanted COE-1 expression or activity, by administering to the subject a COE-1 or an agent which modulates COE-1 expression or at least one COE-1 activity. Subjects at risk for a disease which is caused or contributed to by aberrant or unwanted COE-1 expression or activity can be identified by, for example, any or a combination of diagnostic or prognostic assays as described herein. Administration of a prophylactic agent can occur prior to the manifestation of symptoms characteristic of the COE-1 aberrancy, such that a disease or disorder is prevented or, alternatively, delayed in its progression. Depending on the type of COE-1 aberrancy, for example, a COE-1, COE-1 agonist or COE-1 antagonist agent can be used for treating the subject. The appropriate agent can be determined based on screening assays described herein. 2. Therapeutic Methods Another aspect of the invention pertains to methods of modulating COE-1 expression or activity for therapeutic puφoses. Accordingly, in an exemplary embodiment, the modulatory method of the invention involves contacting a cell capable of expressing COE- 1 with an agent that modulates one or more of the activities of COE- 1 protein activity associated with the cell, such that COE-1 activity in the cell is modulated. An agent that modulates COE-1 protein activity can be an agent as described herein, such as a nucleic acid or a protein, a naturally-occurring target molecule of a COE-1 protein (e.g., a COE-1 substrate or ligand), a COE-1 antibody, a COE-1 agonist or antagonist, a peptidomimetic of a COE-1 agonist or antagonist, or other small molecule. In one embodiment, the agent stimulates one or more COE-1 activities. Examples of such stimulatory agents include active COE-1 protein and a nucleic acid molecule encoding COE-1 that has been introduced into the cell. In another embodiment, the agent inhibits one or more COE-1 activities. Examples of such inhibitory agents include antisense COE-1 nucleic acid molecules, anti-COE-1 antibodies, and COE-1 inhibitors. These modulatory methods can be performed in vitro (e.g., by culturing the cell with the agent) or, alternatively, in vivo (e.g., by administering the agent to a subject). As such, the present invention provides methods of treating an individual afflicted with a disease or disorder characterized by aberrant or unwanted expression or activity of a COE-1 protein or nucleic acid molecule. In one embodiment, the method involves administering an agent (e.g., an agent identified by a screening assay described herein), or combination of agents that modulates (e.g., upregulates or downregulates) COE-1 expression or activity. In another embodiment, the method involves administering a COE-1 protein or nucleic acid molecule as therapy to compensate for reduced, aberrant, or unwanted COE-1 expression or activity. Stimulation of COE-1 activity is desirable in situations in which COE-1 is abnormally downregulated and/or in which increased COE-1 activity is likely to have a beneficial effect. For example, stimulation of COE-1 activity is desirable in situations in which a COE-1 is downregulated and/or in which increased COE-1 activity is likely to have a beneficial effect. Likewise, inhibition of COE-1 activity is desirable in situations in which COE-1 is abnormally upregulated and/or in which decreased COE-1 activity is likely to have a beneficial effect. 3. Pharmacogenomics The COE-1 molecules of the present invention, as well as agents, or modulators which have a stimulatory or inhibitory effect on COE-1 activity (e.g., COE-1 gene expression) as identified by a screening assay described herein can be administered to individuals to treat (prophylactically or therapeutically) COE-1 -associated disorders (e.g., disorders characterized by aberrant gene expression, or cell proliferation and/or differentiation disorders) associated with aberrant or unwanted COE-1 activity. In conjunction with such treatment, pharmacogenomics (i.e., the study of the relationship between an individual's genotype and that individual's response to a foreign compound or drag) may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drag. Thus, a physician or clinician may consider applying knowledge obtained in relevant pharmacogenomics studies in determining whether to administer a COE-1 molecule or COE-1 modulator as well as tailoring the dosage and/or therapeutic regimen of treatment with a COE-1 molecule or COE-1 modulator. Pharmacogenomics deals with clinically significant hereditary variations in the response to drugs due to altered drag disposition and abnormal action in affected persons. See, for example, Eichelbaum, M. et al. (1996) Clin. Exp. Pharmacol Physiol. 23(10-11):983-985 and Linder, M.W. et al. (1997) Clin. Chem. 43(2):254-266. In general, two types of pharmacogenetic conditions can be differentiated. Genetic conditions transmitted as a single factor altering the way drugs act on the body (altered drug action) or genetic conditions transmitted as single factors altering the way the body acts on drugs (altered drug metabolism). These pharmacogenetic conditions can occur either as rare genetic defects or as naturally-occurring polymoφhisms. For example, glucose-6-phosphate carboxylesterase deficiency (G6PD) is a common inherited enzymopathy in which the main clinical complication is haemolysis after ingestion of oxidant drugs (anti-malarials, sulfonamides, analgesics, nitrofurans) and consumption of fava beans. One pharmacogenomics approach to identifying genes that predict drag response, known as "a genome-wide association", relies primarily on a high-resolution map of the human genome consisting of already known gene-related markers (e.g., a "bi-allelic" gene marker map which consists of 60,000-100,000 polymoφhic or variable sites on the human genome, each of which has two variants). Such a high-resolution genetic map can be compared to a map of the genome of each of a statistically significant number of patients taking part in a Phase II/III drug trial to identify markers associated with a particular observed drug response or side effect. Alternatively, such a high resolution map can be generated from a combination of some ten-million known single nucleotide polymoφhisms (SNPs) in the human genome. As used herein, a "SNP" is a common alteration that occurs in a single nucleotide base in a stretch of DNA. For example, a SNP may occur once per every 1000 bases of DNA. A SNP may be involved in a disease process, however, the vast majority may not be disease- associated. Given a genetic map based on the occurrence of such SNPs, individuals can be grouped into genetic categories .depending on a particular pattern of SNPs in their individual genome. In such a manner, treatment regimens can be tailored to groups of genetically similar individuals, taking into account traits that may be common among such genetically similar individuals. Alternatively, a method termed the "candidate gene approach" can be utilized to identify genes that predict drug response. According to this method, if a gene that encodes a drag's target is known (e.g., a COE-1 protein of the present invention), all common variants of that gene can be fairly easily identified in the population and it can be determined if having one version of the gene versus another is associated with a particular drug response. As an illustrative embodiment, the activity of drag metabolizing enzymes is a major determinant of both the intensity and duration of drug action. The discovery