PROHORMONE CONVERTASE TRANSFORMED CELLS

Abstract: Described is the production of mammalian cells expressing prohormone convertase which facilitates the processing of prohormone precursors to active hormones. Also described are variant prohormone convertases, and prohormones. The transformed cells of the present invention may be used in the synthesis of properly processed polypeptide hormones, and in cell culture to reduce dependence upon added hormones and required serum polypeptide factors.

Description: PROHORMONE CONVERTASE TRANSFORMED CELLS Background of the Invention 5 Field of the Invention This invention relates to host cells expressing one or more prohormone convertase enzymes and the production of a biologically active polypeptide from these cells. The 10 invention further relates to polypeptide precursor variants having endoprotease cleavage sites which are processed by the host cell. Description of Related Art Most, if not all proteinaceous hormones are 15 synthesized as relatively large precursor molecules, prohormones, that are biologically inactive (reviewed in Docherty and Steiner 1982; Loh et al . 1984; Mains et al . 1990). Maturation of the prohormone to its active form often requires endoproteolytic cleavage at paired or 20 multiple basic amino acid residues to liberate the active component from the inactive portion of the precursor molecule. Until recently, almost nothing was known concerning the identity of the proteins responsible for this important stage in processing: the prohormone 25 convertase (PC) enzymes. Not every kind of cell has the capacity to correctly convert a prohormone to its active mature form through these specific cleavages. For some classes of prohormone this processing is apparently limited to those cells that 30 contain both constitutive and regulated pathways of protein secretion (Gumbiner and Kelly 1982). Cells having both constitutive and regulated pathways of protein secretion are located almost exclusively in the specialized hormone- ^ producing tissues of the endocrine and neuroendocrine ; 35 systems. An example of a family of hormones that is processed during regulated secretion is the insulin family of hormones. This family includes insulin, the insulin-like growth factors IGF-I and IGF-II, and relaxin. In their native environment, all members of this family are synthesized as precursor molecules that require processing to yield active hormone. When heterologously expressed in cells having only a constitutive pathway of protein secretion, most hormone precursors, such as human preproinsulin, are secreted in an unprocessed prohormone form (Gumbiner and Kelly 1982). Experimental manipulation of mouse AtT-20 cells that disrupted the regulated secretory pathway of those cells has been observed to redirect the polyhormone precursor proopiomelanocor in (POMC) into the constitutive secretory pathway. In that case, POMC was no longer subjected to processing and was found to be secreted from the cell as the intact precursor (Moore et al . 1983). These observations suggest that there is a class of processing enzymes that function only in the regulated pathway of protein secretion; this pathway is apparently limited to certain highly-specialized cell types. The POMC protein is a prohormone that is subject to differential processing. Expression of mature POMC derivatives is highly tissue-specific; alternate processed forms of the same prohormone precursor are produced in different regions of the brain (Douglass et al . 1984) . The enzyme(s) and control mechanisms involved in the generation of this diversity are unknown. The possibility exists that there are tissue-specific enzymes that recognize unique amino acid sites on the prohormone substrate, or alternatively, that only one enzyme is responsible for the endoproteolytic cleavages and is itself under tight metabolic control, with each tissue providing a characteristic intracellular environment that is associated with cleavage at a specific subset of residue pairs. Until recently, the only known eukaryotic prohormone processing enzyme was the KEX2 gene product of th.e yeast Sacc-haroj-πyres cerevisiae (Julius et al . 1983 and 1984; Fuller et al . 1989a) . The kex2 protein is a serine protease related to the subtilisin family of enzymes and has a preference for specific pairs of basic amino acids on its native hormone precursor substrates (pro-a-factor mating type pheromone and the pro-killer toxin) . Kex2 shows maximum enzymatic activity at neutral pH with a strict requirement for the presence of calcium (Julius et al . 1984; Fuller et al . 1989a). It is membrane-bound and the Λ 5 mature, active form of the enzyme is localized in the post- Golgi compartment of the yeast cell (Fuller et al . 1989b; * ■ Redding et al . 1991). It can effectively serve as a substitute convertase for -ona fide mammalian PC enzymes when heterologously expressed in otherwise processing- 10 deficient cells by its demonstrated ability to correctly process certain mammalian prohormones: Nerve growth factor, bNGF, in BSC-40 cells (Bresnahan et al . 1990); protein C in baby hamster kidney BHK cells (Foster et al . 1991); POMC both in BSC-40 cells (Thomas et al . 1988) and in COS-1 15 cells (Zollinger et al . 1990)]. Kex2 was shown to have a highly similar if not identical substrate specificity to the authentic human proalbumin convertase in vi tro (Bathurst et al . 1986; Brennan et al . 1990) . When heterologously expressed in mammalian cells kex2 will home 20 to the post-Golgi compartment, where it is apparently fully active (Germain et al . 1990). These observations have led to speculation that this yeast protein must be both functionally and structurally similar to an authentic mammalian convertase. A search began for the elusive 25 mammalian counterparts of kex2 based upon structural homologieε. KEX2 and Fur Hydrophobic Anchor The Kex2 endoprotease has two hydrophobic regions located at the N-terminal side and C-terminal side. The C- 30 terminal hydrophobic transmembrane anchor is responsible for the anchoring of the Kex2 to a Golgi body of a yeast cell. Deletion of this C-terminal hydrophobic anchor renders the Kex2 endoprotease soluble while still maintaining substrate specificity (EPO PUB No.0327377). 35 An inspection of genetic data bases identified a potential mammalian homologue of kex2 that shared many features of the active site domain of the kex2 protein " : the fur gene product of human liver, furin (Fuller et al . 1989b) . Furin was subsequently cloned and successfully expressed in processing-deficient cells: cotransfection of furin with pro-von Willebrand factor in COS-1 cells (van den Ven et al . 1990; Wise et al . 1990) and with pro-bNGF in African green monkey kidney epithelial BSC-40 cells (Bresnahan et al . 1990) resulted in correct processing of the precursor substrates. However, when furin and a prohormone, prorenin, have been coexpressed in mammalian cells, no processing has been observed (Hatsuzawa,et al The Journal of Biological Chemistry Vol 265 [1990]). Furin also shared with kex2 a requirement for calcium ions, displayed maximum activity at a neutral pH, and, like kex2, was shown to be a membrane-bound protein in the post- Golgi compartment (Bresnahan et al . 199-0) . However, because furin does not seem to be capable of efficiently processing certain hormone precursors such as prorenin, and its mRNA message is apparently expressed in most if not all mammalian cells (Hatsuzawa et al . 1990) , the furin protease may play a role in an essential "housekeeping" function in that it could be responsible for many of the basic amino acid site cleavages occurring in the constitutive secretory pathway of the cell. These functions could be general, .or more confined to specific cell-types with the constitutive pathway-dependent processing of. growth factors like bNGF. Because furin does not appear to be directly involved in the endoproteolytic processing of prohormones in endocrine-like tissues, there must be other mammalian proteins both functionally and structurally similar to furin and yeast kex2 that serve as the authentic prohormone convertases: PC proteins that share distinctive homologies in their active sites. This search for structural homology has recently lead to the discovery of more PC proteins. By using the technique of "Mixed Oligonucleotides Primed Amplification of cDNA" (MOPAC, Innis 1990), Smeekens and Steiner (1990) were able to use the conservation of amino acid sequence surrounding the active sites of both bacterial subtilisin and the yeast kex2 protease to amplify a putative prohormone convertase cDNA from human insulinoma. This PC cDNA, termed mPC2, showed an exceptional degree of homology to the yeast kex2 protease. In similar experiments Seidah and colleagues identified another member of the subtilisin family of proteases, termed, mPCl (Seidah, et al 1991) . The distribution of PCI and PC2 has so far been observed to be confined to neuroendocrine-derived tissues (Seidah et al. 1990; Seidah et al. 1991; Smeekens et al. 1991) , suggesting that these proteins may be candidates for the authentic convertases resident in the regulated secretory pathways of these tissues. The substrate specificities of PCI and PC2 for defined pairs of dibasic amino acids at the prohormone cleavage sites do not appear to be identical (Benjannet et al. 1991; Thomas et al. 1991) , nor do they share the same pattern of tissue distribution in the brain (Seidah et al. 1991). This implies that different classes of prohormones may require unique PC enzymes, and that both PCI and PC2 may be members of a family of specific processing enzymes employed by the endocrine system to generate the diversity of hormones required throughout the entire organism. Precursor processing The biosynthetic process begins with the synthesis of the precursor (prepropeptide) on the rough endoplasmic reticulum (RER) . The signal peptide (pre-portion) is clipped off as the proprotein is transported into the cisternae of the RER where protein folding, di-sulfide bond formation and asparagine-linked glycosyla ion occur (Figure 1) . The precursor is then translocated to the Golgi apparatus where more complex glycosylation and phosphorylation occur. Within the Golgi of some cells, proteins are sorted by an unknown mechanism into two groups: those that will be constitutively secreted and those that undergo regulated secretion. The constitutively secreted proteins will enter vesicles and be transported to their target continually without the need for any specific stimulus. Proteins undergoing regulated secretion are transported to secretory vesicles and will be released ' only when an adequate stimulus is provided. Within the secretory vesicles the excision of bioactive peptides from the larger inactive protein precursors occurs. Two steps involved in this process are endoproteolytic cleavage usually at the carboxyl side of paired basic amino acids (e.g. lys-arg, arg-arg) and exoproteolytic cleavage of flanking basic amino acids by carboxyl- and/or aminopeptidases (reviewed in Mains et al. 1990.). Many proteins, including NGF (Berger and Shooter 1977), are first synthesized as larger precursor proteins. The function of the precursor is still not well understood. One possible role of the precursor is to aid in protein folding (Steiner 1982, Selby et al. 1987, Wise et al. 1988) . The precursor may also direct the protein to the proper location or pathway within the cell as is suggested by Sevarino and colleagues (1989), though this is not the case with the connecting peptide of insulin (Powell et al. 1988, Gross et al. 1990) . Additionally, the precursor has been shown to have roles in gamma carboxylation of glutamic acid residues (Pan and Price 1985, Furie and Furie 1988) , and regulation of the coordinate synthesis of multiple mature peptides from a single precursor polypeptide eg. , POMC. (For review, see Douglass et al. 1984) . Relaxin In the present invention, prorelaxin is used as a typical hormone precursor.. The relaxin is first synthesized as a preprohormone precursor which undergoes specific processing to form the mature two-chain, disulfide-linked active relaxin. A major part of this processing requires endoproteolytic cleavage at specific pairs of basic amino acid residues. This specific processing does not occur when the precursor is heterologously expressed in cells containing only the constitutive pathway of protein secretion. Mature human relaxin is an ovarian hormonal peptide of approximately 6000 daltons in molecular weight known to be responsible for remodeling the reproductive tract before parturition, thus facilitating the birth process. Hisaw, F.L., Proc. Soc. Exp. Biol. Med.. 23:661-663 (1926); Schwabe, C. et al., Biochem. Biophvs. Res. Comm.. 75: 503-570 (1977); James, R. et al., Nature, 267 : 544-546 (1977). This protein appears to modulate the restructuring of connective tissues in target organs to obtain the required changes in organ structure during pregnancy and parturition. Some of the important roles for relaxin as a pregnancy hormone include inhibition of premature labor and cervical ripening at parturition. While predominantly a hormone of pregnancy, relaxin has also been detected in the non- pregnant female as well as in the male. Bryant-Greenwood, G.D., Endocrine Reviews. 3 : 62-90 (1982) and Weiss, G., Ann. Rev. Phvsiol.. 46: 43-52 (1984) . Relaxin consists of two polypeptide chains, referred to as A and B, joined by disulfide bonds with an intra- chain disulfide loop in the A-chain in a manner analogous to that of insulin. Two human genes (HI and H2) for human relaxin have been identified, and only H2 is expressed in the ovary. Porcine relaxin, the sequence of which has also been determined, has been used in human clinical trials for ripening of the cervix and induction of labor. MacLennan et al., Obstetrics & Gvnecolocrv. : 598 (1986). European Pat. Publ. No. 86,649 published Aug. 24, 1983 discloses how to prepare porcine preprorelaxin, porcine prorelaxin, and porcine relaxin. Australian Pat. No. 561,670 issued Aug. 26, 1987, European Pat. Publ. No. 68,375 published January 5, 1983, and Haley et al., DNA, 1: 155-162 (1982) disclose how to prepare porcine relaxin. European Pat. Publ. Nos. 101,309 published Feb. 22, 1984 and 112,149 published June 27, 1984 respectively disclose the molecular cloning and characterization of a gene sequence coding for human relaxin and human H2-relaxin and analogs thereof. U.S. Pat. No. 4,267,101 issued May 12, 1981 discloses a process for obtaining human relaxin from fetal membranes. Nerve Growth Factor Nerve growth factor (NGF) , required for sympathetic and sensory neuron survival (Levi-Montalcini and Booker 1960, Gorin and Johnson 1979), is the most well characterized neurotrophic factor in part due to ' the exceptionally high levels synthesized in the male mouse submaxillary gland. It was from this source that NGF was purified (Cohen 1960) and its complete amino acid sequence determined (Angeletti 1973). Using this information, Scott and colleagues (1983) identified and cloned the mouse NGF gene by screening a mouse submaxillary gland cDNA library using a probe constructed for a hexapeptide based on the least degenerate codons contained within the NGF sequence. Molecular cloning, using the polymerase chain reaction (PCR) (Saiki et al.1985, Mullis et al. 1986), has recently revealed that NGF is a member of a family of neurotrophic factors that also includes BDNF (Leibrock et al. 1989) and NT-3 (Hohn et al. 1990, Rosenthal et al. 1990, Maisonpierre et al. 1990a, Ernfors et al. 1990, Jones and Reichardt 1990) . NGF, BDNF and NT-3 are all translated as preproproteins that require endoproteolytic cleavage in order to be active. There is an extensive amount of homology (>50%) between the mature portions of NGF, BDNF, and NT3. However the homologies of the precursor portions are much lower (-20%) . The efficiency of processing of the three neurotrophic factors, from their inactive pro-form to the active factor, vary substantially with different cell types. Insulin Insulin is a polypeptide.hormone which is produced in the beta cells of the islets of Langerhans situated in the pancreas of all vertebrates. Insulin is secreted directly into the bloodstream where it regulates carbohydrate metabolism, influences the synthesis of protein and of RNA, and the formation and storage of neutral lipids. The Merck Index. 10th edition, 1983. Insulin promotes anabolic processes and inhibits catabolic ones in muscle, liver and adipose tissue. The structure of human insulin was disclosed in Nature 187,483 (1960). Prior to the discovery of recombinant DNA technology, the major source of insulin for human consumption was the pancreases of slaughtered animals. Human insulin was among the first commercial health care products produced by recombinant technology. A review of the research, development, and recombinant production of human insulin is in Science 219, 632-637 (1983) . In addition to its role in vi vo , insulin is also useful in recombinant cell culture. Insulin is an example of a polypeptide factor important for mammalian cell culture proliferation and anabolism. Some cell cultures produce endogenous insulin and some do not; cell cultures which rely on added insulin are problematic because insulin is unstable in some cultures. European publication number, 0307247A2, published March 3, 1989, describes the introduction of nucleic acid encoding insulin into a mammalian host cell to eliminate the need for adding exogenous insulin. Insulin is synthesized as a larger precursor protein, proinsulin. Proinsulin is a single polypeptide chain containing a sequence of about thirty residues that is absent from mature insulin. Proinsulin, like prorelaxin, has a B-C-A chain structure. The C or connecting peptide joins the carboxyl end of the B chain and the amino terminus of the A chain of the future insulin molecule Biochemistry 3rd edition, pg. 995 (1988) . The mature insulin is generated by cleavage of the C peptide at dibasic residues Arg(3D- Arg(32) and Lys (64) -Arg (65) . Two distinct processing enzymes have been defined which are specific for their respective dibasic cleavage sites in proinsulin; type I is substrate specific for the BC junction, while type II is specific for the CA junction (Weiss, Biochemistry 29, 1990) . Naturally occurring mutations in the human insulin gene have been reported by Steiner et al. (Diabetes Care vol. 13, no. 6 pg. 600-609 [1990]). Members of a family with hyperproinsulinemia have a substitution of insulin B chain residue 10, a histidine, with aspartic acid resulting in a proinsulin that is reported to exhibit altered subcellular sorting behavior. In patients having hyperproinsulinemia, a significant proportion of the newly synthesized Aεp-10 proinsulin is secreted from the islets in an unprocessed form via an unregulated or constitutive protein secretory pathway (Steiner et al. PNAS USA, vol. 85, pg. 8943-8947 [1988]) and (Quinn et al. The J. Cell Bio, vol. 113, pg. 987-996 [1991]). Others have shown that insulin containing this BIO H>D mutation results in a more active form of insulin with increased binding to the insulin receptor (Schwartz, et al. PNAS USA vol. 84, pg. 6408-6411 [1987]; Brange et al. Nature vol. 333 pg. 679-682 [1988]; Shoelson et al. vol. Biochem. vol. 31 pg. 1757-1767 [1992]). Brems et al. (Protein Engineering vol. 5 no. 6 pg 519-525 [1992]) report that the replacement of B-chain residue 10, a histidine, with aspartic acid increased the stability of the insulin. Wild-type human insulin exhibits subunit interactions and forms dimers; dimeric insulin binds to Zn 2+ to form hexamerε. The histidine residue at position BIO in insulin is involved in co-ordinating zinc ions and it has been reported by Quinn et al. Supra, that the human insulin mutant, BIO histidine to aspartic acid, allows formation of dimers of human proinsulin but not hexamers. Insulin Like Growth Factor I and II ( GF- and IGF- II) Insulin-like growth factors, or IGFs, by definition are polypeptides with insulin-like structural and biologic properties which are not neutralized by the presence of excess anti-insulin antibodies. (Endocrinology and Metabolism 2nd ed.