KAPPA/MU-LIKE PROTEIN TYROSINE PHOSPHATASE, PTP LAMBDA

Abstract: This invention concerns novel receptor protein tyrosine phosphatase polypeptides. Specifically, this invention concerns the novel receptor protein tyrosine phosphatase lambda which is related to the homotypically adhering receptor protein tyrosine phosphatases kappa and mu . The invention further relates to analogs of these polypeptides in other mammals, functional derivatives thereof, antibodies which are capable of specifically binding to these polypeptides, nucleic acids encoding these polypeptides, vectors containing and capable of expressing such nucleic acid and recombinant host cells transformed with such nucleic acid. Methods for the recombinant production of these receptor protein tyrosine phosphatase polypeptides and assays for identifying agonists and antagonists of these polypeptides are also within the scope of the invention.

Description: KAPPA/MU-LIKE PROTEIN TYROSINE PHOSPHATASE, PTP LAMBDA FIELD OF THE INVENTION This present invention concerns novel receptor protein tyrosine phosphatase polypeptides. More particularly, the present invention concerns a novel receptor protein tyrosine phosphatase designated herein as PTP λ. BACKGROUND OF THE INVENTION An extraordinary number of cellular processes are regulated by the tyrosine phosphorylation of a diversity of proteins. Tyrosine phosphorylation is induced by a plethora of receptor-like molecules as well as by a wide range of intracellular enzymes. The effects of tyrosine phosphorylation are numerous, and they modulate a range of developmental as well as other cellular operations. Of course, the importance of tyrosine phosphorylation is underlined by the need for mechanisms which carefully regulate the levels of these events. Thus, protein tyrosine kinases represent positive mediators of tyrosine phosphorylation, while protein tyrosine phosphatases (PTPs) induce the removal of phosphate from tyrosine. The balance of the levels of tyrosine phosphate is thus mediated by the relative activities of these two types of enzymes. It is therefore clear that the mechanisms which regulate cellular function via tyrosine phosphorylation require specific proteins which mediate both the upregulation as well as the downregulation of the levels of this modified amino acid. PTPs represent a growing family of enzymes that are found in both receptor as well as non-receptor forms (Tonks, Semin. Cell. Biol. 4:373- 453 (1 993), Walton et al. , Ann. Rev. Biochem. 62: 101 -120 ( 1 993) and Sun et a/.. Trends Biochem. Sci. 1 9(1 1 ):480-485 (1994)). Non-receptor PTPs are a highly diverse kindred, and they contain a number of motifs, in addition to the enzymatically active PTP domain, that serve to regulate the region of the cell occupied by these proteins as well as the substrate specificity of these enzymes. The receptor PTPs are also a highly diverse group that are unified by the inclusion of a transmembrane domain which disposes them to the plasma membrane of the cell. Recently, the receptor PTPs have been subdivided into 8 types based upon their domain content (Brady-Kalnay et al. , Curr. Opin. Cell. Biol. 7(5):650-657 (1 995)). These subtypes all contain one or two PTPase domains on their cytoplasmic sides, with a variety of extracellular motifs including heavily O-glycosylated mucin-like domains (for example, CD45), chondroitin sulfate domains (for example, PTP y) and short, highly glycosylated segments (for example, PTP α). The largest family of PTPs is the family which contains various motifs related to those found in adhesion molecules. These motifs include immunoglobulin-like (IgG) domains and fibronectin type III (Fnlll) regions similar to those found in cell adhesion molecules such as ICAM, N-CAM and Ng-CAM (Rao et al. , J. Cell. Biol. 1 18:937-949 (1992)). In addition, a subset of these adhesion-like PTPs, including the PTPs K and μ, contain a third domain termed the MAM, for meprin/A.5/PTP n, motif (Beckman et al. , Trends Biochem. Sci. 18:40-41 (1993)). The MAM motif has been previously shown to be involved with cell-cell recognition in neurons (Jiang et al. , J. Biol. Chem. 267:9185- 91 93 (1992), Takagi et al. , N≤uipn 7:295-307 ( 1 991 ) and Hirata et al. , Neurosci. Res. 17: 159-169 (1993)). Interestingly, recent data suggest that three of these adhesion-like PTPs appear to be involved with neuronal pathfinding during Drosophila development (Desai et al. , Cell 84:599-609 ( 1 996) and Kreuger et al. , £eJl 84:61 1 -622 (1 996)). Together, these structural data are consistent with the conjecture that receptor PTPs encompass a diverse family of enzymatically active proteins which contain a number of interesting cell surface motifs potentially involved with the sensing of the extracellular environment. PTPs K and μ are the receptors that are most well characterized as adhesion molecules (Brady-Kalnay et al. , supra. Jiang et al. , Mol. Cell. Biol.. 13:2942-2951 ( 1 993) and Gebbink et al.. Febs. Lett. 290(1 -2): 1 23- 1 30 (1 991 )). Both of these PTPs have been demonstrated to mediate homotypic adhesion. Thus, a diversity of assays, including cell- as well as molecule-based, have demonstrated that the extracellular domain of these enzymes can bind with high specificity in a homophilic manner (Brady-Kalnay et al.. J. Cell. Biol. 268:961 -972 (1 993), Gebbink et al. , ± Biol. Chem. 268: 1 6101 -16104 ( 1993) and Sap et al. , Mol. Cell. Biol. 14: 1 -9 (1 994)). Interestingly, mixing experiments have revealed that these closely related PTPs will not bind to each other in a heterophilic mode, suggesting that the extracellular domain is meant to recognize other cells specifically expressing identical receptors, a situation highly reminiscent of the cadherin homotypic adhesion system (Kemler et al. , Trends Genet. 9:317-321 (1993)). While the extracellular domains required for this homotypic binding remain controversial, it appears likely that both the MAM motif as well as the IgG region are involved with homophilic interactions (Brady-Kalnay et al. , J. Biol. Chem. 269:28472- 28477 (1994) and Zondag et al., J. Biol. Chem. 270(24): 14247-1 4250 (1 995)) . While these data suggest that these homophilic adhesion enzymes are involved with the recognition of other cells expressing similar types of receptors, other data have suggested that this recognition event may play a role in the attachment of such cells to each other. Thus, Tonks and colleagues have recently demonstrated that the receptor PTP μ specifically associates with the catenin/cadherin complex of homotypic cell adhesion molecules (Brady-Kalnay et al. , J. Cell. Biol. 1 30(4):977-986 (1 995)). They also demonstrated that treatment of cells with the PTP inhibitor pervanadate resulted in the upregulation of tyrosine phosphorylation of cadherins and catenins, a result which suggested a role for a PTP, potentially PTP μ, in the maintenance of the cadherin/catenin complex in an underphosphorylated state. Interestingly, previous work suggested that the level of tyrosine phosphorylation of this complex was correlated with the adhesive capacity of the cadherins (Beherns et al. , J. Cell. Biol. 1 20:757-766 (1993)), a result which is consistent with the hypothesis that the adhesion between cells mediated by the cadherins might be regulated by their tyrosine phosphorylation levels as determined by homotypic interactions between receptor PTPs such as K and μ. The finding that PTPs K and μ mediated homotypic adhesion, together with the somewhat restricted tissue distribution of these PTPs (Jiang et al. , (1 993) supra and Gebbink et al. , ( 1 991 ) supra) , has suggested that additional members of this family of adhesive enzymes might exist. Here we report the cloning and characterization of the third member of this receptor PTP family, termed PTP λ. The PTP λ polypeptide reported here contains structural motifs that are very similar to those found in PTP K and μ. In addition, this novel PTP λ receptor reveals a tissue distribution that is divergent from that previously described for the other members of this family. SUMMARY OF THE INVENTION We have analyzed a large number of PTPs from a primitive murine hematopoietic cell population using consensus PCR. From this population we have cloned a novel receptor protein tyrosine phosphorylase polypeptide which is related to the receptor PTPs K and μ. We have designated this novel protein tyrosine phosphorylase as the "PTP λ". Unlike other known receptor PTP polypeptides, PTP λ is predominantly expressed in mammalian adult brain, lung and kidney tissues but predominantly lacks expression in mammalian adult liver tissue. Accordingly, the present invention concerns an isolated receptor protein tyrosine phosphatase polypeptide (PTP) λ, which (1 ) is predominantly expressed in adult mammalian brain, lung and kidney tissue; and (2) predominantly lacks expression in adult mammalian liver tissue, wherein said polypeptide is capable of dephosphorylating phosphorylated tyrosine residues. The present invention also concerns derivatives of these novel PTP polypeptides which substantially retain the ability to dephosphorylate phosphorylated tyrosine residues. A preferred group of the PTP polypeptides of the present invention includes a polypeptide comprising the amino acid sequence shown in Figure 1 (SEQ ID NO:2); a further mammalian homologue of amino acid sequence shown in Figure 1 and a derivative of any of the above polypeptides which substantially retain the ability to dephosphorylate tyrosine residues. In another aspect, the present invention is directed to agonists and antagonists of the above novel PTP polypeptides. In yet another aspect, the present invention concerns isolated nucleic acid molecules encoding the novel PTP polypeptides disclosed herein. In a further aspect, the invention concerns vectors comprising nucleic acid encoding the novel PTP polypeptides herein, operably linked to control sequences recognized by a host cell transformed with the vector, and to cells transformed with such vectors. In a still further aspect of the present invention, there are provided antibodies capable of specific binding to the novel PTP polypeptides of this invention, and hybridoma cell lines producing such antibodies. The antibodies may be agonist antibodies, which stimulate the ability of the novel PTP polypeptides of the present invention to dephosphorylate tyrosines, or antagonist antibodies, which block this activity. - In yet a further aspect of the present invention, there is provided methods for producing the PTP polypeptides of the present invention comprising transforming a host cell with nucleic acid encoding said polypeptide, culturing the transformed cell and recovering said polypeptide from the cell culture. The present invention further concerns an assay for identifying an antagonist or an agonist of a novel PTP polypeptide of the present invention, which comprises contacting a phosphatase domain of the PTP polypeptide with a candidate antagonist or agonist, and monitoring the ability of the phosphatase domain to dephosphorylate tyrosine residues. BRIEF DESCRIPTION OF THE DRAWINGS Figures 1A-1D. The cDNA and derived protein sequence of PTP λ. Illustrated is the cDNA (SEQ ID NO:1 ) and derived protein sequence (SEQ ID NO:2) of the full length PTP λ clone homologous to a small PCR fragment derived from hematopoietic progenitor cells using consensus PTP primers. Amino acids are presented by their standard one-letter designations. Figures 2A-2B. Homology between PTP λ, PTP K and PTP μ. Illustrated as boxed residues are the amino acid homologies between the PTP λ (ptplambda) (SEQ ID NO:2), PTP K (ptpkappa) (SEQ ID NO:3) and PTP μ (ptpmu) (SEQ ID NO:4) polypeptides. Amino acids are presented by their standard one-letter designations. Also shown above the amino acid sequences are the domains predicted previously from PTP K and PTP μ. These domains include the signal sequence (SS), the MAM (mePrin, A5, PTP #), immunoglobulin-like (IgG), fibronectin type Ill-like (Fnlll), transmembrane domain (TMD), cadherin-like (Cadherin) and dual phosphatase domains (PTPase I and PTPase II). Figure 3. Comparative domain structures of PTP λ, PTP K and PTP μ. Illustrated are the percent amino acid homologies between the various domains of the PTP λ, PTP K and PTP μ polypeptides. These domains include the signal sequence (SS), the MAM (mePrin, Δ5, PTP u) > immunoglobulin-like (IgG), fibronectin type Ill-like (Fnlll), transmembrane domain (TMD), cadherin-like (Cadherin) and dual phosphatase domains (PTPase I and PTPase II). Figure 4. Tyrosine phosphatase activity of PTP λ immunoprecipitates from PC 12 cells. Lysates of PC 12 cells were immunoprecipitated with either preimmune antibody (Pre-immune) or antibody directed against the cytoplasmic domain of the PTP λ polypeptide (AntiPTP λ). The immunoprecipitates were incubated with two different immobilized tyrosine phosphorylated peptides (PPS1 and PPS2) using a commercially available tyrosine phosphatase assay kit. Immunoprecipitates were done either in the absence or presence of the tyrosine phosphatase inhibitor vanadate. Tyrosine phosphatase activity was determined by examining the residual binding of an anti-phosphotyrosine antibody to the immobilized peptide, so that a- decreased OD 405 correlates with tyrosine phosphatase activity. Figure 5. Northern blot analysis of PTP λ expression. Commercially available northern blots were probed with a 32 P-labeled fragment of PTP λ using standard hybridization conditions. The blot on the left illustrates the PTP λ transcript in RNA obtained from murine embryos at the developmental day shown in the figure. The blot on the right illustrates an analysis of the PTP λ transcript in RNA from a. heart, b. brain, c. spleen, d. lung, e. liver, f. skeletal muscle, g. kidney and h. testis. Figure 6. PTP λ mRNA Expression In the E15.5 Rat Embryo. Emulsion autoradiographs of a sagittal embryo section (A), and higher magnifications of embryonic midbrain (C), spinal cord (D), kidney (F), and lung hybridized with a 33 P-UTP labeled PTP λ antisense probe are shown. Opposed to the darkfield autoradiographs are the corresponding lightfield images of the sagittal embryo section (B), kidney (G), and lung (I). Hybridization using a PTP λ sense strand control probe is shown in an E15.5 embryonic spinal cord section (E). (A,B,C,D,E) Bar, 1 .0mm; (F,G,H,I) Bar, 0.2mm. Figure 7. PTP λ mRNA Expression in PI and Adult Rat Brain. Emulsion autoradiographs of coronal sections of P1 rat brain (A,B,C) and adult rat brain (D,E) hybridized with a 33 P-UTP labeled PTP λ antisense probe are shown. Coronal sections of the P1 brain are at the level of the septum (A), hippocampus (B), and substantia nigra (C). For the adult animal, coronal brain sections are at the level of the septum (D) and the hippocampus and substantia nigra (E). Hybridization using a PTP λ sense strand control probe is shown in an adult coronal section at the level of the substantia nigra (F). (A,B,C) Bar, 1 .0mm; (D,E,F) Bar, 1 .0mm. Figure 8. Expression of PTP λ in PC 12 cells. Illustrated is the PTP λ transcript observed in RNA of PC 12 cells either untreated (-) or treated { + ) with 10 ng/ml of nerve growth factor (NGF) for the days shown at the top of the figure. The lower blot shows the β-actin signal obtained for each of the RNAs. Figure 9. Immunofluorescence analysis of PTP λ expression in PC 12 cells. PC 12 cells were either left untreated or treated with 10 ng/ml nerve growth factor (NGF) for 7 days to induce neurite formation. At the end of this time, the cells were permeabilized and stained with either - pre-immune serum or antibodies directed against the intracellular domain of PTP λ. Cells were washed and observed by confocal fluorescence microscopy. Panel A shows the results without NGF and with pre-immune serum. Panel B shows the results without NGF and with anti-PTP λ serum. Panel C shows the results with NGF and anti-PTP λ serum. Panel D shows the results obtained with NGF and anti-PTP λ serum at a higher magnification than in Panel C. The arrows show positively stained extended neurites. DETAILED DESCRIPTION OF THE INVENTION A. Definitions The phrases "receptor protein tyrosine phosphatase λ", "protein tyrosine phosphatase λ" and "PTP λ" are used interchangeably and refer to a native membrane-bound protein tyrosine phosphatase polypeptide which (1 ) is predominantly expressed in adult mammalian brain, lung and kidney tissue and (2) predominantly lacks expression in adult mammalian liver tissue, wherein the polypeptide is capable of dephosphorylating phosphorylated tyrosine residues. The above terms are also intended to encompass functional derivatives of such native tyrosine phosphatases. The term "native tyrosine phosphatase" in this context refers to a naturally occurring tyrosine phosphatase polypeptide, having the described properties, of any human or non-human animal species, with or without the initiating methionine, whether purified from the native source, synthesized, produced by recombinant DNA technology or by any combination of these and/or other methods. Native PTP λ specifically includes the native murine PTP λ protein shown in Figure 1 (SEQ ID NO:2). A "functional derivative" of a polypeptide is a compound having a qualitative biological activity in common with the native polypeptide. Thus, a functional derivative of a native PTP λ polypeptide is a compound that has a qualitative biological activity in common with a native PTP λ polypeptide, for example, as being capable of dephosphorylating phosphorylated tyrosine residues. "Functional derivatives" include, but are not limited to, fragments of native polypeptides from any animal species (including humans), derivatives of native (human and non-human) polypeptides and their fragments, glycosylation variants of a native polypeptide, and peptide and non-peptide analogs of native polypeptides, provided that they have a biological activity in common with a respective native polypeptide. "Fragments" comprise regions within the sequence of a mature native polypeptide. The term "derivative" is used to define amino acid sequence variants, and covalent modifications of a native polypeptide. "Non-peptide analogs" are organic compounds which display substantially the same surface as peptide analogs of the native polypeptides. Thus, the non-peptide analogs of the native PTP λ of the present invention are organic compounds which display substantially the same surface as peptide analogs of the native PTP λ. Such compounds interact with other molecules in a similar fashion as the peptide analogs, and mimic a biological activity of a native PTP λ of the present invention. The polypeptide functional derivatives of the native PTP λ of the present invention preferably have at least about 65%, more preferably at least about 75%, even more preferably at least about 85%, most preferably at least about 95% overall sequence homology with the amino acid sequence shown in Figure 1 (SEQ ID N0:2) and substantially retain the ability to dephosphorylate phosphorylated tyrosine residues. The term "biological activity" in the context of the definition of functional derivatives is defined as the possession of at least one adhesive, regulatory or effector function qualitatively in common with a native polypeptide (e.g. PTP λ). The functional derivatives of the native PTP λ of the present invention are unified by their qualitative ability to dephosphorylate phosphorylated tyrosine residues. Preferably, the functional derivatives of the native PTP λ polypeptides of the present invention qualitatively retain at least one of the following biological properties of the native molecules: mediation of cell adhesion, and involvement in neural pathfinding. The terms "covalent modification" and "covalent derivatives" are used interchangeably and include, but are not limited to, modifications of a native polypeptide or a fragment thereof with an organic proteinaceous or non-proteinaceous derivatizing agent, fusions to heterologous polypeptide sequences, and post-translational modifications. Covalent modifications are traditionally introduced by reacting targeted amino acid residues with an organic derivatizing agent that is capable of reacting with selected sides or terminal residues, or by harnessing mechanisms of post-translational modifications that function in selected recombinant host cells. Certain post-translational modifications are the result of the action of recombinant host cells on the expressed polypeptide. Glutaminyl and asparaginyl residues are frequently post-translationally deamidated to the corresponding glutamyl and aspartyl residues. Alternatively, these residues are deamidated under mildly acidic conditions. Other post- translational modifications include hydroxylation of proline and lysine, phosphorylation of hydroxyl groups of seryl, tyrosine or threonyl residues, methylation of the α-amino groups of lysine, arginine, and histidine side chains [T.E. Creighton, Proteins: Structure and Molecular Properties. W.H. Freeman & Co., San Francisco, pp. 79-86 ( 1 983)]. Covalent derivatives/modifications specifically include fusion proteins comprising native PTP λ sequences of the present invention and their amino acid sequence variants, such as immunoadhesins, and N-terminal fusions to heterologous signal sequences. "Predominantly expressed", "predominant expression" and grammatical equivalents thereof is defined as a level of expression of a nucleic acid encoding an amino acid sequence which is easily detectable using northern blot analysis under stringent conditions. "Identity" or "homology" with respect to a native polypeptide and its functional derivative is defined herein as the percentage of amino acid residues in the candidate sequence that are identical with the residues of a corresponding native polypeptide, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent homology, and not considering any conservative substitutions as part of the sequence identity. Neither N- or C-terminal extensions nor insertions shall be construed as reducing identity or homology. Methods and computer programs for the alignment are well known in the art. The term "agonist" is used to refer to peptide and non-peptide analogs of the native PTP λ of the present invention and to antibodies specifically binding native PTP λ provided that they retain at least one biological activity of a native PTP λ. Preferably, the agonists of the present invention retain the qualitative ability to dephosphorylate phosphorylated tyrosine residues. The term "antagonist" is used to refer to a molecule inhibiting a biological activity of a native PTP λ of the present invention. Preferably, the antagonists herein inhibit the ability of the PTP λ of the present invention to dephosphorylate tyrosines. Preferred antagonists essentially completely block tyrosine dephosphorylation caused by PTP λ. Ordinarily, the terms "amino acid" and "amino acids" refer to all naturally occurring L-α-amino acids. In some embodiments, however, D- amino acids may be present in the polypeptides or peptides of the present invention in order to facilitate conformational restriction. For example, in order to facilitate disulfide bond formation and stability, a D amino acid