of genetic polymoφhisms of drag metabolizing enzymes (e.g., N-carboxylesterase 2 (NAT 2) and cytochrome P450 enzymes CYP2D6 and CYP2C19) has provided an explanation as to why some patients do not obtain the expected drug effects or show exaggerated drug response and serious toxicity after taking the standard and safe dose of a drag. These polymoφhisms are expressed in two phenotypes in the population, the extensive metabolizer (EM) and poor metabolizer (PM). The prevalence of PM is different among different populations. For example, the gene coding for CYP2D6 is highly polymoφhic and several mutations have been identified in PM, which all lead to the absence of functional CYP2D6. Poor metabolizers of CYP2D6 and CYP2C19 quite frequently experience exaggerated drug response and side effects when they receive standard doses. If a metabolite is the active therapeutic moiety, PM show no therapeutic response, as demonstrated for the analgesic effect of codeine mediated by its CYP2D6-formed metabolite moφhine. The other extreme are the so called ultra-rapid metabolizers who do not respond to standard doses. Recently, the molecular basis of ultra-rapid metabolism has been identified to be due to CYP2D6 gene amplification. Alternatively, a method termed the "gene expression profiling", can be utilized to identify genes that predict drug response. For example, the gene expression of an animal dosed with a drag (e.g., a COE-1 molecule or COE-1 modulator of the present invention) can give an indication whether gene pathways related to toxicity have been turned on. Information generated from more than one of the above pharmacogenomics approaches can be used to determine appropriate dosage and treatment regimens for prophylactic or therapeutic treatment an individual. This knowledge, when applied to dosing or drug selection, can avoid adverse reactions or therapeutic failure and thus enhance therapeutic or prophylactic efficiency when treating a subject with a COE-1 molecule or COE-1 modulator, such as a modulator identified by one of the exemplary screening assays described herein. 4. Use of COE-1 Molecules as Surrogate Markers The COE-1 molecules of the invention are also useful as markers of disorders or disease states, as markers for precursors of disease states, as markers for predisposition of disease states, as markers of drag activity, or as markers of the pharmacogenomic profile of a subject. Using the methods described herein, the presence, absence and/or quantity of the COE-1 molecules of the invention may be detected, and may be correlated with one or more biological states in vivo. For example, the COE-1 molecules of the invention may serve as surrogate markers for one or more disorders or disease states or for conditions leading up to disease states. As used herein, a "surrogate marker" is an objective biochemical marker which correlates with the absence or presence of a disease or disorder, or with the progression of a disease or disorder (e.g., with the presence or absence of a tumor). The presence or quantity of such markers is independent of the disease. Therefore, these markers may serve to indicate whether a particular course of treatment is effective in lessening a disease state or disorder. Surrogate markers are of particular use when the presence or extent of a disease state or disorder is difficult to assess through standard methodologies (e.g., early stage tumors), or when an assessment of disease progression is desired before a potentially dangerous clinical endpoint is reached (e.g., an assessment of cardiovascular disease may be made using cholesterol levels as a surrogate marker, and an analysis of HIV infection may be made using HIV RNA levels as a surrogate marker, well in advance of the undesirable clinical outcomes of myocardial infarction or fully-developed AIDS). Examples of the use of surrogate markers in the art include: Koomen et al. (2000) J Mass. Spectrom. 35:258-264; and James (1994) AIDS Treatment News Archive 209. The COE-1 molecules of the invention are also useful as pharmacodynamic markers. As used herein, a "pharmacodynamic marker" is an objective biochemical marker which correlates specifically with drug effects. The presence or quantity of a pharmacodynamic marker is not related to the disease state or disorder for which the drug is being administered; therefore, the presence or quantity of the marker is indicative of the presence or activity of the drag in a subject. For example, a pharmacodynamic marker may be indicative of the concentration of the drag in a biological tissue, in that the marker is either expressed or transcribed or not expressed or transcribed in that tissue in relationship to the level of the drag. In this fashion, the distribution or uptake of the drug may be monitored by the pharmacodynamic marker. Similarly, the presence or quantity of the pharmacodynamic marker may be related to the presence or quantity of the metabolic product of a drug, such that the presence or quantity of the marker is indicative of the relative breakdown rate of the drug in vivo. Pharmacodynamic markers are of particular use in increasing the sensitivity of detection of drug effects, particularly when the drag is administered in low doses. Since even a small amount of a drag may be sufficient to activate multiple rounds of marker (e.g., a COE-1 marker) transcription or expression, the amplified marker may be in a quantity which is more readily detectable than the drug itself. Also, the marker may be more easily detected due to the nature of the marker itself; for example, using the methods described herein, anti-COE-1 antibodies may be employed in an immune-based detection system for a COE-1 protein marker, or COE-1 -specific radiolabeled probes may be used to detect a COE-1 mRNA marker. Furthermore, the use of a pharmacodynamic marker may offer mechanism- based prediction of risk due to drug treatment beyond the range of possible direct observations. Examples of the use of pharmacodynamic markers in the art include: Matsuda et al US 6,033,862; Hattis et al (1991) E . Health Perspect. 90:229-238; Schentag (1999) Am. J. Health-Syst. Pharm. 56 Suppl. 3:S21-S24; and Nicolau (1999) Am. J. Health-Syst. Pharm. 56 Suppl. 3:S16-S20. The COE-1 molecules of the invention are also useful as pharmacogenomic markers. As used herein, a "pharmacogenomic marker" is an objective biochemical marker which correlates with a specific clinical drug response or susceptibility in a subject (see, e.g., McLeod et al (1999) Eur. J. Cancer 35(12).T 650-1652). The presence or quantity of the pharmacogenomic marker is related to the predicted response of the subject to a specific drug or class of drugs prior to administration of the drug. By assessing the presence or quantity of one or more pharmacogenomic markers in a subject, a drug therapy which is most appropriate for the subject, or which is predicted to have a greater degree of success, may be selected. For example, based on the presence or quantity of RNA, or protein (e.g., COE-1 protein or RNA) for specific tumor markers in a subject, a drag or course of treatment may be selected that is optimized for the treatment of the specific tumor likely to be present in the subject. Similarly, the presence or absence of a specific sequence mutation in COE-1 DNA may correlate COE-1 drug response. The use of pharmacogenomic markers therefore permits the application of the most appropriate treatment for each subject without having to administer