[1987]). The complete amino acid sequences of IGF-I and GF-II have been determined (Rinderknecht, et al Journal of Biological Chemistry 253 pg. 2769 [1978]; Rinderknecht. et al FEBS Letters 89, 283 [1978]). They are both single- chain polypeptides with three disulfide bridges and a sequence identity of 49 and 47 percent respectively, to human insulin A and B chains. The connecting peptide or C region is considerably shorter than the one of proinsulin and does not show any significant homology to it. The IGF-I C peptide is not cleaved during the processing to the mature molecule. In addition, IGF-I contains a short, 8 a ino- acid, carboxyterminal extension peptide, termed the D domain, for which no homologous region exists in insulin (Foyt, H.L. ,Insulin-Like Growth Factors: Molecular and Cellular Aspects [1991]) Both IGF-I and IGF-II are derived from precursors by proteolytic processing (Jansen et al Nature 306. 609 [1984];Bell, et al Nature 310, 775 [1984]_*_Jansen et al FEBS letters 179. 243 [1985] . There exists a need for a method of producing polypeptides from their polypeptide precursors in cell culture. It is therefore an object of the present invention to provide host cells that express active prohormone convertases that cleave polypeptide precursors to polypeptides. It is also an object of the present invention to provide a method for the production of a desired polypeptide in cell culture in a manner that results in the proper processing and glycosylation of the desired polypeptide. A related objective of the present invention is the production of polypeptide hormones, such as insulin, relaxin, and IGF-I. A further object of the present invention relates to providing polypeptide precursor mutants having prohormone convertase cleavage sites for processing by the host cell. There also exists a need to eliminate problems associated with supplying necessary polypeptide factors (e.g. insulin or transferrin) for the maintenance and growth of recombinant host cells. This need is particularly evident in the use of mammalian cell culture in the production of commercial polypeptides such as pharmaceutical products. It is therefore an object of the present invention to provide mammalian cell cultures that express prohormone convertases that enable processing of polypeptide factor precursors to polypeptide factors needed for mammalian cell culture proliferation and anabolism. It is an object of the present invention to produce polypeptide factors using host cells expressing prohormone convertases. These and other objects of the invention will be apparent to the ordinary artisan upon consideration of the specification as a whole. Summary of the Invention The present invention describes a method for the production of a desired polypeptide in host cells expressing a prohormone convertase. In one embodiment the desired polypeptide is a prohormone processed to active hormone. In another embodiment, the desired polypeptide is any polypeptide factor needed for cell growth or anabolism. In some embodiments, the invention provides polypeptide factor mutants comprising as cleavage site recognizable by a host cell enzyme, such as a prohormone convertase. In a preferred embodiment, a prohormone convertase precursor is provided which is modified to have a host cell cleavage site allowing for processing of the prohormone convertase precursor to active enzyme in the host cell. in one embodiment the host cell constitutively expresses a prohormone convertase. In another embodiment, the host cell is stably transformed with a prohormone convertase. In one aspect of the present invention the production of a heterologous polypeptide factor, such as insulin or transferrin, in a polypeptide factor-dependent host cell is accomplished by a) introducing into the polypeptide factor- dependent host cell nucleic acid encoding a heterologous polypeptide factor precursor comprising a cleavage site recognizable by a host cell enzyme and wherein said host cell is dependent on the cleavage product of said polypeptide factor precursor; and b) culturing said host cell under conditions wherein the polypeptide factor precursor is cleaved at said cleavage site by the host cell enzyme, thereby producing said polypeptide factor. In another aspect of the present invention the production of a desired polypeptide in a host cell expressing a prohormone convertase is accomplished by a) introducing into the host cell nucleic acid encoding a desired polypeptide; and b) culturing said host cell under conditions wherein said desired polypeptide is expressed. Preferably the desired polypeptide is a polypeptide hormone and may be any polypeptide hormone. Preferably, it may be any polypeptide hormone comprised of two or more polypeptide chains. Among the preferred two-chain hormones are insulin, relaxin, and insulin-like growth factors I or II. Among the preferred prohormones are proinsulin, prorelaxiϊi, and precursors of insulin-like growth factors I or II. The -prohormone may be a prohormone mutant modified to contain one or more prohormone convertase cleavage sites. The prohormone or prohormone mutant may be processed by the prohormone convertase in an in vivo or in vitro manner. The method of producing polypeptide hormones may be further accomplished by inserting into a prohormone, a prohormone convertase cleavage site that facilitates processing by a prohormone convertase. The preferred hormone is a mammalian polypeptide hormone comprised of two or more polypeptide chains, for example insulin, relaxin, insulin-like growth factor I or insulin like growth factor II. In another aspect, the method may be practiced using cells transformed to contain a prohormone convertase fused to a hydrophobic transmembrane Golgi anchor, such as that from kex2 or furin. The present invention discloses nucleic acid (a) encoding murine prohormone convertases 1 and 2, (b) mutants of prohormone convertase that contain inserted convertase cleavage sites, and (c) mutants of prohormone convertase that contain hydrophobic anchor domains, or heterologous pre and prepro sequences from other processed polypeptides. Also disclosed are vectors containing such nucleic acid and cells expressing such nucleic acid. Methods of effecting transformation and methods of providing transformed mammalian cells are disclosed. Brief Description of the Figures FIGURE 1 AtT20 murine prohormone convertase 1 cDNA (Seq. ID.#1) FIGURE 2 AtT20 murine prohormone convertase 2 cDNA (Seq. ID #2) FIGURE 3 Murine PCI amino acid (Seq. ID. #3 FIGURE 4 Murine PC2 amino acid ( Seq . ID . #4 ) FIGURE 5 Relaxin dibasic cleavage site mutants Description of the Preferred Embodiments Definitions The term "desired polypeptide" refers to any polypeptide intended to be produced in a host cell, but which the host cell either normally does not produce or produces in small amounts, and which is not normally necessary for the continued existence of the cell. Desired polypeptides include a polypeptide having as few as about five amino acids as well as much larger proteins such as factor VIII (2332 amino acids) . Desired polypeptides also include any molecule having a pre- or prepro-amino acid sequence, as well as amino acid or glycosylation variants (including natural alleles) capable of exhibiting a biological activity in common with the desired protein. Preferably the polypeptide is heterologous to the host cell in which it is made and is a human polypeptide. Preferred polypeptides are those that have pharmaceutical utility, such as: growth hormones, including human growth hormone, des-N-methionyl human growth hormone, and bovine growth hormone; parathyroid hormone; thyroid stimulating hormone; thyroxine; insulin; follicle stimulating hormone; calcitonin; leutinizing hormone; glucagon; factor VIII; bombesin; factor IX, thrombin; hemopoietic growth factor; tumor necrosis factor-alpha and -beta; relaxin; mouse gonadotropin-associated peptide; tissue factor protein; inhibin; activin; vascular endothelial growth factor; thrombopoietin; rheumatoid factors; nerve growth factor such as NGF-b; platelet-derived growth factor; fibroblast growth factor such as aFGF and bFGF; epidermal growth factor; transforming growth factor (TGF) such as TGF-alpha and TGF-beta; insulin-like growth factor-I and -II; erythropoietin; osteoinductive factors; an interferon such as interferon-alpha, -beta, and -gamma; nerve growth factor (NGF), BNDF, and NT-3; colony stimulating factors (CSFs) , .g., M-CSF, GM-CSF, and G-CSF; interleukins (ILs), e.g., IL-1, IL-2, IL-3, IL-4, etc.; decay accelerating factor; atrial natriuretic peptides A, B or C; and fragments of any of the above-listed polypeptides. In addition, one or more predetermined amino acid residues in the polypeptide may be substituted, inserted, or deleted, for example, to produce products with improved biological properties, or to vary expression levels, such as adding or deleting a dibasic amino acid site susceptible to cleavage by host cell enzyme. Some of the desired polypeptides falling within this present invention may optionally possess covalent or non-covalent modifications of features of a naturally occurring molecule, for example, glycosylation modifications. "Desired polypeptide precursor mutant" refers to a desired polypeptide precursor comprising a non-naturally occurring enzyme cleavage site as well as a desired polypeptide precursor mutant optionally having amino acid substitutions, deletions, and/or insertions at certain other positions provided that the final construct possesses the desired activity. The desired polypeptide precursor mutants of the present invention also include those mutants wherein glycosylation or other features of a naturally occurring molecule have been modified covalently or non- covalently provided that the final mutant construction possesses the desired activity. As used herein, "polypeptide factor, " refers to any protein necessary for the survival or growth of a host cell in culture. The polypeptide factor may be a hormone, growth factor, peptide hormone, autocrine factor, transport protein, oncogene/proto- oncogene and the like. Examples of polypeptide factors that are hormones are, for example, insulin, follicle stimulating hormone (FSH) , calcitonin, leutinizing hormone (LH) , glucagon, parathyroid hormone (PTH) , thyroid stimulating hormone (TSH) , thyroid releasing hormone (TRH) , and growth hormone. Additional examples of polypeptide factors are the transport proteins, such as, transferrin, serum albumin, ceruloplasm, low density lipoprotein (LDL) and high density lipoprotein (HDL) . Some polypeptide factors, often are described as autocrine because, in some instances, the cells they are secreted from can respond to the secreted factor; example of " such factors are interleukin-2, epidermal growth factor (EGF) , fibroblast growth factor (FGF) , thrombin, nerve growth factor, hemopoietic growth - factor and granulocyte- macrophage colony stimulating factor (GM-CSF) . Yet other examples of polypeptide factors are peptides resulting from the expression of certain oncogenes/proto-oncogenes. The proteins encoded by these proto-oncogenes encompassed by the polypeptide factors of this invention are growth factors, transducing proteins and membrane receptors.. Examples of a growth factor is PDGF (b subunit) encoded by the sis oncogene. Examples of peripheral membrane proteins are the truncated cell surface receptor for EGF encoded by erb-B, the cell surface receptor for M-CSF/CSF-1 encoded by fms and the receptors encoded by neu and ros. An example of a transducing protein is tyrosine kinase at the inner surface of the plasma-membrane encoded by abl. hile these polypeptide factors are typically not added to a culture medium, they may be substituted for another polypeptide factor. The definition of polypeptide factor includes amino acid mutants which maintain the functional characteristics of the polypeptide factor. These mutants may comprise one or more amino acid differences in the overall sequence and may be prepared by deletions, substitutions, and/or insertions of one or more amino acids in the overall sequence. Through the use of recombinant DNA technology polypeptide factor mutants may be prepared by altering the underlying DNA. All such variations or alterations in the structure of a polypeptide factor mutant is included within the scope of this invention so long as the functional activity is maintained. "Polypeptide factor precursor mutant" refers to a polypeptide factor precursor comprising a non-naturally occurring enzyme cleavage site. "Polypeptide factor-dependent host cell" refers to a host cell requiring one or more polypeptide factors in the culture medium for growth or survival. The polypeptide factor(s) for a particular host cell is determined using general methods known to the ordinarily skilled artisan.. Elimination of the polypeptide factor from the medium may result in death of the cell or in inhibited growth. "Heterologous polypeptide factor" is defined as a polypeptide factor not naturally occurring in the host cell. A "heterologous" element is defined herein to mean foreign to the cell, or (unless otherwise specified) homologous to the cell but in a position within the host cell in which the element is ordinarily not found. An "endogenous" element is defined herein to mean naturally occurring in the cell. An "endogenous host cell enzyme is defined to mean an enzyme which is endogenous to the cell. "Prohormone" refers to a hormone precursor. "Prohormone convertase" enzymes are specialized proteinases having conserved active site domains which are substrate specific and cleave exclusively at certain sets of basic residues, preferably Lys-Arg, Arg-Arg, Lys-Lys and Arg-Lys. This type of proteinase is responsible for processing large precursor proteins, such as prorelaxin, to their biologically active form. In the present invention prohormone convertase is used to refer to mammalian PCI and PC2, furin, and includes mammalian, yeast, or any prohormone convertase that is biologically active as described above. The yeast enzyme, Kex2, is specifically excluded from the definition of prohormone convertase enzymes. In the present invention "prohormone convertase cleavage site" refers to a cleavage site recognized by a prohormone convertase. "Basic residue" refers to amino acids in which the R groups have a net positive charge at pH 7.0, for example: Lysine, Arginine, Histidine. "Dibasic cleavage site" contains two amino acids with basic charges on their side chains that are specifically cleaved by ]prohormone convertases, the preferred amino acids are Lys-Arg, Arg-Arg, Lys-Lys and Arg-Lys. "Kex2" refers to a Saccharomyces yeast endoprotease which specifically processes a mating type factor and a killer factor. Kex2 contains an amino terminal catalytic domain followed by a cysteine-rich region, a transmembrane domain, and a short cytoplasmic tail. "Furin" refers to a protein encoded by the gene fur which has homology to the Kex2 protein and is involved in processing of protein precursors. Furin is expressed constitutively in most cell types including CHO, HepG2, PC12, BHK and in most tissue. Furin mediates basic cleavages which occur in the Golgi, and has a preference for cleaving Lys-Arg residues. Like Kex2, human furin contains an amino terminal catalytic domain followed by a cysteine- rich region, a transmembrane domain, and a short cytoplasmic tail. "Mammalian PCI ( PCl) " refers to the sequence identified in Fig 4, and all mammalian prohormone convertases having equal to or greater than 95% homology to the sequence in Fig. 4. "Mammalian PC2 (mPC2)" refers to the sequence identified in Fig.5 and all mammalian prohormone convertases having equal to or greater than 95% homology to the sequence in Fig 5. A "cleavage site recognizable by a host cell enzyme" refers to the cleavage site of an enzyme naturally occurring in a host cell The preferred naturally occurring enzyme of the present invention is a prohormone convertase. "Prohormone convertase precursor mutant" refers to a prohormone convertase precursor comprising a non-naturally occurring enzyme cleavage site as well as desired polypeptide precursor mutants optionally having substitutions, deletions, and/or insertions at certain other positions provided that the final construct possesses the desired activity. "Precursor" means a form of the protein which may be converted into the desired protein by processing. It may be a natural pro-form or prepro-form of the protein, or a synthetic pro-form wherein a gene coding for the desired protein is preceded by a heterologous signal, or leader sequence, and such as constructs which are routinely produced in vitro. An "Isolated" polypeptide means polypeptide which has been identified and separated and/or recovered from a component of its natural environment. Contaminant components of its natural environment are materials which would interfere with diagnostic or therapeutic uses for the polypeptide, and may include proteins, hormones, and other substances. In some embodiments, the polypeptide will be purified (1) to greater than 95% by weight of protein as determined by the Lowry method, and most preferably more than 99% by weight, (2) to a degree sufficient to obtain at least 15 residues