cysteine may be provided at one or both termini of a peptide functional derivative or peptide antagonist of the native PTP λ of the present invention. The amino acids are identified by either the single-letter or three-letter designations: Asp D aspartic acid lie 1 isoleucine Thr T threonine Leu L leucine Ser S serine Tyr Y tyrosine Glu E glutamic acid Phe F phenylalanine Pro P proline His H histidine Gly G glycine Lys K lysine Ala A alanine Arg R arginine Cys C cysteine Trp W tryptophan Val V valine Gin Q glutamine Met M methionine Asn N asparagine These amino acids may be classified according to the chemical composition and properties of their side chains. They are broadly classified into two groups, charged and uncharged. Each of these groups is divided into subgroups to classify the amino acids more accurately: I. Charged Amino Acids Acidic Residues: aspartic acid, glutamic acid Basic Residues: lysine, arginine, histidine II. Uncharged Amino Acids Hydrophilic Residues: serine, threonine, asparagine, glutamine Aliphatic Residues: glycine, alanine, valine, leucine, isoleucine Non-polar Residues: cysteine, methionine, proline Aromatic Residues: phenylalanine, tyrosine, tryptophan The term "amino acid sequence variant" refers to molecules with some differences in their amino acid sequences as compared to a native amino acid sequence. Substitutional variants are those that have at least one amino acid residue in a native sequence removed and a different amino acid inserted in its place at the same position. The substitutions may be single, where only one amino acid in the molecule has been substituted, or they may be multiple, where two or more amino acids have been substituted in the same molecule. Insertional variants are those with one or more amino acids inserted immediately adjacent to an amino acid at a particular position in a native sequence. Immediately adjacent to an amino acid means connected to either the α-carboxy or α-amino functional group of the amino acid. Deletional variants are those with one or more amino acids in the native amino acid sequence removed. Ordinarily, deletional variants will have one or two amino acids deleted in a particular region of the molecule. "Antibodies (Abs)" and "immunoglobuiiπs (Igs)" are glycoproteins having the same structural characteristics. While antibodies exhibit binding specificity to a specific antigen, immunoglobulins include both antibodies and other antibody-like molecules which lack antigen specificity. Polypeptides of the latter kind are, for example, produced at low levels by the lymph system and at increased levels by myelomas. Native antibodies and immunoglobulins are usually heterotetrameric glycoproteins of about 150,000 daltons, composed of two identical light (L) chains and two identical heavy (H) chains. Each light chain is linked to a heavy chain by one covalent disulfide bond, while the number of disulfide linkages varies between the heavy chains of different immunoglobulin isotypes. Each heavy and light chain also has regularly spaced intrachain disulfide bridges. Each heavy chain has at one end a variable domain (V H ) followed by a number of constant domains. Each light chain has a variable domain at one and (V L ) and a constant domain • at its other end; the constant domain of the light chain is aligned with the first constant domain of the heavy chain, and the light chain variable domain is aligned with the variable domain of the heavy chain. Particular amino acid residues are believed to form an interface between the light and heavy chain variable domains (Clothia et al. , J. Mol. Biol. 1 86. 651 - 663 [1 985]; Novotny and Haber, Proc. Natl. Acad. Sci. USA 82. 4592- 4596 [1985]). The term "variable" refers to the fact that certain portions of the variable domains differ extensively in sequence among antibodies and are used in the binding and specificity of each particular antibody for its particular antigen. However, the variability is not evenly distributed through the variable domains of antibodies. It is concentrated in three segments called complementarity determining regions (CDRs) or hypervariable regions both in the light chain and the heavy chain variable domains. The more highly conserved portions of variable domains are called the framework (FR). The variable domains of native heavy and light chains each comprise four FR regions, largely adopting a β-sheet configuration, connected by three CDRs, which form loops connecting, and in some cases forming part of, the β-sheet structure. The CDRs in each chain are held together in close proximity by the FR regions and, with the CDRs from the other chain, contribute to the formation of the antigen binding site of antibodies (see Kabat, E.A. et al. , Sequences of Proteins of Immunoloαical Interest. National Institute of Health, Bethesda, MD [1991 ]). The constant domains are not involved directly in binding an antibody to an antigen, but exhibit various effector functions, such as participation of the antibody in antibody-dependent cellular toxicity. Papain digestion of antibodies produces two identical antigen binding fragments, called Fab fragments, each with a single antigen binding site, and a residual "Fc" fragment, whose name reflects its ability to crystallize readily. Pepsin treatment yields an F(ab') 2 fragment that has two antigen combining sites and is still capable of cross-linking antigen. "Fv" is the minimum antibody fragment which contains a complete antigen recognition and binding site. This region consists of a dimer of one heavy and one light chain variable domain in tight, non-covalent association. It is in this configuration that the three CDRs of each variable domain interact to define an antigen binding site on the surface of the V H -V L dimer. Collectively, the six CDRs confer antigen binding specificity to the antibody. However, even a single variable domain (or half of an Fv comprising only three CDRs specific for an antigen) has the ability to recognize and bind antigen, although at a lower affinity than the entire binding site. The Fab fragment also contains the constant domain of the light chain and the first constant domain (CH1 ) of the heavy chain. Fab' fragments differ from Fab fragments by the addition of a few residues at the carboxy terminus of the heavy chain CH 1 domain including one or more cysteines from the antibody hinge region. Fab'-SH is the designation herein for Fab' in which the cysteine residue(s) of the constant domains bear a free thiol group. F(ab') 2 antibody fragments originally were produced as pairs of Fab' fragments which have hinge cysteines between them. Other, chemical couplings of antibody fragments are also known. The light chains of antibodies (immunoglobulins) from any vertebrate species can be assigned to one of two clearly distinct types, called kappa (K) and lambda (λ), based on the amino acid sequences of their constant domains. Depending on the amino acid sequence of the constant domain of their heavy chains, immunoglobulins can be assigned to different classes. There are five major classes of immunoglobulins: IgA, IgD, IgE, IgG and IgM, and several of these may be further divided into subclasses (isotypes), e.g. lgG-1 , lgG-2, lgG-3, and lgG-4; lgA-1 and lgA-2. The heavy chain constant domains that correspond to the different classes of immunoglobulins are called α, delta, epsilon, y, and μ, respectively. The subunit structures and three-dimensional configurations of different classes of immunoglobulins are well known. The term "antibody" is used in the broadest sense and specifically covers single monoclonal antibodies (including agonist and antagonist antibodies), antibody compositions with polyepitopic specificity, as well as antibody fragments (e.g., Fab, F(ab') 2 , and Fv), so long as they exhibit the desired biological activity. The term "monoclonal antibody" as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in minor amounts. Monoclonal antibodies are highly specific, being directed against a single antigenic site. Furthermore, in contrast to conventional (polyclonal) antibody preparations which typically include different antibodies directed against different determinants (epitopes), each monoclonal antibody is directed against a single determinant on the antigen. In addition to their specificity, the monoclonal antibodies are advantageous in that they are synthesized by the hybridoma culture, uncontaminated by other immunoglobulins. The modifier "monoclonal" indicates the character of the antibody as being obtained from a substantially homogeneous population of antibodies, and is not to be construed as requiring production of the antibody by any particular method. For example, the monoclonal antibodies to be used in accordance with the present invention may be made by the hybridoma method first described by Kohler & Milstein, Nature 256:495 ( 1 975), or may be made by recombinant DNA methods [see, e.g. U.S. Patent No. 4,81 6,567 (Cabilly et a/.)]. The monoclonal antibodies herein specifically include "chimeric" antibodies (immunoglobulins) in which a portion of the heavy and/or light chain is identical with or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical with or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity (U.S. Patent No. 4,81 6,567 (Cabilly et al. ; Morrison et al. , Proc. Natl. Acad. Sci. USA 81 . 6851 -6855 [ 1 984]) . "Humanized" forms of non-human (e.g. murine) antibodies are chimeric immunoglobulins, immunoglobulin chains or fragments thereof (such as Fv, Fab, Fab', F(ab') 2 or other antigen-binding subsequences of antibodies) which contain minimal sequence derived from non-human immunoglobulin. For the most part, humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a complementary determining region (CDR) of the recipient are replaced by residues from a CDR of a non-human species (donor antibody) such as mouse, rat or rabbit having the desired specificity, affinity and capacity. In some instances, Fv framework residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, humanized antibody may comprise residues which are found neither in the recipient antibody nor in the imported CDR or framework sequences. These modifications are made to further refine and optimize antibody performance. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin consensus sequence. The humanized antibody optimally also will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. For further details see: Jones et al. , Nature 321 • 522- 525 [1 986]; Reichmann et al. , Mamie. 222, 323-329 [ 1 988); EP-B-239 400 published 30 September 1 987; Presta, Curr. QD . Struct. Biol. 2 593- 596 [ 1 992]; and EP-B-451 21 6 published 24 January 1 996). In the context of the present invention the expressions "cell", "cell line", and "cell culture" are used interchangeably, and all such designations include progeny. It is also understood that all progeny may not be precisely identical in DNA content, due to deliberate or inadvertent mutations. Mutant progeny that have the same function or biological property, as screened for in the originally transformed cell, are included. The terms "replicable expression vector" and "expression vector" refer to a piece of DNA, usually double-stranded, which may have inserted into it a piece of foreign DNA. Foreign DNA is defined as heterologous DNA, which is DNA not naturally found in the host cell. The vector is used to transport the foreign or heterologous DNA into a suitable host cell. Once in the host cell, the vector can replicate independently of the host chromosomal DNA, and several copies of the vector and its inserted (foreign) DNA may be generated. In addition, the vector contains the necessary elements that permit translating the foreign DNA into a polypeptide. Many molecules of the polypeptide encoded by the foreign DNA can thus be rapidly synthesized. The term "control sequences" refers to DNA sequences necessary for the expression of an operably linked coding sequence in a particular host organism. The control sequences that are suitable for prokaryotes, for example, include a promoter, optionally an operator sequence, a ribosome binding site, and possibly, other as yet poorly understood sequences. Eukaryotic cells are known to utilize promoters, polyadenylation signals, and enhancers. Nucleic acid is "operably linked" when it is placed into a functional relationship with another nucleic acid sequence. For example, DNA for a presequence or a secretory leader is operably linked to DNA for a polypeptide if it is expressed as a preprotein that participates in the secretion of the polypeptide; a promoter or enhancer is operably linked to a coding sequence if it affects the transcription of the sequence; or a ribosome binding site is operably linked to a coding sequence if it is positioned so as to facilitate translation. Generally, "operably linked" means that the DNA sequences being linked are contiguous and, in the case of a secretory leader, contiguous and in reading phase. However, enhancers do not have to be contiguous. Linking is accomplished by ligation at convenient restriction sites. If such sites do not exist, then synthetic oligonucleotide adaptors or linkers are used in accord with conventional practice. "Immunoadhesins" or "PTP λ - immunoglobulin chimeras" are chimeric antibody-like molecules that combine the functional domain(s) of a binding protein (usually a receptor, a cell-adhesion molecule or a ligand) with the an immunoglobulin sequence. The most common example of this type of fusion protein combines the hinge and Fc regions of an immunoglobulin (Ig) with domains of a cell-surface receptor that recognizes a specific ligand. This type of molecule is called an "immunoadhesin", because it combines "immune" and "adhesion" functions; other frequently used names are "Ig-chimera", "Ig-" or "Fc- fusion protein", or "receptor-globulin." "Oligonucleotides" are short-length, single- or double-stranded poiydeoxynucleotides that are chemically synthesized by known methods [such as phosphotriester, phosphite, or phosphoramidite chemistry, using solid phase techniques such as those described in EP 266,032, published 4 May 1 988, or via deoxynucleoside H-phosphonate intermediates as described by Froehler et al. , Nucl. Acids Res. 14. 5399 (1986). They are then purified on polyacrylamide gels. Hybridization is preferably performed under "stringent conditions" which means (1 ) employing low ionic strength and high temperature for washing, for example, 0.01 5 sodium chloride/0.001 5 M sodium citrate/0.1 % sodium dodecyl sulfate at 50°C, or (2) employing during hybridization a denaturing agent, such as formamide, for example, 50% (vol/vol) formamide with 0.1 % bovine serum albumin/0.1 % Ficoll/0.1 % polyvinylpyrrolidone/50 nM sodium phosphate buffer at pH 6.5 with 750 mM sodium chloride, 75 mM sodium citrate at 42°C. Another example is use of 50% formamide, 5 x SSC (0.75 M NaCl, 0.075 M sodium citrate), 50 mM sodium phosphate (pH 6/8), 0.1 % sodium pyrophosphate, 5 x Denhardt's solution, sonicated salmon sperm DNA (50 μg/ml), 0.1 % SDS, and 10% dextran sulfate at 42°C, with washes at 42°C in 0.2 x SSC and 0.1 % SDS. Yet another example is hybridization using a buffer of 10% dextran sulfate, 2 x SSC (sodium chloride/sodium citrate) and 50% formamide at 55 °C, followed by a high-stringency wash consisting of 0.1 x SSC containing EDTA at 55 °C. "Transformation" means introducing DNA into an organism so that the DNA is replicable, either as an extrachromosomal element or by chromosomal integration. Depending on the host cell used, transformation is done using standard techniques appropriate to such cells. The calcium treatment employing calcium chloride, as described by Cohen, S.N.. Proc. Natl. Acad. Sci. (USA). 69, 21 10 (1 972) and Mandel et al. J. Mol. Biol. 53, 1 54 (1970), is generally used for prokaryotes or other cells that contain substantial cell-wall barriers. For mammalian cells without such cell walls, the calcium phosphate precipitation method of Graham, F. and van der Eb, A., Virology. 52, 456-457 ( 1 978) is preferred. General aspects of mammalian cell host system transformations have been described by Axel in U.S. Pat. No. 4,399,21 6 issued August 16, 1983. Transformations into yeast are typically carried out according to the method of Van Solingen, P., et al. J. Bact.. 130, 946 (1977) and Hsiao, C.L., et al. Proc. Natl. Acad. Sci. ( USA ) 76, 3829 ( 1 979). However, other methods for introducing DNA into cells such as by nuclear injection, electroporation or by protoplast fusion may also be used. "Recovery" or "isolation" of a given fragment of DNA from a restriction digest means separation of the digest on polyacrylamide or agarose gel by electrophoresis, identification of the fragment of interest by comparison of its mobility versus that of marker DNA fragments of known molecular weight, removal of the gel section containing the desired fragment, and separation of the gel from DNA. This procedure is known generally. For example, see R. Lawn et al. , Nucleic Acids Res. 9, 6103-61 14 ( 1 981 ) and D. Goeddel et al. , Nucleic Acids Res. 8, 4057 ( 1 980). "Ligation" refers to the process of forming phosphodiester bonds between two double stranded nucleic acid fragments (T. Maniatis et al. 1 982, supra, p. 146). Unless otherwise provided, ligation may be accomplished using known buffers and conditions with 10 units of T4 DNA ligase ("ligase") per 0.5 mg of approximately equimolar amounts of the DNA fragments to be ligated. "Preparation" of DNA from transformants means isolating plasmid DNA from microbial culture. Unless otherwise provided, the alkaline/SDS method of Maniatis et al. 1982, supra, p. 90, may be used. B. Production of PTP λ by recombinant DNA technology 1. Identification and isolation of nucleic acid encoding PTP λ The native PTP λ proteins of the present invention may be isolated from cDNA or genomic libraries. For example, a suitable cDNA library can be constructed by obtaining polyadenylated mRNA from cells known to express the desired PTP λ protein, and using the mRNA as a template to synthesize double stranded cDNA. Suitable sources of the mRNA are murine primitive hematopoietic cells and PC1 2 cells. mRNA encoding the native PTP λ of the present invention is expressed, for example, in tissues derived from adult brain, lung, kidney, heart, skeletal muscle and testis. The gene encoding the novel PTP λ polypeptide of the present invention can also be obtained from a genomic library, such as a human genomic cosmid library, or a mouse-derived embryonic cell (ES) genomic library. Libraries, either cDNA or genomic, are then screened with probes designed to identify the gene of interest or the protein encoded by it. For cDNA expression libraries, suitable probes include monoclonal and polyclonal antibodies that recognize and specifically bind to a PTP λ polypeptide. For cDNA libraries, suitable probes include carefully selected oligonucleotide probes (usually of about 20-80 bases in length) that encode known or suspected portions of a PTP λ polypeptide from the same or different species, and/or complementary or homologous cDNAs or fragments thereof that encode the same or a similar gene. Appropriate probes for screening genomic DNA libraries include, without limitation, oligonucleotides, cDNAs, or fragments thereof that encode the same or a similar gene, and/or homologous genomic DNAs or fragments thereof. Screening the cDNA or genomic library with the selected probe may be conducted using standard procedures as described in Chapters 10-12 of Sambrook et al., Molecular Cloning: A Laboratory Manual. New York, Cold Spring Harbor Laboratory Press, 1989. If DNA encoding an enzyme of the present invention is isolated by using carefully selected oligonucleotide sequences to screen cDNA libraries from various tissues, the oligonucleotide sequences selected as probes should be sufficient in length and sufficiently unambiguous that false positives are minimized. The actual nucleotide sequence(s) is/are usually designed based on regions which have the least codon redundance. The oligonucleotides may be degenerate at one or more positions. The use of degenerate oligonucleotides is of particular importance where a library is screened from a species in which preferential codon usage is not known. The oligonucleotide must be labeled such that it can be detected upon hybridization to DNA in the library being screened. The preferred method of labeling is to use ATP (e.g., γ 32 P) and polynucleotide kinase to radiolabel the 5' end of the oligonucleotide. However, other methods may be used to label the oligonucleotide, including, but not limited to, biotinylation or enzyme labeling. cDNAs encoding PTP λ can also be identified and isolated by other known techniques of recombinant DNA technology, such as by direct expression cloning, or by using the polymerase chain reaction (PCR) as described in U.S. Patent No. 4,683, 1 95, issued 28 July 1 987, in section 14 of Sambrook et al., supra, or in Chapter 1 5 of Current Protocols in Molecular Bioloαv. Ausubel et al. eds., Greene Publishing Associates and Wiley-lnterscience 1991 . The use of the PCR technique for obtaining cDNA encoding murine PTP λ is also illustrated in the examples. Once cDNA encoding a PTP λ enzyme from one species has been isolated, cDNAs from other species can also be obtained by cross-species hybridization. According to this approach, human or other mammalian cDNA or genomic libraries are probed by labeled oligonucleotide sequences selected from known PTP λ sequences (such as murine PTP λ) in accord with known criteria, among which is that the sequence should be sufficient in length and sufficiently unambiguous that false positives are minimized. Typically, a 32 P-labeled oligonucleotide having about 30 to 50 bases is sufficient, particularly if the oligonucleotide contains one or more codons for methionine or tryptophan. Isolated nucleic acid will be DNA that is identified and separated from contaminant nucleic acid encoding other polypeptides from the source of nucleic acid. Hybridization is preferably performed under "stringent conditions", as herein above defined. Once the sequence is known, the gene encoding a particular PTP λ polypeptide can also be obtained by chemical synthesis, following one of the methods described in Engels and Uhlmann, Aαnew. Chem. Int. Ed. Enαl. 28. 716 ( 1 989). These methods include triester, phosphite, phosphoramidite and H-phosphonate methods, PCR and other autoprimer methods, and oligonucleotide syntheses on solid supports. 