the therapy. E. Electronic Apparatus Readable Media and Arrays Electronic apparatus readable media comprising COE-1 sequence information is also provided. As used herein, "COE-1 sequence information" refers to any nucleotide and/or amino acid sequence information particular to the COE-1 molecules of the present invention, including but not limited to full-length nucleotide and/or amino acid sequences, partial nucleotide and/or amino acid sequences, polymoφhic sequences including single nucleotide polymoφhisms (SNPs), epitope sequences, and the like. Moreover, information "related to" said COE-1 sequence information includes detection of the presence or absence of a sequence (e.g., detection of expression of a sequence, fragment, polymoφhism, etc.), determination of the level of a sequence (e.g., detection of a level of expression, for example, a quantitative detection), detection of a reactivity to a sequence (e.g., detection of protein expression and/or levels, for example, using a sequence-specific antibody), and the like. As used herein, "electronic apparatus readable media" refers to any suitable medium for storing, holding, or containing data or information that can be read and accessed directly by an electronic apparatus. Such media can include, but are not limited to: magnetic storage media, such as floppy discs, hard disc storage medium, and magnetic tape; optical storage media such as compact discs; electronic storage media such as RAM, ROM, EPROM, EEPROM and the like; and general hard disks and hybrids of these categories such as magnetic/optical storage media. The medium is adapted or configured for having recorded thereon COE-1 sequence information of the present invention. As used herein, the term "electronic apparatus" is intended to include any suitable computing or processing apparatus or other device configured or adapted for storing data or information. Examples of electronic apparatus suitable for use with the present invention include stand-alone computing apparatuses; networks, including a local area network (LAN), a wide area network (WAN) Internet, Intranet, and Extranet; electronic appliances such as a personal digital assistants (PDAs), cellular phone, pager and the like; and local and distributed processing systems. As used herein, "recorded" refers to a process for storing or encoding information on the electronic apparatus readable medium. Those skilled in the art can readily adopt any of the presently known methods for recording information on known media to generate manufactures comprising the COE-1 sequence information. A variety of software programs and formats can be used to store the sequence information on the electronic apparatus readable medium. For example, the sequence information can be represented in a word processing text file, formatted in commercially-available software such as WordPerfect and Microsoft Word, represented in the form of an ASCII file, or stored in a database application, such as DB2, Sybase, Oracle, or the like, as well as in other forms. Any number of dataprocessor structuring formats (e.g., text file or database) may be employed in order to obtain or create a medium having recorded thereon the COE-1 sequence information. By providing COE-1 sequence information in readable form, one can routinely access the sequence information for a variety of puφoses. For example, one skilled in the art can use the sequence information in readable form to compare a target sequence or target structural motif with the sequence information stored within the data storage means. Search means are used to identify fragments or regions of the sequences of the invention which match a particular target sequence or target motif. The present invention therefore provides a medium for holding instructions for performing a method for determining whether a subject has a COE-1 associated disease or disorder or a pre-disposition to a COE-1 associated disease or disorder, wherein the method comprises the steps of determining COE-1 sequence information associated with the subject and based on the COE-1 sequence information, determining whether the subject has a COE-1 associated disease or disorder or a pre-disposition to a COE-1 associated disease or disorder, and/or recommending a particular treatment for the disease, disorder, or pre-disease condition. The present invention further provides in an electronic system and/or in a network, a method for determining whether a subject has a COE-1 associated disease or disorder or a pre-disposition to a disease associated with COE-1 wherein the method comprises the steps of determining COE-1 sequence information associated with the subject, and based on the COE-1 sequence information, determining whether the subject has a COE-1, associated disease or disorder or a pre-disposition to a COE-1 associated disease or disorder, and/or recommending a particular treatment for the disease, disorder or pre-disease condition. The method may further comprise the step of receiving phenotypic information associated with the subject and/or acquiring from a network phenotypic information associated with the subject. The present invention also provides in a network, a method for determining whether a subject has a COE-1 associated disease or disorder or a pre-disposition to a COE-1 associated disease or disorder associated with COE-1, said method comprising the steps of receiving COE-1 sequence information from the subject and/or information related thereto, receiving phenotypic information associated with the subject, acquiring information from the network corresponding to COE-1 and/or a COE-1 associated disease or disorder, and based on one or more of the phenotypic information, the COE-1 information (e.g., sequence information and/or information related thereto), and the acquired information, determining whether the subject has a COE-1 associated disease or disorder or a pre-disposition to a COE-1 associated disease or disorder. The method may further comprise the step of recommending a particular treatment for the disease, disorder or pre-disease condition. The present invention also provides a business method for determining whether a subject has a COE-1 associated disease or disorder or a pre-disposition to a COE-1 associated disease or disorder, said method comprising the steps of receiving information related to COE-1 (e.g., sequence information and/or information related thereto), receiving phenotypic information associated with the subject, acquiring information from the network related to COE-1 and/or related to a COE-1 associated disease or disorder, and based on one or more of the phenotypic information, the COE-1 information, and the acquired information, determining whether the subject has a COE-1 associated disease or disorder or a pre-disposition to a COE-1 associated disease or disorder. The method may further comprise the step of recommending a particular treatment for the disease, disorder or pre-disease condition. The invention also includes an array comprising a COE-1 sequence of the present invention. The array can be used to assay expression of one or more genes in the array. In one embodiment, the array can be used to assay gene expression in a tissue to ascertain tissue specificity of genes in the array. In this manner, up to about 7600 genes can be simultaneously assayed for expression, one of which can be COE-1. This allows a profile to be developed showing a battery of genes specifically expressed in one or more