of N-Terminal or internal amino acid sequence by use of a spinning cup sequenator, or (3) to homogeneity by SDS-PAGE using Coomassie blue or, preferably, silver stain. This definition specifically includes polypeptides present in situ in a host cell wherein the host cell in its native form lacks the polypeptide. Ordinarily, however, isolated polypeptide will be prepared by at least one purification step. In preferred embodiments, isolated prohormone convertase is utilized. "Nucleic acid" refers to a nucleotide sequence comprising a series of nucleic acids in a 5 ' to 3 ' phosphate diester linkage that may be either an RNA or a DNA sequence. If DNA, the nucleotide sequence is either single or double stranded. Polypeptide-encoding nucleic acid is RNA or DNA that encodes a biologically or antigenically active polypeptide, is complementary to nucleic acid sequence encoding such polypeptide, or hybridizes to nucleic acid sequence encoding such polypeptide and remains stably bound to it under stringent conditions. "Isolated" polypeptide nucleic acid is a nucleic acid that is identified and separated from at least one contaminant nucleic acid with which it is ordinarily associated in the natural source of the nucleic acid. Isolated nucleic acid is other than in the form or setting in which it is found in nature. Isolated prohormone convertase nucleic acid therefore distinguishes prohormone convertase nucleic acid as it exists in natural cells. However, isolated prohormone convertase nucleic acid includes prohormone convertase in ordinarily prohormone convertase-expressing cells where the nucleic acid is, for example, in a chromosomal location different from that of natural cells. "Hydrophobic transmembrane anchor" is the hydrophobic region of enzymes localized in the golgi, RER or other cellular membranes which facilitates localization of the enzyme in that region and reduces the loss of enzyme from the cell, specifically illustrating such anchors are the kex2 and furin transmembrane anchors. The term "mutant" as used herein is defined as a molecule in which the amino acid sequence, glycosylation, or other feature of a naturally occurring molecule has been modified covalently or noncovalently and is intended to include variants. Some of the variants falling within this invention possess amino acid substitutions or additions of a host cell enzyme cleavage sites and optionally also substitutions, deletions, and/or insertions at certain other positions provided that the final construct possesses the desired activity. The term "host cell" refers to those cells capable of growth in culture and capable of expressing a prohormone convertase, and / or a desired protein and/or a polypeptide factor(s). The host cells referred to in this disclosure encompass cells in in vitro culture as well as cells that are within a host animal. While the preferred host cells in in vitro culture of this invention are mammalian cells, other cells may be used. Some of the embodiments of this invention involve the use of a host cell enzyme which itself requires processing from a precursor to an active form; for those host cells, such as bacterial or yeast, that lack the enzyme required to process the host cell enzyme, such enzyme may be introduced into the host cell to facilitate practice of the methods of this invention. The expressions "cell," and "cell culture" are used interchangeably and all such designations include progeny and ancestors. 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 activity as screened for in the cell are included. Where distinct designations are intended, it will be clear from the context. "Transfection" refers to the taking up of an expression vector by a host cell whether or not any coding sequences are in fact expressed. Numerous methods of transfection are known to the ordinarily skilled artisan for example, CaPO and electroporation. Successful transfection is generally recognized when any indication of the operation of this vector occurs within the host cell. "Transformation" means introducing DNA into an organism so that the DNA is replicable, either as an extrachromosomal element or by chromosomal integrant. Depending on the host cell used, transformation is done using standard techniques appropriate to such cells. The calcium treatment employing calcium chloride, as described in section 1.82 of Sambrook et al . , supra , is generally used for prokaryotes or other cells that contain substantial cell-wall barriers. Infection with Agrobacterium tϋmefaci ens is used for transformation of certain plant cells, as described by Shaw et al. , Gene. 23: 315 (1983) and WO 89/05859 published 29 June 1989. For mammalian cells without such cell walls, the calcium phosphate precipitation method described in sections 16.30- 16.37 of Sambrook et al , supra , is preferred. General aspects of mammalian cell host system transformations have been described by Axel in U.S. 4,399,216 issued 16 August 1983. Transformations into yeast are typically carried out according to the method of Van Solingen et al . , J. Bact. , 130: 946 (1977) and Hsiao et al . , Proc. Natl. Acad. Sci. (USA) . 76 : 3829 (1979) . However, other methods for introducing DNA into cells such as by nuclear injection, electroporation, or by protoplast fusion may also be used. "Stably transformed host cell" refers to a cell wherein the " inserted nucleic acid is present either integrated in the host cell or extrachromosomally, and wherein the inserted nucleic acid is continuously produced by the cell for about two weeks after insertion of nucleic acid. General aspects of mammalian cell host system transformations have been described by Axel in ' U.S. 4,399,216 issued 16 August 1983. The term "medium" refers to the aqueous environment in which the mammalian cells are grown in culture. The medium comprises the physiochemical, nutritional, and hormonal environment. Traditionally the medium has been formulated by the addition of nutritional and growth factors necessary for growth or survival. "Serum-free medium" refers to a medium lacking serum. The hormones, growth factors, transport proteins, peptide hormones and the like typically found in serum which are necessary for the survival or growth of particular cells in culture are typically added as a supplement to serum-free medium. A "defined medium" refers to a medium comprising nutritional and hormonal requirements necessary for the survival and growth of the cells in culture such that the components of the medium are known. A defined medium provided by the method of the instant invention establishes a local environment for a particular host cell that may differ from the general environment of the medium. Cells in serum-free medium generally require insulin and transferrin for optimal growth. These two factors should be tested first when determining what factors a given cell requires. Most cell lines require one or more of the growth factors. These include epidermal growth factor (EGF) , fibroblast growth factor (FGF) , insulin-like growth factors I and II (IGF-I, IGF-II), nerve growth factor (NGF), etc. Other classes of factors which may be necessary include: transport and binding proteins (e.g., ceruloplas in, high and low density lipoprotein [HDL, LDL] , albumin); and hormones. "Stringent conditions" are those hybridization conditions that (1) employ low ionic strength and high temperature for washing, for example, 0.015 M NaCl ' /0.0015 M sodium citrate/0/1% NaDodS0 4 at 50° C; (2) employ 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 mM sodium phosphate buffer at pH 6.5 with 750 mM NaCl, 75 mM sodium citrate at 42° C; or (3) employ 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 g/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. "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 Lawn et al . , Nucleic Acids Res.. !: 6103-6114 (1981), and Goeddel et al . , Nucleic Acids Res. £: 4057 (1980) . "Polymerase chain reaction, " or "PCR, " as used herein generally refers to a procedure wherein minute amounts of a specific piece of nucleic acid, RNA and/or DNA, are amplified as described in U.S. Pat. No. 4,683,195 issued 28 July 1987. Generally, sequence information from the ends of the region of interest or beyond needs to be available, such that oligonucleotide primers can be designed; these primers will be identical or similar in sequence to opposite strands of the template to be amplified. The 5' terminal nucleotides of the two primers may coincide with the ends of the amplified material. PCR can be used to amplify specific RNA sequences, specific DNA sequences from total genomic DNA, and cDNA transcribed from total cellular RNA, bacteriophage or plasmid sequences, etc. See generally Mullis et al. , Cold Spring Harbor Symp. Quant. Biol .. 51 : 263 (1987); Erlich, ed., PCR Technology. (Stockton Press, NY, 1989). As used herein, PCR is considered to be one, but not the only, example of a nucleic acid polymerase reaction method for amplifying a nucleic acid test sample, comprising the use of a known nucleic acid as a primer and utilizing a nucleic acid polymerase to amplify or generate a specific piece of nucleic acid. "Oligonucleotide-mediated mutagenesis" refers to a method for preparing substitution, deletion, and insertion mutants of prohormone convertase 1 or 2 encoding DNA. This technique is well known in the art as described by Adelman et al . , DNA, 2.: 183 (1983). Briefly, the prohormone convertase 1 or 2 DNA is altered by hybridizing an oligonucleotide encoding the desired mutation to a DNA template, where the template is the single-stranded form of a plasmid or bacteriophage containing the unaltered or native DNA sequence of the prohormone convertase 1 or 2. After hybridization, a DNA polymerase is used to synthesize an entire second complementary strand of the template that will thus incorporate the oligonucleotide primer, and will code for the selected alteration in the prohormone convertase 1 or 2. Generally, oligonucleotides of at least 25 nucleotides in length are used. An optimal oligonucleotide will have 12 to 15 nucleotides that are completely complementary to the template on either side of the nucleotide(s) coding for the mutation. This ensures that the oligonucleotide will hybridize properly to the single-stranded DNA template molecule. The oligonucleotides are readily synthesized using techniques known in the art such as that described by Crea et al . (Proc. Natl. Acad. Sci. USA. 75.: 5765 [1978]). "Glycosylation" refers to the post-translational modification process of adding a series of sugar residues to-* proteins to produce glycoproteins. Glycosylation can occur in the cytosol, the endoplasmic reticulum, or the Golgi apparatus of mammalian cells. "pRK5" and "pRK7" are expression vectors used to transform mammalian cells. The construction of expression vector pRK5 was described in European Patent Application 0307247A2, published March 15, 1989. The pRK7 vector was described in European Patent Application 278,776 published August 17, 1988. "Regulated protein secretory pathway" refers to the cellular pathway for exocytosis which is regulated over short periods of time by physiological stimuli, such as cyclic AMP. This pathway is not required for cell viability and is only present in specialized secretory cells such as .endocrine and exocrine cells. "Constitutive protein secretory pathway" refers to the unregulated cellular pathway which is found in cells such as macrophages and fibroblastε. "Human insulin" refers to a protein exhibiting a biological activity in common with naturally occurring human insulin. Human insulin biological activity includeε promoting glucose utilization, protein synthesiε, and the formation and storage of neutral lipids. "Human proinsulin" is defined to be a molecule containing the B, C, and A chain amino acid sequence and includes amino acid variants that maintain the functional characteriεtics of inεulin discussed above. These variants may comprise one or more amino acid differences in the overall sequence and may be prepared by deletions, subεtitutions, and/or insertionε of one or more amino acids in the overall sequence. Through the use of techniques common in the field, human proinsulin mutants may be prepared by altering the protein itself or the nucleic acid encoding the protein. All εuch variations or alterationε in the structure of human proinεulin resulting in human proinsulin variants are included within the scope of this invention so long as the functional activity of proinεulin iε maintained. "Human relaxin" denoteε a functional protein capable of exhibiting a biological activity. Human relaxin biological activity iε defined as any of 1) immunological cross-reactivity with at least one epitope of human relaxin or 2) the possesεion of a leaεt one hormonal function in common with human relaxin. "Human prorelaxin" iε defined to be a molecule containing the B, C, and A chain amino acid sequence and includes amino acid variants which maintain the functional characteristics discusεed above. These variants may compriεe one or more amino acid differenceε in the overall sequence and may be prepared by deletions, substitutions, and/or insertionε of one or more amino acids in the overall sequence. Through the use of recombinant DNA technology human prorelaxin mutants may be prepared by altering the underlying DNA. All such variations or alterations in the structure of human prorelaxin resulting in human prorelaxin variants are included within the scope of this invention so long as the functional activity is maintained. As used herein, "IGF-I" refers to IGF-I from any species, including bovine, ovine, porcine, equine, and preferably human, in naturally occurring-sequence or in variant form, or from any source, whether natural., synthetic, or recombinant. Variants may comprise one or more amino acid differences in the overall sequence and may be prepared by deletions, substitutions, and/or insertions of one or more amino acids in the overall sequence. All such variations or alterations in the structure of IGF-I resulting in human prorelaxin variants are included within the scope of this invention so long as the functional activity is maintained. Use of Prohormone Convertase in Mammalian Cell Culture In the present invention, the host cells expressing a prohormone convertase may be used to express polypeptide factors needed for cell growth and anabolism. Mammalian cells frequently require one or more hormones from each of the following groups: steroids, prostaglandins, growth factors, pituitary hormones, and polypeptide hormones. Most cell types require insulin to survive in serum-free media. (Sato, G.H. et al. in Growth of Cells in Hormonally Defined Media, [Cold Spring Harbor Press, N.Y., 1982]). In addition to the hormones, cells may require transport proteins such as transferrin (plasma iron transport protein) , ceruloplasmin (a copper transport protein) , and iiigh density lipoprotein (a lipid carrier) to be added to cell media. The set of optimal hormones or transport -proteins will vary for each cell type. Most of these hormones or transport proteins have been added exogenously or, in a rare case, a mutant cell line has been found which does not require a particular factor. Cellular proliferation has been studied to elaborate the events necessary to lead from quiescent growth arrest to the cellular commitment to proliferate. Various polypeptide factors have been found to be involved in that transformation. These transformed cells have been found to produce peptide growth factors in culture. (Kaplan, P.L. et al., PNAS 79:485-489 [1982]). The εecretion from a cell of a factor to which that εame cell can reεpond haε been referred to aε an "autocrine" system. Numerous factors have been described as autocrine: bombesin, interleukin-2 (Duprez, V. et al. PNAS 82:6932 [1985]); inεulin, (Serrero, G. In Vitro Cellular __ Dev. Biol. 21[9] :537 [1985]); transforming growth factor alpha (TGF-a) , platelet-derived growth factor (PDGF) ; tranεforming growth factor-beta (TGF- b) , (Sporn, M.B. & Robertε, A.B., Nature 313:745 [1985]); sarcoma growth factor (SGF) , (Anzano, M.A. et al. , PNAS 80:6264 [1983]); and, hemopoietic growth factor, granulocyte-macrophage colony stimulating factor (GM-CSF) , (Lang, R.A. et al. , Cell 43:531 [1985]). The methods of the present invention are suitable for cells expresεing one or more prohormone convertases and further comprising nucleic acid encoding a polypeptide factor required for proliferation or for maintenance of cellular integrity. In the present invention the preferred polypeptide factor is insulin. In the present invention, the host cells expresεing a prohormone convertaεe may be uεed to expreεε any desired polypeptide which requires processing from a precursor form. The cells of the present invention may be used in cell culture to produce any polypeptide of interest even those not requiring processing by a prohormone convertase. In the present invention nucleic acid encoding a prohormone convertase may be introduced prior to the introduction of nucleic acid encoding a deεired polypeptide or a polypeptide factor. In the present invention, nucleic acid encoding a prohormone convertase may be introduced simultaneously with nucleic acid encoding a desired polypeptide or a polypeptide factor wherein the nucleic acid may be on the same or separate vectors. As described more fully herein, the present invention describes a method for the production of a heterologous polypeptide factor in a polypeptide factor-dependent host cell comprising a) introducing into the polypeptide factor- dependent host cell nucleic acid encoding a heterologous polypeptide factor precursor comprising a cleavage site recognizable by a host cell enzyme and wherein said host cell is dependent on the cleavage product of said polypeptide factor precurεor; and b) culturing said host cell under conditions wherein the polypeptide factor precursor is cleaved at said cleavage site by the host cell enzyme, thereby producing said polypeptide factor. Optionally polypeptide factor is recovered. The present invention further describes a method for the production of a desired polypeptide in a host cell expressing a prohormone convertase comprising a) introducing into the host cell expressing said prohormone convertase nucleic acid encoding a desired polypeptide; and b) culturing said host cell under conditions wherein said desired polypeptide is expressed. Optionally the desired polypeptide is recovered. For any of the cleavage events described herein, additional host cell enzyme or heterologous enzyme is added to the host cell as desired. The present invention discloses nucleic acid encoding a polypeptide factor precursor mutant comprising an