2. Cloning and expression of nucleic acid encoding PTP λ Once the nucleic acid encoding PTP λ is available, it is generally ligated into a replicable expression vector for further cloning (amplification of the DNA), or for expression. Expression and cloning vectors are well known in the art and contain a nucleic acid sequence that enables the vector to replicate in one or more selected host cells. The selection of the appropriate vector will depend on 1 ) whether it is to be used for DNA amplification or for DNA expression, 2) the size of the DNA to be inserted into the vector, and 3) the host cell to be transformed with the vector. Each vector contains various components depending on its function (amplification of DNA of expression of DNA) and the host cell for which it is compatible. The vector components generally include, but are not limited to, one or more of the following: a signal sequence, an origin of replication, one or more marker genes, an enhancer element, a promoter, and a transcription termination sequence. Construction of suitable vectors containing one or more of the above listed components, the desired coding and control sequences, employs standard ligation techniques. Isolated plasmids or DNA fragments are cleaved, tailored, and religated in the form desired to generate the plasmids required. For analysis to confirm correct sequences in plasmids constructed, the ligation mixtures are commonly used to transform E. coli cells, e.g. E. coli K12 strain 294 (ATCC 31 ,446) and successful transformants selected by ampicillin or tetracycline resistance where appropriate. Plasmids from the transformants are prepared, analyzed by restriction endonuclease digestion, and/or sequenced by the method of Messing et al. , Nucleic Acids Res. 9_, 309 (1 981 ) or by the method of Maxam et al. , Methods in Enzvmoloαy 65. 499 (1 980). The polypeptides of the present invention may be expressed in a variety of prokaryotic and eukaryotic host cells. Suitable prokaryotes include gram negative or gram positive organisms, for example E.. coli or bacilli. A preferred cloning host is E. coJi 294 (ATCC 31 ,446) although other gram negative or gram positive prokaryotes such as £. coli B, JE.. coli X1776 (ATCC 31 ,537), £. cojj W31 10 (ATCC 27,325), Pseudomonas species, or Serratia Marcesans are suitable. In addition to prokaryotes, eukaryotic microbes such as filamentous fungi or yeast are suitable hosts for vectors herein. Saccharomyces cerevisiae. or common baker's yeast, is the most commonly used among lower eukaryotic host microorganisms. However, a number of other genera, species and strains are commonly available and useful herein, such as S. pombe [Beach and Nurse, Nature 290. 140 (1981 )], Kluyveromyces lactis [Louvencourt et al. , J. Bacteriol. 737 (1983)]; varrowia (EP 402,226); Pichia pastoris (EP 183,070), Trichoderma reesia (EP 244,234), Neurospora crassa [Case et al. , Proc. Natl. Acad. Sci. USA 76. 5259-5263 (1 979)]; and Aspergillus hosts such as A. nidulans [Ballance et al. , Biochem. Biophvs. Res. Commun. 1 1 2. 284-289 ( 1983); Tilburn et al. , Gene 26. 205-221 ( 1 983); Yelton et al. , Proc. Natl. Acad. Sci. USA 81 . 1470-1474 (1984)] and A. niαer [Kelly and Hynes, EMBO J. 4, 475-479 (1 985)]. Suitable host cells may also derive from multicellular organisms. Such host cells are capable of complex processing and glycosylation activities. In principle, any higher eukaryotic cell culture is workable, whether from vertebrate or invertebrate culture, although cells from mammals such as humans are preferred. Examples of invertebrate cells include plants and insect cells. Numerous baculoviral strains and variants and corresponding permissive insect host cells from hosts such as Spodoptera fruαiperda (caterpillar), Aedes aegypti (mosquito), Aedes albopictus (mosquito), Drosophila melanoαaster (fruitfly), and Bombyx morj host cells have been identified. See, e.g. Luckow et al., Bio/Technologv 6. 47-55 ( 1988); Miller et a/. , in Genetic Engineering. Setlow, J.K. et al. , eds., Vol. 8 (Plenum Publishing, 1 986), pp. 277-279; and Maeda et al., Nature 315. 592-594 (1985). A variety of such viral strains are publicly available, e.g. the L-1 variant of Autographa californica NPV, and such viruses may be used as the virus herein according to the present invention, particularly for transfection of Spodoptera fruoiperda cells. Plant cell cultures of cotton, corn, potato, soybean, petunia, tomato, and tobacco can be utilized as hosts. Typically, plant cells are transfected by incubation with certain strains of the bacterium Agrobacterium tumefaciens. which has been previously manipulated to contain the PTP λ DNA. During incubation of the plant cell culture with A. tumefaciens. the DNA encoding a PTP λ polypeptide is transferred to the plant cell host such that it is transfected, and will, under appropriate conditions, express the PTP λ DNA. In addition, regulatory and signal sequences compatible with plant cells are available, such as the nopaline synthase promoter and polyadenylation signal sequences. Depicker et al. , J. Mol. Ap p l. Gen. 1 . 561 ( 1 982). In addition, DNA segments isolated from the upstream region of the T-DNA 780 gene are capable of activating or increasing transcription levels of plant-expressible genes in recombinant DNA-containing plant tissue. See EP 321 , 1 96 published 21 June 1 989. However, interest has been greatest in vertebrate cells, and propagation of vertebrate cells in culture (tissue culture) is p_ej. ≤e_ well known. See Tissue Culture. Academic Press, Kruse and Patterson, editors (1973). Examples of useful mammalian host cell lines are monkey kidney CV1 line transformed by SV40 (COS-7, ATCC CRL 1 651 ); human embryonic kidney cell line [293 or 293 cells subcloned for growth in suspension culture, Graham et al. , J. Gen. Virol. 36. 59 ( 1 977)]; baby hamster kidney cells 9BHK, ATCC CCL 10); Chinese hamster ovary cells/- DHFR ICHO, Urlaub and Chasin. Proc. Natl. Acad. Sci. USA 77. 4216 (1 980)]; mouse sertolli cells ITM4, Mather, Biol. Reorod. 23. 243-251 ( 1980)]; monkey kidney cells (CV1 ATCC CCL 70); African green monkey kidney cells (VERO-76, ATCC CRL-1 587); human cervical carcinoma cells (HELA, ATCC CCL 2); canine kidney cells (MDCK, ATCC CCL 34); buffalo rat liver cells (BRL 3A, ATCC CRL 1442); human lung cells (W1 38, ATCC CCL75); human liver cells (Hep G2, HB 8065); mouse mammary tumor (MMT 060562, ATCC CCL51 ); TRI cells [Mather et at. , Annals N.Y. Acad. Sci. 383. 44068 ( 1 982)]; MRC 5 cells; FS4 cells; and a human hepatoma cell line (Hep G2). Preferred host cells are human embryonic kidney 293 and Chinese hamster ovary cells. Particularly useful in the practice of this invention are expression vectors that provide for the transient expression in mammalian cells of DNA encoding a PTP λ polypeptide. In general, transient expression involves the use of an expression vector that is able to replicate efficiently in a host cell, such that the host cell accumulates many copies of the expression vector and, in turn, synthesizes high levels of a desired polypeptide encoded by the expression vector. Transient systems, comprising a suitable expression vector and a host cell, allow for the convenient positive identification of polypeptides encoded by clones DNAs, as well as for the rapid screening of such polypeptides for desired biological or physiological properties. Thus, transient expression systems are particularly useful in the invention for purposes of identifying analogs and variants of a PTP λ polypeptide. Other methods, vectors, and host cells suitable for adaptation to the synthesis of the PTP λ polypeptides in recombinant vertebrate cell culture are described in Getting et al. , Nature 293. 620-625 ( 1 981 ); Mantel et al. , Nature 281 . 40-46 ( 1979); Levinson et al. ; EP 1 1 7,060 and EP 1 1 7,058. Particularly useful plasmids for mammalian cell culture expression of the PTP λ polypeptides are pRK5 (EP 307,247) or pSVI6B (PCT Publication No. WO 91 /08291 ). Other cloning and expression vectors suitable for the expression of the PTP λ polypeptides of the present invention in a variety of host cells are, for example, described in EP 457,758 published 27 November 1 991 . A large variety of expression vectors are now commercially available. An exemplary commercial yeast expression vector is pPIC.9 (Invitrogen), while an commercially available expression vector suitable for transformation of E. coli cells is PET1 5b (Novagen). C. Culturinα the host cells Prokaryote cells used to produced the PTP λ polypeptides of this invention are cultured in suitable media as describe generally in Sambrook et at. , supra- Mammalian cells can be cultured in a variety of media. Commercially available media such as Ham's F10 (Sigma), Minimal Essential Medium (MEM, Sigma), RPMI-1640 (Sigma), and Dulbecco's Modified Eagle's Medium (DMEM, Sigma) are suitable for culturing the host cells. In addition, any of the media described in Ham and Wallace, Meth. Enzymol. 5J2, 44 ( 1979); Barnes and Sato, Anal. Biochem. 1£2, 255 (1 980), US 4,767,704; 4,657,866; 4,927,762; or 4,560,655; WO 90/03430; WO 87/001 95 or US Pat. Re. 30,985 may be used as culture media for the host cells. Any of these media may be supplemented as necessary with hormones and/or other growth factors (such as insulin, transferrin, or epidermal growth factor), salts (such as sodium chloride, calcium, magnesium, and phosphate), buffers (such as HEPES), nucleosides (such as adenosine and thymidine), antibiotics (such as Gentamycin™ drug) trace elements (defined as inorganic compounds usually present at final concentrations in the micromolar range), and glucose or an equivalent energy source. Any other necessary supplements may also be included at appropriate concentrations that would be known to those skilled in the art. The culture conditions, such as temperature, pH and the like, suitably are those previously used with the host cell selected for cloning or expression, as the case may be, and will be apparent to the ordinary artisan. The host cells referred to in this disclosure encompass cells in in vitro cell culture as well as cells that are within a host animal or plant. It is further envisioned that the PTP λ polypeptides of this invention may be produced by homologous recombination, or with recombinant production methods utilizing control elements introduced into cells already containing DNA encoding the particular PTP λ polypeptide. D. Detecting Gene Amplification/Expression Gene amplification and/or expression may be measured in a sample directly, for example, by conventional Southern blotting, Northern blotting to quantitate the transcription of mRNA [Thomas, Proc. Natl. Acad. Sci. USA 77. 5201 -5205 (1 980)], dot blotting (DNA analysis), or in situ hybridization, using an appropriately labeled probe, based on the sequences provided herein. Various labels may be employed, most commonly radioisotopes, particularly 32 P. However, other techniques may also be employed, such as using biotin-modified nucleotides for introduction into a polynucleotide. The biotin then serves as a site for binding to avidin or antibodies, which may be labeled with a wide variety of labels, such as radionuclides, fluorescers, enzymes, or the like. Alternatively, antibodies may be employed that can recognize specific duplexes, including DNA duplexes, RNA duplexes, and DNA-RNA hybrid duplexes or DNA-protein duplexes. The antibodies in turn may be labeled and the assay may be carried out where the duplex is bound to the surface, so that upon the formation of duplex on the surface, the presence of antibody bound to the duplex can be detected. Gene expression, alternatively, may be measured by immunological methods, such as immunohistochemical staining of tissue sections and assay of cell culture or body fluids, to quantitate directly the expression of gene product. With immunohistochemical staining techniques, a cell sample is prepared, typically by dehydration and fixation, followed by reaction with labeled antibodies specific for the gene product coupled, where the labels are usually visually detectable, such as enzymatic labels, fluorescent labels, luminescent labels, and the like. A particularly sensitive staining technique suitable for use in the present invention is described by Hse et al. , Am. J. Clin. Pharm. 75. 734-738 (1980). Antibodies useful for immunohistochemical staining and/or assay of sample fluids may be either monoclonal or polyclonal, and may be prepared in any animal. Conveniently, the antibodies may be prepared against a native PTP λ polypeptide, or against a synthetic peptide based on the DNA sequence provided herein as described further hereinbelow. E. Amino Acid Sequence Variants of Native PTP λ Polypeptides Amino acid sequence variants of native PTP λ polypeptides are prepared by methods known in the art by introducing appropriate nucleotide changes into a PTP λ DNA, or by in vitro synthesis of the desired polypeptide. There are two principal variables in the construction of amino acid sequence variants: the location of the mutation site and the nature of the mutation. With the exception of naturally-occurring alleles, which do not require the manipulation of the DNA sequence encoding the PTP λ polypeptide, the amino acid sequence variants of PTP λ polypeptides are preferably constructed by mutating the DNA, either to arrive at an allele or an amino acid sequence variant that does not occur in nature. One group of the mutations will be created within at least one of the phosphatase domains (PTPasel and/or PTPasell) of a native PTP λ protein. In view of the involvement of these domains in the enzymatic activity of PTP λ, amino acid alterations within these domains are expected to result in marked changes in the enzymatic properties of the native proteins. Non-conservative substitutions might ultimately result in PTP λ variants which lose the ability to dephosphatase tyrosines and will, therefore, be useful as antagonists of native PTP λ. PTP λ variants mutated to enhance the enzymatic activity of the native proteins may also be obtained, and will find use, for example, as potent mediators of cell adhesion. Similarly, amino acid alterations in the MAM of IgG domains of the native PTP λ proteins are expected to affect the ability of these receptors to mediate homotypic cell adhesion, and the specificity of the homophilic interaction mediated. Alternatively or in addition, amino acid alterations can be made at sites that differ in PTP λ proteins from various species, or in highly conserved regions, depending on the goal to be achieved. Sites at such locations will typically be modified in series, e.g. by ( 1 ) substituting first with conservative choices and then with more radical selections depending upon the results achieved, (2) deleting the target residue or residues, or (3) inserting residues of the same or different class adjacent to the located site, or combinations of options 1 -3. One helpful technique is called "alanine scanning" (Cunningham and Wells, Science 244, 1081 - 1085 [1 989]). The replacement of sequence motifs within the MAM, IgG, FNIII or PTPase domains of the native PTP λ proteins of the present invention by sequences from native PTP K and/or PTP μ receptors is expected to result in variants having altered specificities. In yet another group of the variant PTP λ polypeptides of the present invention, one or more of the functionally less significant domains may be deleted or inactivated. For example, the deletion or inactivation of the transmembrane domain yields soluble variants of the native protein. Alternatively, or in addition, the cytoplasmic domain may be deleted, truncated or otherwise altered. Naturally-occurring amino acids are divided into groups based on common side chain properties: (1 ) hydrophobic: norleucine, met, ala, val, leu, ile; (2) neutral hydrophobic: cys, ser, thr; (3) acidic: asp, glu; (4) basic: asn, gin, his, lys, arg; (5) residues that influence chain orientation: gly, pro; and (6) aromatic: trp, tyr, phe. Conservative substitutions involve exchanging a member within one group for another member within the same group, whereas non- conservative substitutions will entail exchanging a member of one of these classes for another. Substantial changes in function or immunological identity are made by selecting substitutions that are less conservative, i.e. differ more significantly in their effect on maintaining (a) the structure of the polypeptide backbone in the area of substitution, for . example as a sheet or helical conformation, (b) the charge or hydrophobicity of the molecule at the target site or (c) the bulk of the side chain. The substitutions which in general are expected to produce the greatest changes in the properties of the novel native PTP λ polypeptides of the present invention will be those in which (a) a hydrophilic residue, e.g. seryl or threonyl, is substituted for (or by) a hydrophobic residue, e.g. leucyl, isoleucyl, phenylalanyl, valyl or alanyl; (b) a cysteine or proline is substituted for (or by) any other residue; (c) a residue having an electropositive side chain, e.g. lysyl, arginyl, or histidyl, is substituted for (or by) an electronegative residue, e.g., glutamyl or aspartyl; or (d) a residue having a bulky side chain, e.g., phenylalanine, is substituted for (or by) one not having a side chain, e.g. glycine. Amino acid sequence deletions generally range from about 1 to 30 residues, more preferably about 1 to 10 residues, and typically are contiguous. Typically, the transmembrane and cytoplasmic domains, or only the cytoplasmic domains are deleted. However, deletion from the C- terminal to any other suitable N-terminal to the transmembrane region which preserves the biological activity or immunological cross-reactivity of a native PTP λ is suitable. A preferred class of substitutional and/or deletional variants of the present invention are those involving a transmembrane region of a novel PTP λ molecule. Transmembrane regions are highly hydrophobic or lipophilic domains that are the proper size to span the lipid bilayer of the cellular membrane. They are believed to anchor the PTP λ protein in the cell membrane and allow for homotypic complex formation. Inactivation of the transmembrane domain, typically by deletion or substitution of transmembrane domain hydroxylation residues, will facilitate recovery and formulation by reducing its cellular or membrane lipid affinity and improving its aqueous solubility. If the transmembrane and cytoplasmic domains are deleted one avoids the introduction of potentially immunogenic epitopes, whether by exposure of otherwise intracellular polypeptides that might be recognized by the body as foreign or by insertion of heterologous polypeptides that are potentially immunogenic. Inactivation of the membrane binding function is accomplished by deletion of sufficient residues to produce a substantially hydrophilic hydropathy profile at this site or by substituting with heterologous residues which accomplish the same result. A principle advantage of the transmembrane inactivated variants of the PTP λ polypeptides of the present invention is that they may be secreted into the culture medium of recombinant hosts. These variants are soluble in body fluids such as blood and do not have an appreciable affinity for cell membrane lipids, thus considerably simplifying their recovery from recombinant cell culture. As a general proposition, such soluble variants will not have a functional transmembrane domain and preferably will not have a functional cytoplasmic domain. For example, the transmembrane domain may be substituted by any amino acid sequence, e.g. a random or predetermined sequences of about 5 to 50 serine, threonine, lysine, arginine, glutamine, aspartic acid and like hydrophilic residues, which altogether exhibit a hydrophilic hydropathy profile. Like the deletional (truncated) soluble variants, these variants are secreted into the culture medium of recombinant hosts. Amino acid insertions include amino- and/or carboxyl-terminal fusions ranging in length from one residue to polypeptides containing a hundred or more residues, as well as intrasequence insertions of single or multiple amino acid residues. Intrasequence insertions (i.e. insertions within the PTP λ protein amino acid sequence) may range generally from about 1 to 10 residues, more preferably 1 to 5 residues, more preferably 1 to 3 residues. Examples of terminal insertions include PTP λ polypeptides with an N-terminal methionyl residue, an artifact of its direct expression in bacterial recombinant cell culture, and fusion of a heterologous N-terminal signal sequence to the N-terminus of the PTP λ molecule to facilitate the secretion of the mature PTP λ from recombinant host cells. Such signal sequences will generally be obtained from, and thus homologous to, the intended host cell species. Suitable sequences - include STIl or Ipp for E. coli. alpha factor for yeast, and viral signals such as herpes gD for mammalian cells. Other insertional variants of the native PTP λ molecules include the fusion of the N- or C-terminus of the PTP λ molecule to immunogenic polypeptides, e.g. bacterial polypeptides such as beta-lactamase or an enzyme encoded by the E. coli trp locus, or yeast protein, and C-terminal fusions with proteins having a long half-life such as immunoglobulin regions (preferably immunoglobulin constant regions), albumin, or ferritin, as described in WO 89/02922 published on 6 April 1 989. Further insertional variants are immunologically active derivatives of the novel PTP λ polypeptides, which comprise the PTP polypeptide and a polypeptide containing an epitope of an immunologically competent extraneous polypeptide, i.e. a polypeptide which is capable of eliciting an immune response in the animal to which the fusion is to be administered or which is capable of being bound by an antibody raised against an extraneous polypeptide. Typical examples of such immunologically competent polypeptides are allergens, autoimmune epitopes, or other potent immunogens or antigens recognized by pre-existing antibodies in the fusion recipient, including bacterial polypeptides such as trpLE, β- galactosidase, viral polypeptides such as herpes gD protein, and the like. Immunogenic fusions are produced by cross-linking in vitro or by recombinant cell culture transformed with DNA encoding an immunogenic polypeptide. It is preferable that the immunogenic fusion be one in which the immunogenic sequence is joined to or inserted into a novel PTP λ molecule or fragment thereof by (a) peptide bond(s). These products therefore consist of a linear polypeptide chain containing the PTP λ epitope and at least one epitope foreign to the PTP λ polypeptide. It will be understood that it is within the scope of this invention to introduce the epitopes anywhere within a PTP λ molecule of the present invention or a fragment thereof. These immunogenic insertions are particularly useful when formulated into a pharmacologically acceptable carrier and administered to a subject in order to raise antibodies against the PTP λ molecule, which antibodies in turn are useful as diagnostics, in tissue- typing, or in purification of the novel PTP λ polypeptides by immunoaffinity techniques known per se. Alternatively, in the purification of the PTP λ polypeptides of the present invention, binding partners for the fused extraneous polypeptide, e.g. antibodies, receptors or ligands, are used to adsorb the fusion from impure admixtures, after which the fusion is eluted and, if desired, the novel PTP λ is recovered from the fusion, e.g. by enzymatic cleavage. Since it is often difficult to predict in advance the characteristics of a variant PTP λ polypeptide, it will be appreciated that some screening will be needed to select the optimum variant. After identifying the desired mutation(s), the gene encoding a PTP λ variant can, for example, be obtained by chemical synthesis as hereinabove described. More preferably, DNA encoding a PTP λ amino acid sequence variant is prepared by site-directed mutagenesis of DNA that encodes an earlier prepared variant or a nonvariant version of the PTP λ. Site-directed (site-specific) mutagenesis allows the production of PTP λ variants through the use of specific oligonucleotide sequences that encode the DNA sequence of the desired mutation, as well as a sufficient number of adjacent nucleotides, to provide a primer sequence of sufficient size and sequence complexity to form a stable duplex on both sides of the deletion junction being traversed. Typically, a primer of about 20 to 25 nucleotides in length is preferred, with about 5 to 10 residues on both sides of the junction of the sequence being altered. In general, the techniques of site-specific mutagenesis are well known in the art, as exemplified by publications such as, Edelman et al. , DNA 2. 