tissues. In addition to such qualitative determination, the invention allows the quantitation of gene expression. Thus, not only tissue specificity, but also the level of expression of a battery of genes in the tissue is ascertainable. Thus, genes can be grouped on the basis of their tissue expression per se and level of expression in that tissue. This is useful, for example, in ascertaining the relationship of gene expression between or among tissues. Thus, one tissue can be perturbed and the effect on gene expression in a second tissue can be determined. In this context, the effect of one cell type on another cell type in response to a biological stimulus can be determined. Such a determination is useful, for example, to know the effect of cell-cell interaction at the level of gene expression. If an agent is administered therapeutically to treat one cell type but has an undesirable effect on another cell type, the invention provides an assay to determine the molecular basis of the undesirable effect and thus provides the opportunity to co-administer a counteracting agent or otherwise treat the undesired effect. Similarly, even within a single cell type, undesirable biological effects can be determined at the molecular level. Thus, the effects of an agent on expression of other than the target gene can be ascertained and counteracted. In another embodiment, the array can be used to monitor the time course of expression of one or more genes in the array. This can occur in various biological contexts, as disclosed herein, for example development of a COE-1 associated disease or disorder, progression of COE-1 associated disease or disorder, and processes, such a cellular transformation associated with the COE-1 associated disease or disorder. The array is also useful for ascertaining the effect of the expression of a gene on the expression of other genes in the same cell or in different cells (e.g., ascertaining the effect of COE-1 expression on the expression of other genes). This provides, for example, for a selection of alternate molecular targets for therapeutic intervention if the ultimate or downstream target cannot be regulated. The array is also useful for ascertaining differential expression patterns of one or more genes in normal and abnormal cells. This provides a battery of genes (e.g., including COE-1) that could serve as a molecular target for diagnosis or therapeutic intervention. This invention is further illustrated by the following examples which should not be construed as limiting. The contents of all references, patents and published patent applications cited throughout this application, as well as the figures and the Sequence Listing, are incoφorated herein by reference. EXAMPLES EXAMPLE 1 : IDENTIFICATION AND CHARACTERIZATION OF HUMAN COE-1 cDNA In this example, the identification and characterization of the gene encoding human COE-1 (clone Fbh25869) is described. Isolation of the human COE-1 cDNA The invention is based, at least in part, on the discovery of genes encoding novel ■, members of the carboxylesterase family. The entire sequence of human clone Fbh25869 was determined and found to contain an open reading frame termed human "COE-1." The nucleotide sequence encoding the human COE-1 is shown in Figures 1 A- IB and is set forth as SEQ ID NO: 1. The protein encoded by this nucleic acid comprises about 547 amino acids and has the amino acid sequence shown in Figures 1A-1B and set forth as SEQ ID NO:2. The coding region (open reading frame) of SEQ ID NO is set forth as SEQ ID NO:3. Clone Fbh25869, comprising the coding region of human COE- 1, was deposited with the American Type Culture Collection (ATCC®), 10801 University Boulevard, Manassas, VA 20110-2209, on , and assigned Accession No. . Analysis of the human COE-1 Molecules The amino acid sequence of human COE-1 was analyzed using the program PSORT (available online) to predict the localization of the proteins within the cell. This program assesses the presence of different targeting and localization amino acid sequences within the query sequence. The results of the analyses show that human COE-1 may be localized to the cytoplasm, to the nucleus, or to the mitochondria. Searches of the amino acid sequence of human COE-1 were performed against the HMM database (Figures 2A-2B). These searches resulted in the identification of a "carboxylesterase domain" at about residues 5-523 of SEQ ID NO:2 (score = 516.6). Searches of the amino acid sequence of human COE-1 were further performed against the Prosite database. These searches resulted in the identification in the amino acid sequence of human COE-1 of a potential N-glycosylation site and a number of potential protein kinase C phosphorylation sites, casein kinase II phosphorylation sites, and N-myristoylation sites. These searches further resulted in the identification of a carboxylesterases type-B serine active site at about residues 192-207 of SEQ ID NO:2. A "catalytic triad" was also identified in the human COE- 1. Based on an alignment with a mouse liver carboxylesterase precursor (GenBank Accession No. Q63880; SEQ ID NO:4), two of the catalytic triad amino acids were identified as Ser 205 and His 426 (see Figure 3). A "catalytic serine motif was also identified in the human COE-1. Based on an alignment with a mouse liver carboxylesterase precursor (GenBank Accession No. Q63880; SEQ ID NO:4; Figure 4), a catalytic serine motif was identified at about residues 203-207 of human COE-1 (SEQ ID NO:2). An "ER retention signal" was also identified in the human COE-1. Based on homology to other proteins known to have ER retention signals, an ER retention signal was identified in the amino acid sequence of human COE-1 (SEQ ID NO:2) at about residues 544-547. Global alignments of the human COE-1 amino acid sequence (SEQ ID NO:2) revealed that human COE-1 has a 67.279% identity with the amino acid sequence of a mouse liver carboxylesterase precursor (SEQ ID NO:4; GenBank Accession No. Q63880; Figure 4) and a 46%) identity with the amino acid sequence of rat liver carboxylesterase 10 precursor (also referred to as ES-10; SEQ ID NO:5; GenBank Accession No. P16303; Figure 5). Tissue Distribution of COE-1 mRNA This example describes the tissue distribution of human COE-1 mRNA, as may be determined using in situ hybridization analysis. For in situ analysis, various tissues, e.g., tissues obtained from brain, are first frozen on dry ice. Ten-micrometer-thick sections of the tissues are postfϊxed with 4%> formaldehyde in DEPC-treated IX phosphate-buffered saline at room temperature for 10 minutes before being rinsed twice in DEPC IX phosphate-buffered saline and once in 0.1 M triethanolamine-HCl (pH 8.0). Following incubation in 0.25% acetic anhydride-0.1 M triethanolamine-HCl for 10 minutes, sections are rinsed in DEPC 2X SSC (IX SSC is 0.15 M NaCl plus 0.015 M sodium citrate). Tissue is then dehydrated through a series of ethanol washes, incubated in 100% chloroform for 5 minutes, and then rinsed in 100%> ethanol for 1 minute and 95% ethanol for 1 minute and allowed to air dry. Hybridizations are performed with 35$-radiolabeled (5 X 10^ cpm/ml) cRNA probes. Probes are incubated in the presence of a solution containing 600 mM NaCl, 10 mM Tris (pH 7.5), 1 mM EDTA, 0.01% sheared salmon sperm DNA, 0.01% yeast tRNA, 0.05% yeast total RNA type XI, IX Denhardt's solution, 50% formamide, 10% dextran sulfate, 100 mM dithiothreitol, 0.1 % sodium dodecyl sulfate (SDS), and 0.1 % sodium thiosulfate for 18 hours at 55°C. After hybridization, slides are washed with 2X SSC. Sections are then sequentially incubated at 37°C in TNE (a solution containing 10 mM Tris-HCl (pH 7.6), . 