prohormone convertase cleavage site. Another aspect of the present invention is a nucleic, acid encoding a prohormone convertase that is joined to nucleic acid encoding a hydrophobic transmembrane anchor. This joined nucleic acid directs the synthesis of a polypeptide fusion product wherein the catalytically active prohormone convertase is covalently attached to a hydrophobic transmembrane anchor. Among the preferred hydrophobic transmembrane anchors are the KEX2 hydrophobic transmembrane anchor and the furin hydrophobic transmembrane anchor. The present invention also provides for a prohormone convertase precursor mutant having nucleic acid encoding a prohormone convertase cleavage site. The present invention further provides for host cells having nucleic acid encoding a polypeptide factor precursor mutant comprising a prohormone convertase cleavage site. The nucleic acid and methods disclosed herein are suitable for use for expression in a wide range of host cell lines. Mammalian cells are the preferred host cell for expressing prohormone convertases. The host cell of the present invention may be a mammalian cell that does not normally expresε detectable amountε of prohormone convertase. In addition, the mammalian cell of the present invention may be a mammalian cell that produces levels of prohormone convertase that are insufficient to process the desired polypeptide precursor to desired polypeptide. Transformation of such cells by nucleic acid encoding a prohormone convertase results in an increaεe in prohormone convertase sufficient to process desired polypeptide precursor to polypeptide. Isolation of Nucleic Acid The nucleic acid encoding the prohormone, convertase, or other polypeptide of interest may be obtained from any cDNA library prepared from tiεεue or cells believed to posseεε the polypeptide mRNA and to expreεε it at a detectable level . The deεired gene may also be obtained from a genomic library. Libraries are screened with probes designed to identify the gene of interest or the protein encoded by it. For cDNA expreεεion libraries, suitable probes include monoclonal or polyclonal antibodieε that recognize and εpecifically bind to the deεired polypeptide; oligonucleotideε of about 20-80 baεeε in length that encode known or εuspected portions of the polypeptide of interest's cDNA from the same or different species; and/or complementary or homologous cDNAs or fragmentε thereof that encode the εame or a εimilar gene. Appropriate probes for screening genomic DNA libraries include, but are not limited to, oligonucleotides; cDNAs or fragments thereof that encode the same or a εimilar gene; and/or homologouε 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. , supra. An alternative meanε to iεolate the gene encoding the polypeptide of interest is to use polymerase chain reaction (PCR) methodology as described in section 14 of Sambrook et al., supra. This method requires the use of oligonucleotide probes that will hybridize to the gene of interest. Strategies for selection of oligonucleotides are described below. Another alternative method for obtaining the gene of interest is to chemically synthesize it using one of the methods described in Engels et al. (Agnew. Chem. int. Ed. Engl., 28: 716-734 [1989]). These methods include triester, phosphite, phosphoramidite and H-Phosphonate methods, PCR and other autoprimer methods, and oligonucleotide syntheses on solid supports. These methods may be used if the entire nucleic acid sequence of the gene is known, or the sequence of the nucleic acid complementary to the coding strand is available, or alternatively, if the target amino acid sequence is known, one may infer potential nucleic acid sequences using known and preferred coding residues for each amino acid residue. A preferred method of practicing this invention is to use carefully selected oligonucleotide sequences to screen cDNA libraries from variouε tissues, depending on the source of the gene or polypeptide of interest. The oligonucleotide sequenceε selected as probes should be of sufficient length and sufficiently unambiguous that false positives are minimized. The actual nucleotide sequence(s) is usually based on conserved or highly homologous nucleotide sequences or regions of other polypeptides homologous to the polypeptide of interest. The oligonucleotides may be degenerate at one or more positions. The use of degenerate oligonucleotides may be of particular importance where a library is screened from a species in which preferential codon usage in that species 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 32-P labeled ATP with polynucleotide kinase ' , as is well known in the art, to radiolabel the oligonucleotide. However, other methods may be used to label the oligonucleotide, including, but not limited to, biotinylation or enzyme labeling. Of particular interest is prohormone convertase nucleic acid that encodes a full-length polypeptide. in some preferred embodiments, the nucleic acid sequence includes the prohormone convertase signal sequence. Nucleic acid having all the protein coding sequence is obtained by screening selected cDNA or genomic libraries, and, if necessary, using conventional primer extension procedures aε deεcribed in section 7.79 of Sambrook et al., supra, to detect precursorε and proceεεing intermediateε of mRNA that may not have been reverεe-transcribed into cDNA. In preferred embodiments of this invention DNA hybridization probeε are uεed to identify novel prohormone convertaεe candidate enzyme messages in cell lines containing regulated secretory pathways. The murine pituitary tumor cell line AtT-20 is suitable because it is neuroendocrine-derived, and secretes ACTH. It would therefore be expected to contain procesεing enzymeε involved in the converεion of the prohormone proopiomelanocortin (POMC) precurεor to mature ACTH, a process which requires cleavage at specific pairs of basic amino acids in the prohormone substrate. Candidate cDNAs expressed, in the AtT-20 cells may be amplified by the MOPAC procedure (Innis 1990) using degenerate primer sequences based on those of Smeekens and Steiner (1990) . In particularly preferred embodiments, two PC-like cDNAs are amplified and cloned from the AtT-20 cells: mPC2 (greater than 95% homologous to the human PC2 of Smeekens and Steiner) and second sequence similar to mPC2 , termed mPCl. Construction of polypeptide mutants Amino acid sequence variants of the prohormone convertase, polypeptide factor, deεired polypeptide or other polypeptide of intereεt are prepared by introducing appropriate nucleotide changeε into the encoding DNA, or by in vitro synthesiε of the deεired polypeptide. ' Such variants include, for example, deletions from, or insertions or εubεtitutions of, reεidues within the amino acid sequence for the polypeptide of interest. Any combination of deletion, insertion, and substitution can be made to arrive at the final construct, provided that the final construct possesses the desired characteristics. The amino acid changes also may alter post-translational processes of the polypeptide, such as changing the number or position of glycosylation sites, altering the membrane anchoring characteristics, and/or altering the intra- cellular location of the polypeptide by inserting, deleting, or otherwise affecting the leader sequence of the naturally occurring polypeptide of interest. In designing amino acid sequence polypeptide variants, the location of the mutation site and the nature of the mutation will method of labeling is to use 32-P labeled ATP with polynucleotide kinase, as is well known in the art, to radiolabel the oligonucleotide. However, other methods may be used to label the oligonucleotide, including, but not limited to, biotinylation or enzyme labeling, substituting first with conservative amino acid choices and then with more radical selections depending upon the results achieved, (2) deleting the target residue, or (3) inserting residues of the same or a different class adjacent to the located site, or combinations of options 1-3. • 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. In general, the location and nature of the mutation chosen will depend upon the characteristic to be modified. Amino acid sequence deletions generally range from about 1 to 30 residues, more preferably about 1 to 10 residues, and typically are contiguous. Deletions may be introduced into regions of low homology between the polypeptide of interest and other polypeptides to modify the activity of the polypeptide of interest. Deletions from the polypeptide of interest in areas of substantial homology with any other polypeptide will be more likely to modify the biological activity of the polypeptide of interest more significantly. The number of consecutive deletions will be selected so as to preserve the tertiary structure of polypeptide of interest in the affected domain, e.g., beta-pleated sheet or alpha helix. Amino acid εequence insertions include amino- and/or carboxyl-terminal fuεions 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. Intraεequence inεertions (i.e., insertions within the sequence of the polypeptide of interest) may range generally from about 1 to 10 residueε, more preferably 1 to 5, most preferably 1 to 3. An example of a terminal insertion is an N-terminal methionyl residue, an artifact of the direct expresεion of a polypeptide in bacterial recombinant cell culture. Other inεertional variants of the polypeptide of intereεt include the fuεion to the N- or C-terminus of the polypeptide of immunogenic polypeptideε, e.g., bacterial polypeptideε εuch as beta-lactamase or an enzyme encoded by the E. coli trp locuε, or yeaεt protein, and C-terminal fusions with proteins having a long half-life such as immunoglobulin constant regions (or other immunoglobulin regions), albumin, or ferritin, as described in WO 89/02922 published 6 April 1989. Another group of variants are amino acid εubεtitution variants. These variants have at least one amino acid residue in the polypeptide of intereεt removed and a different reεidue inεerted in its place. The sites of greatest interest for substitutional mutagenesiε include sites identified as the active εite(ε)« of the polypeptide of intereεt, and sites where the amino acids found in homologous polypeptides from various specieε are εubεtantially different in terms of εide-chain bulk, charge, and/or hydrophobicity. DNA encoding amino acid εequence variantε of the beta- 8 integrin subunit is prepared by a variety of methods known in the art. These methods include, but are not limited to, isolation from a natural source (in the case of naturally occurring amino acid sequence variants ' ) or preparation by oligonucleotide-mediated (or site-directed) mutagenesis, PCR mutageneεis, and caεsette mutagenesis of an earlier prepared variant or a non-variant version of the beta-8 integrin subunit. These techniques may utilized beta-8 integrin subunit nucleic acid (DNA or RNA) , or nucleic acid complementary to the beta-8 integrin subunit nucleic acid. In the present invention, the site-directed mutagenesis method of Kunkel, Methods of Enzymoloαv 154:367-383, 1987 are particularly preferred. Another method for preparing the prohormone convertase mutants of this invention are preferably constructed by mutating the nucleic acid sequences that encode the native prohormone convertase. Generally, particular regionε or sites of the nucleic acid will be targeted for mutagenesis, and thus the general methodology employed to accomplish this is termed site-directed mutagenesiε. In the preεent invention the preferred method of site-directed mutagenesis is by the method of Kunkel (Methods of Enzymology 154:367- 382, 1987). Another method for preparing mutants of this invention is by oligo-mediated mutagenesis. Oligonucleotide-mediated mutagenesis is a preferred method for preparing substitution, deletion, and insertion mutants of prohormone convertase 1 or 2 encoding DNA. This technique is well known in the art as deεcribed by Adelman et al . , DNA, 2.: 183 (1983). Briefly, the prohormone convertase 1 or 2 DNA is altered by hybridizing an oligonucleotide encoding the desired mutation to a DNA template, where the template is the single-stranded form of a plasmid or bacteriophage containing the unaltered or naturally occurring DNA sequence of the prohormone convertase 1 or 2. After hybridization, a DNA polymerase iε used to synthesize an entire second complementary strand of the template that will thus incorporate the oligonucleotide primer, and will code for the selected alteration in the prohormone convertase 1 or 2. Generally, oligonucleotides of at least 25 nucleotides in length are used. An optimal oligonucleotide will have 12 to 15 nucleotides that are completely complementary to the template on either side of the nucleotide(s) coding for the mutation. This ensures that the oligonucleotide will hybridize properly to the single-stranded DNA template molecule. The oligonucleotides are readily synthesized using techniques known in the art such as that described by Crea et al . (Proc. Natl. Acad. Sci. USA. 75: 5765 [1978]) . PCR mutagenesis is also εuitable for making amino acid mutantε While the following diεcuεεion herein may refer to DNA, it iε underεtood that the technique also finds application with RNA. The PCR technique refers to the procedure outlined in Genetic Engineering Vol 12 pp 115-137, [1990] by Arnheim; Analytical Chemistry, vol 62 pp 1202-1214 [1990] by Gibbs; and Science vol 252 pp. 1643-1651 [1991] by Gelfand Mutants Affecting Polypeptide precursor processing One aεpect of the preεent invention iε a polypeptide factor precurεor mutant containing modification within the nucleic acid encoding pre-pro or pro sequence which optimizes the precursor processing by the prohormone convertase. Cells vary widely in their processing capability, and consequently, in the prohormone maturation products that are ultimately secreted from them. This difference in procesεing of polypeptide factor precurεor mutantε could be the reεult of εeveral factors: (a) the precursor sequence itself could influence the accesεibility of the prohormone convertase to the cleavage site, (b) each specific pattern could represent a distinctly different procesεing enzyme, (c) there could be a limited number of prohormone convertaεeε that exhibit εpecificity due to their location (microenvironment) or relative abundance within the cell, (d) similar precursorε could be modified in the variouε cell types influencing their accesεibility to the prohormone convertase. In the present invention, one preferred polypeptide factor precurεor mutant iε a human proinsulin mutant having a prohormone convertase cleavage site wherein the cleavage site is processed in the constitutive pathway of the host cell. The preferred proinsulin variant is one comprising a residue substitution for naturally occurring residues in the Type I and/or Type II cleavage sites as outlined: Proinsulin residue Lys 29 is subεtituted with any of a residue selected from the group of Arg, His, Cys, Met, Phe, Tyr, Trp, Pro, Gly, Ala, Val, lie, Leu, Ser, Thr, Asp, Glu, Gin, Asn, and most preferably Arg. Proinsulin residue Arg 31 is substituted with any of a residue selected from the group of Lyε, His, Cys, Met, Phe, Tyr, Trp, Pro, Gly, Ala, Val, lie. Leu, Ser, Thr, Asp, Glu, Gin, Asn, and moεt preferably Lyε. Proinsulin residue Leu 62 is substituted with any of a residue selected from the group of Arg, His, Cys, Met, Phe, Tyr, Trp, Pro, Gly, Ala, Val, lie, Lys, Ser, Thr, Asp, Glu, Gin, Asn, and most preferably Lys or Arg. Site-directed mutagenesis by the method of Kunkel (Kunkel 1987) is a preferred method for preparing substitution, deletion, and insertion variants of polypeptide precurεorε. A preferred mammalian prohormone convertaεe 1 (mPCl) precursor mutant comprises a residue substitution for naturally occurring residues in the prohormone. convertase cleavage site of the precursor as outlined: mPCl precursor residue Lys 80 is substituted with any of a residue selected from the group Arg, His, Cys, Met, Phe, Tyr, Trp, Pro, Gly, Ala, Val, lie. Leu, Ser, Thr, Asp, Glu, Gin, Asn, and most preferably Arg. A preferred mammalian prohormone convertase 2 (mPC2) precursor mutant comprises a residue substitution for naturally occurring residues in the prohormone convertase cleavage site of the precursor as outlined. mPC2 precursor residue Lys 77 iε subεtituted with any of a residue selected from the group Arg, His, Cys, Met, Phe, Tyr, Trp, Pro, Gly, Ala, Val, lie, Leu, Ser, Thr, Asp, Glu, Gin, Asn, and most preferably Arg. mPC2 precursor residue Arg 78 is substituted with any of a residue selected from the group Lys, His, Cys, Met, Phe, Tyr, Trp, Pro, Gly, Ala, Val, lie, Leu, Ser, Thr, Asp, Glu, Gin, Asn, and most preferably Ala. mPC2 precursor residue Arg 79 is substituted with any of a residue selected from the group Lys, His, Cys, Met, ' Phe, Tyr, Trp, Pro, Gly, Ala, Val, lie, Leu, Ser, Thr, Asp, Glu, Gin, Asn, and most preferably Lys. Insertion of DNA into a Cloning Vehicle The cDNA or genomic DNA is inserted into a replicable vector for further cloning (amplification of the DNA) or for expression. Construction of suitable vectors containing the desired coding and control εequenceε employε standard recombinant techniques . Isolated plasmidε or DNA fragments are cleaved, tailored, and religated to form the desired plaεmid. Many vectors are available, and selection of the appropriate vector will depend on 1) whether it is to be used for DNA amplification or for DNA expresεion, 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 or expresεion 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 εignal εequence, an origin of replication, one or more marker genes, an enhancer element, a promoter, and a transcription termination sequence. The preferred replicable vector is pRK5 or pRK7. Signal Sequence Component In general, the signal sequence may be a component of the vector, or it may be a part of the prohormone convertase DNA that is inserted into the vector. For example the native prohormone convertaεe DNA encodeε a signal sequence at the amino terminus (5' end of the DNA) of the polypeptide that is cleaved during post- translational procesεing of the polypeptide to form the mature prohormone convertase polypeptide. Included within the scope of this invention are polypeptides with the native signal sequence deleted and replaced with a heterologous εignal sequence. The heterologous signal sequence selected should be one that is recognized and procesεed (i.e. cleaved by a εignal peptidaεe) by the hoεt cell. In mammalian cell expreεεion the native εignal sequence is generally satiεfactory, although other mammalian signal sequences may be suitable. Origin of Replication Component Most expression vectors are "shuttle" vectors, i.e. they are capable of replication in at least one clasε of organisms but can be transfected into another organism for expression. For example, a vector is cloned in E. coli and then the same vector is tranεfected into yeast or mammalian cells for expression even though it is not capable of replicating independently of the host cell chromosome. DNA may also be amplified by insertion into the host genome. This is readily accomplished using Bacil lus species as hosts, for example, by including in the vector a DNA sequence that is complementary to a sequence found in Bacillus genomic DNA. Transfection of Bacillus with this vector results in homologous recombination with the genome and insertion of the prohormone convertase subunit DNA. Selection Gene Component Expression and cloning vectors should contain a selection gene, also termed a selectable marker. This gene encodes a protein necessary for the survival or growth of transformed host cells grown in a selective culture medium. Host cells not transformed with the vector containing the selection gene will not survive in the culture medium. Typical selection genes encode proteins that (a) confer resistance to antibiotics or other toxins, e.g. ampicillin, neomycin, methotrexate, or tetracycline, (b) complement auxotrophic deficiencies, or (c) supply critical nutrients not available from complex media. One example of a selection scheme utilizes a drug to arrest growth of a host cell. Thoεe cellε that are successfully transformed with a heterologous gene express a protein conferring drug resistance and thus survive the selection regimen. Examples of such dominant selection use the drugs neomycin (Southern et al . , J. Molec. Appl. Genet. , 1: 327 [1982]), mycophenolic acid (Mulligan et al . , Science. 