183 ( 1983). As will be appreciated, the site-specific mutagenesis technique typically employs a phage vector that exists in both a single-stranded and double-stranded form. Typical vectors useful in site-directed mutagenesis include vectors such as the M1 3 phage, for example, as disclosed by Messing et al. , Third Cleveland Symposium on Macromolecules and Recombinant DNA. A. Walton, ed., Elsevier, Amsterdam ( 1 981 ). This and - other phage vectors are commercially available and their use is well known to those skilled in the art. A versatile and efficient procedure for the construction of oligodeoxyribonucleotide directed site-specific mutations in DNA fragments using M13-derived vectors was published by Zoller, M.J. and Smith, M., Nucleic Acids Res. 10. 6487-6500 [ 1 982]). Also, plasmid vectors that contain a single-stranded phage origin of replication (Veira et al. , Meth. Enzvmol. 1 53. 3 [1987]) may be employed to obtain single-stranded DNA. Alternatively, nucleotide substitutions are introduced by synthesizing the appropriate DNA fragment in vitro, and amplifying it by PCR procedures known in the art. The PCR technique may also be used in creating amino acid sequence variants of a PTP λ polypeptide. In a specific example of PCR mutagenesis, template plasmid DNA (1 μg) is linearized by digestion with a restriction endonuclease that has a unique recognition site in the plasmid DNA outside of the region to be amplified. Of this material, 100 ng is added to a PCR mixture containing PCR buffer, which contains the four deoxynucleotide triphosphates and is included in the GeneAmp" kits (obtained from Perkin-Elmer Cetus, Norwalk, CT and Emeryville, CA), and 25 pmole of each oligonucleotide primer, to a final volume of 50 μ\. The reaction mixture is overlayered with 35 μ\ mineral oil. The reaction is denatured for 5 minutes at 100°C, placed briefly on ice, and then 1 μ\ Thermus aquaticus (Taq) DNA polymerase (5 units/ul), purchased from Perkin-Elmer Cetus, Norwalk, CT and Emeryville, CA) is added below the mineral oil layer. The reaction mixture is then inserted into a DNA Thermal Cycler (purchased from Perkin-Elmer Cetus) programmed as follows: 2 min. 55oC, 30 sec. 72°C, then 1 9 cycles of the following: 30 sec. 94oC, 30 sec.55oC, and 30 sec.72oC. At the end of the program, the reaction vial is removed from the thermal cycler and the aqueous phase transferred to a new vial, extracted with phenol/chloroform (50:50 vol), and ethanol precipitated, and the DNA is recovered by standard procedures. This material is subsequently subjected to appropriate treatments for insertion into a vector. Another method for preparing variants, cassette mutagenesis, is based on the technique described by Wells et al. rGene 34. 31 5 (1985)]. Additionally, the so-called phagemid display method may be useful in making amino acid sequence variants of native or variant PTP λ polypeptides or their fragments. This method involves (a) constructing a replicable expression vector comprising a first gene encoding a receptor to be mutated, a second gene encoding at least a portion of a natural or wild-type phage coat protein wherein the first and second genes are heterologous, and a transcription regulatory element operably linked to the first and second genes, thereby forming a gene fusion encoding a fusion protein; (b) mutating the vector at one or more selected positions within the first gene thereby forming a family of related plasmids; (c) transforming suitable host cells with the plasmids; (d) infecting the transformed host cells with a helper phage having a gene encoding the phage coat protein; (e) culturing the transformed infected host cells under conditions suitable for forming recombinant phagemid particles containing at least a portion of the plasmid and capable of transforming the host, the conditions adjusted so that no more than a minor amount of phagemid particles display more than one copy of the fusion protein on the surface of the particle; (f) contacting the phagemid particles with a suitable antigen so that at least a portion of the phagemid particles bind to the antigen; and (g) separating the phagemid particles that bind from those that do not. Steps (d) through (g) can be repeated one or more times. Preferably in this method the plasmid is under tight control of the transcription regulatory element, and the culturing conditions are adjusted so that the amount or number of phagemid particles displaying more than one copy of the fusion protein on the surface of the particle is less than about 1 %. Also, preferably, the amount of phagemid particles displaying more than one copy of the fusion protein is less than 10% of the amount of phagemid particles displaying a single copy of the fusion protein. Most preferably, the amount is less than 20%. Typically in this method, the expression vector will further contain a secretory signal sequence fused to the DNA encoding each subunit of the polypeptide and the transcription regulatory element will be a promoter system. Preferred promoter systems are selected from lac Z, λ PL , tac. T7 polymerase, tryptophan, and alkaline phosphatase promoters and combinations thereof. Also, normally the method will employ a helper phage selected from M1 3K07, M1 3R408, M1 3-VCS, and Phi X 1 74. The preferred helper phage is M13K07, and the preferred coat protein is the M 1 3 Phage gene III coat protein. The preferred host is £. coli, and protease-deficient strains of E. coli. Further details of the foregoing and similar mutagenesis techniques are found in general textbooks, such as, for example, Sambrook et al. , supra, and Current Protocols in Molecular Biology. Ausubel et al. eds., supra. F. Glvcosylation Variants Glycosylation variants are included within the scope of the present invention. They include variants completely lacking in glycosylation (unglycosylated), variants having at least one less glycosylated site than the native form (deglycosylated) as well as variants in which the glycosylation has been changed. Included are deglycosylated and unglycosylated amino acid sequences variants, deglycosylated and unglycosylated native PTP λ, and other glycosylation variants. For example, substitutional or deletional mutagenesis may be employed to eliminate the N- or O-linked glycosylation sites in the a native or variant PTP λ molecule of the present invention, e.g. the asparagine residue may be deleted or substituted for another basic residue such as lysine or histidine. Alternatively, flanking residues making up the glycosylation site may be substituted or deleted, even though the asparagine residues remain unchanged, in order to prevent glycosylation by eliminating the glycosylation recognition site. Additionally, unglycosylated PTP λ polypeptides which have the glycosylation sites of a native molecule may be produced in recombinant prokaryotic cell culture because prokaryotes are incapable of introducing glycosylation into polypeptides. Glycosylation variants may be produced by selecting appropriate host cells or by in vitro methods. Yeast and insect cells, for example, introduce glycosylation which varies significantly from that of mammalian systems. Similarly, mammalian cells having a different species (e.g. hamster, murine, porcine, bovine or ovine), or tissue origin (e.g. lung, liver, lymphoid, mesenchymal or epidermal) than the source of the PTP λ polypeptide are routinely screened for the ability to introduce variant glycosylation as characterized for example by elevated levels of mannose or variant ratios of mannose, fucose, sialic acid, and other sugars typically found in mammalian glycoproteins. In vitro processing of the PTP λ typically is accomplished by enzymatic hydrolysis, e.g. neuraminidase digestion. G. Covalent Modification of PTP λ Polypeptides Covalent modifications of PTP λ polypeptides are included within the scope herein. Such modifications are traditionally introduced by reacting targeted amino acid residues of the PTP λ polypeptides with an organic derivatizing agent that is capable of reacting with selected sides or terminal residues, or by harnessing mechanisms of post-translational modifications that function in selected recombinant host cells. The resultant covalent derivatives are useful in programs directed at identifying residues important for biological activity, for immunoassays of the PTP λ polypeptide, or for the preparation of anti-PTP λ antibodies for immunoaffinity purification of the recombinant. For example, complete inactivation of the biological activity of the protein after reaction with ninhydrin would suggest that at least one arginyl or lysyl residue is critical for its activity, whereafter the individual residues which were modified under the conditions selected are identified by isolation of a peptide fragment containing the modified amino acid residue. Such modifications are within the ordinary skill in the art and are performed without undue experimentation. Cysteinyl residues most commonly are reacted with α-haloacetates (and corresponding amines), such as chloroacetic acid or chloroacetamide, to give carboxymethyl or carboxyamidomethyl derivatives. Cysteinyl residues also are derivatized by reaction with bromotrifluoroacetone, α-bromo-β-(5-imidozoyl)propionic acid, chloroacetyl phosphate, N-alkylmaleimides, 3-nitro-2-pyridyl disulfide, methyl 2-pyridyl disulfide, p-chloromercuribenzoate, 2-chloromercuri-4- nitrophenol, or chloro-7-nitrobenzo-2-oxa-1 ,3-diazole. Histidyl residues are derivatized by reaction with diethylpyro- carbonate at pH 5.5-7.0 because this agent is relatively specific for the histidyl side chain. Para-bromophenacyl bromide also is useful; the reaction is preferably performed in 0.1 M sodium cacodylate at pH 6.0. Lysinyl and amino terminal residues are reacted with succinic or other carboxylic acid anhydrides. Derivatization with these agents has the effect of reversing the charge of the lysinyl residues. Other suitable reagents for derivatizing α-amino-containing residues include imidoesters such as methyl picolinimidate; pyridoxal phosphate; pyridoxal; chloroborohydride; trinitrobenzenesulfonic acid; O-methylisourea; 2,4- pentanedione; and transaminase-catalyzed reaction with glyoxylate. Arginyl residues are modified by reaction with one or several conventional reagents, among them phenylglyoxal, 2,3-butanedione, 1 ,2- cyclohexanedione, and ninhydrin. Derivatization of arginine residues requires that the reaction be performed in alkaline conditions because of the high pK a of the guanidine functional group. Furthermore, these reagents may react with the groups of lysine as well as the arginine epsilon-amino group. The specific modification of tyrosyl residues may be made, with particular interest in introducing spectral labels into tyrosyl residues by reaction with aromatic diazonium compounds or tetranitromethane. Most commonly, N-acetylimidizole and tetranitromethane are used to form O- acetyl tyrosyl species and 3-nitro derivatives, respectively. Tyrosyl residues are iodinated using 125 l or 131 l to prepare labeled proteins for use in radioimmunoassay. Carboxyl side groups (aspartyl or glutamyl) are selectively modified by reaction with carbodiimides (R'-N = C = N-R') such as 1 -cyclohexyl-3- (2-morpholinyl-4-ethyl) carbodiimide or 1 -ethyl-3-(4-azonia-4,4- dimethylpentyl) carbodiimide. Furthermore, aspartyl and glutamyl residues are converted to asparaginyl and glutaminyl residues by reaction with ammonium ions. Glutaminyl and asparaginyl residues are frequently deamidated to the corresponding glutamyl and aspartyl residues. Alternatively, these residues are deamidated under mildly acidic conditions. Either form of these residues falls within the scope of this invention. Other modifications include hydroxylation of proline and lysine, phosphorylation of hydroxyl groups of seryl, threonyl or tyrosyl residues, methylation of the α-amino groups of lysine, arginine, and histidine side chains (T.E. Creighton, Proteins: Structure and Molecular Properties. W.H. Freeman & Co., San Francisco, pp. 79-86 [1983]), acetylation of the N-terminal amine, and amidation of any C-terminal carboxyl group. The molecules may further be covalently linked to nonproteinaceous polymers, e.g. polyethylene glycol, polypropylene glycol or polyoxyalkylenes, in the manner set forth in U.S.S.N. 07/275,296 or U.S. patents 4,640,835; 4,496,689; 4,301 , 144; 4,670,417; 4,791 , 1 92 or 4, 179,337. Derivatization with bifunctional agents is useful for preparing intramolecular aggregates of PTP λ polypeptides with polypeptides as well as for cross-linking the PTP λ polypeptide to a water insoluble support matrix or surface for use in assays or affinity purification. In addition, a study of interchain cross-links will provide direct information on conformational structure. Commonly used cross-linking agents include 1 , 1 -bis(diazoacetyl)-2-phenylethane, glutaraldehyde, N- hydroxysuccinimide esters, homobifunctional imidoesters, and bifunctional maleimides. Derivatizing agents such as methyl-3-[(p- azidophenyl)dithio]propioimidate yield photoactivatable intermediates which are capable of forming cross-links in the presence of light. Alternatively, reactive water insoluble matrices such as cyanogen bromide activated carbohydrates and the systems reactive substrates described in U.S. Patent Nos. 3,959,642; 3,969,287; 3,691 ,01 6; 4, 1 95, 1 28; 4,247,642; 4,229,537; 4,055,635; and 4,330,440 are employed for protein immobilization and cross-linking. Certain post-translational modifications are the result of the action of recombinant host cells on the expressed polypeptide. Glutaminyl and aspariginyl residues are frequently post-translationally deamidated to the corresponding glutamyl and aspartyl residues. Alternatively, these residues are deamidated under mildly acidic conditions. Either form of these residues falls within the scope of this invention. Other post-translational modifications include hydroxylation of proline and lysine, phosphorylation of hydroxyl groups of seryl, threonyl or tyrosyl residues, methylation of the α-amino groups of lysine, arginine, and histidine side chains [T.E. Creighton, Proteins: Structure and Molecular Properties. W.H. Freeman & Co., San Francisco, pp. 79-86 ( 1983)]. Further derivatives of the PTP λ polypeptides herein are the so- called "immunoadhesins", which are chimeric antibody-like molecules combining the functional domain(s) of a binding protein (usually a receptor, a cell-adhesion molecule or a ligand) with the an immunoglobulin sequence. The most common example of this type of fusion protein combines the hinge and Fc regions of an immunoglobulin (Ig) with domains of a cell-surface receptor that recognizes a specific ligand. This type of molecule is called an "immunoadhesin", because it combines "immune" and "adhesion" functions; other frequently used names are "Ig-chimera", "Ig-" or "Fc-fusion protein", or "receptor- globulin." To date, more than fifty immunoadhesins have been reported in the art. Immunoadhesins reported in the literature include, for example, fusions of the T cell receptor (Gascoigne et al., Proc. Natl. Acad. Sci. USA 84.2936-2940 [1987]); CD4 (Capon etal.. Nature 337.525-531 [1989]; Traunecker etal., Nature 339.68-70 [1989]; Zettmeissi etal., DNA Cell Biol. USA 9.347-353 [1990]; Byrn etal.. Nature 344.667-670 [1990]); L-selectin (homing receptor) (Watson et al., J. Cell. Biol. 110. 2221-2229 [1990]; Watson et al., Naluifi 2ΔR, 164-167 [1991]); E- selectin [Mulligan etal.. J. Immunol. 151.6410-17 [1993]; Jacob et al., Biochemistry 34.1210-1217 [1995]); P-selectin (Mulligan et al., supra: Hollenbaugh etal., Biochemistry 34.5678-84 [1995]); ICAM-1 (Stauton etal.. J. Exp. Med. 176.1471-147611992]; Martin etal., J. Virol.67. 3561-68 [1993]; Roep etal., Lancet 343. 1590-93 [1994]); ICAM-2 (Damle et al., J. Immunol. 148.665-71 [1992]); ICAM-3 (Holness etal., J. Biol. Chem.270.877-84 [1995]); LFA-3 (Kanner et al., J. Immunol. 148.2-23-29 [1992]); L1 glycoprotein (Doherty et al., Neuron 14.57-66 [1995]); TNF-R1 (Ashkenazi etal., Proc. Natl. Acad. Sci. USA 88.10535- 539 [1991]; Lesslauer et al., Eur. J. Immunol.21.2883-86 [1991]; Peppel etal.. J. EXP. Med. 174.1483-1489 [1991]); TNF-R2 (Zack et al. , Proc. Natl. Acad. Sci. USA 9j2, 2335-39 [ 1993] ; Wooley et al. , J ^ Immunol.151.6602-07 [1993]); CD44 [Aruffo etal., £eJl £1, 1303-1313 (1990)]; CD28 and B7 [Linsley etal.. J. Exp. Med. 173.721-730 (1991)); CTLA-4 [Lisley etal.. J. Exp. Med.174.561-569 (1991)]; CD22 [Stamenkovic etal., £≤]i ££.1133-1144 (1991)]; NP receptors [Bennett etal., J. Biol. Chem.266.23060-23067 (1991)]; IgE receptor α [Ridgway and Gorman, J. Cell. Biol.115. abstr. 1448 (1991)]; HGF receptor [Mark, M.R. et al., 1992, J. Biol. Chem. submitted]; IFN-γR α- and β-chain [Marsters et al., Proc. Natl. Acad. Sci. USA 92.5401-05 [1995]); trk-A, -B, and -C (Shelton et al., J. Neurosci. 15.477-91 11 995]); IL-2 ( Landolfi. J. Immunol. 146. 91 5-19 [ 1 991 ]); IL-10 (Zheng et al.. J. Immunol. 1 54. 5590-5600 [1 995]). The simplest and most straightforward immunoadhesin design combines the binding region(s) of the 'adhesin' protein with the hinge and Fc regions of an immunoglobulin heavy chain. Ordinarily, when preparing the PTP λ-immunoglobulin chimeras of the present invention, nucleic acid encoding the desired PTP λ polypeptide will be fused C-terminally to nucleic acid encoding the N-terminus of an immunoglobulin constant domain sequence, however N-terminal fusions are also possible. Typically, in such fusions the encoded chimeric polypeptide will retain at least functionally active hinge, CH2 and CH3 domains of the constant region of an immunoglobulin heavy chain. Fusions are also made to the C-terminus of the Fc portion of a constant domain, or immediately N- terminal to the CH1 of the heavy chain or the corresponding region of the light chain. The precise site at which the fusion is made is not critical; particular sites are well known and may be selected in order to optimize the biological activity, secretion or binding characteristics of the PTP λ- immunoglobulin chimeras. In a preferred embodiment, the sequence of a native, mature PTP λ polypeptide, or a soluble (transmembrane domain-inactivated) form thereof, is fused to the N-terminus of the C-terminal portion of an antibody (in particular the Fc domain), containing the effector functions of an immunoglobulin, e.g. lgG-1 . It is possible to fuse the entire heavy chain constant region to the PTP λ sequence. However, more preferably, a sequence beginning in the hinge region just upstream of the papain cleavage site (which defines IgG Fc chemically; residue 216, taking the first residue of heavy chain constant region to be 1 14 [Kobet ef al. , supral. or analogous sites of other immunoglobulins) is used in the fusion. In a particularly preferred embodiment, the PTP λ sequence (full length or soluble) is fused to the hinge region and CH2 and CH3 or CH1 , hinge, CH2 and CH3 domains of an lgG-1 , lgG-2, or lgG-3 heavy chain. The precise site at which the fusion is made is not critical, and the optimal site can be determined by routine experimentation. In some embodiments, the PTP λ-immunoglobulin chimeras are assembled as multimers, and particularly as homo-dimers or -tetramers (WO 91 /08298). Generally, these assembled immunoglobulins will have known unit structures. A basic four chain structural unit is the form in which IgG, IgD, and IgE exist. A four unit is repeated in the higher molecular weight immunoglobulins; IgM generally exists as a pentamer of basic four units held together by disulfide bonds. IgA globulin, and occasionally IgG globulin, may also exist in multimeric form in serum. In the case of multimer, each four unit may be the same or different. Various exemplary assembled PTP λ-immunoglobulin chimeras within the scope herein are schematically diagramed below: (a) AC L -AC L ; (b) AC H -[AC H , AC L -AC H , AC L -V H C H , or V L C L -AC H ]; (c) AC L -AC H -[AC L -AC H , AC L -V H C H , V L C L -AC H , or V L C L -V H C H l; (d) AC L -V H C H -[AC H , or AC L -V H C H , or V L C L -AC H ]; (e) V L C L -AC H -[AC L -V H C H , or V L C L -AC H ]; and (f) IA-Y] n -[V L C L -V H C H ] 2 , wherein each A represents identical or different novel PTP λ polypeptide amino acid sequences; V L is an immunoglobulin light chain variable domain; V H is an immunoglobulin heavy chain variable domain; C L is an immunoglobulin light chain constant domain; C H is an immunoglobulin heavy chain constant domain; n is an integer greater than 1 ; Y designates the residue of a covalent cross-linking agent. In the interests of brevity, the foregoing structures only show key features; they do not indicate joining (J) or other domains of the immunoglobulins, nor are disulfide bonds shown. However, where such domains are required for binding activity, they shall be constructed as being present in the ordinary locations which they occupy in the immunoglobulin molecules. Alternatively, the PTP λ amino acid sequences can be inserted between immunoglobulin heavy chain and light chain sequences such that an immunoglobulin comprising a chimeric heavy chain is obtained. In this embodiment, the PTP λ polypeptide sequences are fused to the 3' end of an immunoglobulin heavy chain in each arm of an immunoglobulin, either between the hinge and the CH2 domain, or between the CH2 and CH3 domains. Similar constructs have been reported by Hoogenboom, H. R. et al.. Mol. Immunol. 28. 