500 mM NaCl, and 1 mM EDTA), for 10 minutes, in TNE with lOμg of RNase A per ml ι for 30 minutes, and finally in TNE for 10 minutes. Slides are then rinsed with 2X SSC , at room temperature, washed with 2X SSC at 50°C for 1 hour, washed with 0.2X SSC at., 55°C for 1 hour, and 0.2X SSC at 60°C for 1 hour. Sections are then dehydrated rapidly through serial ethanol-0.3 M sodium acetate concentrations before being air dried and exposed to Kodak Biomax MR scientific imaging film for 24 hours and subsequently dipped in NB-2 photoemulsion and exposed at 4°C for 7 days before being developed and counter stained. Analysis of Human COE-1 Expression using the Taqman Procedure The Taqman™ procedure is a quantitative, real-time PCR-based approach to detecting mRNA. The RT-PCR reaction exploits the 5' nuclease activity of AmpliTaq Gold™ DNA Polymerase to cleave a TaqMan™ probe during PCR. Briefly, cDNA was generated from the samples of interest and served as the starting material for PCR amplification. In addition to the 5' and 3' gene-specific primers, a gene-specific oligonucleotide probe (complementary to the region being amplified) was included in the reaction (i.e., the Taqman™ probe). The TaqMan™ probe included an oligonucleotide with a fluorescent reporter dye covalently linked to the 5' end of the probe (such as FAM (6-carboxyfluorescein), TET (6-carboxy-4,7,2',7'- tetrachlorofluorescein), JOE (6-carboxy-4,5-dichloro-2,7-dimethoxyfluorescein), or VIC) and a quencher dye (TAMRA (6-carboxy-N,N,N',N'-tetramethylrhodamine) at the 3' end of the probe. During the PCR reaction, cleavage of the probe separated the reporter dye and the quencher dye, resulting in increased fluorescence of the reporter. Accumulation of PCR products was detected directly by monitoring the increase in fluorescence of the reporter dye. When the probe was intact, the proximity of the reporter dye to the quencher dye resulted in suppression of the reporter fluorescence. During PCR, if the target of interest was present, the probe specifically annealed between the forward and reverse primer sites. The 5 '-3' nucleolytic activity of the AmpliTaq™ Gold DNA Polymerase cleaved the probe between the reporter and the quencher only if the probe hybridized to the target. The probe fragments were then displaced from the target, and polymerization of the strand continued. The 3' end of the probe was blocked to prevent extension of the probe during PCR. This process occurred in every cycle and did not interfere with the exponential accumulation of product. RNA was prepared using the trizol method and treated with DNase to remove contaminating genomic DNA. cDNA was synthesized using standard techniques. Mock cDNA synthesis in the absence of reverse transcriptase resulted in samples with no detectable PCR amplification of the control GAPDH or β-actin gene confirming efficient removal of genomic DNA contamination. Taqman analysis showed that human COE-1 was highly expressed in the kidney, colon, liver, brain, small intestine, and skeletal muscle (see Figure 7). Expression of human COE-1 was upregulated in marmoset monkeys treated with cholestyramine, a drug which lowers cholesterol and/or lipids in the blood. EXAMPLE 2: EXPRESSION OF RECOMBINANT COE-1 PROTEIN IN BACTERIAL CELLS In this example, human COE-1 is expressed as a recombinant glutathione-S- transferase (GST) fusion polypeptide in E. coli and the fusion polypeptide is isolated and characterized. Specifically, human COE-1 is fused to GST and this fusion polypeptide is expressed in E. coli, e.g., strain PEB199. Expression of the GST-COE-1 fusion protein in PEB199 is induced with IPTG. The recombinant fusion polypeptide is purified from crade bacterial lysates of the induced PEB199 strain by affinity chromatography on glutathione beads. Using polyacrylamide gel electrophoretic analysis of the polypeptide purified from the bacterial lysates, the molecular weight of the resultant fusion polypeptide is determined. EXAMPLE 3: EXPRESSION OF RECOMBINANT COE-1 PROTEIN IN COS CELLS To express the human COE-1 gene in COS cells, the pcDNA/Amp vector by Invitrogen Coφoration (San Diego, CA) is used. This vector contains an SV40 origin of replication, an ampicillin resistance gene, an E. coli replication origin, a CMV promoter followed by a polylinker region, and an SV40 intron and polyadenylation site. A DNA fragment encoding the entire COE-1 protein and an HA tag (Wilson et al. (1984) Cell 31:161) or a FLAG tag fused in-frame to its 3' end of the fragment is cloned into the polylinker region of the vector, thereby placing the expression of the recombinant protein under the control of the CMV promoter. To construct the plasmid, the COE-1 DNA sequence is amplified by PCR using two primers. The 5' primer contains the restriction site of interest followed by approximately twenty nucleotides of the COE-1 coding sequence starting from the initiation codon; the 3' end sequence contains complementary sequences to the other restriction site of interest, a translation stop codon, the HA tag or FLAG tag and the last 20 nucleotides of the COE-1 coding sequence. The PCR amplified fragment and the pCDNA/Amp vector are digested with the appropriate restriction enzymes and the vector is dephosphorylated using the CIAP enzyme (New England Biolabs, Beverly, MA). Preferably the two restriction sites chosen are different so that the COE-1 gene is inserted in the correct orientation. The ligation mixture is transformed into E. coli cells (strains HB101, DH5α, SURE, available from Stratagene Cloning Systems, La Jolla, CA, can be used), the transformed culture is plated on ampicillin media plates, and resistant colonies are selected. Plasmid DNA is isolated from transformants and examined by restriction analysis for the presence of the correct fragment. COS cells are subsequently transfected with the COE-1-pcDNA/Amp plasmid DNA using the calcium phosphate or calcium chloride co-precipitation methods, DEAE- dextran-mediated transfection, lipofection, or electroporation. Other suitable methods for transfecting host cells can be found in Sambrook, J., Fritsh, E.F., and Maniatis, T. Molecular Cloning: A Laboratory Manual. 2nd, ed., Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1989. The expression of the COE-1 polypeptide is detected by radiolabeling (35s-methionine or 35s-cysteine available from NEN, Boston, MA, can be used) and immunoprecipitation (Harlow, E. and Lane, D. Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1988) using an HA specific monoclonal antibody. Briefly, the cells are labeled for 8 hours with 3 s-methionine (or 35s-cysteine). The culture media are then collected and the cells are lysed using detergents (RIPA buffer, 150 mM NaCl, 1% NP-40, 0.1% SDS, 0.5% DOC, 50 mM Tris, pH 7.5). Both the cell lysate and the culture media are precipitated with an HA specific monoclonal antibody. Precipitated polypeptides are then analyzed by SDS-PAGE. Alternatively, DNA containing the COE-1 coding sequence is cloned directly into the polylinker of the pCDNA Amp vector using the appropriate restriction sites. The resulting plasmid is transfected into COS cells in the manner described above, and the expression of the COE-1 polypeptide is detected by radiolabeling and immunoprecipitation using a COE-1 specific monoclonal antibody. EXAMPLE 4: ANALYSIS OF HUMAN COE-1 ACTIVITY The activity, e.g., the lipase activity, of COE-1 molecules of the present invention may be determined by the use of any of the following assays. All of the following assays are performed as described in Lehner, R. and Vance, D.E. (1999) Biochem. J. 343:1-10, the contents of which are incoφorated herein by reference. Materials Oleic acid, essentially fatty acid-free bovine serum albumin (BSA),/?