209: 1422 [19801) or hygromycin (Sugden et al . , Mol. Cell. Biol.. 5_: 410-413 [1985]). The three examples given above employ bacterial genes under eukaryotic control to convey resistance to the appropriate drug G418 or neomycin (geneticin) , xgpt (mycophenolic acid) , or hygromycin, respectively. An example of suitable selectable markers for mammalian cells are those that enable the identification of cells competent to take up the prohormone convertase nucleic acid, such as dihydrofolate reductase (DHFR) or thymidine kinase. The mammalian cell transformants are placed under selection pressure which only the transformants are uniquely adapted to survive by virtue of having taken up the marker. Selection presεure iε imposed by culturing the transformantε under conditions in which the concentration of selection agent in the medium is succeεεively changed, thereby leading to amplification of both the selection gene and the DNA that encodes the polypeptide of interest. Amplification is the process by which genes in greater demand for the production of a protein critical ' for growth are reiterated in tandem within the chromosomes of succesεive generationε of recombinant cells. Increased quantities of the polypeptide of intereεt are synthesized from the amplified DNA. For example, cells tranεformed with the DHFR εelection gene are first identified by culturing all of the transformants in a culture medium that contains methotrexate (Mtx) , a competitive antagonist of DHFR. An appropriate host cell when wild-type DHFR is employed is the Chinese hamster ovary (CHO) cell line deficient in DHFR activity, prepared and propagated as described by Urlaub and Chaεin, Proc. Natl. Acad. Sci. USA. 77 : 4216 [1980] . The transformed cells are then expoεed to increased levels of methotrexate. This leadε to the εyntheεiε of multiple copies of the DHFR gene, and, concomitantly, multiple copies of other DNA compriεing the expreεεion vectorε, εuch as the DNA encoding the prohormone convertase. This amplification technique can be used with any otherwise suitable host, e.g., 293 or CHO cells, ATCC No. CCL61 CHO- Kl, notwithstanding the presence of endogenous DHFR if, for example, a mutant DHFR gene that is highly resistant to Mtx is employed (EP 117,-060) . Alternatively, host cells (particularly wild-type hosts that contain endogenous DHFR) transformed or co-transformed with DNA sequences encoding the polypeptide of interest, wild-type DHFR protein, and another selectable marker such as aminoglycoside 3 ' phosphotransferase (APH) can be selected by cell growth in medium containing a selection agent for the selectable marker such as an aminoglycosidic antibiotic, e.g., kanamycin, neomycin, or G418. See U.S. Pat. No. 4,965,199. Promoter Component Expression and cloning vectors usually contain a promoter that is recognized by the host organism and is operably linked to the nucleic acid encoding the polypeptide of interest. Promoters are untranslated sequences located upstream (5') to the start codon of a structural gene (generally within about 100 to 1000 bp) that control the tranεcription and translation of a particular nucleic acid sequence, such as that encoding a prohormone convertase, to which they are operably linked. Such promoters typically fall into two classes, inducible and constitutive. Inducible promoters are promoters that initiate increased levels of transcription from DNA under their control in response to some change in culture conditions, e.g. the presence or absence of a nutrient or a change in temperature. At this time a large number of promoters recognized by a variety of potential host cells are well known. These promoters are operably linked to DNA encoding the polypeptide of interest by removing the promoter from the source DNA by restriction enzyme digestion and inserting the isolated promoter sequence into the vector. Both the native promoter sequence and many heterologous promoters may be used to direct amplification and/or expression of the polypeptide of interest. ' However, heterologous promoters are preferred, as they generally permit greater transcription and higher yields of expressed polypeptide of interest as compared to the native prohormone convertase promoter. Promoter sequences are known for eukaryotes. Virtually all eukaryotic genes have an AT-rich region located approximately 25 to 30 bases upstream from the site where transcription is initiated. Another sequence found 70 to 80 baεeε upstream from the start of transcription of many genes is a CXCAAT region where X may be any nucleotide. At the 3' end of most eukaryotic genes is an AATAAA sequence that may be the signal for addition of the poly A tail to the 3' end of the coding sequence. All of these sequences are suitably inεerted into mammalian expression vectors . Polypeptide transcription from vectors in mammalian host cells is controlled by promoters obtained from the genomes of viruses such as polyoma virus, fowlpox virus (UK 2,211,504 published 5 July 1989), adenovirus (such as Adenovirus 2), bovine papilloma virus, avian sarcoma virus, cytomegalovirus, a retrovirus, hepatitiε-B virus and most preferably Simian Virus 40 (SV40) , from heterologous mammalian promoters, e.g. the actin promoter or an immunoglobulin promoter, from heat-shock promoters, and from the promoter normally asεociated with the polypeptide of intereεt, provided εuch promoters are compatible with the host cell systems. The early and late promoters of the SV40 virus are conveniently obtained as an SV40 restriction fragment that also containε the SV40 viral origin of replication. Fiers et al . , Nature. 223:113 (1978); Mulligan and Berg, Science, 209: 1422-1427 (1980); Pavlakis et al . , Proc. Natl. Acad. Sci. USA. 78 : 7398-7402 (1981) . The immediate early promoter of the human cytomegaloviruε iε conveniently obtained aε a Hindlll E restriction fragment. Greenaway et al . , Gene, 18: 355-360 (1982) . A syεtem for expreεεing DNA in mammalian hoεtε using the bovine papilloma virus as a vector is disclosed in U.S. 4,419,446. A modification of this system is described in U.S. 4,601,978. See also Gray et al . , Nature, 295: 503-508 (1982) on expresεing cDNA encoding immune interferon in monkey cells; , Reyes et al . , Nature . 297 : 598-601 (1982) on expresεion of human -interferon cDNA in mouse cells under the control of a thymidine kinase promoter from herpes simplex virus, Canaani and Berg, Proc. Natl. Acad. Sci. USA, 79: 5166-5170 (1982) on expression of the human interferon 1 gene in cultured mouse and rabbit cells, and Gorman et al . , Proc . Natl. Acad. Sci. USA, 79: Sill- 6781 (1982) on expression of bacterial CAT sequences in CV-1 monkey kidney cells, chicken embryo fibroblasts, Chinese hamster ovary cells, HeLa cells, and mouse NIH-3T3 cells using the Rous sarcoma virus long terminal repeat as a promoter. Enhancer Element Component Transcription of a DNA encoding the polypeptide of interest of this invention by higher eukaryotes is often increased by inserting an enhancer sequence into the vector. Enhancers are cis-acting elements of DNA, usually about from 10-300 bp, that act on a promoter to increase its transcription. Enhancers are relatively orientation and position independent having been found 5' (Laimins et al . , Proc. Natl. Acad. Sci. USA, 78: 993 [1981]) and 3' (Lusky et al . , Mol. Cell Bio. , 3_: 1108 [1983]) to the transcription unit, within an intron (Banerji et al . , Cell. 33 : 729 [1983]) as well as within the coding sequence itself (Osborne et al . , Mol. Cell Bio.. 4.: 1293 [1984]). Many enhancer sequences are now known from mammalian genes (globin, elastase, albumin, a-fetoprotein and insulin) . Typically, however, one will use an enhancer from a eukaryotic cell virus. Examples include the SV40 enhancer on the late side of the replication origin (bp 100-270), the cytomegalovirus early promoter enhancer, the polyoma enhancer on the late εide of the replication origin, and adenovirus enhancerε. See alεo Yaniv, Nature, 297: 17-18 (1982) on enhancing elementε for activation of eukaryotic promoters. The enhancer may be spliced into the vector at a position 5' or 3' to the desired DNA, but is preferably located at a site 5" from the promoter. Transcription Termination Component Expression vectors used in eukaryotic host cells (insect, plant, animal, human, or mammalian cells) will also contain sequences necessary for the termination of transcription and for stabilizing the mRNA. Such sequences are commonly available from the 5' and, occasionally 3 ' untranslated regions of eukaryotic or viral DNAs or cDNAs. These regions contain nucleotide segments transcribed as polyadenylated fragments in the untranslated portion of the mRNA encoding the prohormone convertase. The 3 ' untranslated regions also include transcription termination sites. Construction of suitable vectors containing one or more of the above listed components and including the desired coding and control sequenceε employε εtandard ligation techniques. Isolated plasmids or nucleic acid fragments are cleaved, tailored, and religated in the form deεired to generate the plasmids required. Particularly useful in the practice of thiε invention are expression vectors that provide for the transient expression in mammalian cells of DNA encoding the polypeptide of interest. In general, transient expresεion involveε 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, syntheεizeε high levelε of a desired polypeptide encoded by the expression vector. Transient expression systems, comprising a suitable expression vector and a host cell, allow for the convenient positive identification of polypeptides encoded by cloned 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 polypeptide analogs and variants that have desired activity. Other methods, vectors, and host cells suitable for adaptation to the synthesiε of the prohormone convertaεe and other polypeptideε of this invention in recombinant mammalian cell culture are described in Gething et al . , Nature. 293 : 620-625 [1981]; Mantei et al . , Nature, 281: 40-46 [1979]; Leyinson et al . ; EP 117,060; and EP 117,058. A particularly useful plaεmid for mammalian cell culture expreεεion of the prohormone convertaεe εubunit iε pRK5 (EP pub. no. 307,247) or pSVIδB. Selection and Transformation of Host Cells Suitable hoεt cells for cloning or expressing the vectors herein are the higher eukaryote cells described above. Suitable host cells for the expresεion of glycosylated polypeptide are derived from multicellular organisms. Such hose cells are capable of complex processing and glycosylation activities. In principle, any higher eukaryotic cell culture is workable, whether from 5 vertebrate or invertebrate culture. Examples of invertebrate cells include plant and insect cells. However, interest has been greatest in vertebrate cells*, and propagation of vertebrate cells in culture (tissue culture) has become a routine procedure in recent years 0 rTissue Culture. Academic Press, Kruse and Patterson, editors (1973)]. Examples of useful mammalian host cell lines are monkey kidney CVl line transformed by SV40 (COS- 7, ATCC CRL 1651); human embryonic kidney line (293 or 293 cells subcloned for growth in suεpenεion culture, Graham et 5 al . , J. Gen Virol.. 36: 59 [1977]); baby hamster kidney cells (BHK, ATCC CCL 10); Chinese hamster ovary cells/-DHFR (CHO, Urlaub and' Chasin, Proc. Natl. Acad. Sci. USA. 77: 4216 [1980]); mouse sertoli cells (TM4, Mather, Biol. Reorod.. 23: 243-251 [1980]); monkey kidney cells (CVl ATCC 0 CCL 70); African green monkey kidney cells (VERO-76, ATCC CRL- 1587); 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 (W138, ATCC CCL 75); human liver cells (Hep G2, HB 8065); 5 mouse mammary tumor (MMT 060562, ATCC CCL51) ; TRI cells (Mather et al . , Annals N.Y. Acad. Sci.. 383: 44-68 [1982]); 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. ό Host cells are transfected and preferably transformed with the above-described expression or cloning vectors of this invention and cultured in conventional nutrient media modified as appropriate for inducing promoters, selecting transformants, or amplifying the genes encoding the -desired sequences. It is further envisioned that the cells comprising nucleic acid encoding the polypeptide of interest of ' this invention may be produced by homologous recombination, or with recombinant production methodε utilizing control elementε introduced into cells already containing nucleic acid encoding the polypeptide of intereεt currently in use in the field. For example, a powerful promoter/enhancer element, a suppreεsor, or an exogenous transcription modulatory element iε inεerted in the genome of the intended hoεt cell in proximity and orientation εufficient to influence the tranεcription of nucleic acid encoding a deεired prohormone convertase. The control element does not encode the prohormone convertase of this invention, but affects the prohormone convertase nucleic acid which is present in the host cell genome. One next screens for cells making the prohormone convertase of this invention, or increaεed or decreaεed levels of expreεεion, as desired. Mammalian cells may be stably tranεformed uεing any acceptable vector known to transform a particular cell type. A preferred vector is the pRK5 used in the present invention with 293 human kidney cell. For example, the mammalian cells are transformed to produce a prohormone convertase and these cells are then used to produce properly processed hormone by transforming them to express a prohormone. Among the preferred prohormones are those that when procesεed result in hormoneε containing two or more polypeptide chains. Preferred two chain hormones are relaxin and insulin. Culturing the host cells Prokaryotic cells used to produce the polypeptide of this invention are cultured in suitable media aε described generally in Sambrook et al . , supra . The mammalian host cells used to produce the polypeptides of this invention may 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'ε Medium ( [DMEM] , Sigma) 'are εuitable for culturing the hoεt cells. In addition, any of the media deεcribed in Ham and Wallace, Meth. Enz. , 58: 44 (1979), Barnes and Sato, Anal. Biochem.. 