1027-1037 ( 1991 ). Although the presence of an immunoglobulin light chain is not required in the immunoadhesins of the present invention, an immunoglobulin light chain might be present either covalently associated to a PTP λ-immunoglobulin heavy chain fusion polypeptide, or directly fused to the PTP λ polypeptide. In the former case, DNA encoding an immunoglobulin light chain is typically coexpressed with the DNA encoding the PTP λ-immunoglobulin heavy chain fusion protein. Upon secretion, the hybrid heavy chain and the light chain will be covalently associated to provide an immunoglobulin-like structure comprising two disulfide-linked immunoglobulin heavy chain-light chain pairs. Method suitable for the preparation of such structures are, for example, disclosed in U.S. Patent No. 4,81 6,567 issued 28 March 1 989. In a preferred embodiment, the immunoglobulin sequences used in the construction of the immunoadhesins of the present invention are from an IgG immunoglobulin heavy chain constant domain. For human immunoadhesins, the use of human lgG-1 and lgG-3 immunoglobulin sequences is preferred. A major advantage of using lgG-1 is that lgG-1 immunoadhesins can be purified efficiently on immobilized protein A. In contrast, purification of lgG-3 requires protein G, a significantly less versatile medium. However, other structural and functional properties of immunoglobulins should be considered when choosing the Ig fusion partner for a particular immunoadhesin construction. For example, the lgG-3 hinge is longer and more flexible, so it can accommodate larger 'adhesin' domains that may not fold or function properly when fused to lgG-1 . While IgG immunoadhesins are typically mono- or bivalent, other Ig subtypes like IgA and IgM may give rise to dimeric or pentameric structures, respectively, of the basic Ig homodimer unit. Multimeric immunoadhesins are advantageous in that they can bind their respective targets with greater avidity than their IgG-based counterparts. Reported examples of such structures are CD4-lgM (Traunecker et al., supra): ICAM-lgM (Martin et al. , J. Virol. 67. 3561 -68 [1 993]); and CD2-lgM (Arulanandam et al., J. Exp. Med. 177. 1439-50 [1 993]). For PTP λ-lg immunoadhesins, which are designed for in vivo application, the pharmacokinetic properties and the effector functions specified by the Fc region are important as well. Although lgG-1 , lgG-2 and IgG-4 all have in vivo half-lives of 21 days, their relative potencies at activating the complement system are different. IgG-4 does not activate complement, and lgG-2 is significantly weaker at complement activation than lgG-1 . Moreover, unlike lgG-1 , lgG-2 does not bind to Fc receptors on mononuclear cells or neutrophils. While lgG-3 is optimal for complement activation, its in vivo half-life is approximately one third of the other IgG isotypes. Another important consideration for immunoadhesins designed to be used as human therapeutics is the number of allotypic variants of the particular isotype. In general, IgG isotypes with fewer serologically-defined allotypes are preferred. For example, lgG-1 has only four serologically-defined allotypic sites, two of which (G 1 m and 2) are located in the Fc region; and one of these sites G1 m1 , is non-immunogenic. In contrast, there are 12 serologically- defined allotypes in lgG-3, all of which are in the Fc region; only three of these sites (G3m5, 1 1 and 21 ) have one allotype which is nonimmunogenic. Thus, the potential immunogenicity of a γ3 immunoadhesin is greater than that of a γ1 immunoadhesin. PTP λ-lg immunoadhesins are most conveniently constructed by fusing the cDNA sequence encoding the PTP λ portion in-frame to an Ig cDNA sequence. However, fusion to genomic Ig fragments can also be used (see, e.g. Gascoigne et al.. Proc. Natl. Acad. Sci. USA 84. 2936- 2940 [1987]; Aruffo et al., £eJi £l, 1 303-1 31 3 [1 990]; Stamenkovic ef a/., £eJi ££, 1 1 33-1 144 [1 991 ]). The latter type of fusion requires the presence of Ig regulatory sequences for expression. cDNAs encoding IgG heavy-chain constant regions can be isolated based on published sequence from cDNA libraries derived from spleen or peripheral blood lymphocytes, by hybridization or by polymerase chain reaction (PCR) techniques. Other derivatives comprise the novel peptides of this invention covalently bonded to a nonproteinaceous polymer. The nonproteinaceous polymer ordinarily is a hydrophilic synthetic polymer, i.e. a polymer not otherwise found in nature. However, polymers which exist in nature and are produced by recombinant or in vitro methods are useful, as are polymers which are isolated from nature. Hydrophilic polyvinyl polymers fall within the scope of this invention, e.g. polyvinylalcohol and polyvinylpyrrolidone. Particularly useful are polyvinylalkylene ethers such a polyethylene glycol, polypropylene glycol. The PTP λ polypeptides may be linked to various nonproteinaceous polymers, such as polyethylene glycol, polypropylene glycol or polyoxyalkylenes, in the manner set forth in U.S. Patent Nos. 4,640,835; 4,496,689; 4,301 , 144; 4,670,417; 4,791 , 1 92 or 4, 1 79,337. The PTP λ polypeptides may be entrapped in microcapsules prepared, for example, by coacervation techniques or by interfacial polymerization, in colloidal drug delivery systems (e.g. liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules), or in macroemulsions. Such techniques are disclosed in Remington's Pharmaceutical Sciences. 16th Edition, Oslo, A., Ed. ( 1980). H. Anti-PTP λ Antibody Preparation (i) Polyclonal antibodies Polyclonal antibodies to a PTP λ molecule generally are raised in animals by multiple subcutaneous (sc) or intraperitoneal (ip) injections of the PTP λ and an adjuvant. It may be useful to conjugate the PTP λ or a fragment containing the target amino acid sequence to a protein that is immunogenic in the species to be immunized, e.g. keyhole limpet hemocyanin, serum albumin, bovine thyroglobulin, or soybean trypsin inhibitor using a bifunctional or derivatizing agent, for example maleimidobenzoyl sulfosuccinimide ester (conjugation through cysteine residues), N-hydroxysuccinimide (through lysine residues), glutaraldehyde, succinic anhydride, SOCI 2 , or R 1 N = C = NR, where R and R 1 are different alkyl groups. Animals are immunized against the immunogenic conjugates or derivatives by combining 1 mg or 1 μg of conjugate (for rabbits or mice, respectively) with 3 volumes of Freud's complete adjuvant and injecting the solution intradermally at multiple sites. One month later the animals are boosted with 1 /5 to 1 /10 the original amount of conjugate in Freud's complete adjuvant by subcutaneous injection at multiple sites. 7 to 14 days later the animals are bled and the serum is assayed for anti-PTP λ antibody titer. Animals are boosted until the titer plateaus. Preferably, the animal boosted with the conjugate of the same PTP λ, but conjugated to a different protein and/or through a different cross-linking reagent. Conjugates also can be made in recombinant cell culture as protein fusions. Also, aggregating agents such as alum are used to enhance the immune response. (ii) Monoclonal antibodies Monoclonal antibodies are obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally- occurring mutations that may be present in minor amounts. Thus, the modifier "monoclonal" indicates the character of the antibody as not being a mixture of discrete antibodies. For example, the anti-PTP λ monoclonal antibodies of the present invention may be made using the hybridoma method first described by Kohler & Milstein, Nature 256_:495 (1 975), or may be made by recombinant DNA methods [Cabilly, et al. , U.S. Pat. No. 4,81 6,567]. DNA encoding the monoclonal antibodies of the invention is readily isolated and sequenced using conventional procedures (e.g., by using oligonucleotide probes that are capable of binding specifically to genes encoding the heavy and light chains of murine antibodies) . The hybridoma cells of the invention serve as a preferred source of such DNA. Once isolated, the DNA may be placed into expression vectors, which are then transfected into host cells such as simian COS cells, Chinese hamster ovary (CHO) cells, or myeloma cells that do not otherwise produce immunoglobulin protein, to obtain the synthesis of monoclonal antibodies in the recombinant host cells. The DNA also may be modified, for example, by substituting the coding sequence for human heavy and light chain constant domains in place of the homologous murine sequences, Morrison, et al. , Proc. Nat. Acad. Sci. 81 . 6851 (1 984), or by covalently joining to the immunoglobulin coding sequence all or part of the coding sequence for a non-immunoglobulin polypeptide. In that manner, "chimeric" or "hybrid" antibodies are prepared that have the binding specificity of an anti-PTP λ monoclonal antibody herein. Typically such non-immunoglobulin polypeptides are substituted for the constant domains of an antibody of the invention, or they are substituted for the variable domains of one antigen-combining site of an antibody of the invention to create a chimeric bivalent antibody comprising one antigen-combining site having specificity for a PTP λ polypeptide and another antigen-combining site having specificity for a different antigen. Chimeric or hybrid antibodies also may be prepared in vitro using known methods in synthetic protein chemistry, including those involving crosslinking agents. For example, immunotoxins may be constructed using a disulfide exchange reaction or by forming a thioether bond. Examples of suitable reagents for this purpose include iminothiolate and methyl-4-mercaptobutyrimidate. For diagnostic applications, the antibodies of the invention typically will be labeled with a detectable moiety. The detectable moiety can be any one which is capable of producing, either directly or indirectly, a detectable signal. For example, the detectable moiety may be a radioisotope, such as 3 H, 14 C, 32 P, 35 S, or 12δ l, a fluorescent or chemiluminescent compound, such as fluorescein isothiocyanate, rhodamine, or luciferin; biotin; radioactive isotopic labels, such as, e.g., 125 l, 32 P, 14 C, or 3 H, or an enzyme, such as alkaline phosphatase, beta- galactosidase or horseradish peroxidase. Any method known in the art for separately conjugating the antibody to the detectable moiety may be employed, including those methods described by Hunter, et al. , Nature 144:945 (1962); David, ef al., Biochemistry 1 3: 1014 (1974); Pain, et al., J. Immunol. Meth. 40:219 ( 1981 ); and Nygren. J. Histochem. and Cytochem. 30:407 ( 1982). The antibodies of the present invention may be employed in any known assay method, such as competitive binding assays, direct and indirect sandwich assays, and immunoprecipitation assays. Zola, Monoclonal Antibodies: A Manual of Techniques, pp.147-1 58 (CRC Press, Inc., 1 987). (iii) Humanized antibodies Methods for humanizing non-human antibodies are well known in the art. Generally, a humanized antibody has one or more amino acid residues introduced into it from a source which is non-human. These non-human amino acid residues are often referred to as "import" residues, which are typically taken from an "import" variable domain. Humanization can be essentially performed following the method of Winter and co-workers [Jones et al. , Nature 321 . 522-525 ( 1 986); Riechmann et al. , Nature 332. 323-327 (1 988); Verhoeyen et al. , Science 239. 1 534-1536 ( 1 988)], by substituting rodent CDRs or CDR sequences for the corresponding sequences of a human antibody. Accordingly, such "humanized" antibodies are chimeric antibodies (Cabilly, supra), wherein substantially less than an intact human variable domain has been substituted by the corresponding sequence from a non-human species. In practice, humanized antibodies are typically human antibodies in which some CDR residues and possibly some FR residues are substituted by residues from analogous sites in rodent antibodies. It is important that antibodies be humanized with retention of high affinity for the antigen and other favorable biological properties. To achieve this goal, according to a preferred method, humanized antibodies are prepared by a process of analysis of the parental sequences and various conceptual humanized products using three dimensional models of the parental and humanized sequences. Three dimensional immunoglobulin models are commonly available and are familiar to those skilled in the art. Computer programs are available which illustrate and display probable three-dimensional conformational structures of selected candidate immunoglobulin sequences. Inspection of these displays permits analysis of the likely role of the residues in the functioning of the candidate immunoglobulin sequence, i.e. the analysis of residues that influence the ability of the candidate immunoglobulin to bind its antigen. In this way, FR residues can be selected and combined from the consensus and import sequence so that the desired antibody characteristic, such as increased affinity for the target antigen(s), is achieved. In general, the CDR residues are directly and most substantially involved in influencing antigen binding. For further details see U.S. application Serial No. 07/934,373 filed 21 August 1 992, which is a continuation-in-part of application Serial No. 07/71 5,272 filed 14 June 1991 . Alternatively, it is now possible to produce transgenic animals (e.g. mice) that are capable, upon immunization, of producing a full repertoire of human antibodies in the absence of endogenous immunoglobulin production. For example, it has been described that the homozygous deletion of the antibody heavy chain joining region (J H ) gene in chimeric and germ-line mutant mice results in complete inhibition of endogenous antibody production. Transfer of the human germ-line immunoglobulin gene array in such germ-line mutant mice will result in the production of human antibodies upon antigen challenge. See, e.g. Jakobovits et al. , Proc. Natl. Acad. Sci. USA 90. 2551 -255 (1993); Jakobovits et al. , Nature 362. 255-258 ( 1 993). (iv) Bispecific antibodies Bispecific antibodies are monoclonal, preferably human or humanized, antibodies that have binding specificities for at least two different antigens. In the present case, one of the binding specificities is for a PTP λ polypeptide, the other one is for any other antigen. Methods for making bispecific antibodies are known in the art. Traditionally, the recombinant production of bispecific antibodies is based on the coexpression of two immunoglobulin heavy chain-light chain pairs, where the two heavy chains have different specificities (Millstein and Cuello, Nature 305. 537-539 ( 1 983)). Because of the random assortment of immunoglobulin heavy and light chains, these hybridomas (quadromas) produce a potential mixture of 10 different antibody molecules, of which only one has the correct bispecific structure. The purification of the correct molecule, which is usually done by affinity chromatography steps, is rather cumbersome, and the product yields are low. Similar procedures are disclosed in PCT application publication No. WO 93/08829 (published 1 3 May 1 993), and in Traunecker et al. , EMBO JLQ, 3655-3659 (1 991 ). According to a different and more preferred approach, antibody variable domains with the desired binding specificities (antibody-antigen combining sites) are fused to immunoglobulin constant domain sequences. The fusion preferably is with an immunoglobulin heavy chain constant domain, comprising at least part of the hinge, and second and third constant regions of an immunoglobulin heavy chain (CH2 and CH3). It is preferred to have the first heavy chain constant region (CHI ) containing the site necessary for light chain binding, present in at least one of the fusions. DNAs encoding the immunoglobulin heavy chain fusions and, if desired, the immunoglobulin light chain, are inserted into separate expression vectors, and are cotransfected into a suitable host organism. This provides for great flexibility in adjusting the mutual proportions of the three polypeptide fragments in embodiments when unequal ratios of the three polypeptide chains used in the construction provide the optimum yields. It is, however, possible to insert the coding sequences for two or all three polypeptide chains in one expression vector when the expression of at least two polypeptide chains in equal ratios results in high yields or when the ratios are of no particular significance. In a preferred embodiment of this approach, the bispecific antibodies are composed of a hybrid immunoglobulin heavy chain with a first binding specificity in one arm, and a hybrid immunoglobulin heavy chain-light chain pair (providing a second binding specificity) in the other arm. It was found that this asymmetric structure facilitates the separation of the desired bispecific compound from unwanted immunoglobulin chain combinations, as the presence of an immunoglobulin light chain in only one half of the bispecific molecule provides for a facile way of separation. This approach is disclosed in PCT application WO 94/04690 published 3 March 1994. For further details of generating bispecific antibodies see, for example, Suresh et al. , Methods in Enzvmolooy 1 21 . 210 ( 1 986). (v) Heteroconjugate antibodies Heteroconjugate antibodies are also within the scope of the present invention. Heteroconjugate antibodies are composed of two covalently joined antibodies. Such antibodies have, for example, been proposed to target immune system cells to unwanted cells (U.S. Patent No. 4,676,980), and for treatment of HIV infection (PCT application publication Nos. WO 91 /00360 and WO 92/200373; EP 03089). Heteroconjugate antibodies may be made using any convenient cross- linking methods. Suitable cross-linking agents are well known in the art, and are disclosed in U.S. Patent No. 4,676,980, along with a number of cross-linking techniques. I. Peptide and Non-Peptide Analogs of PTP λ Polypeptides Peptide analogs of the PTP λ polypeptides of the present invention are modeled based upon the three-dimensional structure of the native polypeptides. Peptides may be synthesized by well known techniques such as the solid-phase synthetic techniques initially described in Merrifield, J. Am. Chem. Soc. 1 5. 2149-21 54 ( 1 963). Other peptide synthesis techniques are, for examples, described in Bodanszky et al. , Peptide Synthesis, John Wiley & Sons, 2nd Ed., 1 976, as well as in other reference books readily available for those skilled in the art. A summary of peptide synthesis techniques may be found in Stuart and Young, Solid Phase Peptide Synthelia, Pierce Chemical Company, Rockford, IL (1 984). Peptides may also be prepared by recombinant DNA technology, using a DNA sequence encoding the desired peptide. In addition to peptide analogs, the present invention also contemplates non-peptide (e.g. organic) compounds which display substantially the same surface as the peptide analogs of the present invention, and therefore interact with other molecules in a similar fashion. J. Use of the PTP λ Polypeptides The PTP λ polypeptides of the present invention are useful for a variety of purposes. For example, the PTP λ polypeptides of the present invention are useful in the identification and purification of the PTP λ ligand, for which a possible location is the brain. The purification may be performed by using the native receptor(s) or immunoadhesins, comprising a fusion of the extracellular domain of the receptor(s) to an immunoglobulin heavy chain constant region. The ligands are expected to be useful in the treatment of paralytic-type diseases. An increased level of expression of the PTP λ receptors of the present invention may be useful in reducing metastasis of various tumors of the lung and other organs. The expression of the receptor may be upregulated by anti-PTP λ antibodies, which are capable of cross-linking and thereby activating the receptors. Non-antibody cross-liking agents may also be employed for this purpose. The PTP λ polypeptides of the present invention are also useful as molecular markers of the tissues in which they are specifically expressed. As such, the PTP λ polypeptide is useful for tissue typing of specific mammalian tissues. Native PTP λ polypeptides and their functional equivalents are also useful in screening assays designed to identify agonists or antagonists of native PTP λ polypeptides. Such assays may take the form of any conventional cell-type or biochemical binding assay, and can be performed in a variety of assay formats well known to those skilled in the art. An example is the so called "two-hybrid" assay format using the Matchmaker Two-Hybrid System (Clontech) according to the manufacturers instructions. The native PTP λ polypeptides of the present invention are also useful as protein molecular weight markers for protein gels. Nucleic acids encoding the PTP λ polypeptides of the present invention are also useful in providing hybridization probes for searching cDNA and genomic libraries for the coding sequence of other PTP λ polypeptides analogs in other species. Antagonists of the PTP λ polypeptide of the present invention are useful for inhibiting the biological activity of the enzyme, thereby inhibiting the biological effects of tyrosine dephosphorylation. Agonists of the PTP λ polypeptide are useful for increasing or simulating the biological effects of the native PTP λ polypeptide. K. Materials and Methods 1. RNA Isolation and Polymerase Chain Reaction Messenger RNA was isolated from the non-adherent Lin l0 CD34 hl fraction of fetal yolk sac cells (Micro-FastTrack, InVitrogene). Poly A + RNA was reverse transcribed with random hexamers (Promega) and Molony murine Leukemia virus reverse transcriptase (Superscript II, GIBCO BRL). One quarter of this cDNA was amplified by PCR using degenerate mixed oligonucleotide primers. Sense and anti-sense primers corresponding to the amino acid sequences (H/D)FWRM(I/V)W (SEQ ID NO:5) (5'-A(C/T)TT(C/T)TGG(A/C)GIATG(A/G)TITGG-3') (SEQ ID N0:6) and WPD(F/H)GVP (SEQ ID NO:7) (5 * -GGIAC(G/A)(T/A)(G/A)(G/A)TCIG GCCA-3') (SEQ ID NO:8) respectively were used. PCR was carried out in 1 X Taq DNA polymerase buffer (GIBCO BRL) plus 0.2 mM of each dNTP, 10% DMSO and 5 units Taq polymerase (GIBCO BRL) for 25 cycles of 94°C for 1 minute, 55°C for 1 minute and 72°C for 1 minute. The PCR products were treated with Klenow enzyme (New England Biolabs) at 30°C for 30 minutes, cloned into the Smal site of the pRK-5 plasmid (Genentech, Inc.) and subsequently sequenced (Sequenase, USB) . 2. Isolation of cDNA clones Adapter-linked double stranded cDNA was prepared from A + RNA of day- 10 mice embryos (Marathon-ready cDNA synthesize kit, Clontech) using either random hexamer or oligo dT primers. Full-length cDNA was isolated by 5' or 3' rapid amplification of cDNA ends (RACE) of the marathon-ready cDNAs. A lambda cDNA library of adult mouse lung was screened following the standard protocol using cDNA fragments isolated by RACE as probes. 3. Bacterial Expression of GST-PTP Fusion Protein cDNA sequences encoding amino acids 791 to 1436 or amino acids 43 to 741 containing either the cytoplasmic region or the extracellular region of PTP λ was obtained by PCR. PCR fragments were - then treated with Sail and Notl restriction enzymes and cloned into the pGEX-4T-1 plasmid (Pharmacia). Fusion proteins were affinity purified using Glutathione sepharose columns (Pharmacia). Polyclonal anti-serum against either the cytoplasmic (Cy) or extracellular (Ex) region was generated by immunizing rabbits with each purified GST-fusion protein. 4. Indirect Immunofluorescence of PC-12 Cells NGF-treated or untreated PC-12 cells grown on cover slips were fixed with 4% formaldehyde and 0.1 % Triton X-100 in phosphate- buffered saline (PBS) and permeabilized with 0.05% saponin. Fixed cells were then blocked with 10% normal goat serum plus 0.05% NP40 in PBS, incubated with polyclonal rabbit anti-Cy primary antiserum (1 :3000 dilution), washed, and incubated with phycoerytherin (PE)-tagged goat antibody to rabbit immunoglobulin G. Cells were viewed and digital images were taken by fluorescence confocal microscopy. 