- nitrophenyl fatty acyl esters and Protein A-Sepharose CL 4B are purchased from Sigma (St. Louis, MO, U.S. A.). [9,10-3H]Triolein (28 mCi/mmol) is from Dupont NEN (Boston, MA, U.S.A.). [l,3- 3 H]glycerol (2.6 Ci/mmol), [U- 14 C]glycerol (149 mCi/mmol), [9, 10-Η]oleic acid (10 Ci/mmol), L-[4,5- 3 H]leucine (57 Ci/mmol) and ECL Western blotting reagents are obtained from Amersham Canada (Oakville, Ontario, Canada). Dulbecco's modified Eagle's medium (DMEM), sodium pyruvate, penicillin/streptomycin, fetal bovine and horse sera and Geneticin (G-418 sulfate) are from Gibco BRL (Life Technologies Inc., Grand Island, NY, U.S.A.). Triascin C is purchased from Biomol Research Laboratories, Inc. (Plymouth Meeting, PA, U.S.A.). All other chemicals and solvents are of reagent or better quality and are obtained from any number of suppliers known to those of skill in the art. Sheep anti- [human apolipoprotein (apo)B] IgG is from Boehringer-Mannheim. Cell culture Primary hepatocytes are isolated from male Sprague-Dawley rats (body weight 125-150 g), fed ad libitum, by collagenase perfusion of the liver. The cells are cultured in DMEM containing 15%) (v/v) fetal bovine serum, as described in Yao, Z. and Vance, D.E. (1988) J Biol. Chem. 263:449-509. HepG2 cells, obtained from A.T.C.C., are ' cultured in minimal Eagle's medium containing 0.1 mM nonessential amino acids, 1 mM sodium pyruvate, penicillin (10 units/ml), streptomycin (100 μg/ml) and 10%> fetal bovine serum. McArdle RH7777 cells obtained from A.T.C.C, are cultured in DMEM containing pyruvate, antibiotics, 10% fetal bovine serum, and 10%> (v/v) horse seram. All cultures are maintained in 100 mm dishes (Corning) at 37°C in humidified air (89- 91% saturation) containing 5% CO 2 . Generation of stable cell lines expressing COE-1 cDNA Cells, e.g., McArdle RH7777 cells, are transfected with 10 μg of pBK-CMV plasmid vector (Stratagene) with or without COE-1 cDNA insert using a calcium precipitation procedure, as described in Chen, C. and Okayama, H. (1987) Mol. Cell. Biol. 7:2745-2752. Cells stably expressing either the empty vector or the vector containing the COE-1 cDNA are selected for resistance to the antibiotic G-418 (0.08% w/v). Transfected McArdle RH7777 cells are grown in DMEM supplemented with 10% horse serum and 10% fetal bovine serum, penicillin/streptomycin (40 units/ml) and 0.02% (w/v) G-418. Cells are maintained at 37°C in humidified air containing 5% CO 2 . Preparation of microsomal membranes Cells, e.g., McArdle RH7777 cells, from ten 100 mm diameter culture dishes (approximately 50 mg of protein) are harvested into 5 ml of 10 mM Tris/HCl, pH 7.4, containing 250 mM sucrose and 5 mM EDTA. Cells are homogenized with a Polytron, and the microsomal membranes are isolated by ultracentrifugation from a post- mitochondrial supernatant, as described in Lehner, R. and Kuksis, A. (1993) J. Biol. Chem. 268:8781-8786. Lipase assay Lipolytic activities in microsomal membranes (50 μg of protein) isolated from 'mock' transfected (empty vector) and COE-1 cDNA transfected cells (e.g., McArdle RH7777 cells) are assessed using either radiolabeled triolein or a chromogenic substrate (p-nitrophenyl laurate) as described in Lehner, R. and Verger, R. (1997) Biochemistry 36:1861-1868. Immunoblot analysis Cells, e.g., McArdle RH7777 cells (non-transfected, 'mock' transfected, and COE-1 cDNA transfected) are harvested in phosphate-buffered saline (PBS) and disrupted by brief sonication. Cell homogenates (35 μg of protein) are electrophoresed on an SDS/12% (w/v) polyacrylamide gel, transferred to a nitrocellulose membrane, and the expression of COE-1 is analyzed by blotting with anti-COE-1 antibodies using standard methods. Lipid uptake by transfected cells Cells, e.g., McArdle RH7777 cells (at approximately 80% confluency in 60 mm diameter culture dishes) are incubated with 2 ml of serum-free DMEM containing 0.5% BSA and 100 μCi [ 3 H] oleic acid for 1 hour. The medium is aspirated, the cells are washed with DMEM/0.5% BSA, and subsequently the cells are incubated with 5 ml of DMEM/0.5% BAS for 2 hours. The medium is removed, diluted with DMEM/0.5% BSA and 5 ml aliquots are added to the cells, e.g., McArdle RH7777 cells, stably transfected with either pBK-CMV vector or with pBK-CMV containing COE-1 cDNA. Aliquots of medium (1 ml) are taken after 2, 4, and 6 hours of incubation. At the end of the incubation period, the cells are washed with ice-cold PBS, harvested in the same buffer, and dispersed by brief sonication. Cellular and medium lipids are extracted as described in Folch, J. et al. ((1951) J. Biol. Chem. 226:449-509) in the presence of non- labeled lipid carriers. The lipids are applied to TLC plates and developed to one-third the height with chloroform/methanol/acetic acid/water (25:15:4:2, by volume) to separate glycerophospholipids, followed by development in heptane/isopropyl ether/acetic acid (60:40:4, by volume) to separate neutral lipids. Lipids are made visible by exposure to iodine; bands corresponding to various lipid classes are scraped, and the associated radioactivity is determined by scintillation counting. Effect oftriascin C on glycerolipid synthesis and secretion Cells, e.g., McArdle RH7777 cells, stably transfected with pBK-CMV or pBK- CMV containing COE-1 cDNA are grown to approximately 10% confluency in 60 mm diameter dishes and incubated for 24 hours with serum-free DMEM containing 0.1 mM oleic acid complexed with BSA (0.13%) final concentration). The medium is aspirated and the cells are incubated for 1 hour with DMEM containing 0.1 mM oleic acid/BSA and various concentrations oftriascin C in DMSO. The final concentration of DMSO is 0.4%). After a 1 hour incubation ± triascin C, 10 μCi/dish of [ 3 H]glycerol is added. Cells and medium are collected after 2 hours, lipids are extracted, and the radioactivity associated with phosphatidylcholine and triacylglycerol is analyzed as described above. Intracellular lipid turnover in transfected cells Cells, e.g., McArdle RH7777 cells, stably transfected with pBK-CMV or pBK- CMV containing COE-1 cDNA (grown to approximately 10% confluency) are incubated with serum-free DMEM containing 0.1 mM oleic acid complexed with BSA (0.13%) final concentration) and 20 μCi [ H]glycerol for 15 hours. After 13 hours, triascin C (20 μM final concentration) is added. After an additional 2 hours of labeling, medium is removed, cells are washed and incubated for 6 hours ± triascin C (chase). Cells are harvested, lipids are extracted and separated by TLC, and the amount of radioactivity in phosphatidylcholine and triacylglycerol is determined. Utilization of intracellular triacylglycerol stores for lipoprotein assembly and secretion Contribution of f^CJglycerol-labeled intracellular triacylglycerol pools in the presence of exogenous oleate: pulse-chase protocol Cells are incubated for 2 hours with 0.375 mM oleic acid/0.5%> BSA to increase the triacylglycerol stores. Cells are then washed and incubated for 1 hour with DMEM followed by 2 hours with 0.375 mM oleic acid/0.5% BSA and 0.25 