102: 255 (1980), U.S. 4,767,704; 4,657,866; 4,927,762; or 4,560,655; WO 90/03430; WO 87/00195; U.S. Pat. Re. 30,985; or U.S. 5,122,469, issued 16-Jun-1992 may be used aε culture media for the hoεt 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 a.s sodium chloride, calcium, magnesium, and phosphate) , buffers (such as HEPES) , nucleosides (such as adenosine and thymidine) , antibiotics (such as Gentamycin TM 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, are those previously used with the host cell selected for expression, and will be apparent to the ordinarily skilled artisan. *********** The foregoing written specification is considered to be sufficient to enable one skilled in the art to practice the invention. Various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description and fall within the scope of the appended claims. The following examples are intended to illustrate the best mode now known for practicing the invention, but the invention is not to be considered limited to these examples. EXAMPLE 1 Cloning of Murine Prohormone Convertases Type 1 (mPCl) and Type 2 (mPC2) The mouse pituitary tumor cell line, AtT20, was used as the source for candidate prohormone convertase mRNA's. The AtT-20 ' cell line was obtained from the American Type Culture Collection (Rockville, MD) . Cells were grown in Dulbecco's modified Eagle's medium (DMEM) containing 10% fetal calf serum. Total RNA was prepared from confluent cells (Maniatis 1983) and cDNA was generated by incubation of 5ug total RNA with 400 U Moloney murine leukemia ' virus reverse transcriptase (GIBCO-BRL) , 2.5 mg GeneAmp 10 X reaction buffer (Perkin Elmer-Cetus) , 20 U RNasin ribonuclease inhibitor (Promega) , 400mM dNTPε, 0.5 mg oligo- dT (United States Biochemical) , 1.4 mM MgCl 2 , 10 mM DTT; all in a total volume of 25 uL for 1 hour at 37 degrees C. Amplification uεing a degenerate polymeraεe chain reaction (PCR) of candidate prohormone convertase targets was carried out in the same reaction tube by adding 50 pmol each of forward and reverse MOPAC PCR primers, 0.02 mmol dNTPs, with an additional 7.5 mL 10X reaction buffer plus 5 U Tag DNA polymerase. The primer sequences were based on the conserved aspartate and εerine catalytic reεidueε of KEX2, PC2, Proproteaεe B, and εubtiliεin BPN as described in Smeekens, et al (The Journal of Biological Chemistry Vol 265, pp. 2997-3000 [1990]) . The forward primer used was: 5 'GCAAAATCTAGA(C/T) (G/T)GCIAT (C/T)GTIGA(C/T)GA(G/T)GGI3 ' (Seq. ID #5) and the reverse primer was: 5'AAGCATGAGCTCIGG(A/G)GC(A/G)GC(A/G)GCIGAICC3 ' (Seq. ID #6) . Thirty cycles of degenerate PCR were done, each consiεting of denaturation (1 min, 94 degreeε C) , primer annealing (2 min, 48 degreeε C for the first 5 cycles; 2 min at 55 degreeε C thereafter) , and primer extenεion (3 min, 72 degrees C) . The products from the PCR reaction were electrophoresed in a 2.5% NuSieve-GTG low melting agarose gel (FMC) . Diεcrete bandε of approximately 600 bp were excised and subcloned into pUCllδ for DNA sequence analysis. Partial mPCl and mPC2 sequences were derived by this procedure. A cDNA pool was prepared as a source of template for the cloning of full length sequenceε of the candidate PC enzymes (Frohman 1988; Innis 1990) . Mouse AtT-20 total RNA (5mg) was heated for 3 min at 65 "C and immediately chilled on ice. The denatured RNA was added together with 200 U reverse transcriptase to a first strand cDNA synthesis reaction containing 4 mL 5 X H-RT buffer (GIBCO-BRL) , 10 mM DTT, 1 mM dNTPs, 20 U RNasin, and 2.5 pmol R Q Ri-d(T)i 7 adapter primer: 5' GATATCACTCAGATCGATGAATTCGAGCTC (T) 17 3' (Seq. ID #7) all in a final volume of 20uL. The mixture waε incubated for 1 hour at 37 degrees C and diluted to 1 mL with Tris/EDTA. Aliquots (5-10 uL) of the cDNA pool were used for amplifications of unknown 3 ' and 5 ' regions by RACE-PCR (rapid amplification of cDNA endε, Frohman 1988; Inniε 1990) using a combination of gene-specific PCR primers (for mPCl they were: 3 'RACE primer 5'AAGCTTTCTAGAGGATCCCTCTGGTGGATTTGG3 ' (Seq ID #8) and 5'RACE primer 5 'AAGCTTGAATTCTCCAACCCCACACTTGTG3 ' (Seq. ID #9) and the inner adapter R PCR primer 5 ' AGATCGATGAATTCGAGCTC 3 ' (Seq. ID No. 10). Final construction of the full length mPCl and mPC2 cDNAε was though the technique of recombinant PCR (Innis 1990) . All PCR cloning reactions were carried out with Vent DNA polymerase (New England Biolabs) to minimize the introduction of mismatched bases during amplification of template. All mPC clones were sequenced with the Sequenase 2.0 kit from USB and cloned into PUC118 (Vieira, et al Methods Enzvmologv 153 [1987]). EXAMPLE 2 Relaxin Production in Transfected Cells Construction of relaxin and prohormone convertase expression vectors The cDNA clone of the preprorelaxin gene, pCIS.Rx, provided the coding sequence of the human preprorelaxin. The pCIS mammalian expreεsion vector is described in (Gorman DNA Prot Eno Tech 2:3-10, 1990). The cDNA encoding H2 preprorelaxin was excised from the cloning vector as described in Hudson, P et al.. The EMBO Journal 3, 2333- 2339, [1984] by using a complete Hpa II digest followed by a Hinf I partial digest. pCIS.Rx was digested by restriction endonucleases XBA I and ECO RI to excise the coding region of preprorelaxin. pRK7 was digested by restriction endonucleases XBA I and ECO RI. The resultant XBA I/ECO RI human preprorelaxin coding region was ligated into the XBA I/ECO RI digested pRK7 yielding the final preprorelaxin mammalian expression vector, pRK.Rx. The cDNA clone of the mPCl gene, PUCllδ.mPCl from example 1, provided the coding sequence of the mPCl for construction of plasmids to direct the expression of " mPCl in transfected mammalian cells. PUCllδ.mPCl is digested with restriction endonucleases SAC I and ECO RI. pRK7 is digeεted with restriction endonucleaεes SAC I and ECO RI . The reεultant SAC I/ECO RI mPCl coding region is ligated into the SAC I/ECO RI digested pRK7 to yield the final mPCl mammalian expresεion vector, pRK.mPCl. The cDNA clone of the mPC2 gene, PUC118.mPC2 from example 1, provided the coding εequence of the mPC2 for conεtruction of plaεmidε to direct the expreεsion of mPC2 in transfected mammalian cells. PUCll8.mPC2 is digested with restriction endonucleaseε XBA I and ECO RI . pRK7 is digested with restriction endonuclease XBA I and ECO RI . The resultant XBA I/ECO RI mPC2 coding region is ligated into the XBA I/ECO RI digested pRK7 to yield the final mPC2 mammalian expresεion vector, pRK.mPC2. The cDNA clone of the KEX2 gene, pYEp24.pJ28 (Julius, et al , Cell vol 37, p 1075 [1984]) .provided the coding εequence of the KEX2 gene for conεtruction of the final KEX2 mammalian expreεεion plaε id. Vector pYEp24.pJ28 waε digested with restriction endonucleaεe Eco RI and run on an Agarose gel. A 3.3 kb fragment containing the coding region was isolated. pRK5 was digested with restriction endonuclease Eco RI, and then treated with bacterial alkaline phosphataεe (BAP) . The Eco RI digeεted, BAP treated pRK5 waε run on an agaroεe gel and a 4.7 kb fragment was isolated. The 3.3 kb fragment of pYEp24.pJ28 was ligated to the 4.7kb fragment of pRK5 to form vector pRK.KEX.Rl. pRK.KEX.Rl was digested with restriction nuclease Dde I, then treated with Klenow, and further digested with restriction endonuclease Hind III. The Dde I/Hind III treated pRK.KEX.Rl was run on a polyacrylamide gel and a 425bp fragment waε isolated. pRK5 was digested with restriction endonuclease Sma I/Hind III, then treated with BAP, run on an agarose gel and a 4.7kb fragment waε isolated. The 4.7kb fragment of pRK5 was ligated to the 425 bp fragment of pRK.KEX.Rl to form vector pRK5.5'KEX. pRK5.5'KEX was digeεted with Hind III and treated with BAP. A 2 kb Hind III fragment encoding the 3 ' end of KEX2 was derived from vector pYEp24.pJ28 and was ligated to the Hind III/BAP treated vector pRK5.5' .KEX forming the final KEX mammalian expression vector pRK . KEX2 which directs the expression of KEX2 in transf ected mammalian cells . Transient transfection of relaxin in human kidney 293 cells . Human Kidney 293 cells were . subj ected to transient transfection by the method of Gorman (Gorman DNA Prot Eng Tech 2 : 3 -10 . 1990 ) . Expression vector containing prorelaxin cDNA, pRK.Rx, (lOug) was transfected into 293 cells alone (100 mm dish) , or together with an equal amount of expression vectors for mPCl (pRK.mPCl) , mPC2 (pRK.mPC2) or kex2 (pRK.kex2 ) cDNAs . Stable transfection of relaxin in Human Kidney 293 Cel ls General aspects of mammalian cell host syεtem transformations have been described by Axel in U . S . 4 , 399 , 216 issued 16 August 1983 . The preferred method for stable transformation of a mammalian cell of the present invention is the calcium phosphate precipitation method described in sections 16.30-16.37 of Sambrook et al, supra. The preferred host cell is the human embryonic kidney line (293 ) or Chineεe hamster ovary cellε/-DHFR (CHO) . The preferred media containε the antibiotic neomycin or genet icin. Characterization of Processed Relaxin Immunoaf f inity purificat ion Following tranεf ection, culture medium was removed and replaced by 2mL DMEM (minus cysteine and methionine) containing 200uCi each of 35 S- cysteine and 35S -methionine (Amersham) . After a 3 hr " incubation, the supernatant was collected and cells were washed with PBS . Cells were lysed with 1 mL lysis buf fer (150 mM NaCl , 1% NP-40 , 50mM Tris- HCl pH 8.0 ) . Both supernatant and whole-cell lysate were analyzed by immunoprecipitation. Supernatants (500uL) and whole-cell lysates (250uL) from the transfections were mixed with 5 mg of anti-relaxin monoclonal antibody (MAbRlx6) for an overnight incubation, with gentle rocking at 4 degrees C . Antibody-antigen complexes were absorbed onto protein A-Sepharose CL4B beads (Pharmacia-LKB) at 4 degrees C for 1 hour. The beads were briefly centrifuged and gently washed three timeε with lyεiε buffer. Liquid was aεpirated off and 50 mL 2 X tricine/SDS εample buffer (25% glycerol, 8% SDS, 1.5% Serva Blue G, 0.9 M Tiε-HCl pH 8.45) was added to the beads. Samples were heated for 10 min at 85 degrees C and lOuL aliquots were applied to pre-cast tricine/SDS 10-20% polyacrylamide gradient gels (Novex) . Following electrophoresiε, gels were fixed, soaked in Ampligy (Amerεham) , dried and exposed to X-ray film at -80 degree C. Following tranεfection of 293 cells with the expression plasmid for prorelaxin, pRK.Rx, only the precurεor prorelaxin immunoprecipitated from cell lyεateε or cell εupernatants. The prorelaxin bands at about 6.0 KD on a 10-20% polyacrylamide gradient gel. Co-transfection of 293 cells with the expreεsion plasmid for prorelaxin, pRK.Rx, and pRK.mPC2, which directs expresεion of the mouse mPC2 cDNA, yieldε only the precursor prorelaxin, indicating that mPC2 is not involved in procesεing native prorelaxin in thiε εyεtem. Co-expression of prorelaxin and mPCl cDNA's or prorelaxin and KEX2 yielded mature, bonafide relaxin, which bandε at about 3.0 KD on a 10-20% polyacrylamide gradient gel. Reverse phase HPLC and mass spectrometry analysis For preparative analyεiε of cell-εecreted protein, three 10 cm dishes of confluent cells were transfected with substrate proH2Relaxin alone, or with a combination of proH2Relaxin (wild-type or mutant) and processing enzyme cDNAs. A total of 30 uL of supernatant was collected from each transfection and passed twice over a small (300uD column of anti-relaxin monoclonal antibody linked to Sepharose-CL4B for immunoaffinity purification. The column was washed with PBS and no-εpecifically absorbed material was removed by a 1 M NaCl in PBS wash, followed by 2 M guanidine»HCl in 10 mM Tris-HCl pH 7.5. Antibody-bound protein was eluted with a small volume of ' 4 M guanidine»HCl/Tris->HCl. The immunoaffinity column eluant was applied without further purification to a 2 X 100 mm RP-C 4 reverse phase HPLC column (Synchrom) . Material was eluted by application of a linear gradient of acetonitrile in 0.1% Trifluoroacetic acid from 20% (0-5 min) to 60% (5-45 min) . The flow rate waε held at 0.5 mL/min and the abεorbance at the column outlet waε monitored at 214 nm. Eluants from major peaks of absorbance were collected for analysis by mass spectrometry (Figure 8) . The intact molecular weights of prorelaxin and processed relaxin were measured by electrospray ionization mass spectrometry. Micromolar solutions (1-lOpmol/ul) of protein in aqueous acetonitrile (50/50, v/v) with 1% acetic acid were infused at 1.5 ul/min into a SCIEX API III mass spectrometer. The quadrupole mass spectrometer was operated with the Ionspray articulated nebulizer (SCIEX, Thornhill, Canada) at 4600 V, the interface plate at 600 V, and the orifice at 100-120V. Data were collected every 0.1 v with the quadrupole scanning from 600-2200 u in 32 seconds. Molecular weights of the individual A and B chains were determined by fast atom bombardment (FAB) mass spectrometry following on-probe reduction as described by Stults et al. (Biomed Environ Mass Soectrom 19:655-664 {1991}). Transfection of pRK.Rx alone resulted in the secretion of prorelaxin as the major product. This species had an HPLC elution time of 29 minutes. Co-transfection of pRK.Rx with either pRK.mPCl or pRK.KEX2 generated a major species that gave an HPLC retention time of 17 minutes. This retention time was very similar to that observed for authentic mature relaxin purified from human corpus luteum. Co-transfection major peaks eluting from the column were collected for analysis by mass spectrometry. Electrospray measurements generated mass values consistent with authentic mature relaxing This was confirmed further by fast atom bombardment analysis of reduced 5963 Da species. Two peaks of 2657 and 3313 mass units were obtained, exactly corresponding to the predicted values for reduced relaxin A and B chains, respectively. Material from the 5963 Da relaxin was εubjected to εeveral rounds of N-terminal peptide sequencing in a gas phase sequencer. No sequence was obtained for the A-chain as expected due to the pyroglutamyl residue that blocks itε N-terminuε. All amino acids detected were from the B chain and had a peptide sequence consistent with correct removal of the 24 amino acid signal sequence that precedes the B chain. Additionally, the mature B-chain terminates with a εerine residue at its C-terminus suggesting that carboxypeptidase activity preεent in the 293 cellε removed the reεidual basic residues, KR, which remain following cleavage at the B-chain / C-peptide junction. EXAMPLE 3 Human Relaxin Mutants and PC Specificity Prohormone convertase subεtrate specificity is exemplified by processing of human prorelaxin mutants. A series of mutant prorelaxin cDNAs were made in which baεic residues thought to be required for processing were replaced with alanine. Two dibasic residues, KR, are located at the B-chain / C-peptide junction and both are required for processing. When either of these baεic amino acids is replaced by alanine, unprocesεed prorelaxin is secreted from the 293 cells. There is no indication of intermediate proteinε indicative of a partially processed precursor, which might have resulted from partial cleavage at the C-peptide / A-chain junction. Site-directed mutagenesis of prorelaxin Site-directed mutageneεiε waε performed on the relaxin mammalian expression vector, pRK.Rx, by the method of Kunkel (Kunkel 1987) with some minor modifications. Transformation-competent (CaCl 2 ) CJ236 strain of E. Coli was used as the bacterial host for the synthesis of uracil- containing template phagemid DNA, and T 4 enzyme. The oligonucleotide extension reaction was performed in a 10 uL volume for an initial period of 15 min at room temperature, followed by a 75 min incubation at 37 degrees C. The reaction was terminated by the addition of Tris/EDTA buffer to a final volume of 50 uL. A 10 uL aliquot was used to transform an ung+ strain of E. coli , MM299, for selection against uracil-containing wild-type template DNA. This strain was also used to produce single strand DNA for use in sequencing analysis by the chain termination method (Sequenase kit, United States Biochemical) . Identification of prohormone convertase substrate specificity. Prorelaxin alanine mutations of the basic residues K- and R were constructed to define murine prohormone convertase 1 specificity. Figure 11. The following mutations were tested for substrate specificity to murine prohormone convertase 1: 1.4 , 2.4, 3.2, 4.3, 7.2 and 8.6. The relaxin (Rx) mutants have the following sequence in the prohormone convertase cleavage site. C- chain/ A-chain junction mutants Native Rx H ' S R K K R Q (Seq. No. #48) CAT TCT CGA AAA AAG AGA CAA (Seq. No. #11) Rx 1.4 H S V K K R Q (Seq. No.- #49) CAT TCT GTA AAA AAG AGA CAA (Seq. No. #12) Rx 2.4 H S R A K R Q (Seq. No. #50) CAT TCT AGA GCA AAG AGA CAA (Seq. No. #13) Rx 3.2 H S R K A R Q (Seq. No. #51) CAT TCT AGA AAA GCA AGA CAA (Seq. No. #14) Rx 4.3 H S R K R A Q (Seq. No. #52) CAT TCT AGA AAA AGA GCA CAA (Seq. No . #15) B-chain/C-chain junction mutants Native Rx T W S K R S L (Seq. No. #53) ACC TGG AGC AAA AGG TCT CTG (Seq. No. #16) Rx7.2 T W S A R S L (Seq. No. #54 ' ) ACC TGG AGC GCT AGG TCT CTG (Seq. No. #17) Rx8 . 6 T W S K A S L ( Seq . No . #55 ) ACC TGG AGC AAA GCT TCT CTG (Seq. No. #18) Figure 9 illustrates murine prohormone convertase 1 procesεing of theεe mutantε. Mutantε 1.4 and 2.4 are proceεεed the εame aε wild-type and mutant 3.2 iε partially proceεεed.. Mutant 4.3 doesn't appear to be proceεsed and mutants 7.2 and 8.6 are not processed. Disrupting the B-C chain junction at either the position mutated at mutants 7.2 or 8.6 prevents any cleavage of prorelaxin. The C-A chain is probably not available for cleavage by murine prohormone convertase 1 until the B-C chain junction is cleaved. This data supports a progresεive cleavage mechaniεm involving cleavage of thiε upεtream εite firεt. The B-C chain εite requireε both baεic reεidueε. Mutantε 3.2 and 4.3 point out that while basic reεidueε are required (aε εeen with 7.2 and 8.6) they are not sufficient. Both mutantε 3.2 and 4.3 have intact KR sites and mutant 3.2 is not cleaved as well as wild-type and mutant 4.3 is not cleaved by murine prohormone convertase 1. Murine prohormone convertase 2 does not cleave the wildtype prorelaxin. Murine prohormone convertaεe 2 doeε not cleave any of the prorelaxin mutants with the exception of 4.3 where there iε some processing. This suggeεtε that there is a difference in the specificity of cleavage for murine prohormone convertase 1 and murine prohormone convertase 2 which is defined by sequences other than the dibasic residues. Non-substrate proteins can be made to be substrates by appropriate mutagenesis. Mutant 7.2 is not cleaved by murine prohormone convertase 2. Mutation of an upstream site in prorelaxin prevents downstream cleavage illustrating the presence of progreεsive cleavage of prorelaxin. EXAMPLE 4 Construction of Proinsulin Mutants and Insulin Expression in Transfected 293 Cells The cDNA clone of the human preproinsulin gene , pSVEHIGDHFR, described in Australian patent 616 , 201 issued February 18, 1992, provided the coding sequence of the human preproinsulin gene for the final mammalian expression vector. Aliquots (5-10 uL) of pSVEHIGDHFR were used for amplification of the coding region by RACE-PCR (rapid amplification of cDNA ends, Frohman 1988; Innis 1990) using a combination of gene-specific PCR primers: for the 5" end they were CAT AAG CTT ACC ATG GCC CTG TGG ATG CGC (Seq ID #18) (sequence given 5' to 3').and for the 3' end they were CAT TCT AGA CTA GTT GCA GTA GTT CTC CAG (Seq. ID #19) (sequence given 5' to 3 ' ) . All PCR cloning reactions were carried out with Vent DNA polymerase (New England Biolabs) to minimize the introduction of mismatched bases during amplification of template. All proinsulin clones were sequenced with the Sequenase 2.0 kit from USB and cloned into restriction digested pRK5. The final preproinsulin mammalian vector is pRK.proins. A human proinsulin mutant having a non-naturally occurring prohormone convertase cleavage site is constructed by mutating the human proinsulin cDNA, ' pRK.proins, encoding the naturally occurring basic cleavage site at the B-chain/C-peptide junction (KTRR) (Seq ID #20) and/or A-chain/C-peptide junction (LQKR) (Seq ID #21) by site-directed mutagenesiε (Kunkel 1987) . The following proinsulin variantε were constructed: proins.RTKR.Ip (Seq ID #22), proinε.RQKR.IIp (Seq ID #23), proins.RTKR.Ip (Seq ID #24) . The following double proinsulin variants were constructed: proins.KR.Ip/RQKR.IIp (Seq ID #23), and proins.RTKR.Ip (Seq. ID #22) /RQKR.IIp (Seq. ID #23). Ip is the Type I enzyme cleavage site and lip is the Type II enzyme cleavage site. Primers used in proinsulin mutant construction were the following: PROINS.RTKR.Ip CTCTGCCTCCCGCTTGGTCCTGGGTGTGTAG (Seq. ID #25) PROINS.RQKR.Up CACGCTTCTGCCGGGATCCCTC (Seq. ID #26) PROINS.KTKR.Ip CTCTGCCTCCCGCTTGGTCTTCGGTGTGTAG (Seq. ID #27) The sequences are listed in 5 ' —>3 ' orientation. The double proinsulin mutant proins.KR.Ip/RQKR.IIp (Seq. ID #23) changes the native human proinsulin residue Arg 31 to Lys 31 at the Type I enzyme cleavage site, and proinsulin residue Leu 62 is changed to Arg 62 at the Type II enzyme cleavage site. The double proinsulin mutant proins RTKR.Ip (Seq. ID #22) /RQKR.IIp (Seq. ID #23) changes the native human proinsulin residue Lys 29 to Arg 29 at the Type I enzyme