5. Immunoprecipitation and Tyrosine Phosphatase Assay of PTPλ PC-12 cells expressing endogenous PTP λ were washed in cold PBS, then lysed in buffer containing 50 mM Tris-HCI, pH 8.0, 1 50 mM NaCl, 1 mM EDTA, 1 mM EGTA, 1 mM DTT, 1 mM benzamidine, 1 mg/ml leupeptin, 1 mg/ml aprotinin, 10 mM NaF, 0.5 mM okadaic acid, 10% (v/v) glycerol, 1 % (v/v) Triton X-100, 0.5% (w/v) sodium deoxycholate and 0.01 % (w/v) SDS (AUTHOR?, EMBO J. , 13(1 6):3763-3771 ( 1 994)). Cell lysates were precieared by incubating with 50 ml of washed protein A-Sepharose beads (Pharmacia). Precieared lysate was then incubated with protein A-Sepharose beads pre-coupled with rabbit polyclonal antiserum (20 ml serum/50 ml beads) at 40°C for 1 5 hours. The protein A-Sepharose/PTP λ immunoprecipitate complex was then processed as described (Jiang et al. , Mol. Cell Biol. 13(5):2942-2951 ( 1993)). Briefly, the complex was washed four times with HNTG buffer (20 mM HEPES, pH 7.5, 1 50 mM NaCl, 10% glycerol, 0.1 % Triton X-100) and once with M7.6 buffer (60 mM Tris-HCI, pH 7.6, 5 mM EDTA, 10 mM DTT, 50 mM NaCl, 50 mg/ml bovine serum albumin). Washed immunoprecipitate complex was resuspended in M7.6 buffer and subject to non-radioactive protein tyrosine phosphatase assay with synthetic oligopeptide substrates (PPS1 corresponds to the hirudin 53-63 C-terminal fragment: Biotin- DGDFEEIPEEY-P0 4 (SEQ ID N0:9), PPS2 corresponds to amino acids 1 -1 7 of human gastrin: Biotin-EGPWLEEEEEAY-P0 4 (SEQ ID N0: 10)). PTPase assay was carried out following the manufacturer's procedures (Tyrosine Phosphatase Assay Kit, Boehringer Mannheim). 6. Northern Analysis A 2.5 kb cDNA fragment encoding the cytoplasmic region of PTP λ was used to probe the murine multi-tissue northern blots (Clontech) or the A + RNA of PC-1 2 cells. 7. In Situ Hybridization Rat E1 5.5 embryos and P1 brains were immersion fixed overnight at 4°C in 4% paraformaldehyde, then cryoprotected overnight in 1 5% sucrose. Adult rat brains were fresh frozen with powdered dry ice. All tissues were sectioned at 1 6um, and processed for in-situ hybridization for PTP λ using 33 P-UTP labeled RNA probes. Sense and antisense probes were synthesized from a 2.5kb DNA fragment of PTP λ using SP6 or T7 polymerase, respectively. Further experimental details will be apparent from the following non-limiting examples. L. Examples EXAMPLE I - Isolation and Characterization of the cDNA encoding PTP λ In order to isolate novel receptor protein tyrosine phosphatases (PTPs) expressed in murine primitive hematopoietic cells, we undertook the cloning of PCR fragments produced by priming with sequences - directed against conserved protein motifs found in PTPs from a number of different genes and species (Dixon, Ann. Ny. Acad. Sci. 766: 18-22 ( 1 995)). Analysis of 70 different PCR-derived subclones revealed an array of previously described PTPs, as well as two novel PTPs. One of these novel PTPs, termed PTP HSC, is a member of the PTP PEST family of enzymes, and it has been previously described (Cheng et al. , Blood, in press). The second novel PCR fragment was homologous to PTPs K and μ, both related receptor-type PTPs that mediate homophilic adhesion ■ Rrady-Kalnay et al.. Curr. Ooin. Cell. Biol. 7(5):650-657 (1995)). In order to further characterize the cDNA encoding this novel PTP, a combined cloning approach that utilized RACE as well as cloning from phage cDNA libraries was performed. The composite cDNA (SEQ ID NO: 1 ) and derived protein (SEQ ID NO:2) sequences determined from these various clones is shown in Figures 1 A-1 D. The ATG start codon utilized for translation of this large open reading frame was embedded within a consensus Kozak sequence, and there are several translational stop codons upstream of this initiator codon. As can be seen from Figures 1 A-1 D, the protein (SEQ ID NO:2) derived from this cDNA (SEQ ID NO:1 ) is a large receptor-like molecule of 1 ,436 amino acids and a molecular weight of approximately 161 , 176 daltons. Figures 2A-2B illustrate that the novel, hematopoietically-derived PTP-related protein reported here shows a high degree of homology to both PTP K ("60%) and PTP μ ( " 53%) throughout their entire lengths (Jiang et al., (1 993) sjjjjia and Gebbink et al. , ( 1 991 ) supra ) . Because this novel PTP is homologous throughout its entire length to PTPs K and μ, it appears that the new PTP polypeptide contains MAM, IgG, 4 fibronectin type 111, and two cytoplasmically localized phosphatase domains (see Figures 2A-2B) (Brady-Kalnay et al. , Curr. Ooin. Cell. Biol. 7(5):650-657 (1995), Jiang et al. , (1993) supra and Gebbink et al. , (1991 ) supra). These homologies with the novel PTP polypeptide are somewhat less than the homology between PTP K and μ { " 62%), suggesting that the novel PTP polypeptide reported here is rather more distantly related to these two PTPs than they are to each other. These data suggest that this novel PTP is the third member of the homotypically interacting PTP family containing PTPs K and μ, and we have therefore named the novel receptor PTP λ. As can be seen from Figure 3, the relative sequence homologies in each of the domains of these three enzymes suggests that they are indeed closely related. Interestingly, previous data suggested that both the MAM and IgG domains mediated specific homotypic adhesion between PTPs K and μ (Brady-Kalnay et al. , (1 994) supra and Zondag et al. , (1 995) supra), and it is clear from the sequence comparisons between these three related proteins that these two domains are substantially homologous. However, the fact that there are a large number of sequence changes between these two motifs is also consistent with the supposition that they can mediate specific homotypic interactions. Thus, it is likely that, while these motifs are undoubtedly structurally related, differences in their relative sequences are involved with homotypic recognition. The overall sequence homologies between the three proteins is also relatively high in the Fnlll domains, although the homology in the first of these domains is significantly higher than in the others. Previous work has also demonstrated that a juxtamembrane site between the transmembrane domain and the first phosphatase domain is distantly homologous to a similar region in the cadherins (Brady-Kalnay et al. , i Cell. Biol. 130{4):977-986 (1995)), and this site shows a high degree of homology between these three receptors. A high degree of sequence homology is also found between the first PTPase domains of these three receptors, with a somewhat lower level of homology between the second PTPase domains of these proteins. This latter result may be significant, since it has been reported that the first phosphatase domain is the most important enzymatic motif of the dual phosphatase regions in the receptor PTPs (Pot et al.. J. Biol. Chem. 266(291: 19688-19696 (1 991 )) . The homology between these PTPase domains includes many of the residues previously found to be important for substrate recognition and tyrosine dephosphorylation in the PTP 1 B (Jia et a/. , Science 268(5218): 1 754- 1 758 (1 995)), although not all of these residues are completely conserved. In summary, the sequence homologies between these three proteins suggest a common ancestor as well as potentially similar functions. EXAMPLE 2 - Analysis of the Enzymatic Activity of PTP λ In order to analyze the enzymatic activity of the PTPase domains of the novel PTP λ polypeptide, we immunoprecipitated the enzyme from PC 1 2 cells which we show below express the protein. In these experiments, a polyclonal antibody directed against the entire cytoplasmic domain as predicted from the cDNA sequence was produced by injecting rabbits with a GST fusion containing this region of the receptor. The immunoprecipitate was incubated with a tyrosine phosphorylated peptide using a commercial kit, and the degree of dephosphorylation was determined using an anti-phosphotyrosine antibody. As is shown in Figure 4, the immunoprecipitate obtained using the immune serum had clear phosphatase activity, while the preimmune serum immunoprecipitate showed no such activity. In addition, Figure 4 demonstrates that this enzymatic activity was completely inhibited by the inclusion of vanadate, a potent tyrosine phosphatase inhibitor. Thus, the PTP λ polypeptide encoded by the cDNA (SEQ ID NO:1 ) described herein and shown in Figures 1 A-1 D is clearly a receptor tyrosine phosphatase protein. EXAMPLE 3 - Tissue Expression of the PTP λ Transcript As is shown in Figure 5, northern blot analysis of fetal as well as adult tissues demonstrates that PTP λ mRNA is expressed in a diversity of tissues outside of the hematopoietic progenitor cells from which it was originally cloned. Thus, the expression of PTP λ mRNA is detected throughout embryonic development beginning in the very early embryo at day 7. Interestingly, analysis of adult organs reveals that the PTP λ transcript is expressed specifically in only a subset of tissues. Thus, there appears to be a very high level of expression of the PTP λ polypeptide in adult brain, lung and kidney, a much decreased level in heart, skeletal muscle and testis, and a lack of obvious expression at this exposure in spleen and liver. The high level of PTP λ expression in lung and brain, together with the lack of expression in liver, is in contrast to PTP K, a PTP which is expressed at high levels in liver but is almost undetectable in lung and brain (Jiang et al. , (1993) supra). Thus, in spite of the fact that PTP K was originally isolated from hematopoietic stem cells, there is no obvious expression in two sites which contain hematopoietic cells, the spleen and the liver. The lack of signal in the spleen, an organ which contains mostly mature hematopoietic cells, suggests, therefore, that this receptor may be expressed specifically in earlier hematopoietic progenitor cells. Interestingly, there appears to also be an alternatively spliced transcript in the lung which is not detected in the other two organs that express this receptor at high levels nor in the embryos although the nature of this alternatively spliced transcript remains to be determined. In summary, these data demonstrate that PTP λ is specifically expressed in a subset of adult tissues, some of which are divergent from PTP K. EXAMPLE 4 - In Situ Hybridization Analysis We performed in-situ mRNA analysis of the rat E1 5.5 embryo, P1 and adult rat brain to determine potential sites of PTP λ production. The results in Figure 6 shown that extensive PTP λ expression was observed in developing skeletal, epithelial, and neuronal structures throughout the E1 5.5 embryo. Systemic expression was observed in various developing skeletal elements such as vertebral perichondrium, intervertebral discs, teeth, mandible and maxilla (Figure 6, Panels A and B). Expression of PTP λ within urogenital structures included the genital tubercle (Figure 6, Panels A and B), urethra, and urogenital sinus (not shown). Other positive areas of PTP λ expression included the anal canal (not shown), skin, olfactory and oral epithelium, esophagus (Figure 6, Panels A and B), pituitary (Figure 6, Panels A, B and C), aura mater (Figure 6, Panels A, B and D), kidney (Figure 6, Panels A and B), and lung (Figure 6, Panels A and B). Higher magnification reveals expression restricted to developing glomeruli in the cortical region of the kidney (Figure 6, Panels F and G), and bronchiolar epithelium of the lung (Figure 6, Panels H and I). Within the E1 5.5 embryonic nervous system, high levels of expression were observed in the developing cerebral cortex (Figure 6, Panels A and B), floor of the midbrain, choroid plexus primordium, gigantocellular reticular nucleus of the brain stem (Figure 6, Panels A, B and C), aura mater and spinal cord (Figure 6, Panels A, B and D). High magnification of the spinal cord reveals highest expression of PTP λ in the ventrolateral motor column (Figure 6, Panel D). In P1 and adult brain, expression of PTP λ was localized to regions derived from embryonic anlage that also contained high levels of expression. For instance, expression in the embryonic midbrain preceded the high levels of PTP λ expression in the P1 and adult substantia nigra (Figure 7, Panels C and E, respectively). Expression in the embryonic forebrain (Figure 6, Panel A) preceded expression observed in the inner layers of the P1 and adult cortex (Figure 7, Panels A, B and D, E, respectively). Expression in the choroid plexus primordia of the embryo begets high levels of expression in the P1 brain (Figure 7, Panel A), and low levels of expression in the adult brain (Figure 7, Panel D). In general, PTP λ expression in the adult brain appears to be downregulated relative to the P1 brain (Figure 7) . However, other areas of prominent expression in both P1 and adult brain include piriform cortex and endopiriform nucleus (Figure 7, Panels A and D, respectively), amygdaloid nuclei, subiculum, and CAT, CA2 and, to a lesser extent, CA3 of the hippocampal formation (Figure 7, Panels B and E, respectively). The P1 brain also exhibits strong expression throughout the septal area, basal ganglia, thaiamus, and midbrain (Figure 7, Panels A, B and C). Weak expression is observed in the adult superior colliculus as well as scattered expression throughout the thalamus (Figure 7, Panel E) . EXAMPLE 5 - Expression of PTP λ in PC 12 Cells The expression of PTP λ in various regions throughout the embryonic, neonatal and adult brain suggested that this receptor might be expressed in PC12 cells, a cell line which is derived from a neural pheochromocytoma. Indeed, the immunoprecipitation experiments described in Example 2 above demonstrated enzymatic activity in anti-PTP λ precipitates derived from these cells. In addition, these cells will differentiate and extend neurites in response to nerve growth factor, so they provided a system to test a possible role for PTP λ in this developmental transition. As is shown in Figure 8, the novel PTP λ receptor polypeptide is indeed expressed in these neuronal progenitor cells. Figure 8 also illustrates that treatment of these cells with NGF results in a modest upregulation ( " 5 fold) of the transcript encoding this receptor with relatively slow kinetics. These data are thus consistent with a role for this receptor in some aspect of neuronal differentiation in this cell line. In order to investigate the distribution of PTP λ on PC1 2 cells, immunofluorescence was performed using cells that were left untreated or were treated with NGF to induce neurite outgrowth stained with an antibody directed against the cytoplasmic domain of the PTP λ receptor. As is shown in Figure 9, PTP λ is expressed at significant levels in both treated and untreated cells, confirming the enzymatic analysis shown in Figure 4 and the northern blot analysis shown in Figure 8. Perhaps more interesting, however, is the cellular distribution of the PTP λ polypeptide. As Figure 9 shows, PTP λ is found to be partitioned on the neurites as well as on the growth cone-like structures at the neurite tips. These data are consistent with a role for this receptor in neurite function, perhaps analogous to that recently described for two different Drosophila receptor PTPs (Desai et al. , supra and Kreuger et al. , supra).. M. Discussion The relative levels of tyrosine phosphorylation of a diversity of proteins is critical for the regulation of a number of activities during embryonic differentiation and throughout the life of the mammalian organism. The absolute levels of this modification are mediated through the balance of the enzymatic activities of tyrosine kinases with those of the tyrosine phosphatases. In both cases, these large families of proteins perform their roles through conserved enzymatic domains that are coupled to a plethora of specificity-determining motifs. These various motifs are found in the context of both membrane traversing, receptor-like molecules as well as intracellular forms of the enzymes. The similarities in overall structure of the tyrosine kinases and tyrosine phosphatases suggest that they mediate their relative specific activities through the use of these various domains. In the cases of some of the receptor PTPs, the extracellular motifs are somewhat unusual in that they contain highly glycosylated regions with currently unknown ligand specificity. Alternatively, a subset of these receptor-phosphatases also contain a diversity of domains, including immunoglobulin-like and fibronectin-like, which are associated with cell adhesion and ligand binding activities in other protein families. Among the most interesting of these types of adhesion-associated PTPs are the K and μ receptors which are involved with homotypic types of interactions. Earlier predictions, based upon the likely function of these receptors in mediating cell adhesion as well as their limited tissue distribution, suggested that there might be other K and μ-like receptor PTPs with different tissue dispositions. We here report the isolation of the third member of this family of homotypically interacting receptor PTPs, PTP λ, which may be associated with the construction of epithelial and neural structures during development and in the adult. The strongest data suggesting that the novel PTP λ polypeptide described herein is homologous to the K and μ receptors lies in the high degree of sequence conservation between these three proteins. Analysis of these three receptors clearly revealed that the novel PTP λ polypeptide of the present invention had a high degree of sequence homology with PTP K and PTP μ throughout the entire length of the proteins. This homology included the four major types of domains contained in this family including the MAM, the immunoglobulin (IgG), the fibronectin type 111 (FN III) and the dual phosphatase (PTPase) domains (Jiang et al., ( 1993) supra and Gebbink et al., ( 1 991 ) supra). Because previous data have suggested that both the MAM as well as the IgG domain appear to be involved with homotypic adhesion (Brady-Kalnay et al. , (1 994) supra and Zondag et al. , supra), it is likely that these motifs are used for a similar function in PTP λ, a hypothesis that is consistent with a role for this receptor in cell adhesion. However, the degree of sequence homology of these domains between the herein reported PTP λ receptor and the PTP K and PTP μ receptors is quite divergent, suggesting that the novel receptor may also specifically mediate a homophilic interaction only to itself and not to these domains in the other family members (Zondag et al. , supra) . As will be discussed below, these results, together with the tissue localization of this receptor, suggest that it may be involved with the formation of very specific edifices during development. It will, of course, be interesting to determine the structural aspects of these domains which are involved with homophilic binding, especially in light of the recent crystallographic analysis of one of the homophilically interacting cadherins (Shapiro et al. , Nature 374(6520):327-337 ( 1 995)). While it is difficult to currently interpret the significance of the conservation of the FNlll domains, which may act as spacer domains to extend the functionally critical MAM and IgG domains from the cell surface, the conservation of the dual PTP domains lends itself to some comment. For example, the higher degree of conservation of the first domain as compared to the second substantiates previous work suggesting that the N-terminal PTPase motif is the enzymatically active one, while the C-terminal domain may be involved with the regulation of enzyme activity (Pot et al. , supra). We have attempted, without success, to bacterially express enzymatically active forms of the PTPase domains of PTP λ under conditions which gave a high level of activity with another PTP, the PTP HSC (Cheng et al., supra) (J. Cheng and L. Lasky-unpublished observations). These negative data, which of course might be technical, suggest that the PTP λ polypeptide may require an activation event, although it is clear from the immunoprecipitation studies with PC 1 2 cells that this receptor is endowed with enzymatic activity. Finally, previous data have suggested a role for this category of receptor PTPs in cadherin/catenin regulation, and other investigators have pointed to an intracellular, juxtamembrane site with significant homology to a similarly localized region in the cadherins (Brady-Kalnay et al. , Curr. Opin. Cell. Biol. 7(51:650-657 (1 995) and Brady-Kalnay et al. , J. Cell. Biol. 130(4):977-986 ( 1 995)). We have also found a very high degree of sequence conservation in this region, again consistent with a potential role for this domain in cadherin interactions. In summary, the data reported here are consistent with PTP λ being the third member of the homotypically interacting receptor PTP family. The in situ hybridization analysis of the expression of PTP λ in the developing embryo and adult suggest some potentially important hypotheses. The expression of this receptor in a diversity of developing skeletal areas as well as in epithelial sites which line various organ systems with a layer of these cells, coupled with the proposed role for PTP μ (Brady-Kalnay et al. , Curr. Ooin. Cell. Biol. 7(51:650-657 ( 1 995) and Brady-Kalnay et al. , J. Cell. Biol. 130(4):977-986 (1 995)), and potentially PTP K, in the control of cadherin adhesion suggests that the novel PTP λ might be involved in a similar type of adhesion control in the developing embryo. For example, the development of epithelial layers in the lung bronchioles and kidney glomeruli requires that a sheet of epithelial cells that is one cell thick be constructed. Thus, as the cells grow and migrate during embryogenesis, they would require a mechanism where they sensed the location of other epithelial cells that were in contact with them, so that this cellular contiguity initiated an adhesive response that inhibited further epithelial movement via the enhancement of cell adhesion. One mechanism that would provide for such a sensing phenomenon would be that proposed by Tonks and colleagues (Brady- Kalnay et al. , Curr. Ooin. Cell. Biol. 7(51:650-657 ( 1 995) and Brady- Kalnay et al. , J. Cell. Biol. 1 30(4):977-986 (1 995)). In this hypothesis, the μ receptor PTP comes into homophilic contact with another μ receptor PTP on an adjacent cell, and this contact upregulates cadherin-mediated adhesion through the dephosphorylation of the cadherin/catenin complex. The formation of single cell-thick epithelial structures in these embryonic organs could be mediated by a similar type of sensing mechanism using PTP K. The expression of this receptor PTP in bone forming chondrocytes would also be expected to perform a similar type of sensing and adhesion function to assemble these structures, although this type of anatomy, which is more complex than the thin-walled epithelial-like morphology described above, would be expected to involve more elaborate types of sensing and adhesive mechanisms. Finally, because many common types of tumors of the lung and other organs involve epithelial cells, it is possible that disruptions in the proposed function of this type