μCi [ 14 C]glycerol. Radioactivity in cellular and medium phosphatidylcholine and triacylglycerol is analyzed following lipid extraction and TLC as described above. Secretion of ' P HJglycerol-prelabeled intracellular triacylglycerol pools in the absence of oleate Cells are incubated for 16 hours with serum-free DMEM containing 0.375 mM oleic acid/0.5%) BSA and 0.25 μCi [ 14 C]glycerol, washed and incubated with DMEM in the absence of extracellular oleate for up to 8 hours. Radioactivity in cellular medium lipids is analyzed. Lipid secretion from transfected cells Cells, e.g., McArdle RH7777 cells, at 60-70% confluency are washed with DMEM and incubated in the absence of serum for 2 hours. One set of dishes is . incubated for 4 hours with serum-free DMEM containing 0.5%> BSA and 10 μCi ,, [ 3 H]gIycerol. The other set of dishes is incubated for 4 hours with serum-free DMEM containing 0.375 mM oleic acid/0.5% BSA and 10 μCi [ 3 H]glycerol. At the end of a 4 hour pulse, a set of oleate-treated cells is washed with DMEM and incubated for various times with serum-free DMEM containing 0.5%) BSA (chase). Medium and cells are collected, and lipids are extracted in the presence of non-labeled lipid carriers. Lipids are separated by TLC and made visible by exposure to iodine, and the radioactivity associated with phosphatidylcholine and triacylglycerol is determined. Triacylglycerol and phosphatidylcholine mass secretion from transfected cells The experimental design for determination of the mass of triacylglycerol and phosphatidylcholine secreted is identical to that described above, except that cells are grown in 100 mm diameter dishes, and medium from three dishes is combined. Lipids are extracted by TLC, and the mass of phosphatidylcholine is determined as described in Chalvardjian, A. and Rudnicki, E. (1910) Anal. Biochem. 36:225-226. The mass of triacylglycerol is determined according to the methods of Snyder, F. and Stephens, N. ((1959) Biochim. Biophys. Acta 34:244-245) using trioleoylglycerol as an authentic standard. Determination of intracellular and secreted triacylglycerol mass Cells (e.g., freshly prepared primary rat hepatocytes seeded at (5-6) x IO 6 cells/60 mm diameter dish; McArdle RH7777 cells at 80%> confluency; or HepG2 cells) are incubated for 12 hours in their respective growth media supplemented with 0.375 mM oleate/0.5%) BSA. Cells are then washed with DMEM and incubated for 2 hours with DMEM containing 0.375 mM oleate/0.5%) BSA. The media are then collected and triacylglycerol mass is analyzed (triacylglycerol secretion at 2 hours of supplementation with oleate). Cells are washed and incubated for 2 hours with DMEM in the absence of oleate. Medium is removed, the cells washed, and fresh DMEM replenished. The procedure is repeated every 2 hours. Media and cell lipids are extracted and triacylglycerol mass determined as described above. ApoB secretion Cells stably transfected with either pBK-CMV or pBK-CMV containing COE-1 cDNA grown to approximately 70%> confluency in 60 mm diameter dishes are incubated for 16 hours with serum-free DMEM. Cells are then incubated for 2 hours with DMEM containing 0.375 mM oleic acid/0.5% BSA, washed for 1 hour with leucine-free medium ± oleic acid/BSA and incubated for 2 hours with 2 ml of either leucine-free DMEM containing 0.5% BSA and 250 μCi of [ 3 H]leucine, or leucine-free DMEM containing 0.375 mM oleic acid/0.5%> BSA and 250 μCi [ H]leucine. Medium is removed and briefly centrifuged to remove cellular debris. A 0.1 ml aliquot of lOx immunoprecipitation buffer (1.5 M NaCl, 0.5 M Tris/HCl, pH 7.4, 50 mM EDTA, 5% (v/v) Triton X-100, 1% (w/v) SDS; Wu, X. et al (1996) J Lipid Res. 37:1198-1206) is added to the culture medium (0.9 ml containing 1 mM final concentration of benzamidine). Anti (human apoB) IgG (10 μl) is then added. The mixture is incubated for 12 hours at 4°C, then 50 μl of Protein A-Sepharose is added, and the mixture is incubated for 3 more hours. The beads are pelleted by brief centrifugation, washed three times with an excess of immunoprecipitation buffer, then 0.1 μg of rat VLDL protein is added, followed by electrophoresis sample buffer (125 mM Tris/HCl, pH 6.8, 4%> SDS, 20%) (v/v) glycerol, 10% (v/v) β-mercaptoethanol, 0.02%> Bromophenol Blue; Wu et al. (1996) supra). Samples are boiled and electrophoresed through 5%> (w/v) polyacrylamide gels containing 0.1% SDS. Gels are silver stained (Rabilloud, T. et al. (1988) Electrophoresis 9:288-291), and bands corresponding to apoB48 and apoBlOO are excised, dissolved at 60°C in 0.2 ml of 60%) (v/v) perchloric acid followed by 0.4 ml of 30%) (v/v) hydrogen peroxide (Mahin, D.T. and Lofberg, R.T. (1966) Anal. Biochem. 16:500-509), and the radioactivity associated with apoB48 and apoBlOO is determined using Hionic-Fluor scintillation cocktail (Packard Instrument Co., Meriden, CT, U.S.A.). For detection of apoB in VLDL, density centrifugation is performed according to Chung et al. ((1980) J Lipid Res. 21:284-291). To 1.2 ml of medium (containing 1 mM benzamidine) are added 100 μl of freshly prepared rat plasma and 0.7 grams KBr (4 M final concentration of KBr, density 1.3 g/ml). The mixture is placed into 5.5 ml Quick- Seal centrifuge tubes (Beckman), carefully overlayed with 0.9% NaCl, and centrifuged for 45 minutes at 41,600 g (65,000 revolutions/minute; VTi 65.2 rotor). Fractions of 0.5 ml are collected from the bottom of the tubes, and the densities are determined. Top fractions containing VLDL have a density of <1.013 g/ml. Fractions are adjusted to 0.9 ml with water, and apoB is immunoprecipitated and analyzed as described above. Other methods 7.5 mM oleic acid/10% (w/v) BSA stock solution is prepared by dissolving fatty acid-free BSA in DMEM. The solution is heated to 56°C, added to 0.106 grams oleic acid, stirred until the solution clarifies, and sterilized by filtration. Protein concentration is determined using the Bio-Rad Protein Assay kit using BSA as a protein standard. Equivalents Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims: What is claimed: 1. An isolated nucleic acid molecule selected from the group consisting of: (a) a nucleic acid molecule comprising the nucleotide sequence set forth in SEQ ID NOT; and (b) a nucleic acid molecule comprising the nucleotide sequence set forth in SEQ ID NO:3. 2. An isolated nucleic acid molecule which encodes a polypeptide comprising the amino acid sequence set forth in SEQ ID NO:2. 3. An isolated nucleic acid molecule comprising the nucleotide sequence contained in the plasmid deposited with ATCC® as Accession Number . 4. An isolated nucleic acid molecule which encodes a naturally-occurring allelic variant of a polypeptide comprising the amino acid sequence set forth in SEQ ID NO:2. 5. An isolated nucleic acid molecule selected from the group consisting of: (a) a nucleic acid molecule comprising a nucleotide sequence which is at least 60%) identical to the nucleotide sequence of SEQ ID NOT or 3, or a complement thereof; (b) a nucleic acid molecule comprising a fragment of at least 30 nucleotides of a nucleic acid comprising the nucleotide sequence of SEQ ID NOT or 3, or a complement thereof; (c) a nucleic acid molecule which encodes a polypeptide comprising an amino acid sequence at least about 60% identical to the amino acid sequence of SEQ ID NO:2; and (d) a nucleic acid molecule which encodes a fragment of a polypeptide comprising the amino acid sequence of SEQ ID NO:2, wherein the fragment comprises at least 10 contiguous amino acid residues of the amino acid sequence of SEQ ID NO:2. 