cleavage site, reεidue Arg 31 to Lyε 31 at the Type I enzyme cleavage εite and proinsulin residue Leu 62 is changed to Arg 62 at the Type II enzyme cleavage site. All mutants were εcreened through the primer regionε with the Sequenaεe 2.0 kit from USB. DNA from all proinεulin mutantε and naturally occurring proinεulin waε CεCl banded and uεed for 293 cell tranεient tranεfection by the method of Gorman (Gorman DNA Prot Eno Tech 2:3-10, 1990) . The next day, cells were labeled with 35S Met and 3- c .S Cys (200uCi/ml) and labeled for 4-6 hours. Immunoaffinity purification Supernatants (500uL) or whole-cell lysateε (500uL) from the tranεfections were mixed with 4 ul of Cone. Guinea Pig Anti-Human Insulin Lot 101, from Biomeda for an overnight incubation, with gentle rocking at 4 degrees C. Protein A Sepharose (CL4B-Pharmacia 17-0963-03) waε prepared by washing 5 mis of Protein A Sepharose with NP40 lysis buffer. The wash procedure was repeated 4 times. After the last wash was aspirated, enough buffer was added to provide a 25% v/v slurry of Protein A Sepharose-Cl4B. 100 ul 25% protein A slurry was added to each overnight sample containing the Cone. Guinea Pig Anti-Human Insulin Lot 101, from Biomeda. Incubate 1 hour at 4 degreeε with rocking. Centrifuge 15 seconds, aspirate εupernatant into waste, and wash 3 times with NP 40 lysiε buffer. Aspirate buffer. Add 30 ul 2x Tricine-SDS sample buffer to- each sample tube. Heat 100 degrees for 10 minutes and apply lOuL aliquotε to pre-cast tricine/SDS 16% polyacrylamide gradient gels (Novex) . Following electrophoreεis, gels were fixed, soaked in Ampligy (Amersham) , dried and exposed to X-ray film at -80 degree C. Gel results Transfections using native human proinsulin DNA resulted in a prominent protein band at 6.5 KD and a faint band at 3.4 KD. Transfectionε using the DNA of proinsulin variant proins.RTKR.Ip (Seq. ID #22)/RQKR.IIp (Seq. ID #23), resulted in protein bands at 3.4KD and 2.35 KD where authentic insulin B and A chains, respectively, run on 16% tricine/SDS polyacrylamide gradient gels (NOVEX) . Transfections using the DNA of proinsulin mutants, proins.RQKR.Up (Seq. ID #23) or double mutant proins.KR.Ip/RQKR.IIp (Seq. ID #23), resulted in two bands, one band at about 6.0 KD representing the B-chain/C-peptide intermediate band and one band at 2.35 KD representing the insulin A-chain. Transfections using the DNA of proinsulin variant, proins.RTKR.Ip (Seq. ID #22), resulted in two bands, one band running slightly below the B-chain/C-peptide intermediate band representing the C-peptide/A-chain intermediate band and one band at 3.4 KD representing the insulin B-chain. Transfections using the DNA of proinsulin mutant, proins.KTKR.Ip(Seq. ID #24) resulted in one prominent band at 6.5 KD and a faint band at 3.4 KD. EXAMPLE 5 Construction of Prohormone Convertase Mutants Prohormone convertase precursor residues involved in processing of the precursor form of the prohormone convertase to the bioactive form of the prohormone convertase are mutated such that the prohormone convertase precursor is processed by the prohormone convertase naturally occurring in the human kidney 293 cell Site-directed mutagenesis of the mammalian expression vector, pRK.mPCl or mammalian expression vector, pRK.mPC2 is by the method of Kunkel (Kunkel 1987) . The following primers were used in the Prohormone Convertase precursor mutant construction: mPCl primer GAT ATG AAG AGC AGA TCT TTT GGA CCT CCG AGG ATG (Seq. ID #28) mPC2 primer CTT ATG GTG TAA GCT TCG TTT TGC TCT GGC CTT TGC AAG (Seq. ID #29) where primerε are given in a 5' to 3 ' direction. The PCI primer results in a mammalian prohormone convertase 1 mutant having the native residue ARG.80 mutated to LYS.80. The PC2 primer results in a prohormone convertase mutant having the native mammalian prohormone convertase 2 residues LYS.77 ARG.78 ARG.79 mutated to ARG.77 ALA.78 LYS.79 All mutants were εcreened through the primer regions with the Sequenase 2.0 kit from USB. EXAMPLE 6 Processing of NGF, BNDF and NT-3 Mutants by mPC 1 and 2 To elucidate the role of the precursor in the processing of the neurotrophic factors, chimeric pRK5 expression vectors were conεtructed to contain the precursor of NGF, NT-3, or BDNF linked to the mature portion of NGF or the NT-3 precursor linked to the mature portion of BDNF. The entire PCR amplified region of each chimera containing the * NGF mature εequence waε found to be identical to the publiεhed εequenceε for each precurεor portion and for the mature NGF with the exception of a silent point mutation in codon #403 in pRK5.BDNFNGF. Plasmid vector pRK5 was used in all constructions. Nerve Growth Factor (NGF) , Neurotrophic Factor 3 (NT-3), or Brain Derived Neurotrophic Factor (BDNF) Nerve Growth Factor (NGF) , Neurotrophic Factor 3. (NT- 3), or Brain Derived Neurotrophic Factor (BDNF) cDNA were inserted into the cloning linker of pRK5 producing pRK5.NGF, pRK5.BDNF, and pRK5.NT-3. Plasmid DNA was transformed into E. coli 294 cells and cultured to saturation in 1 liter of Super Broth (12% tryptone in H2θ, 24% yeast extract in H2O, 0.5% glycerol, 70 mM K2HPO4, 25 mM KH2PO4) . The plasmid DNA was isolated by alkaline lysis and purified via cesium chloride double banding according to the procedures in Sambrook et al. (1989). PRK.NT3NGF plasmid construction DNA encoding prepro NT-3 was spliced to the DNA encoding the mature portion of NGF using a polymerase chain reaction (PCR) (Saiki et al., 1985, Mullis et al. 1986). 0.5 μg of both pRK5.NT3 and pRK5.NGF were linearized with Hind III. The precurεor portion of NT3 was amplified using primers a and b while the mature portion of NGF was amplified using the c and d primers as shown in Table 1. PRIMER SEQUENCE 5'-->3' LOCATION /strand a TACAACTCACCGCGGGTCCTG (Seq ID #30) 1247-1267 NT3 /S b AAGATGGGATGGGATGATGACCGTTTCCGCCTTGATGT (Seq ID #31) 1349-1366 NT3 /AS 1407-1426 NGF /AS c ACATCACGGCGGAAACGGTCATCATCCCATCCCATCTT (Seq ID #32) 1349-1366 NT3 /S 1407-1426 NGF /S d GATATAAGCTTGAGAGTGTAGAAGGGGC (Seq ID #33) 1794-1810 NGF /AS The location of priming within each plasmid is listed as well as the strandedness (" r S" indicates sense primers and "AS" indicates antisense primers) . PCR was performed on a Thermal Cycler 460 (Perkin-Elmer Cetus) under the following conditions: 100 mL reaction volumes, 50 pmol primers, 200 μM dNTP's, 10 mM b- mercaptoethanol, 16.6 mM (NH )2S0 , 67 nM Tris-HCl pH " 8.8, 6.7 mM MgCl2, 6.7 mM EDTA, and 0.15 mg/ml BSA. The reaction cycle consisted of denaturation at 94 degrees C for 1 min, annealing at 55 degrees C for 1 min, and elongation at 72 degrees C for 3 min. After 35 cycles, aliquots of PCR reactions 1 and 2 were purified on an 8% acrylamide gel. Bands of 119 base pairε for the NT3 precursor and 414 base pairs for NGF mature were cut out and the DNA was recovered via electroelution as previously described (Maniatis et al. 1982). Purified products from reactions 1 and 2 were spliced together in PCR reaction 3 using the a and d primers under the same amplification conditions. (Both a and d primers contain a restriction site that will be used for cloning back into the pRK vector.) Final PCR reaction products were phenol/chloroform extracted, ethanol precipitated, and digested to completion with Sst II and Hind III. Digestion products were electrophoresed on a 1% NuSieve gel. The 533 base pair fragment was cut out of the gel and used in the ligation reactions described below to generate the pRK5.NT3NGF ' fusion plasmid. Plasmid pRK5.NT3 was digeεted to completion with HindiII and Eco RI in one reaction and Eco RI and Sst II in a second reaction. Reaction products were electrophoresed on a 1% NuSieve gel. The 4681 and 337 base pair bands were cut out of the gel, melted, and ligated together with the melted 533 baεe pair fuεion product deεcribed above according to standard protocol. (Maniatis, 1989) .. Ligation products were melted for 5 minutes at 65 degrees C, diluted with 100 μl 10 mM MgCl2, and transformed into E. coli 299 cells. After picking colonies and screening them via restriction endonuclease digestion, single stranded DNA was prepared and sequenced through the entire PCR fusion area as previously stated. PRK5.BDNFNGF plasmid construction The BDNF precursor was fused to mature NGF in a similar manner as above with the exception that the fusion area was created in just one PCR reaction. 0.5 mg of Hind III linearized pRK5.BDNF and pRK5.NGF DNA was amplified in one reaction containing all four primers: a,b,c, and d (Table 2) . All other conditions of the amplification were as stated above. The PCR products were phenol/chloroform extracted, ethanol precipitated and digested to completion with Bs t BI and Hind III. Digestion products were electrophoresed on a 1% NuSieve gel and the 650 base pair fusion band was cut out and saved for the ligation below. Primers used in pRK5.BDNFNGF construction are shown below: PRIMER SEQUENCE 5'-->3* LOCATION /STRAND GGCTTGACATCATTGGCTGACACTTTCGAACACATGATAG (Seq ID #34) 1332-1371 BDNF / S AAGATGGGATGGGATGATGAGCGCCGGACCCTCATGGACAT (Seq ID #35) 1533-1553 BDNF / AS 1407-1426 NGF/ AS ATGTCCATGAGGGTCCGGCGCTCATCATCCCATCCCATCTT (Seq ID #36) 1533-1553 BDNF / S 1407-1533 NGF / S GATATAAGCTTGAGAGTGTAGAAGGGGC (Seq ID #37.) 1794-1810 NGF / AS The location of priming within each plasmid is listed as well as the strandedness ("S" indicates sense primers and "AS" indicates antisense primers) . Plasmid pRK5.BDNFNGF was constructed by digesting pRKS.BDNF to completion with Hind III and Bst BI. The products were electrophoresed on a 1% NuSieve gel. The 5181 base pair band was cut out, melted, and ligated to the melted 650 bp PCR fusion band. Ligation products were transformed, screened, and sequenced through the PCR region as stated above. DNA for all of the above constructs was prepared via cesium chloride banding as stated earlier. PRK5.NT3BDNF Plasmid Construction Plasmid pRK5.NT-3 and pRK5.BDNF were digested to completion with Esp I and Kpn I. Digestion products were electrophoresed on a 1% NuSieve gel. The 4810 and 944 base pair fragments ^ were cut out of the gel and ligated together. The missing 126 base pair region containing the 3 ' end of the NT-3 precursor and the 5 ' end of the BDNF mature waε prepared uεing synthetic DNA oligonucleotides. Six overlapping primerε (εense and anti-senεe, Table 3) were ligated together in one reaction according to εtandard protocol. The ligation products were then digested with Esp I to generate the 126 base pair fusion fragment. Plasmid pRK5.NTBD was digested to completion with Esp I and ligated to the 126 base pair fragment. Following screening, pRK5.NT3BDNF was sequenced throughout the entire 126 basepair fusion area. Primerε Used in NT3BDNF Synthetic Fusion Area are shown below. Primer Sequence 5'-->3' Is TGAGCGACAGCACCCCCTTGGAGCCCCCGCCCTTGTATCTCATGGAGGATT (Seq ID #38) la TCAGCTCCCCTCGTCGGGCGGGGTCCGAGTGCCGTTTCCGCCGTGATGTTC (Seq ID #39) 2s ACGTGGGCAGCCCCGTGGTGGCGAACAGAACATCACGGCGGAAACGGC (Seq ID #40) 2a TGTTCGCCACCACGGGGCTGCCCACGTAATCCTCCATGAGATACAAGG (Seq ID #41) 3s ACTCGGACCCCGCCCGACGAGGGGAGC (Seq ID #42) 3a GCGGGGGCTCCAAGGGGGTGCTGTCGC (Seq ID #43) The "s" following the number of the plasmid indicateε a sense strand plasmid and the "a" indicates an anti-sense strand. The primers were constructed to overlap each other when ligated together. Kunkel mutagenesis To control for variation in the 5' portion of each gene within the vector and to optimize conditions for translation of the neurotrophic mRNA' s , an 'ACC' translation consensus sequence was added to the 5 ' ends of the cDNA inserts and extra base pairs of 5 ' sequence originally cloned into pRK5.BDNF (including two ATG sites) and pRK5.NGF was removed. Kunkel Mutagenesiε was performed on plasmids pRK5.NGF, pRK5.NT-3, pRK5.BDNF, pRK5.NT3NGF and pRK5.BDNFNGF. 2 μg plasmid DNA was transformed into CaCl2 competent E. coli strain CJ236. Single stranded uracil containing template DNA was prepared according to Sambrook et al. (1989) with the exception that after PEG precipitation, the pellet was resuspended in 100 μL TE, extracted once with 50 μL phenol/chloroform (1:1), and twice with 500 μL chloroform. After ethanol precipitation, the pellet was resuεpended in 45 μL dH2θ and spun-dialysed through a Sepharose CL-6B (Pharmacia / LKB) column. 100 pmol synthetic oligonucleotide primers containing the 5' ACC (Table 4) were phosphorylated with T4 polynucleotide kinase. Mutagenesis was performed using the Muta-Gene Phagemid in vitro Mutagenesis kit (BioRad) according to manufacturer's instructions. The products were transformed into E. coli 299 cells and resulting colonies were picked and screened. Single stranded DNA was prepared for sequencing (Sambrook et al. , 1989) with the following modifications: precipitation of the phagemid particles was at 4 degrees C followed by resuspension in 0.3 M NaOAc/lmM EDTA. DNA was extracted with a 2X volume of phenol/chloroform. The final pellet was resuspended in 50 μL dH2θ. Single-stranded plasmid DNA was sequenced through the priming area with the Sequenase Version 2.0 Sequencing Kit (USB) according to manufacturer's instructions. Table 4: Primers (antisense) used in 5" Kunkel Mutagenesis Primer Sequence 5'-->3' NGF5" GTAGAACAACATGGACATGGTGGCAATATTGTCGACTCTGGAGTCGACCTGCAG (Seq ID #44) NT3.5'CACATAAAACAAGATGGACATGGTCTTGTTCACCTGTAGGATCCCCGG (Seq ID #45) BDNF 5'AGTAAGGAAAAGGATGGTCATGGTGGAGGTCGACAAGCTTGAGAATTCAATCG (Seq ID #46) The altered reεtriction εites used for screening purposeε are underlined. Cell Culture--ELISA Plaεmids were prepared for transfection via cesium chloride double banding.. Both the original plasmidε and the 5' end mutagenized plasmids pRK5.NGF, pRK5.NT3NGF, and pRK5.BDNFNGF were transfected along with an hGH control plasmid into the human kidney cell line (293) using the calcium phosphate precipitation method (Gorman et al . 1990) . 36 hours poεt-tranεfection the εupernatants were assayed for NGF and hGH (as a control) expresεion with the enzyme linked immunosorbant asεay (ELISA) . ELISA's were performed by Immunoasεay Services, Genentech, Inc. Supernatantε of all construct transfections were also assured to have bioactivity by their effects on dorsal root ganglia and sympathetic neurons. Cell culture—radioactive protein labelling Plasmids pRK5.NGF, pRK5.NT-3, pRK5.BDNF, pRK5.NT3NGF, pRK5.BDNFNGF and pRK5.NT3BDNF were transfected into the human kidney cell line (293). 24 hours post transfection, the cells were washed with PBS and labelled for 12-14 hours with [ 35 S] -methionine and [ 35 S] -cysteine at 200 μci/ml in cysteine/methionine minus DMEM media. Selected plates of ceils were labelled with either [ 35 S] -cyεteine alone, or [ 35 S] -methionine alone in cysteine minuε media, or methionine minus media, respectively. The radioactive supernatants were collected and either concentrated 5-10 fold in a Centricon-10 (Amicon) according to manufacturer's instructions or immunoprecipitated along with cell lysateε as stated below. One-fifth of each concentrated sample was loaded on a pre-cast 16% Tris-glycine, SDS-PAGE denaturing reducing mini-protein gel (1.5 mm) and electrophoreεed according to manufacturer's directions. (Novex) . The gels were fixed with Amplify (Amersham) as suggested in the instructions. Fixed, dried gels were exposed to film at -70 degree C for 8 to 24 hours. Cell lysates were collected by waεhing the cellε with PBS and lysing with triton lysis buffer. (1% triton, 5mM HEPES pH 7.2) . Cell debris waε removed by centrifugation. Lyεates and supernatants were immunoprecipitated as follows. Rabbit anti-NGF and goat anti-hGH antibodies were provided by Immunoassay Services, Genentech, Inc. One half of each supernatant and lysate was immunoprecipitated with rabbit anti-NGF antibodies alone. The other half, serving as a transfection control, was co-immunoprecipitated with the rabbit anti-NGF and goat anti-hGH antibodies. [35gj -labelled supernatants and lysates were preincubated with 100 μL 10% Pansorbin cells ( Staphylococcus aureus ) in phosphate buffered saline (Calbiochem) for 30 to 60 minutes at 4 degrees C with rotation. Cells were removed by centrifugation and the supernatants were incubated as above with saturating levels of rabbit anti-NGF antibodies or rabbit anti-NGF and goat anti-hGH antibodies. 120 μL 10% Pansorbin cells were added to the mixture and incubated for 1 hour at 4 degrees C with rotation. Each tube was centrifuged for 2 minutes in a " microcentrifuge. Supernatants were removed and the pellets were washed once with Buffer #1 (1M NaCl, 0.05 M Tris pH 6.8 in water), twice with Buffer #2 (1M Tris pH 8.8, 0.2M NaCl , 1% NP40, 0.3% SDS), and once with cold dH2θ. Washed pellets were resuspended in .40 μL 2X Tris-Glycine SDS loading buffer. 20 μL was loaded on a pre-cast 16% Tris- glycine SDS reducing mini-protein gel (1.5 mm) and electrophoresed according to manufacturer's directions. (Novex) . The gels were fixed with En^Hance (Dupont) as suggested with the exception that the final wash in water included 5% glycerol to avoid gel cracking. Fixed, dried gels were exposed to film at -70 degrees C for 9-66 hours. Effects of precursor on NGF expression The effects of the 5' mutations on secreted NGF levels were determined by three hGH controlled experiments performed in duplicate. In these experiments, the hGH controlled for potential differences due to transfection efficiencies. For example, in any one experiment, NGF and hGH expreεεion varied with each plate. Since each NGF expression value was compared only to the hGH expresεion in the same plate, relative comparisonε could be made. The reεultε of the 5' changed plaεmidε (pRK5.NGF 5'ACC, pRK5.NT3NGF5 'ACC, and pRK5.BDNFNGF 5 'ACC ) are summarized in Table 5. The chimeric proteins were compared to the wildtype NGF expresεion level which was set at 100 %. Though there seems to be about a 2-fold difference in the levels of NGF production from pRK5.NGF and pRK5.NT3NGF, the production levels from pRK5.BDNFNGF have dropped about 50-fold. Table 5: Effects of Precursor on Expression. Plasmid NGF/hGH Average % of NGF Expression PRK5 .NGF5 ΑCC 0 . 194 0 . 258 100 0 . 215 0 . 