of adhesion sensing mechanism might be involved with the disorganized morphology and high rate of metastasis of these tumors (Kemler, supra and Beherens et al. , supra). Together, these hypotheses suggest a critical role for PTP λ in the formation of various epithelial-like structures in the embryo. Recent data from the Drosophila system also suggest interesting possibilities for the function of PTP λ in the developing nervous system (Desai et al. , supra and Kreuger et al. , supra). In these reports, three different Drosophila receptor PTPs, termed DPTP69D, DPTP99A and DLAR, which all contain IgG and fibronectin type III adhesion domains similar to those found in PTP λ, were shown to be critically involved with neuronal pathfinding in the developing nervous systems. Thus, mutations in either of these receptors resulted in a loss of the ability of certain neural subsets to become reoriented during their formation in the embryo. Because PTP λ is expressed in a number of developing neural sites, it is possible that it plays a similar role in the pathfinding of nerves in mammals. Thus, the expression of this PTP in the developing midbrain, forebrain, and other neural sites would dispose it to function as a mediator of pathfinding in these maturing systems. Interestingly, the expression of this receptor in these embryonic anlage was confirmed by expression in the adult sites which arise from these embryonic structures. However, the expression in the adult appeared to be somewhat reduced as compared to that observed in the embryo, and it was far more organized. These data suggest that this enzyme might be utilized during adult neuronal formation, although the apparent decrease in adult expression suggests a potentially more critical role during embryogenesis. The observed expression of this receptor in neuronal progenitor PC 12 cells, coupled with the upregulation of the transcript during neurite formation in response to NGF in these cells, also agrees with a role for this receptor PTP during neural pathfinding. Indeed, the observation that this PTP is expressed on neurites as well as on the growth-cone like structures at the tips of these processes is consistent with a potential role for this receptor in neuronal pathfinding in the mammalian nervous system. However, the relatively slow kinetics of upregulation suggest that this may be a late function. Finally, while the clear observation of the loss of pathfinding in Drosophila will be difficult to recapitulate in the mouse, due to the relatively high complexity of the mammalian nervous system, it will nevertheless be potentially of interest to examine the formation of the nervous system in animals which have been made null for the expression of this receptor. In summary, the data reported herein demonstrate the existence of a third member of the family of receptor PTPs, PTP λ, that appear to be involved with homotypic adhesion and, potentially, cadherin mediated organ formation. The role that this novel receptor might play in the formation of epithelial sheets and neuronal structures remains to be determined. However, the existence of three of these types of receptors further suggests that this growing family may be involved with the specific formation of various types of complex structures during development as well as in the adult. N. Concluding Remarks: The foregoing description details specific methods which can be employed to practice the present invention. Having detailed such specific methods, those skilled in the art will well enough known how to devise alternative reliable methods at arriving at the same information in using the fruits of the present invention. Thus, however, detailed the foregoing may appear in text, it should not be construed as limiting the overall scope thereof; rather, the ambit of the present invention is to be determined only by the lawful construction of the appended claims. All documents cited herein are expressly incorporated by reference. SEQUENCE LISTING (1) GENERAL INFORMATION: (i) APPLICANT:Genentech, Inc. (ll) TITLE OF INVENTION: A NOVEL KAPPA/MU-LIKE PROTEIN TYROSINE PHOSPHATASE, PTP LAMBDA (ill) NUMBER OF SEQUENCES: 10 <ιv) CORRESPONDENCE ADDRESS: (A) ADDRESSEE: Flehr, Hohbach, Test, Albritton & Herbert (B) STREET: Four Embarcadero Center, Suite 3400 (C) CITY: San Francisco (D) STATE: California (E) COUNTRY: United States (F) ZIP: 94111 (v) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Floppy disk (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-D0S/MS-DOΞ (D) SOFTWARE: Patentln Release #1.0, Version #1.30 (vi) CURRENT APPLICATION DATA: (A) APPLICATION NUMBER. PCT/US97/ (B) FILING DATE: HEREWITH (C) CLASSIFICATION: (vil) PRIOR APPLICATION DATA: (A) APPLICATION NUMBER: US 08/652,971 (B) FILING DATE: 23-JAN-1996 (vm) ATTORNEY/AGENT INFORMATION: (A) NAME: Dreger, Walter H. (B) REGISTRATION NUMBER: 24,190 (C) REFERENCE/DOCKET NUMBER: A-64254 (IX) TELECOMMUNICATION INFORMATION: (A) TELEPHONE. (415) 781-1989 (B) TELEFAX: (415) 398-3249 (2) INFORMATION FOR SEQ ID NO:l: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5769 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 379..4686 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1: GTTGACTACT CAGCTGCCAG AACATCCAAT CTGGCTCCTG CAACTTTAGA CCAACATATT 60 GTGTTTGATC TTCTCCTGAA CAACTTGGGA GATACGTCTG ATCTTCAGCT TGGTACATAC 120 AGTTGCGCAG TGAATGGCAC TTACGTGTTC ATTGTGCACA TGCTAAAGCT GGCATGATTA 180 ATGTTCGACT GCTATGTCAA CCTGATTAAC AATGAGGATG TCTTGGTGTC AGCTATGCCA 240 ACGATGGTGC TCCAGACCGG CGCCAGTCCC GCTCCGCGCG GCACTGTCCA CTACGGCTCC 300 CGCTCGCCTT GGGCTCCCGG TCGGGCTCCG GAGGCGTCGC CTCCCCAGCT GCGGGTCTCC 360 AGGACCTAGG CGGCGGCC ATG GCC CGG GCT CAG GCT CTG GTC CTG GCG CTC 411 Met Ala Arg Ala Gin Ala Leu Val Leu Ala Leu 1 5 10 ACC TTC CAG TTC TGC GCG CCT GAG ACC GAG ACT CCC GCA GCT GGC TGC 459 Thr Phe Gin Phe Cys Ala Pro Glu Thr Glu Thr Pro Ala Ala Gly Cys 15 20 25 ACC TTC GAG GAG GCG AGT GAC CCG GTC GTG CCC TGC GAG TTC AGC CAG 507 Thr Phe Glu Glu Ala Ser Asp Pro Val Val Pro Cys Glu Phe Ser Gin 30 35 40 GCT CAG TAT GAC GAC TTC CAA TGG GAG CAA GTG CGG ATC CAC CCC GGC 555 Ala Gin Tyr Asp Asp Phe Gin Trp Glu Gin Val Arg He His Pro Gly 45 50 55 ACC CGG ACC CCT GAA GAC CTG CCC CAT GGT GCC TAC TTG ATG GTC AAT 603 Thr Arg Thr Pro Glu Asp Leu Pro His Gly Ala Tyr Leu Met Val Asn 60 65 70 75 GCT TCT CAG CAT ACC CCA GGT CAG AGG GCC CAC ATC ATC TTC CAG ACC 651 Ala Ser Gin His Thr Pro Gly Gin Arg Ala His He He Phe Gin Thr 80 85 90 CTG AGC GAG AAC GAC ACC CAT TGT GTG CAG TTC AGC TAC TTC CTG TAC 699 Leu Ser Glu Asn Asp Thr His Cys Val Gin Phe Ser Tyr Phe Leu Tyr 95 100 105 AGC AGG GAT GGG CAC AGC CCA GGC ACC CTG GGG GTC TAC GTG CGC GTG 747 Ser Arg Asp Gly His Ser Pro Gly Thr Leu Gly Val Tyr Val Arg Val 110 115 120 AAT GGG GGC CCT CTG GGC AGT GCC GTG TGG AAT ATG ACC GGA TCC CAC 795 Asn Gly Gly Pro Leu Gly Ser Ala Val Trp Asn Met Thr Gly Ser His 125 130 135 GGC CGT CAG TGG CAC CAG GCT GAG CTG GCT GTC AGC ACC TTC TGG CCC 843 Gly Arg Gin Trp His Gin Ala Glu Leu Ala Val Ser Thr Phe Trp Pro 140 145 150 155 AAT GAG TWT CAG GTG CTG TTT GAG GCC CTC ATC TCC CCA GAC CAC AAG 891 Asn Glu Xaa Gin Val Leu Phe Glu Ala Leu He Ser Pro Asp His Lys 160 165 170 GGC TAC ATA GGC TTA GAC GAC ATC TTG CTC TTC AGC TAT CCC TGC GCA 939 Gly Tyr He Gly Leu Asp Asp He Leu Leu Phe Ser Tyr Pro Cys Ala 175 180 185 AAG GCC CCT CAC TTC TCC CGC CTT GGG GAC GTG GAG GTC AAT GCA GGC 987 Lys Ala Pro His Phe Ser Arg Leu Gly Asp Val Glu Val Asn Ala Gly 190 195 200 CAG AAC GCA TCC TTC CAA TGC ATG GCA GCA GGC AGA GCC GCA GAG GCA 1035 Gin Asn Ala Ser Phe Gin Cys Met Ala Ala Gly Arg Ala Ala Glu Ala 205 210 215 GAA CAC TTC TTC CTG CAG CGT CAG AGT GGA GTG CTG GTG CCT GCG GCC 1083 Glu His Phe Phe Leu Gin Arg Gin Ser Gly Val Leu Val Pro Ala Ala 220 225 230 235 GGG GTG CGG CAC ATC AGT CAC CGT CGC TTC CTG GCC ACT TTT CCG CTG 1131 Gly Val Arg His He Ser His Arg Arg Phe Leu Ala Thr Phe Pro Leu 240 245 250 GCC TCG GTA GGC CGC TCA GAG CAG GAT CTG TAC CGT TGC GTG TCC CAG 1179 Ala Ser Val Gly Arg Ser Glu Gin Asp Leu Tyr Arg Cys Val Ser Gin 255 260 265 GCC CCG CGT GGT GCT GGC GTC TCC AAC TTT GCA GAG CTC ATC GTC AAA 1227 Ala Pro Arg Gly Ala Gly Val Ser Asn Phe Ala Glu Leu He Val Lys 270 275 280 GAG CCT CCC ACC CCC ATC GCG CCC CCA CAG CTG CTG CGT GCA GGC CCC 1275 Glu Pro Pro Thr Pro He Ala Pro Pro Gin Leu Leu Arg Ala Gly Pro 285 290 295 ACC TAC CTC ATT ATC CAG CTC AAC ACC AAC TCC ATC ATT GGC GAC GGG 1323 Thr Tyr Leu He He Gin Leu Asn Thr Asn Ser He He Gly Asp Gly 300 305 310 315 CCG ATC GTG CGC AAG GAG ATC GAG TAC CGC ATG GCA CGG GGC CCG TGG 1371 Pro He Val Arg Lys Glu He Glu Tyr Arg Met Ala Arg Gly Pro Trp 320 325 330 GCC GAG GTG CAC GCT GTC AAC CTG CAR ACC TAC AAG CTG TGG CAT CTG 1419 Ala Glu Val His Ala Val Asn Leu Xaa Thr Tyr Lys Leu Trp His Leu 335 340 345 GAC CCA GAC ACT GAG TAT GAA ATC AGC GTG CTG CTC ACA CGC CCG GGA 1467 Asp Pro Asp Thr Glu Tyr Glu He Ser Val Leu Leu Thr Arg Pro Gly 350 355 360 GAT GGA GGC ACA GGC CGC CCT GGG CCA CCA CTG ATC AGC CGG ACC AAG 1515 Asp Gly Gly Thr Gly Arg Pro Gly Pro Pro Leu He Ser Arg Thr Lys 365 370 375 TGC GCA GAG CCC ACG AGG GCC CCC AAA GGT CTG GCT TTT GCT GAG ATC 1563 Cys Ala Glu Pro Thr Arg Ala Pro Lys Gly Leu Ala Phe Ala Glu He 380 385 390 395 CAG GCT CGC CAG CTG ACC CTG CAG TGG GAG CCC CTG GGC TAT AAT GTC 1611 Gin Ala Arg Gin Leu Thr Leu Gin Trp Glu Pro Leu Gly Tyr Asn Val 400 405 410 ACA CGT TGT CAT ACC TAC GCT GTG TCC CTT TGC TAT CGC TAC ACC CTG 1659 Thr Arg Cys His Thr Tyr Ala Val Ser Leu Cys Tyr Arg Tyr Thr Leu 415 420 425 GGC GGC AGC CAC AAC CAG ACC ATC CGG GAG TGT GTG AAG ATG GAG CGG 1707 Gly Gly Ser His Asn Gin Thr He Arg Glu Cys Val Lys Met Glu Arg 430 435 440 GGT GCC AGC CGC TAC ACC ATC AAG AAT CTG CTG CCA TTC AGA AAC ATC 1755 Gly Ala Ser Arg Tyr Thr He Lys Asn Leu Leu Pro Phe Arg Asn He 445 450 455 CAC GTG CGT CTG ATT CTC ACA AAC CCT GAG GGG CGC AAG GAG GGC AAG 1803 His Val Arg Leu He Leu Thr Asn Pro Glu Gly Arg Lys Glu Gly Lys 460 465 470 475 GAG GTC ACC TTC CAG ACA GAT GAA GAT GTG CCT GGT GGG ATT GCA GCT 1851 Glu Val Thr Phe Gin Thr Asp Glu Asp Val Pro Gly Gly He Ala Ala 480 485 490 GAG TCC CTA ACC TTC ACT CCA CTG GAG GAC ATG ATC TTT CTC AAG TGG 1899 Glu Ser Leu Thr Phe Thr Pro Leu Glu Asp Met He Phe Leu Lys Trp 495 500 505 GAG GAG CCC CAG GAG CCC AAT GGC CTC ATC ACT CAG TAT GAG ATC AGC 1947 Glu Glu Pro Gin Glu Pro Asn Gly Leu He Thr Gin Tyr Glu He Ser 510 515 520 TAC CAA AGC ATT GAG TCC TCA GAC CCA GCA GTG AAC GTG CCC GGC CCG 1995 Tyr Gin Ser He Glu Ser Ser Asp Pro Ala Val Asn Val Pro Gly Pro 525 530 535 AGA CGC ACC ATC TCC AAA CTC CGG AAT GAG ACT TAC CAC GTC TTC TCC 2043 Arg Arg Thr He Ser Lys Leu Arg Asn Glu Thr Tyr His Val Phe Ser 540 545 550 555 AAC CTG CAT CCC GGC ACC ACG TAT CTG TTC TCC GTG CGT GCT CGG ACG 2091 Asn Leu His Pro Gly Thr Thr Tyr Leu Phe Ser Val Arg Ala Arg Thr 560 565 570 AGC AAG GGC TTC GGC CAG GCG GCT CTC ACT GAG ATA ACC ACC AAC ATC 2139 Ser Lys Gly Phe Gly Gin Ala Ala Leu Thr Glu He Thr Thr Asn He 575 580 585 TCA GCT CCC AGC TTT GAT TAT GCC GAC ATG CCG TCA CCC CTG GGC GAG 2187 Ser Ala Pro Ser Phe Asp Tyr Ala Asp Met Pro Ser Pro Leu Gly Glu 590 595 600 TCC GAG AAC ACC ATC ACT GTG CTG TTG AGG CCG GCC CAG GGC CGA GGA 2235 Ser Glu Asn Thr He Thr Val Leu Leu Arg Pro Ala Gin Gly Arg Gly 605 610 615 GCC CCC ATC AGC GTC TAC CAG GTG GTT GTG GAG GAA GAG CGG CCA CGG 2283 Ala Pro He Ser Val Tyr Gin Val Val Val Glu Glu Glu Arg Pro Arg 620 625 630 635 CGC TTG CGG CGG GAG CCC GGA GCT CAG GAC TGC TTC TCG GTA CCT CTG 2331 Arg Leu Arg Arg Glu Pro Gly Ala Gin Asp Cys Phe Ser Val Pro Leu 640 645 650 ACC TTT GAG ACG GCC CTG GCT CGC GGC CTG GTG CAC TAC TTT GGG GCT 2379 Thr Phe Glu Thr Ala Leu Ala Arg Gly Leu Val His Tyr Phe Gly Ala 655 660 665 GAA CTG GCT GCC AGC AGC CTG CTT GAG GCC ATG CCC TTC ACC GTG GGT 2427 Glu Leu Ala Ala Ser Ser Leu Leu Glu Ala Met Pro Phe Thr Val Gly 670 675 680 GAC AAC CAG ACC TAT CGT GGC TTC TGG AAC CCA CCG CTT GAG CCC AGA 2475 Asp Asn Gin Thr Tyr Arg Gly Phe Trp Asn Pro Pro Leu Glu Pro Arg 685 690 695 AAG GCC TAT CTC ATC TAT TTC CAG GCA GCA AGC CAC CTG AAA GGG GAA 2523 Lys Ala Tyr Leu He Tyr Phe Gin Ala Ala Ser His Leu Lys Gly Glu 700 705 710 715 ACC CGA CTG AAC TGC ATC CGA ATT GCC AGG AAA GCT GCG TGC AAG GAG 2571 Thr Arg Leu Asn Cys He Arg He Ala Arg Lys Ala Ala Cys Lys Glu 720 725 730 AGC AAG CGA CCC CTC GAA GTG TCC CAG AGA TCG GAG GAG ATG GGG CTC 2619 Ser Lys Arg Pro Leu Glu Val Ser Gin Arg Ser Glu Glu Met Gly Leu 735 740 745 ATC CTG GGC ATC TGT GCA GGT GGT CTT GCC GTC CTC ATT CTC CTC CTG 2667 He Leu Gly He Cys Ala Gly Gly Leu Ala Val Leu He Leu Leu Leu 750 755 760 GGG GCC ATC ATT GTC ATC ATC CGC AAA GGG AAG CCA GTG AAC ATG ACG 2715 Gly Ala He He Val He He Arg Lys Gly Lys Pro Val Asn Met Thr 765 770 775 AAA GCC ACG GTC AAC TAC CGC CAG GAG AAG ACT CAC ATG ATG AGT GCC 2763 Lys Ala Thr Val Asn Tyr Arg Gin Glu Lys Thr His Met Met Ser Ala 780 785 790 795 GTG GAC CGC AGC TTC ACA GAT CAG AGT ACT CTG CAG GAG GAT GAG CGG 2811 Val Asp Arg Ser Phe Thr Asp Gin Ser Thr Leu Gin Glu Asp Glu Arg 800 805 810 TTG GGT CTG TCC TTT ATG GAT GCT CCT GGC TAT AGT CCT CGT GGA GAC 2859 Leu Gly Leu Ser Phe Met Asp Ala Pro Gly Tyr Ser Pro Arg Gly Asp 815 820 825 CAG CGA AGC GGT GGT GTC ACC GAG GCC AGC AGC CTC CTG GGG GGT TCT 2907 Gin Arg Ser Gly Gly Val Thr Glu Ala Ser Ser Leu Leu Gly Gly Ser 830 835 840 CCA AGG CGC CCA TGC GGC CGG AAG GGT TCT CCG TAT CAT ACC GGG CAG 2955 Pro Arg Arg Pro Cys Gly Arg Lys Gly Ser Pro Tyr His Thr Gly Gin 845 850 855 CTC CAC CCT GCA GTC CGA GTG GCT GAC CTT CTA CAG CAC ATC AAC CAG 3003 Leu His Pro Ala Val Arg Val Ala Asp Leu Leu Gin His He Asn Gin 860 865 870 875 ATG AAG ACA GCC GAG GGC TAC GGC TTC AAG CAG GAG TAC GAG AGT TTC 3051 Met Lys Thr Ala Glu Gly Tyr Gly Phe Lys Gin Glu Tyr Glu Ser Phe 880 885 890 TTT GAG GGC TGG GAC GCC ACC AAG AAG AAA GAC AAG CTC AAG GGC GGC 3099 Phe Glu Gly Trp Asp Ala Thr Lys Lys Lys Asp Lys Leu Lys Gly Gly 895 900 905 CGA CAG GAG CCA GTG TCT GCC TAT GAT CGA CAC CAT GTG AAA CTA CAC 3147 Arg Gin Glu Pro Val Ser Ala Tyr Asp Arg His His Val Lys Leu His 910 915 920 CCG ATG CTG GCA GAC CCT GAT GCC GAC TAC ATC TCT GCC AAC TAC ATA 3195 Pro Met Leu Ala Asp Pro Asp Ala Asp Tyr He Ser Ala Asn Tyr He 925 930 935 GAC GGC TAC CAC AGG TCA AAC CAC TTC ATA GCC ACT CAA GGG CCA AAG 3243 Asp Gly Tyr His Arg Ser Asn His Phe He Ala Thr Gin Gly Pro Lys 940 945 950 955 CCT GAG ATG ATC TAC GAT TTC TGG CGC ATG GTG TGG CAG GAA CAG TGT 3291 Pro Glu Met He Tyr Asp Phe Trp Arg Met Val Trp Gin Glu Gin Cys 960 965 970 GCG AGC ATC GTC ATG ATC ACC AAG CTG GTA GAG GTG GGC AGG GTG AAG 3339 Ala Ser He Val Met He Thr Lys Leu Val Glu Val Gly Arg Val Lys 975 980 985 TGT TCT CGC TAC TGG CCT GAG GAC TCA GAC ATG TAT GGG GAC ATC AAG 3387 Cys Ser Arg Tyr Trp Pro Glu Asp Ser Asp Met Tyr Gly Asp He Lys 990 995 1000 ATC ACG CTG GTA AAG ACA GAG ACA CTG GCT GAG TAT GTG GTG CGC ACC 3435 He Thr Leu Val Lys Thr Glu Thr Leu Ala Glu Tyr Val Val Arg Thr 1005 1010 1015 TTT GCC CTG GAG CGG AGA GGT TAC TCA GCC CGG CAT GAG GTC CGC CAG 3483. Phe Ala Leu Glu Arg Arg Gly Tyr Ser Ala Arg His Glu Val Arg Gin 1020 1025 1030 1035 TTC CAT TTC ACA GCG TGG CCA GAG CAT GGT GTC CCC TAC CAC GCC ACG 3531 Phe His Phe Thr Ala Trp Pro Glu His Gly Val Pro Tyr His Ala Thr 1040 1045 1050 GGG CTG CTG GCC TTC ATC CGG CGT GTG AAG GCT TCC ACT CCA CCT GAT 3579 Gly Leu Leu Ala Phe He Arg Arg Val Lys Ala Ser Thr Pro Pro Asp 1055 1060 1065 GCC GGG CCC ATT GTC ATT CAC TGC AGT GCA GGA ACT GGC CGC ACA GGC 3627 Ala Gly Pro He Val He His Cys Ser Ala Gly Thr Gly Arg Thr Gly 1070 1075 1080 TGC TAC ATC GTC CTG GAT GTG ATG CTG GAC ATG GCT GAA TGT GAG GGG 3675 Cys Tyr He Val Leu Asp Val Met Leu Asp Met Ala Glu Cys Glu Gly 1085 1090 1095 GTC GTG GAC ATT TAC AAC TGT GTG AAG ACC CTC TGT TCC CGA CGG GTC 3723 Val Val Asp He Tyr Asn Cys Val Lys Thr Leu Cys Ser Arg Arg Val 1100 1105 1110 1115 AAC ATG ATC CAG ACG GAG GAA CAA TAT ATC TTC ATC CAC GAT GCA ATC 3771 Asn Met He Gin Thr Glu Glu Gin Tyr He Phe He His Asp Ala He 1120 1125 1130 TTG GAG GCC TGC CTG TGT GGG GAG ACC ACC ATC CCT GTC AAC GAG TTC 3819 Leu Glu Ala Cys Leu Cys Gly Glu Thr Thr He Pro Val Asn Glu Phe 1135 1140 1145 AGG GCC ACC TAC AGG GAG ATG ATC CGC ATT GAC CCT CAG AGC AAT TCC 3867 Arg Ala Thr Tyr Arg Glu Met He Arg He Asp Pro Gin Ser Asn Ser 1150 1155 1160 TCC CAG CTT CGG GAA GAG TTC CAG ACG CTG AAC TCG GTC ACG CCG CCG 3915 Ser Gin Leu Arg Glu Glu Phe Gin Thr Leu Asn Ser Val Thr Pro Pro 1165 1170 1175 CTG GAT GTG GAG GAG TGT AGC ATT GCC CTG CTG CCC CGG AAT CGA GAC 3963 Leu Asp Val Glu Glu Cys Ser He Ala Leu Leu Pro Arg Asn Arg Asp 1180 1185 1190 1195 AAG AAC CGT AGC ATG GAT GTG CTG CCA CCA GAC CGC YGC CTG CCC TTC 4011 Lys Asn Arg Ser Met Asp Val Leu Pro Pro Asp Arg Xaa Leu Pro Phe 1200 1205 1210 CTC ATC TCC AGT GAT GGG GAC CCC AAT AAC TAC ATC AAT GCA GCA CTG 4059 Leu He Ser Ser Asp Gly Asp Pro Asn Asn Tyr He Asn Ala Ala Leu 1215 1220 1225 ACT GAC AGC TAC ACA CGG AGC GCC GCC TTC ATC GTG ACC CTG CAC CCG 4107 Thr Asp Ser Tyr Thr Arg Ser Ala Ala Phe He Val Thr Leu His Pro 1230 1235 1240 CTG CAG AGT ACC ACG CCC GAC TTC TGG CGG CTG GTC TAC GAC TAC GGG 4155 Leu Gin Ser Thr Thr Pro Asp Phe Trp Arg Leu Val Tyr Asp Tyr Gly 1245 1250 1255 TGC ACC TCC ATC GTC ATG CTG AAC CAA CTT AAC CAG TCC AAC TCC GCC 4203 Cys Thr Ser He Val Met Leu Asn Gin Leu Asn Gin Ser Asn Ser Ala 1260 1265 1270 1275 TGG CCC TGC TTG CAG TAC TGG CCG GAG CCA GGC CGA CAG CAG TAT GGG 4251 Trp Pro Cys Leu Gin Tyr Trp Pro Glu Pro Gly Arg Gin Gin Tyr Gly 1280 1285 1290 CTC ATG GAG GTG GAG TTT GTG TCT GGC ACA GCA AAC GAG GAT TTG GTG 4299 Leu Met Glu Val Glu Phe Val Ser Gly Thr Ala Asn Glu Asp Leu Val 1295 1300 1305 TCC CGA GTG TTC CGG GTG CAG AAC TCT TCT CGG CTG CAG GAG GGT CAC 4347 Ser Arg Val Phe Arg Val Gin Asn Ser Ser Arg Leu Gin Glu Gly His 1310 1315 1320 CTG CTG GTA CGG CAC TTC CAG TTT CTG CGT TGG TCT GCT TAT CGG GAC 4395 Leu Leu Val Arg His Phe Gin Phe Leu Arg Trp Ser Ala Tyr Arg Asp 1325 1330 1335 ACG CCT GAC TCC AGG AAG GCC TTT CTG CAC CTG TTG GCT GAG GTG GAC 4443 Thr Pro Asp Ser Arg Lys Ala Phe Leu His Leu Leu Ala Glu Val Asp 1340 1345 1350 1355 AAG TGG CAG GCA GAG AGT GGG GAT GGG CGC ACC GTG GTG CAT TGT CTC 4491 Lys Trp Gin Ala Glu Ser Gly Asp Gly Arg Thr Val Val His Cys Leu 1360 1365 1370 AAC GGG GGT GGC CGC AGT GGC ACC TTC TGC GCC TGT GCC ACG GTC TTG 4539 Asn Gly Gly Gly Arg Ser Gly Thr Phe Cys Ala Cys Ala Thr Val Leu 1375 1380 1385 GAG ATG ATC CGC TGT CAC AGC CTG GTG GAT GTT TTC TTT GCT GCC AAA 4587 Glu Met He Arg Cys His Ser Leu Val Asp Val Phe Phe Ala Ala Lys 1390 1395 1400 ACA CTT CGG AAC TAC AAG CCC AAT ATG GTG GAG ACC ATG GAT CAG TAT 4635 Thr Leu Arg Asn Tyr Lys Pro Asn Met Val Glu Thr Met Asp Gin Tyr 1405 1410 1415 CAT TTC TGC TAC GAC GTG GCC CTG GAG TAC CTG GAG GCT CTG GAG TTG 4683 His Phe Cys Tyr Asp Val Ala Leu Glu Tyr Leu Glu Ala Leu Glu Leu 1420 1425 1430 1435 AGA TAGCAGGCGC CTGACCTGGG GCACCCAGTG AACACCCAGG GCATGGCCCA 4736 Arg TCATCCCAGA TGARGAGGGC CTGTGGCCCC AACTTTGCTC AGCCATAATT CCACAGGGAC 4796 AACACTGGAA CGGACGGACA CTGCACCATC TTGGTGACCC CCACGGGAAG GCTGCAGGCC 4856 AAGGAGAAGC TTTGCAAGAC TGTATCAGCC CCACCTCTAG AGGGCCCTGC AGACCTGTGC 4916 AGAGAAGCTC GCCTGGACCA AAATAGCTAG TGCTGGAGAG CACAGGCCAG GCCCCTCTGC 4976 TCCATCACAG TCCTTGGCCA GAAATGAATG AGTGTCTGCA GAGAGCACCC ATGGTTTGCA 5036 CCCAGTATGG TCCTTTCTGC ACGTGGTGGA GGCTCACTGG GACTTGGCAG GGGCTGAGTC 5096 CCCGAGAGTC CTGAAGCTGG GACTCTTCCC CGTCTCGCCG GTGGGACCCG CTGAGCATCC 5156 TGCAGCTCCA TTCTCCATCC CCACTGCCCC TACAGACCTG GGGTGCTTTG CTCGCTTTCC 5216 TCCTGCTTCT GAGCTTTTCC TGCAACAGGA CCCGTGCCTC CTTCCTGGGC TCCATCCCTG 5276 CCTGGCCCAG TATATGCAGA ATGATATACT TCAGCTCCTT CTTCCCCTGG CCTTTGGGTC 5336 TCCATGGTTC AGTCCTGCTC AGCTTGGGCC TGTGACAATC CACAAGGCTG AATCACAGCC 5396 CCTGGGGTTG AGGTCCCTGT GGCTCTTGGT GAGGCTGCCA CTGGATCGGG GCAGGCTAGA 5456 ACAGGGCTGG TGTCAGCTCC TAGAGTACAG AGGAAGAAGG GATACTTTGG AATGGAGGAC 5516 CAGTGCTTTT TTTGTTGTTG TTATTTTGTT ATTTTTTTGA TGGGAGGGTG GGAAGTTCTC 5576 TTTATAATGG GGTAGGCCAC ACCCCCATTT CGTGCCTCAA TTTCCCCATC TGTAAACTGT 5636 AGATATGACT ACTGACCTAC CTCACAGGGG GCTGTGGGGA GGTGTAAGGT AATGTTTGTA 5696 AAGCGCTTTG TAAATAAATG TGCTCTCTGA ATGCCAAAAA AAAAAAAAAA AAAAAAAAAA 5756 AAAAAAAAAA AAA 5769 (2) INFORMATION FOR SEQ ID NO:2: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1436 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2: Met Ala Arg Ala Gin Ala Leu Val Leu Ala Leu Thr Phe Gin Phe Cys 1 5 10 15 Ala Pro Glu Thr Glu Thr Pro Ala Ala Gly Cys Thr Phe Glu Glu Ala 20 25 30 Ser Asp Pro Val Val Pro Cys Glu Phe Ser Gin Ala Gin Tyr Asp Asp 35 40 45 Phe Gin Trp Glu Gin Val Arg He His Pro Gly Thr Arg Thr Pro Glu 50 55 60 Asp Leu Pro His Gly Ala Tyr Leu Met Val Asn Ala Ser Gin His Thr 65 70 75 80 Pro Gly Gin Arg Ala His He He Phe Gin Thr Leu Ser Glu Asn Asp 85 90 95 Thr His Cys Val Gin Phe Ser Tyr Phe Leu Tyr Ser Arg Asp Gly His 100 105 110 Ser Pro Gly Thr Leu Gly Val Tyr Val Arg Val Asn Gly Gly Pro Leu 115 120 125 Gly Ser Ala Val Trp Asn Met Thr Gly Ser His Gly Arg Gin Trp His 130 135 140 Gin Ala Glu Leu Ala Val Ser Thr Phe Trp Pro Asn Glu Xaa Gin Val 145 150 155 160 Leu Phe Glu Ala Leu He Ser Pro Asp His Lys Gly Tyr He Gly Leu 165 170 175 Asp Asp He Leu Leu Phe Ser Tyr Pro Cys Ala Lys Ala Pro His Phe 180 185 190 Ser Arg Leu Gly Asp Val Glu Val Asn Ala Gly Gin Asn Ala Ser Phe 195 200 205 Gin Cys Met Ala Ala Gly Arg Ala Ala Glu Ala Glu His Phe Phe Leu 210 215 220 Gin Arg Gin Ser Gly Val Leu Val Pro Ala Ala Gly Val Arg His He 225 230 235 240 Ser His Arg Arg Phe Leu Ala Thr Phe Pro Leu Ala Ser Val Gly Arg 245 250 255 Ser Glu Gin Asp Leu Tyr Arg Cys Val Ser Gin Ala Pro Arg Gly Ala 260 265 270 Gly Val Ser Asn Phe Ala Glu Leu He Val Lys Glu Pro Pro Thr Pro 275 280 285 He Ala Pro Pro Gin Leu Leu Arg Ala Gly Pro Thr Tyr Leu He He 290 295 300 Gin Leu Asn Thr Asn Ser He He Gly Asp Gly Pro He Val Arg Lys 305 310 315 320 Glu He Glu Tyr Arg Met Ala Arg Gly Pro Trp Ala Glu Val His Ala 325 330 335 Val Asn Leu Xaa Thr Tyr Lys Leu Trp His Leu Asp Pro Asp Thr Glu 340 345 350 Tyr Glu He Ser Val Leu Leu Thr Arg Pro Gly Asp Gly Gly Thr Gly 355 360 365 Arg Pro Gly Pro Pro Leu He Ser Arg Thr Lys Cys Ala Glu Pro Thr 370 375 380 Arg Ala Pro Lys Gly Leu Ala Phe Ala Glu He Gin Ala Arg Gin Leu 385 390 395 400 Thr Leu Gin Trp Glu Pro Leu Gly Tyr Asn Val Thr Arg Cys His Thr 405 410 415 Tyr Ala Val Ser Leu Cys Tyr Arg Tyr Thr Leu Gly Gly Ser His Asn 420 425 430 Gin Thr He Arg Glu Cys Val Lys Met Glu Arg Gly Ala Ser Arg Tyr 435 440 445 Thr He Lys Asn Leu Leu Pro Phe Arg Asn He His Val Arg Leu He 450 455 460 Leu Thr Asn Pro Glu Gly Arg Lys Glu Gly Lys Glu Val Thr Phe Gin 465 470 475 480 Thr Asp Glu Asp Val Pro Gly Gly He Ala Ala Glu Ser Leu Thr Phe 485 490 495 Thr Pro Leu Glu Asp Met He Phe Leu Lys Trp Glu Glu Pro Gin Glu 500 505 510 Pro Asn Gly Leu He Thr Gin Tyr Glu He Ser Tyr Gin Ser He Glu 515 520 525 Ser Ser Asp Pro Ala Val Asn Val Pro Gly Pro Arg Arg Thr He Ser 530 535 540 Lys Leu Arg Asn Glu Thr Tyr His Val Phe Ser Asn Leu His Pro Gly 545 550 555 560 Thr Thr Tyr Leu Phe Ser Val Arg Ala Arg Thr Ser Lys Gly Phe Gly 565 570 575 Gin Ala Ala Leu Thr Glu He Thr Thr Asn He Ser Ala Pro Ser Phe 580 585 590 Asp Tyr Ala Asp Met Pro Ser Pro Leu Gly Glu Ser Glu Asn Thr He 595 600 605 Thr Val Leu Leu Arg Pro Ala Gin Gly Arg Gly Ala Pro He Ser Val 610 615 620 Tyr Gin Val Val Val Glα Glu Glu Arg Pro Arg Arg Leu Arg Arg Glu 625 630 635 640 Pro Gly Ala Gin Asp Cys Phe Ser Val Pro Leu Thr Phe Glu Thr Ala 645 650 655 Leu Ala Arg Gly Leu Val His Tyr Phe Gly Ala Glu Leu Ala Ala Ser 660 665 670 Ser Leu Leu Glu Ala Met Pro Phe Thr Val Gly Asp Asn Gin Thr Tyr 