6. An isolated nucleic acid molecule which hybridizes to the nucleic acid molecule of any one of claims 1, 2, 3, 4, or 5 under stringent conditions. 7. An isolated nucleic acid molecule comprising a nucleotide sequence which is complementary to the nucleotide sequence of the nucleic acid molecule of any one of claims 1, 2, 3, 4, or 5. 8. An isolated nucleic acid molecule comprising the nucleic acid molecule of any one of claims 1, 2, 3, 4, or 5, and a nucleotide sequence encoding a heterologous polypeptide. 9. A vector comprising the nucleic acid molecule of any one of claims 1 , 2, 3, 4, or 5. 10. The vector of claim 9, which is an expression vector. 11. A host cell transfected with the expression vector of claim 10. 12. A method of producing a polypeptide comprising culturing the host cell of claim 11 in an appropriate culture medium to, thereby, produce the polypeptide. 13. An isolated polypeptide selected from the group consisting of: a) a fragment of a polypeptide comprising the amino acid sequence of SEQ ID NO:2, wherein the fragment comprises at least 10 contiguous amino acids of SEQ ID NO :2; b) a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence of SEQ ID NO:2, wherein the polypeptide is encoded by a nucleic acid molecule which hybridizes to a nucleic acid molecule consisting of SEQ ID NO:l or 3 under stringent conditions; c) a polypeptide which is encoded by a nucleic acid molecule comprising a nucleotide sequence which is at least 60% identical to a nucleic acid comprising the nucleotide sequence of SEQ ID NOT or 3; and d) a polypeptide comprising an amino acid sequence which is at least 60%) identical to the amino acid sequence of SEQ ID NO:2. 14. The isolated polypeptide of claim 13 comprising the amino acid sequence of SEQ ID NO:2. 15. The polypeptide of claim 13, further comprising heterologous amino acid sequences. 16. An antibody which selectively binds to a polypeptide of claim 13. 17. A method for detecting the presence of a polypeptide of claim 13 in a sample comprising: a) contacting the sample with a compound which selectively binds to the polypeptide; and b) determining whether the compound binds to the polypeptide in the sample to thereby detect the presence of a polypeptide of claim 13 in the sample. 18. The method of claim 17, wherein the compound which binds to the polypeptide is an antibody. 19. A kit comprising a compound which selectively binds to a polypeptide of claim 13 and instractions for use. 20. A method for detecting the presence of a nucleic acid molecule of any one of claims 1, 2, 3, 4, or 5 in a sample comprising: a) contacting the sample with a nucleic acid probe or primer which selectively hybridizes to the nucleic acid molecule; and b) determining whether the nucleic acid probe or primer binds to a nucleic acid molecule in the sample to thereby detect the presence of a nucleic acid molecule of any one of claims 1, 2, 3, 4, or 5 in the sample. 21. The method of claim 20, wherein the sample comprises mRNA molecules and is contacted with a nucleic acid probe. 22. A kit comprising a compound which selectively hybridizes to a nucleic acid molecule of any one of claims 1, 2, 3, 4, or 5 and instructions for use. 23. A method for identifying a compound which binds to a polypeptide of claim 13 comprising: a) contacting the polypeptide, or a cell expressing the polypeptide with a test compound; and b) determining whether the polypeptide binds to the test compound. 24. The method of claim 23 , wherein the binding of the test compound to the polypeptide is detected by a method selected from the group consisting of: a) detection of binding by direct detection of test compound/polypeptide binding; b) detection of binding using a competition binding assay; and c) detection of binding using an assay for COE-1 activity. 25. A method for modulating the activity of a polypeptide of claim 13 comprising contacting the polypeptide or a cell expressing the polypeptide with a compound which binds to the polypeptide in a sufficient concentration to modulate the activity of the polypeptide. 26. A method for identifying a compound which modulates the activity of a polypeptide of claim 13 comprising: a) contacting a polypeptide of claim 13 with a test compound; and b) determining the effect of the test compound on the activity of the polypeptide to thereby identify a compound which modulates the activity of the polypeptide. 27. A method of identifying a subject having a carboxylesterase-associated disorder, or at risk for developing a carboxylesterase-associated disorder comprising: a) contacting a sample obtained from said subject comprising nucleic acid molecules with a hybridization probe comprising at least 25 contiguous nucleotides of SEQ ID NO:l; and b) detecting the presence of a nucleic acid molecule in said sample that hybridizes to said probe, thereby identifying a subject having a carboxylesterase- associated disorder. 28. A method of identifying a subject having a carboxylesterase-associated disorder, or at risk for developing a carboxylesterase-associated disorder comprising: a) contacting a sample obtained from said subject comprising nucleic acid molecules with a first and a second amplification primer, said first primer comprising at least 25 contiguous nucleotides of SEQ ID NOT and said second primer comprising at least 25 contiguous nucleotides from the complement of SEQ ID NOT; b) incubating said sample under conditions that allow nucleic acid amplification; and c) detecting the presence of a nucleic acid molecule in said sample that is amplified, thereby identifying a subject having a carboxylesterase-associated disorder, or at risk for developing a carboxylesterase-associated disorder. 29. A method of identifying a subject having a carboxylesterase-associated disorder, or at risk for developing a carboxylesterase-associated comprising: a) contacting a sample obtained from said subject comprising polypeptides with a COE-1 binding substance; and b) detecting the presence of a polypeptide in said sample that binds to said COE-1 binding substance, thereby identifying a subject having a carboxylesterase- associated disorder, or at risk for developing a carboxylesterase-associated disorder. 30. A method for identifying a compound capable of treating a carboxylesterase-associated disorder characterized by aberrant COE-1 nucleic acid expression or COE-1 polypeptide activity comprising assaying the ability of the compound to modulate COE-1 nucleic acid expression or COE-1 polypeptide activity, thereby identifying a compound capable of treating a carboxylesterase-associated disorder characterized by aberrant COE-1 nucleic acid expression or COE-1 polypeptide activity. 31. A method for treating a subject having a carboxylesterase-associated disorder characterized by aberrant COE-1 polypeptide activity or aberrant COE-1 nucleic acid expression comprising administering to the subject a COE-1 modulator, thereby treating said subject having a carboxylesterase-associated disorder. 32. The method of claim 31 , wherein the carboxylesterase-associated disorder is a lipid homeostasis disorder.

Inventors: CURTIS RORY A J, LOGAN THOMAS JOSEPH, CURTIS, RORY, A., J., LOGAN, THOMAS, JOSEPH
Applicants: CURTIS RORY A J, LOGAN THOMAS JOSEPH, MILLENNIUM PHARM INC, CURTIS, RORY, A., J., LOGAN, THOMAS, JOSEPH, MILLENNIUM PHARMACEUTICALS, INC.
Application year: 2001
Main classification: C12N9
IPC codes: A61K38, C12N9