675 680 685 Arg Gly Phe Trp Asn Pro Pro Leu Glu Pro Arg Lys Ala Tyr Leu He 690 695 700 Tyr Phe Gin Ala Ala Ser His Leu Lys Gly Glu Thr Arg Leu Asn Cys 705 710 715 720 He Arg He Ala Arg Lys Ala Ala Cys Lys Glu Ser Lys Arg Pro Leu 725 730 735 Glu Val Ser Gin Arg Ser Glu Glu Met Gly Leu He Leu Gly He Cys 740 745 750 Ala Gly Gly Leu Ala Val Leu He Leu Leu Leu Gly Ala He He Val 755 760 765 He He Arg Lys Gly Lys Pro Val Asn Met Thr Lys Ala Thr Val Asn 770 775 780 Tyr Arg Gin Glu Lys Thr His Met Met Ser Ala Val Asp Arg Ser Phe 785 790 795 800 Thr Asp Gin Ser Thr Leu Gin Glu Asp Glu Arg Leu Gly Leu Ser Phe 80S 810 815 Met Asp Ala Pro Gly Tyr Ser Pro Arg Gly Asp Gin Arg Ser Gly Gly 820 825 830 Val Thr Glu Ala Ser Ser Leu Leu Gly Gly Ser Pro Arg Arg Pro Cys 835 840 845 Gly Arg Lys Gly Ser Pro Tyr His Thr Gly Gin Leu His Pro Ala Val 850 855 860 Arg Val Ala Asp Leu Leu Gin His He Asn Gin Met Lys Thr Ala Glu 865 870 875 880 Gly Tyr Gly Phe Lys Gin Glu Tyr Glu Ser Phe Phe Glu Gly Trp Asp 885 890 895 Ala Thr Lys Lys Lys Asp Lys Leu Lys Gly Gly Arg Gin Glu Pro Val 900 905 910 Ser Ala Tyr Asp Arg His His Val Lys Leu His Pro Met Leu Ala Asp 915 920 925 Pro Asp Ala Asp Tyr He Ser Ala Asn Tyr He Asp Gly Tyr His Arg 930 935 940 Ser Asn His Phe He Ala Thr Gin Gly Pro Lys Pro Glu Met He Tyr 945 950 955 9P0 Asp Phe Trp Arg Met Val Trp Gin Glu Gin Cys Ala Ser He Val Met 965 970 975 He Thr Lys Leu Val Glu Val Gly Arg Val Lys Cys Ser Arg Tyr Trp 980 985 990 Pro Glu Asp Ser Asp Met Tyr Gly Asp He Lys He Thr Leu Val Lys 995 1000 1005 Thr Glu Thr Leu Ala Glu Tyr Val Val Arg Thr Phe Ala Leu Glu Arg 1010 1015 1020 Arg Gly Tyr Ser Ala Arg His Glu Val Arg Gin Phe His Phe Thr Ala 1025 1030 1035 1040 Trp Pro Glu His Gly Val Pro Tyr His Ala Thr Gly Leu Leu Ala Phe 1045 1050 1055 He Arg Arg Val Lys Ala Ser Thr Pro Pro Asp Ala Gly Pro He Val 1060 1065 1070 He His Cys Ser Ala Gly Thr Gly Arg Thr Gly Cys Tyr He Val Leu 1075 1080 1085 Asp Val Met Leu Asp Met Ala Glu Cys Glu Gly Val Val Asp He Tyr 1090 1095 1100 Asn Cys Val Lys Thr Leu Cys Ser Arg Arg Val Asn Met He Gin Thr 1105 1110 1115 1120 Glu Glu Gin Tyr He Phe He His Asp Ala He Leu Glu Ala Cys Leu 1125 1130 1135 Cys Gly Glu Thr Thr He Pro Val Asn Glu Phe Arg Ala Thr Tyr Arg 1140 1145 1150 Glu Met He Arg He Asp Pro Gin Ser Asn Ser Ser Gin Leu Arg Glu 1155 1160 1165 Glu Phe Gin Thr Leu Asn Ser Val Thr Pro Pro Leu Asp Val Glu Glu 1170 1175 1180 Cys Ser He Ala Leu Leu Pro Arg Asn Arg Asp Lys Asn Arg Ser Met 1185 1190 1195 1200 Asp Val Leu Pro Pro Asp Arg Xaa Leu Pro Phe Leu He Ser Ser Asp 1205 1210 "-215 Gly Asp Pro Asn Asn Tyr He Asn Ala Ala Leu Thr Asp St Tyr Thr 1220 1225 12-iO Arg Ser Ala Ala Phe He Val Thr Leu His Pro Leu Gin Ser Thr Thr 1235 1240 1245 Pro Asp Phe Trp Arg Leu Val Tyr Asp Tyr Gly Cys Thr Ser He Val 1250 1255 1260 Met Leu Asn Gin Leu Asn Gin Ser Asn Ser Ala Trp Pro Cys Leu Gin 1265 1270 1275 1280 Tyr Trp Pro Glu Pro Gly Arg Gin Gin Tyr Gly Leu Met Glu Val Glu 1285 1290 1295 Phe Val Ser Gly Thr Ala Asn Glu Asp Leu Val Ser Arg Val Phe Arg 1300 1305 1310 Val Gin Asn Ser Ser Arg Leu Gin Glu Gly His Leu Leu Val Arg His 1315 1320 1325 Phe Gin Phe Leu Arg Trp Ser Ala Tyr Arg Asp Thr Pro Asp Ser Arg 1330 1335 1340 Lys Ala Phe Leu His Leu Leu Ala Glu Val Asp Lys Trp Gin Ala Glu 1345 1350 1355 1360 Ser Gly Asp Gly Arg Thr Val Val His Cys Leu Asn Gly Gly Gly Arg 1365 1370 1375 Ser Gly Thr Phe Cys Ala Cys Ala Thr Val Leu Glu Met He Arg Cys 1380 1385 1390 His Ser Leu Val Asp Val Phe Phe Ala Ala Lys Thr Leu Arg Asn Tyr 1395 1400 1405 Lys Pro Asn Met Val Glu Thr Met Asp Gin Tyr His Phe Cys Tyr Asp 1410 1415 1420 Val Ala Leu Glu Tyr Leu Glu Ala Leu Glu Leu Arg 1425 1430 1435 (2) INFORMATION FOR SEQ ID NO:3: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1457 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3 : Met Asp Val Ala Ala Ala Ala Leu Pro Ala Phe Val Ala Leu Trp Leu 1 5 10 15 Leu Tyr Pro Trp Pro Leu Leu Gly Ser Ala Leu Gly Gin Phe Ser Ala 20 25 30 Gly Gly Cys Thr Phe Asp Asp Gly Pro Gly Ala Cys Asp Tyr His Gin 35 40 45 Asp Leu Tyr Asp Asp Phe Glu Trp Val His Val Ser Ala Gin Glu Pro 50 55 60 His Tyr Leu Pro Pro Glu Met Pro Gin Gly Ser Tyr Met Val Val Asp 65 70 75 80 Ser Ser Asn His Asp Pro Gly Glu Lys Ala Arg Leu Gin Leu Pro Thr 85 90 95 Met Lys Glu Asn Asp Thr His Cys He Asp Phe Ser Tyr Leu Leu Tyr 100 105 110 Ser Gin Lys Gly Leu Asn Pro Gly Thr Leu Asn He Leu Val Arg Val 115 120 125 Asn Lys Gly Pro Leu Ala Asn Pro He Trp Asn Val Thr Gly Phe Thr 130 135 140 Gly Arg Asp Trp Leu Arg Ala Glu Leu Ala Val Ser Thr Phe Trp Pro 145 150 155 160 Asn Glu Tyr Gin Val He Phe Glu Ala Glu Val Ser Gly Gly Arg Ser 165 170 175 Gly Tyr He Ala He Asp Asp He Gin Val Leu Ser Tyr Pro Cys Asp 180 185 190 Lys Ser Pro His Phe Leu Arg Leu Gly Asp Val Glu Val Asn Ala Gly 195 200 205 Gin Asn Ala Thr Phe Gin Cys He Ala Thr Gly Arg Asp Ala Val His 210 215 220 Asn Lys Leu Trp Leu Gin Arg Arg Asn Gly Glu Asp He Pro Val Ala 225 230 235 240 Gin Thr Lys Asn He Asn His Arg Arg Phe Ala Ala Ser Phe Arg Leu 245 250 255 Gin Glu Val Thr Lys Thr Asp Gin Asp Leu Tyr Arg Cys Val Thr Gin 260 265 270 Ser Glu Arg Gly Ser Gly Val Ser Asn Phe Ala Gin Leu He Val Arg 275 280 285 Glu Pro Pro Arg Pro He Ala Pro Pro Gin Leu Leu Gly Val Gly Pro 290 295 300 Thr Tyr Leu Leu He Gin Leu Asn Ala Asn Ser He He Gly Asp Gly 305 310 315 320 Pro He He Leu Lys Glu Val Glu Tyr Arg Met Thr Ser Gly Ser Trp 325 330 335 Thr Glu Thr His Ala Val Asn Ala Pro Thr Tyr Lys Leu Trp His Leu 340 345 350 Asp Pro Asp Thr Glu Tyr Glu He Arg Val Leu Leu Thr Arg Pro Gly 355 360 365 Glu Gly Gly Thr Gly Leu Pro Gly Pro Pro Leu He Thr Arg Thr Lys 370 375 380 Cys Ala Glu Pro Met Arg Thr Pro Lys Thr Leu Lys He Ala Glu He 385 390 395 400 Gin Ala Arg Arg He Ala Val Asp Trp Glu Ser Leu Gly Tyr Asn He 405 410 415 Thr Arg Cys His Thr Phe Asn Val Thr He Cys Tyr His Tyr Phe Arg 420 425 430 Gly His Asn Glu Ser Arg Ala Asp Cys Leu Asp Met Asp Pro Lys Ala 435 440 445 Pro Gin His Val Val Asn His Leu Pro Pro Tyr Thr Asn Val Ser Leu 450 455 460 Lys Met He Leu Thr Asn Pro Glu Gly Arg Lys Glu Ser Glu Glu Thr 465 470 475 480 He He Gin Thr Asp Glu Asp Val Pro Gly Pro Val Pro Val Lys Ser 485 490 495 Leu Gin Gly Thr Ser Phe Glu Asn Lys He Phe Leu Asn Trp Lys Glu 500 505 510 Pro Leu Glu Pro Asn Gly He He Thr Gin Tyr Glu Val Ser Tyr Ser 515 520 525 Ser He Arg Ser Phe Asp Pro Ala Val Pro Val Ala Gly Pro Pro Gin 530 535 540 Thr Val Ser Asn Leu Trp Asn Ser Thr His His Val Phe Met His Leu 545 550 555 560 His Pro Gly Thr Thr Tyr Gin Phe Phe He Arg Ala Ser Thr Val Lys 565 570 575 Gly Phe Gly Pro Ala Thr Ala He Asn Val Thr Thr Asn He Ser Ala 580 585 590 Pro Ser Leu Pro Asp Tyr Glu Gly Val Asp Ala Ser Leu Asn Glu Thr 595 600 605 Ala Thr Thr He Thr Val Leu Leu Arg Pro Ala Gin Ala Lys Gly Ala 610 615 620 Pro He Ser Ala Tyr Gin He Val Val Glu Gin Leu His Pro His Arg 625 630 635 640 Thr Lys Arg Glu Ala Gly Ala Met Glu Cys Tyr Gin Val Pro Val Thr 645 650 655 Tyr Gin Asn Ala Leu Ser Gly Gly Ala Pro Tyr Tyr Phe Ala Ala Glu 660 665 670 Leu Pro Pro Gly Asn Leu Pro Glu Pro Ala Pro Phe Thr Val Gly Asp 675 680 685 Asn Arg Thr Tyr Lys Gly Phe Trp Asn Pro Pro Leu Ala Pro Arg Lys 690 695 700 Gly Tyr Asn He Tyr Phe Gin Ala Met Ser Ser Val Glu Lys Glu Thr 705 710 715 720 Lys Thr Gin Cys Val Arg He Ala Thr Lys Ala Ala Ala Thr Glu Glu 725 730 735 Pro Glu Val He Pro Asp Pro Ala Lys Gin Thr Asp Arg Val Val Lys 740 745 750 He Ala Gly He Ser Ala Gly He Leu Val Phe He Leu Leu Leu Leu 755 760 765 Val Val He Val He Val Lys Lys Ser Lys Leu Ala Lys Lys Arg Lys 770 775 780 Asp Ala Met Gly Asn Thr Arg Gin Glu Met Thr His Met Val Asn Ala 785 790 795 800 Met Asp Arg Ser Tyr Ala Asp Gin Ser Thr Leu His Ala Glu Asp Pro 805 810 815 Leu Ser Leu Thr Phe Met Asp Gin His Asn Phe Ser Pro Arg Leu Pro 820 825 830 Asn Asp Pro Leu Val Pro Thr Ala Val Leu Asp Glu Asn His Ser Ala 835 840 845 Thr Ala Glu Ser Ser Arg Leu Leu Asp Val Pro Arg Tyr Leu Cys Glu 850 855 860 Gly Thr Glu Ser Pro Tyr Gin Thr Gly Gin Leu His Pro Ala He Arg 865 870 875 880 Val Ala Asp Leu Leu Gin His He Asn Leu Met Lys Thr Ser Asp Ser 885 890 895 Tyr Gly Phe Lys Glu Glu Tyr Glu Ser Phe Phe Glu Gly Gin Ser Ala 900 905 910 Ser Trp Asp Val Ala Lys Lys Asp Gin Asn Arg Ala Lys Asn Arg Tyr 915 920 925 Gly Asn He He Ala Tyr Asp His Ser Arg Val He Leu Gin Pro Val 930 935 940 Glu Asp Asp Pro Ser Ser Asp Tyr He Asn Ala Asn Tyr He Asp He 945 950 955 960 Trp Leu Tyr Arg Asp Gly Tyr Gin Arg Pro Ser His Tyr He Ala Thr 965 970 975 Gln Gly Pro Val His Glu Thr Val Tyr Asp Phe Trp Arg Met Val Trp 980 985 990 Gin Glu Gin Ser Ala Cys He Val Met Val Thr Asn Leu Val Glu Val 995 1000 1005 Gly Arg Val Lys Cys Tyr Lys Tyr Trp Pro Asp Asp Thr Glu Val Tyr 1010 1015 1020 Gly Asp Phe Lys Val Thr Cys Val Glu Met Glu Pro Leu Ala Glu Tyr 1025 1030 1035 1040 Val Val Arg Thr Phe Thr Leu Glu Arg Arg Gly Tyr Asn Glu He Arg 1045 1050 1055 Glu Val Lys Gin Phe His Phe Thr Gly Trp Pro Asp His Gly Val Pro 1060 1065 1070 Tyr His Ala Thr Gly Leu Leu Ser Phe He Arg Arg Val Lys Leu Ser 1075 1080 1085 Asn Pro Pro Ser Ala Gly Pro He Val Val His Cys Ser Ala Gly Ala 1090 1095 1100 Gly Arg Thr Gly Cys Tyr He Val He Asp He Met Leu Asp Met Ala 1105 1110 1115 1120 Glu Arg Glu Gly Val Val Asp He Tyr Asn Cys Val Lys Ala Leu Arg 1125 1130 1135 Ser Arg Arg He Asn Met Val Gin Thr Glu Glu Gin Tyr He Phe He 1140 1145 1150 His Asp Ala He Leu Glu Ala Cys Leu Cys Gly Glu Thr Ala He Pro 1155 1160 1165 Val Cys Glu Phe Lys Ala Ala Tyr Phe Asp Met He Arg He Asp Ser 1170 1175 1180 Gin Thr Asn Ser Ser His Leu Lys Asp Glu Phe Gin Thr Leu Asn Ser 1185 1190 1195 1200 Val Thr Pro Arg Leu Gin Ala Glu Asp Cys Ser He Ala Cys Leu Pro 1205 1210 1215 Arg Asn His Asp Lys Asn Arg Phe Met Asp Met Leu Pro Pro Asp Arg 1220 1225 1230 Cys Leu Pro Phe Leu He Thr He Asp Gly Glu Ser Ser Asn Tyr He 1235 1240 1245 Asn Ala Ala Leu Met Asp Ser Tyr Arg Gin Pro Ala Ala Phe He Val 1250 1255 1260 Thr Gin Tyr Pro Leu Pro Asn Thr Val Lys Asp Phe Trp Arg Leu Val 1265 1270 1275 1280 Tyr Asp Tyr Gly Cys Thr Ser He Val Met Leu Asn Glu Val Asp Leu 1285 1290 1295 Ser Gin Gly Cys Pro Gin Tyr Trp Pro Glu Glu Gly Met Leu Arg Tyr 1300 1305 1310 Gly Pro He Gin Val Glu Cys Met Ser Cys Ser Met Asp Cys Asp Val 1315 1320 1325 He Asn Arg He Phe Arg He Cys Asn Leu Thr Arg Pro Gin Glu Gly 1330 1335 1340 Tyr Leu Met Val Gin Gin Phe Gin Tyr Leu Gly Trp Ala Ser His Arg 1345 1350 1355 1360 Glu Val Pro Gly Ser Lys Arg Ser Phe Leu Lys Leu He Leu Gin Val 1365 1370 1375 Glu Lys Trp Gin Glu Glu Cys Glu Glu Gly Glu Gly Arg Thr He He 1380 1385 1390 His Cys Leu Asn Gly Gly Gly Arg Ser Gly Met Phe Cys Ala He Gly 1395 1400 1405 He Val Val Glu Met Val Lys Arg G3n Asn Val Val Asp Val Phe His 1410 1415 1420 Ala Val Lys Thr Leu Arg Asn Ser Lys Pro Asn Met Val Glu Ala Pro 1425 1430 1435 1440 Glu Gin Tyr Arg Phe Cys Tyr Asp Val Ala Leu Glu Tyr Leu Glu Ser 1445 1450 1455 Ser (2) INFORMATION FOR SEQ ID NO:4: (l) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1452 ammo acids (B) TYPE: ammo acid (C) STRANDEDNESS: (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID Nθ:4: Met Arg Thr Leu Gly Thr Cys Leu Val Thr Leu Ala Gly Leu Leu Leu 1 5 10 15 Thr Ala Ala Gly Glu Thr Phe Ser Gly Gly Cys Leu Phe Asp Glu Pro 20 25 30 Tyr Ser Thr Cys Gly Tyr Ser Gin Ala Asp Glu Asp Asp Phe Asn Trp 35 40 45 Glu Gin Val Asn Thr Leu Thr Lys Pro Thr Ser Asp Pro Trp Met Pro 50 55 60 Ser Gly Ser Phe Met Leu Val Asn Thr Ser Gly Lys Pro Glu Gly Gin 65 70 75 80 Arg Ala His Leu Leu Leu Pro Gin Leu Lys Glu Asn Asp Thr His Cys 85 90 95 He Asp Phe His Tyr Phe Val Ser Ser Lys Ser Asn Ala Ala Pro Gly 100 105 110 Leu Leu Asn Val Tyr Val Lys Val Asn Asn Gly Pro Leu Gly Asn Pro 115 120 125 He Trp Asn He Ser Gly Asp Pro Thr Arg Thr Trp His Arg Ala Glu 130 135 140 Leu Ala He Ser Thr Phe Trp Pro Asn Phe Tyr Gin Val He Phe Glu 145 150 155 160 Val Val Thr Ser Gly His Gin Gly Tyr Leu Ala He Asp Glu Val Lys 165 170 175 Val Leu Gly His Pro Cys Thr Arg Thr Pro His Phe Leu Arg He Gin 180 185 190 Asn Val Glu Val Asn Ala Gly Gin Phe Ala Thr Phe Gin Cys Ser Ala 195 200 205 He Gly Arg Thr Val Ala Gly Asp Arg Leu Trp Leu Gin Gly He Asp 210 215 220 Val Arg Asp Ala Pro Leu Lys Glu He Lys Val Thr Ser Ser Arg Arg 225 230 235 240 Phe He Ala Ser Phe Asn Val Val Asn Thr Thr Lys Arg Asp Ala Gly 245 250 255 Lys Tyr Arg Cys Met He Cys Thr Glu Gly Gly Val Gly He Ser Asn 260 265 270 Tyr Ala Glu Leu Val Val Lys Glu Pro Pro Val Pro He Ala Pro Pro 275 280 285 Gin Leu Ala Ser Val Gly Ala Thr Tyr Leu Trp He Gin Leu Asn Ala 290 295 300 Asn Ser He Asn Gly Asp Gly Pro He Val Ala Arg Glu Val Glu Tyr 305 310 315 320 Cys Thr Ala Ser Gly Ser Trp Asn Asp Arg Gin Pro Val Asp Ser Thr 325 330 335 Ser Tyr Lys He Gly His Leu Asp Pro Asp Thr Glu Tyr Glu He Ser 340 345 350 Val Leu Leu Thr Arg Pro Gly Glu Gly Gly Thr Gly Ser Pro Gly Pro 355 360 365 Ala Leu Arg Thr Arg Thr Lys Cys Ala Asp Pro Met Arg Gly Pro Arg 370 375 380 Lys Leu Glu Val Val Glu Val Lys Ser Arg Gin He Thr He Arg Trp 385 390 395 400 Glu Pro Phe Gly Tyr Asn Val Thr Arg Cys His Ser Tyr Asn Leu Thr 405 410 415 Val His Tyr Gly Tyr Gin Val Gly Gly Gin Glu Gin Val Arg Glu Glu 420 425 430 Val Ser Trp Asp Thr Asp Asn Ser His Pro Gin His Thr He Thr Asn 435 440 445 Leu Ser Pro Tyr Thr Asn Val Ser Val Lys Leu He Leu Met Asn Pro 450 455 460 Glu Gly Arg Lys Glu Ser Gin Glu Leu Thr Val Gin Thr Asp Glu Asp 465 470 475 480 Leu Pro Gly Ala Val Pro Thr Glu Ser He Gin Gly Ser Ala Phe Glu 485 490 495 Glu Lys He Phe Leu Gin Trp Arg Glu Pro Thr Gin Thr Tyr Gly Val 500 505 510 He Thr Leu Tyr Glu He Thr Tyr Lys Ala Val Ser Ser Phe Asp Pro 515 520 525 Glu He Asp Leu Ser Asn Gin Ser Gly Arg Val Ser Lys Leu Gly Asn 530 535 540 Glu Thr His Phe Leu Phe Phe Gly Leu Tyr Pro Gly Thr Thr Tyr Ser 545 550 555 560 Phe Thr He Arg Ala Ser Thr Ala Lys Gly Phe Gly Pro Pro Ala Thr 565 570 575 Asn Gin Phe Thr Thr Lys He Ser Ala Pro Ser Met Pro Ala Tyr Glu 580 585 590 Phe Glu Thr Pro Leu Asn Gin Thr Asp Asn Thr Val Thr Val Met Leu 595 600 605 Lys Pro Ala Gin Ser Arg Gly Ala Pro Val Ser Val Tyr Gin He Val 610 615 620 Val Glu Glu Glu Arg Pro Arg Arg Thr Lys Lys Thr Thr Glu He Leu 625 630 635 640 Lys Cys Tyr Pro Val Pro He His Phe Gin Asn Ala Ser He Leu Asn 645 650 655 Ser Gin Tyr Tyr Phe Ala Ala Glu Phe Pro Ala Asp Ser Leu Gin Ala 660 665 670 Ala Gin Pro Phe Thr He Gly Asp Asn Lys Thr Tyr Asn Gly Tyr Trp 675 680 685 Asn Thr Pro Leu Leu Pro His Lys Ser Tyr Arg He Tyr Tyr Gin Ala 690 695 700 Ala Ser Arg Ala Asn Gly Glu Thr Lys He Asp Cys Val Arg Val Ala 705 710 715 720 Thr Lys Gly Ala Val Thr Pro Lys Pro Val Pro Glu Pro Glu Lys Gin 725 730 735 Thr Asp His Thr Val Lys He Ala Gly Val He Ala Gly He Leu Leu 740 745 750 Phe Val He He Phe Leu Gly Val Val Leu Val Met Lys Lys Arg Lys 755 760 765 Leu Ala Lys Lys Arg Lys Glu Thr Met Ser Ser Thr Arg Gin Glu Met 770 775 780 Thr Val Met Val Asn Ser Met Asp Lys Ser Tyr Ala Glu Gin Gly Thr 785 790 795 800 Asn Cys Asp Glu Ala Phe Ser Phe Met Gly Thr His Asn Leu Asn Gly 805 810 815 Arg Ser Val Ser Ser Pro Ser Ser Phe Thr Met Lys Thr Asn Thr Leu 820 825 830 Ser Thr Ser Val Pro Asn Ser Tyr Tyr Pro Asp Glu Thr His Thr Met 835 840 845 Ala Ser Asp Thr Ser Ser Leu Ala Gin Pro His Thr Tyr Lys Lys Arg 850 855 860 Glu Ala Ala Asp Val Pro Tyr Gin Thr Gly Gin Leu His Pro Ala He 865 870 875 880 Arg Val Ala Asp Leu Leu Gin His He Thr Gin Met Lys Cys Ala Glu 885 890 895 Gly Tyr Gly Phe Lys Glu Glu Tyr Glu Ser Phe Phe Glu Gly Gin Ser 900 905 910 Ala Pro Trp Asp Ser Ala Lys Lys Asp Glu Asn Arg Met Lys Asn Arg 915 920 925 Tyr Gly Asn He He Ala Tyr Asp His Ser Arg Val Arg Leu Gin Met 930 935 940 Leu Glu Gly Asp Asn Asn Ser Asp Tyr He Asn Gly Asn Tyr He Asp 945 950 955 960 Gly Tyr His Arg Pro Asn His Tyr He Ala Thr Gin Gly Pro Met Gin 965 970 975 Glu Thr He Tyr Asp Phe Trp Arg Met Val Trp His Glu Asn Thr Ala 980 985 990 Ser He He Met Val Thr Asn Leu Val Glu Val Gly Arg Val Lys Cys 995 1000 1005 Cys Lys Tyr Trp Pro Asp Asp Thr Glu He Tyr Lys Asp He Lys Val 1010 1015 1020 Thr Leu He Asp Thr Glu Leu Leu Ala Glu Tyr Val He Arg Thr Phe 1025 1030 1035 1040 Ala Val Glu Lys Arg Gly He His Glu He Arg Glu He Arg Gin Phe 1045 1050 1055 His Phe Thr Gly Trp Pro Asp His Gly Val Pro Tyr His Ala Thr Gly 1060 1065 1070 Leu Leu Gly Phe Val Arg Gin Val Lys Ser Lys Ser Pro Pro Asn Ala 1075 1080 1085 Gly Pro Leu Val Val His Cys Ser Ala Gly Ala Gly Arg Thr Gly Cys 1090 1095 1100 Phe He Val He Asp He Met Leu Asp Met Ala Glu Arg Glu Gly Val 1105 1110 1115 1120 Val Asp He Tyr Asn Cys Val Arg Glu Leu Arg Ser Arg Arg Val Asn 1125 1130 1135 Met Val Gin Thr Glu Glu Gin Tyr Val Phe He His Asp Ala He Leu 1140 1145 1150 Glu Ala Cys Leu Cys Gly Asp Thr Ser He Pro Ala Ser Gin Val Arg 1155 1160 1165 Ser Leu Tyr Tyr Asp Met Asn Lys Leu Asp Pro Gin Thr Asn Ser Ser 1170 1175 1180 Gin He Lys Glu Glu Phe Arg Thr Leu Asn Met Val Thr Pro Thr Leu 1185 1190 1195 1200 Arg Val Glu Asp Cys Ser He Ala Leu Leu Pro Arg Asn His Glu Lys 1205 1210 1215 Asn Arg Cys Met Asp He Leu Pro Pro Asp Arg Cys Leu Pro Phe Leu 1220 1225 1230 He Thr He Asp Gly Glu Ser Ser Asn Tyr He Asn Ala Ala Leu Met 1235 1240 1245 Asp Ser Tyr Lys Gin Pro Ser Ala Phe He Val Thr Gin His Pro Leu 1250 1255 1260 Pro Asn Thr Val Lys Asp Phe Trp Arg Leu Val Leu Asp Tyr His Cys 1265 1270 1275 1280 Thr Ser Val Val Met Leu Asn Asp Val Asp Pro Ala Gin Leu Cys Pro 1285 1290 1295 Gin Tyr Trp Pro Glu Asn Gly Val His Arg His Gly Pro He Gin Val 1300 1305 1310 Glu Phe Val Ser Ala Asp Leu Glu Glu Asp He He Ser Arg He Phe 1315 1320 1325 Arg He Tyr Asn Ala Ser Arg Pro Gin Asp Gly His Arg Met Val Gin 1330 1335 1340 Gin Phe Gin Phe Leu Gly Trp Pro Met Tyr Arg Asp Thr Pro Val Ser 1345 1350 1355 1360 Lys Arg Ser Phe Leu Lys Leu He Arg Gin Val Asp Lys Trp Gin Glu 1365 1370 1375 Glu Tyr Asn Gly Gly Glu Gly Pro Thr Val Val His Cys Leu Asn Gly 1380 1385 1390 Gly Gly Arg Ser Gly Thr Phe Cys Ala He Ser He Val Cys Glu Met 1395 1400 1405 Leu Arg His Gin Arg Thr Val Asp Val Phe His Ala Val Lys Thr Leu 1410 1415 1420 Arg Asn Asn Lys Pro Asn Met Val Asp Leu Leu Asp Gin Tyr Lys Phe 1425 1430 1435 1440 Cys Tyr Glu Val Ala Leu Glu Tyr Leu Asn Ser Gly 1445 1450 (2) INFORMATION FOR SEQ ID NO: 5 : (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (ix) FEATURE: (A) NAME/KEY: Active-site (B) LOCATION: 1..2 (D) OTHER INFORMATION: /note= "Let 'X' located at position 1 represent either Histidine or Aspartic Acid" (ix) FEATURE: (A) NAME/KEY: Modified-site (B) LOCATION: 6..7 (D) OTHER INFORMATION: /note= "Let 'X' located at position 6 represent either Isoleucine or Valine." (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 5 : Xaa Phe Trp Arg Met Xaa Trp 1 5 (2) INFORMATION FOR SEQ ID NO:6: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 20 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (ix) FEATURE: (A) NAME/KEY: mιsc_feature (B) LOCATION: 11..12 (D) OTHER INFORMATION: /note= "Let the 'N' at position 11 represent Inosine." (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 17..18 (D) OTHER INFORMATION: /note= "Let the 'N' at position 17 represent Inosine." (xi) SEQUENCE DESCRIPTION: SEQ ID Nθ:6: AYTTYTGGMG NATGRTNTGG 20 (2) INFORMATION FOR SEQ ID NO:7: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7 amino acids (B) TYPE: ammo acid (C) STRANDEDNESS: (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (ix) FEATURE: (A) NAME/KEY: Modifled-site (B) LOCATION: 4..5 (D) OTHER INFORMATION: /note= "Let 'X' located at position 4 represent either Phenyalanine or Histidine." (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7 : Trp Pro Asp Xaa Gly Val Pro 1 5 (2) INFORMATION FOR SEQ ID NO:8: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 17 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 3..4 (D) OTHER INFORMATION : /note= "Let ' N ' located at position 3 represent Inosine . " ( ix) FEATURE : (A) NAME/KEY: misc_feature (B) LOCATION: 12..13 (D) OTHER INFORMATION: /note= "Let 'N' located at position 12 represent Inosine." (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 8: GGNACRWRRT CNGGCCA 17 (2) INFORMATION FOR SEQ ID NO:9: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 11 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: (D) TOPOLOGY : linear ( ii ) MOLECULE TYPE : protein (Xi ) SEQUENCE DESCRIPTION : SEQ ID NO : 9 : Asp Gly Asp Phe Glu Glu He Pro Glu Glu Tyr 1 5 10 (2) INFORMATION FOR SEQ ID NO:10: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 12 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 10: Glu Gly Pro Trp Leu Glu Glu Glu Glu Glu Ala Tyr 1 5 10

Claims: WHAT IS CLAIMED IS: 1 . An isolated receptor protein tyrosine phosphatase λ polypeptide, which ( 1 ) is predominantly expressed in adult mammalian brain, lung and kidney tissue; and (2) predominantly lacks expression in adult mammalian liver tissue; wherein said polypeptide is capable of dephosphorylating phosphorylated tyrosine residues. 2. The protein tyrosine phosphatase λ polypeptide of Claim 1 which is human. 3. The protein tyrosine phosphatase λ polypeptide of Claim 1 which is murine. 4. A derivative of the protein tyrosine phosphatase λ polypeptide of Claim 1 which substantially retains the ability to dephosphorylate phosphorylated tyrosine residues. 5. An antagonist of the protein tyrosine phosphatase λ polypeptide of Claim 1 . 6. An isolated receptor protein tyrosine phosphatase λ polypeptide selected from the group consisting of: (1 ) a polypeptide comprising the amino acid sequence shown in Figure 1 (SEQ ID NO:2); (2) a further mammalian homologue of polypeptide ( 1 ); (3) a derivative of any of the polypeptides (1 ) - (2), substantially retaining the ability to dephosphorylate phosphorylated tyrosine residues. 7. The protein tyrosine phosphatase λ polypeptide of Claim 6 comprising the amino acid sequence shown in Figure 1 (SEQ ID NO:2). 8. An antagonist of the protein tyrosine phosphatase λ polypeptide of Claim 6. 9. An isolated nucleic acid molecule encoding the protein tyrosine phosphatase λ polypeptide of Claim 1 . 10. An isolated nucleic acid molecule encoding the protein tyrosine phosphatase λ polypeptide of Claim 6. 1 1 . An isolated nucleic acid molecule encoding the protein tyrosine phosphatase λ polypeptide of Claim 7. 1 2. A vector comprising the nucleic acid molecule of Claims 9, 10 or 1 1 operably linked to control sequences recognized by a host cell transformed with the vector. 1 3. A host cell transformed with the vector of Claim 1 2. 14. An antibody capable of specifically binding to the protein tyrosine phosphatase λ polypeptide of Claims 1 , 6 or 7 that is free of antibody capable of specifically binding to protein tyrosine phosphatase K or protein tyrosine phosphatase μ. 1 5. A hybridoma cell line producing an antibody of Claim 14. 1 6. A process for producing the protein tyrosine phosphatase λ polypeptide of Claims 1 , 6 or 7 comprising transforming a host cell with nucleic acid encoding said polypeptide, culturing the transformed cell and recovering said polypeptide from the cell culture. 17. An assay for identifying an antagonist or agonist of a protein tyrosine phosphatase λ polypeptide of Claims 1 , 6 or 7 which comprises contacting a phosphatase domain of said protein tyrosine phosphatase λ polypeptide with a candidate antagonist or agonist and monitoring the ability of said phosphatase domain to dephosphorylate phosphorylated tyrosine residues.

Inventors: CHENG JILL, LASKY LAURENCE A, CHENG, JILL, LASKY, LAURENCE, A.
Applicants: GENENTECH INC, GENENTECH, INC.
Application year: 1997
Main classification: C12N15
IPC codes: C07K7, C07K14, C07K16, C12N9, C12N15, C12P21, G01N33