328 0.286 0.266 0.264 PRK5.NT3 GF5ΑCC 0.105 0.147 57 0.169 0.163 0.149 0.148 pRK5.BDNFNGF5 'ACC 0.007 0.006 2 0.007 0.006 0.006 0.005 0.004 Since it- is in its normal form (wildtype), pRK5.NGF5 'ACC was given the value of 100 %. The two chimeras were then compared as a percentage of this value in the last column. There are similarities and differences in the amino acid sequences of NGF, NT-3 and BDNF. Most apparently, the mature protein factors are quite homologous (> 50%) especially when compared to the precursor portions of each preproprotein. (- 20% homology) . Some major differences are observed when comparing the three precursors. Firεt, NGF and NT-3 contain the dibaεic pair Lys-Arg at the primary procesεing site while BDNF contains an Arg-Arg pair. Secondly, only NGF and NT3 contain upstream dibasic sites (Arg-Arg) ; NGF has two sites whereas NT-3 has only one and BDNF does not have any. Cell culture with proteases Kex2 r mPCl, and mPC2 Plasmids pRK5.BDNF and pRK5.NT-3 were transfected as above with the exception that an additional 3 μg of expression plasmid pRK.Kex2, pRK.mPCl, or pRK.mPC2 DNA per plate (100mm) was added to the transfection mixture. Given the difference in the dibasic cleavage pattern with each precursor, the effectε of the enzymeε, Kex2, mPCl and mPC2 on NT-3 and BDNF were examined. Kex2 cleaved the upεtream Arg-Arg site in NT-3 , but was unable to process the BDNF upstream region because there is no such site. mPCl and. mPC2 have no additional effect on the processing of NT-3 or BDNF in the 293 cells. EXAMPLE 7 Construction of proinsulin BIO Histidine to Aspartic Acid mutant and insulin expression in transfected 293 cells. The cDNA clone of the human preproinsulin gene, pSVEHIGDHFR, described in Australian patent 616,201 issued February 18, 1992, provided the coding sequence of the human preproinsulin gene for the final mammalian expression vector. A second source of the human preproinsulin gene, pH13 (Sures et al. Science 208:57-59 [1980]) has also been used in experiments to provide the coding sequence of human proinsulin. Aliquots (5-10 μD of pSVEHIGDHFR were used for amplification of the coding region by RACE-PCR (rapid amplification of cDNA ends, Frohman 1988; Innis 1990) using a combination of gene-specific PCR primers: for the 5' end they were CAT AAG CTT ACC ATG GCC CTG TGG ATG CGC (sequence given 5' to 3').and for the 3' end they were.CAT TCT AGA CTA GTT GCA GTA GTT CTC CAG (sequence given 5' to 3' ) . All PCR cloning reactions were carried out with Vent DNA polymerase (New England Biolabs) to minimize " the introduction of mismatched bases during amplification of template. All proinsulin clones were sequenced with the Sequenaεe 2.0 kit from USB and cloned into restriction digested pRK5. The final preproinsulin mammalian vector is pRK7.proins. A human proinεulin mutant having a non-naturally occurring prohormone convertaεe cleavage εite iε conεtructed by mutating the human proinεulin cDNA, pRK.proins, encoding the naturally occurring basic cleavage site at the B-chain/C-peptide junction (KTRR) and A- chain/C-peptide junction (LQKR) by site-directed mutagenesis (Kunkel Supra) . The double proinsulin variant, proins.RTKR.Ip/RQKR.IIp, waε constructed. Ip is the Type I enzyme cleavage site and Up is the Type II enzyme cleavage site. Primers used in construction of the proinsulin mutant, proins .RTKR. Ip/RQKR. Up, are described in example 4. The double proinsulin mutant proins RTKR. Ip/RQKR. Up changes the native human proinsulin residue Lys 29 to Arg 29 at the Type I enzyme cleavage site, residue Arg 31 to Lys 31 at the Type I enzyme cleavage site and proinsulin residue Leu 62 is changed to Arg 62 at the Type II enzyme cleavage εite. Other proinsulin mutants, proins.RTKR.Ip, proins . RQKR. Up, proins.KR.Ip/RQKR.IIp, and proins.KTKR.Ip were conεtructed as in example 4. All mutants were screened through the primer regions with the Sequenase 2.0 kit from USB. Proinsulin, pRK7.proins, and the proinsulin mutant, proinε.RTKR.Ip/RQKR.Up, were then mutagenized by the site- directed mutagenesiε of Kunkel et al . (Methods Enzvmol. vol.154, pg. 367-382 [1987]) to yield pRK7.proins.B10H>D, proinsulin having the histidine at position 10 in the B- chain replaced with an aspartic acid, and the proinsulin mutant, proins.RTKR.Ip/RQKR. Up.B10H>D having the histidine at position 10 in the B-chain replaced with an aspartic acid. The primer used in the Kunkel et al . Supra , method was GC-TTC-CAC-CAG-GTC-GGA-TCC-GCA-CAG-GTG, with the sequence given in a 5 ' to 3 ' direction. All mutants were screened through the primer regions with the Sequenase 2.0 kit from USB. DNA from the proinsulin mutants, proins .RTKR. Ip/RQKR. Up, proins .RTKR. Ip/RQKR.Up. BlθH>D, pRK7.proins.Bl0H>D, and proinsulin, pRK7.proins. was CsCl banded and used for human embryonic kidney cell line 293 (ATCC CRL 1573) transient transfection by the method of Gorman (Gorman DNA Prot Enσ Tech 2:3-10. 1990). Cells were labelled as described by Gorman, Supra and cells and lysates were analyzed for insulin-like proteins. Protein-A sepharose immunoprecipitation was performed by the method of Harlow and Lane (from Antibodies: A Laboratory Manual, pub. Cold Spring Harbor Laboratory, chapter 11, pp. 421-470 [1988] ) on both supernatant and lysate samples using concentrated guinea pig anti-human insulin antibodies (Biomeda I 01) . Immunoprecipitation products were resuspended in either 2X Tris-Glycine Sample Buffer (from Novex)/8M urea pluε b-mercaptoethanol or 2X Tricine buffer plus b-mercaptoethanol, heated for 5 minuteε at 100 °C, spun briefly, and run reduced on 18% Tris-glycine SDS or 16% Tricine gels, respectively, according to manufacturer's directions (Novex) . The gels were fixed (10% acetic acid, 25% isopropanol, 65% water), and soaked with Amplify (Amersham) as suggested in the instructions. Fixed, dried gels were exposed to film at -70 °C for 1 to 4 days. DNA from the proinsulin mutants was used for transient transfection by the method of Gorman Supra and twelve to sixteen hours post transfection, the transfection media was replaced with serum free media and secretion products were collected for 36-56 hours. Processed insulin was measured in the collected supernatants by radioimmunoassay (RIA) using the Equate® RIA INSULIN, kit from Binax, Inc. according to the provided instructions. To detect the bioactivity and specific activity of proinsulin or mutant proinsulin, secretion products were measured by quantitating the increase in tyrosine phosphorylation of the beta chain of the insulin receptor in 293 cells. 293 cells were plated in 2 -well Costar plates in F12-DMEM medium containing serum (10%) (50,000 cells per well) and allowed to attach overnight. Cells were transferred into medium without serum for 8-16 hours. Serum free media was aspirated and cells were stimulated with 1 mL of various concentrations of wildtype bovine insulin (Novo Industri A/S) or mutant inεulin from conditioned supernatants. After a 10-15 minute incubation at 37°C, the reaction was stopped by the addition of 100 μl 2X Tris-Glycine sample buffer (from Novex) plus b- mercaptoethanol (50 μl per mL of εample buffer) . The samples were vortexed vigorously, heated for 5 minutes at 100°C and 20μL was electrophoresed on an 8% Tris-Glycine SDS gel (Novex) . After electrophoresis, tyrosine phosphorylation of the b chain of the insulin receptor was detected and quantitated by immunoblotting with anti- phosphotyroεine antibodieε followed by scanning densitometry as described by Holmes et al . cience 256:1205-1210 [1992]) . NIH 3T3 HIR3.5 cells (Whitaker et al . PNAS USA. 84: 5237-5249 [1987] ) overexpressing the human insulin receptor were incubated in εerum free medium with various concentrations of unlabelled wildtype inεulin or insulin mutant and a constant amount of 1 F I-labelled Insulin (Amersham) for 16 hours at 4 °C . Unbound ligand was removed and cells were washed with ice cold medium. The amount of radioactivity bound waε determined after solubilizing the cells with 0.1 N NaOH containing SDS (0.1%) . Relative binding of wildtype insulin and the insulin mutants was determined using a non-linear regression program. Determination of insulin receptor binding waε determined by the following method: Human kidney cellε (293) or 3T3 cellε overexpreεεing the human inεulin receptor, Whitaker et al . Supra were plated at about 100,000 cell per well dishes. One to two days after plating, the cellε were washed in PBS and starved for 8-16 hours in binding buffer (F12/DMEM (50/50) ;2mM Gin; 10 mM HEPES; 1 mg/ml BSA; penicillin and streptomycin (Gibco 600- 5140 Ag 100 units/ml) . Cells were placed on ice and washed twice with cold binding buffer. 480μl of non-radioactive insulin ligand (mutantε or standards) in triplicate were placed in each well followed by 20μl (50,000-100,000 cpm/well) I2 5 j -labelled insulin (at tyrosine-Al4 ) (Amersham) . Cells were incubated at 4°C for 14-16 hours with gentle rocking. The media was removed and cells were washed twice with cold binding buffer. The amount of radioactivity bound was determined after solubilizing the cellε with 0.1N NaOH containing SDS (0.1%). A standard curve was generated using 0 to lOOOnM human insulin standards (USP) or bovine standards (Novo Industri A/S) . Relative binding of the insulin mutants was determined using a non-linear binding regression program. RESULTS ng/ L PRK7.proins PRK7.proins >63 PRK7.proins >63 PRK7.proins PRK7.proins >63 PRK7.proins 63 pRK7.proins.1* pRK7.proins.1 27 pRK7.proins.1 27 pRK7.proins.1 pRK7.proins.1 pRK7.proins.1 27 pRK7.proins.2* pRK7.proins.2 >625 pRK7.proins.2 pRK7.proins.2 833 pRK7.proins.2 pRK7.proins.2 pRK7.proins.2 1041 pRK7.proins.2 1458 pRK7.proins.3* pRK7.proins.3 146 pRK7.proins.3 208 pRK7.proins.3 333 pRK7.proins.3 pRK7.proins.3 pRK7.proins.3 312 pRK7.proins.3 291 I no dil LOST control I 1:5 LOST control J no dil LOST control J 1:5 7600 LTS* control *pRK7.proins.1 is proins .RTKR. Ip/RQKR. Up *pRK7.proins.2 is proins.BIO H>D. *pRK7.proins.3 is proins.RTKR.Ip/RQKR. Up.B10H>D. *GTS is greater than standard *LTS is leεε than εtandard construct ng/ml PRK7.proinε 125 PRK7.proinε 115 PRK7.proinε PRK7.proinε PRK7.proinε.1* 6 PRK7.proinε.1 7.5 PRK7.proinε.1 PRK7.proins.1 5 PRK7.proinε.1 6.5 PRK7.proinε.1 8.7 PRK7.proins .2* PRK7.proins.2 560 PRK7.proins.2 833 PRK7.proins.2 PRK7.proins.2 520 PRK7.proinε.2 916 PRK7.proinε.3* PRK7.proinε.3 PRK7.proinε.3 >1125 PRK7.proinε.3 PRK7.proinε .3 PRK7.proinε.3 >1125 PRK7.proinε.4* PRK7.proins.4 PRK7.proins.4 35 PRK7.proinε.4 GTS PRK7 . proins . 4 840 PRK7.proins.4 35 245 - PRK7. roins.5* 10-11 195 PRK7.proins.5 10-11 270 PRK7. roins.5 10-11 PRK7.proins.5 10-11 435 PRK7.proins.5 10-11 270 PRK7.proins.5 10-11 GTS PRK7.proins.6* GTS PRK7.proins.6 420 PRK7.proins.6 17.5 GTS PRK7.proins.6 PRK7.proins.6 420 PRK7.proins.6 17.5 GTS PRK7.proins.7* 2100 PRK7.proins.7 8.8 LTS* control 0 * pRK7.proins.1 is proins.RTKR.Ip/RQKR.Up * pRK7.proins.2 is proins.B10 H>D. * pRK7.proins.3 is proins.RTKR.Ip/RQKR.Up.B10 H>D. * pRK7.proins.4 is proins.RTKR.Ip * pRK7.proins.5 iε proins.RQKR.Up * pRK7.proins.6 is proins.KR.Ip/RQKR.IIp * pRK7.proins.7 iε proins.RTKR.Ip * GTS is greater than standard * LTS is less than standard Expression of proinsulin Following transfection with an expression vector carrying the wildtype proinsulin cDNA, 293 HEK cells synthesize and secrete uncleaved proinsulin with a molecular weight of 6.5 kD. Unprocessed, [ 35 S] -labelled proinsulin is immunoprecipitated from both the cell lysate and the media using an insulin specific antibody. The unprocessed material migrates with the 6.5kD molecular marker. Mature insulin, when reduced, migrates similarly to the A and B chainε at 2.35 and 3.4 kD when compared to the two bandε of the molecular weight protein εtandardε. Expression of Proinsulin Mutants Proins .RTKR. Ip/RQKR. Up iε proceεεed into productε that co-migrate with the A and B chainε of inεulin aε well aε processing intermediates. When proins.RTKR.Ip or proins.RQKR.IIp, representing a mutant cleavage site at the B-/C-chain junction or the A-/C-chain junction respectively, are transfected, only one of the mature chainε waε detected along with intermediateε . When the mutant cleavage εite is at the A-/C-chain junction, the A chain iε detected along with a εlower migrating band conεiεtent with the B-C intermediate. When the mutant cleavage εite iε at the B-/C-chain junction, the B chain iε detected along with a faster migrating band consiεtent with the A-C intermediate. Intermediates disappear when the amount of 293 homologous-cell enzyme that recognizes the mutant cleavage sites is increased by cotransfection with an expression vector expressing the 293 homologous-cell enzyme. Proins.KTKR.Ip was resiεtant to cleavage by the 293 cell enzyme. Detection of Bioactivity When mature, active inεulin bindε to the A-chain of the insulin receptor outside the cell, tyrosine residueε on the B-chain of the inεulin receptor are autophoεphorylated (Kaεuga et al., Science. 215:185-186 [1982] ) Therefore, insulin bioactivity was aεεayed by meaεuring the ability of the B-chain of the inεulin receptor to become autophosphorylated. Phosphorylation of the B-chain can be visually observed on an immunoblot. Upon stimulation with increasing concentrations of bovine insulin, the B-chain is increasingly observed at a masε of 96 kD by probing with antiphosphotyrosine antibodieε. A εimilar increaεe in B- chain phosphorylation is detected by stimulation with various concentrations of the insulin mutants, proins.RTKR. Ip/RQKR.Up and proins .RTKR. Ip/RQKR. Up.BIO H>D. Relative Specific Activity and Insulin Binding Studies Relative specific activity was determined by guantitating the amount of phosphorylation stimulated by each insulin mutant compared to insulin standards. Both the proins.RTKR.Ip/RQKR.Up and proins .RTKR.Ip/RQKR.Up.BIO H>D have similar activity to the bovine insulin standards within experimental error. Insulin receptor binding studies indicated similar binding affinities to the wildtype insulin standards with both the proins.RTKR.Ip/RQKR.Up and proinε.RTKR.Ip/RQKR.Up.BIO H>D insulin mutants. BIO H>D Insulin Mutants The relative amount of secretion products detected from proins.RTKR.Ip/RQKR.Up.BIO H>D is greatly increased as compared to proins.RTKR.Ip/RQKR.Up which lacks the BIO His to Asp change. When quantitated by RIA, the increase in the amount of processed insulin ranges from 10-40 fold depending on transfection efficiency. In addition to an increase in the accumulation of active insulin due to proins.RTKR.Ip/RQKR.Up.BlO H>D, there is an increase in the accumulation of processing intermediates with the B10H>D mutant in the wildtype proinsulin background. Transfection with wildtype proinsulin does not yield insulin A and B chains; however, transfection with proin.B10H>D does yield detectable insulin A and B chain. The proins .RTKR. Ip/RQKR. Up. BIO H>D and proins. TKR.Ip/RQKR.Up have the same specific activity as measured by B-chain phosphorylation and the same capacity for binding to the insulin receptor. 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Structural homology between the human fur gene product and the εubtiliεin-like proteaεe encoded by yeast KEX2. Nucleic Acids Res. 18:664 (1990). Wise, R.J.; Pittman, D.D.; Handin, R.I.; Kaufman, R.J.; Orkin, S.H. The propeptide of von Willebrand factor independently mediates the assembly of von Willebrand multimers. Cell 52:229-236 (1988). Yoshimasa, Y. ; Paul, J.I.; Whit taker, J.; Steiner, D.F. Effectε of amino acid replacementε within the tetrabasic cleavage site on the procesεing of the human insulin receptor precursor expressed in Chinese hamster ovary cells. J. Biol. Chem. 265:17230-17237.(1990) SEQUENCE LISTING (1) GENERAL INFORMATION: (i) APPLICANT: Genentech, Inc. Gorman, Cornelia M. , Marriott. Dave, Groskreutz, Debrya J. (ii) TITLE OF INVENTION: Prohormone Convertase Transformed Cells and Polypeptide Synthesis (iii) NUMBER OF SEQUENCES: 54 (iv) CORRESPONDENCE ADDRESS: (A) ADDRESSEE: Genentech, Inc. (B) STREET: 4S0 Point San Bruno Blvd (C) CITY: South San Francisco (D) STATE: California (E) COUNTRY: USA (F) ZIP: 94080 (v) COMPUTER READABLE FORM: (A) MEDIUM TYPE: 5.25 inch, 360 Kb floppy disk (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS (D) SOFTWARE: patin (Genentech) (Vi) CURRENT APPLICATION DATA: (A) APPLICATION NUMBER: (B) FILING DATE: 04-DEC-1992 (C) CLASSIFICATION: (vii) PRIOR APPLICATION DATA: (A) APPLICATION NUMBER: 07/837265 (B) FILING DATE: 22-MAY-1992 (vii) PRIOR APPLICATION DATA: (A) APPLICATION NUMBER: 07/803631 (B) FILING DATE: 06-DEC-1992 (viii) ATTORNEY/AGENT INFORMATION: (A) NAME: Adler, Carolyn R. (B) REGISTRATION NUMBER: 32,324 (C) REFERENCE/DOCKET NUMBER: 748P2.4 (ix) TELECOMMUNICATION INFORMATION: (A) TELEPHONE: 415/225-2614 (B) TELEFAX: 415/952-9881 (C) TELEX: 910/371-7168 (2) INFORMATION FOR SEQ ID NO:l: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 2355 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:l: TCTAGATCTA GCTGGTGTGT CTCTGATCTT GCTTCTTTTC TCCCAGCCCT 50 TCCTACTTGT GTGAGAACAA GGTTTTGAGC CATGGAGCAA AGAGGTTGGA 100 CTCTGCAGTG TACTGCTTTC GCCTTCTTTT GCGTTTGGTG TGCACTAAGC 150 AGTGTAAAAG CAAAGAGGCA GTTTGTTAAT GAATGGGCGG CGGAGATCCC 200 CGGAGGGCAA GAAGCTGCCT CTGCCATCGC CGAAGAACTG GGGTATGACC 250 TTTTGGGTCA GATTGGATCA CTTGAAAATC ACTATTTATT CAAACACAAA 300 AGCCATCCTC GGAGGTCCCG AAGAAGCGCT CTTCATATCA CTAAGAGGTT 350 ATCTGATGAT GATCGTGTGA CGTGGGCTGA ACAACAGTAT GAAAAAGAGA 400 GAAGTAAACG TTCAGTTCAA AAAGACTCAG CATTGGATCT CTTCAATGAT 450 CCAATGTGGA ATCAGCAGTG GTACTTGCAA GATACCAGAA TGACTGCAGC 500 TCTGCCCAAG CTGGACCTTC ATGTAATACC TGTTTGGGAA AAGGGTATTA 550 CTGGCAAAGG AGTTGTTATT ACTGTACTGG ATGATGGCTT GGAGTGGAAT 600 CACACAGACA TTTATGCCAA TTATGATCCA GAGGCTAGCT ATGATTTTAA 650 CGATAATGAT CATGATCCAT TTCCCCGATA TGATCTCACA AATGAAAACA 700 AACATGGAAC AAGATGTGCA GGTGAAATTG CCATGCAAGC AAATAATCAC 750 AAGTGTGGGG TTGGAGTTGC ATATAATTCC AAAGTTGGAG GCATAAGAAT 800 GCTGGATGGC ATTGTAACTG ATGCCATTGA GGCTAGTTCA ATTGGATTCA 850 ACCCTGGCCA TGTGGATATT TACAGTGCAA GCTGGGGCCC TAATGATGAT 900 GGAAAAACTG TGGAGGGGCC TGGCAGACTA GCCCAGAAGG CATTTGAATA 950 TGGTGTCAAA CAGGGGAGAC AAGGGAAAGG CTCCATCTTT GTCTGGGCTT 1000 CAGGGAATGG GGGTCGTCAG GGAGATAACT GTGACTGTGA TGGCTACACA 1050 GACAGCATTT ACACCATCTC TATCAGCAGT GCCTCCCAGC AAGGCCTGTC 1100 ACCTTGGTAT GCAGAGAAGT GTTCTTCCAC ATTGGCTACC TCCTACAGCA 1150 GTGGTGATTA CACAGACCAG CGAATAACAA GCGCTGACCT GCACAATGAC 1200 TGCACAGAGA CCCACACAGG CACCTCGGCT TCAGCACCCC TGGCTGCTGG 1250 TATCTTTGCT CTGGCCTTGG AGGCAAACCC AAATCTTACC TGGAGAGATA 1300 TGCAGCATCT GGTTGTCTGG ACCTCTGAGT ACGACCCATT GGCCAGTAAC 1350 CCAGGTTGGA AAAAGAATGG GGCAGGCTTG ATGGTGAACA GCCGATTTGG 1400 ATTTGGCTTG CTAAATGCCA AAGCTCTGGT GGATTTGGCT GATCCTCGGA 1450 CCTGGAGAAA TGTGCCTGAG AAGAAAGAAT GTGTTGTAAA AGACAATAAC 1500 TTTGAGCCTA GAGCCCTGAA AGCTAATGGA GAAGTAATTG TTGAAATCCC 1550 AACAAGAGCT TGTGAAGGAC AAGAAAATGC TATCAAGTCT CTGGAACATG 1600 TGCAATTTGA AGCAACAATT GAATATTCTC GTAGAGGAGA CCTTCATGTC 1650 ACACTCACTT CTGCTGTTGG AACCAGCACT GTACTGTTGG CTGAAAGGGA 1700 AAGAGATACA TCCCCCAATG GCTTTAAGAA TTGGGACTTC ATGTCTGTTC 1750 ATACATGGGG AGAGAATCCT GTAGGCACCT GGACATTGAA AATTACAGAC 1800 ATGTCTGGAA GAATGCAAAA TGAAGGAAGG ATTGTGAACT GGAAGTTGAT 1850 TTTGCATGGG ACATCTTCTC AACCAGAGCA CATGAAGCAG CCCCGTGTGT 1900 ACACATCCTA CAATACAGTC CAGAATGACA GGAGAGGAGT GGAAAAGATG 1950 GTGAATGTTG TGGAGAAGCG GCCCACACAA AAGAGCCTGA ATGGCAATCT 2000 CCTGGTACCC AAAAACTCCA GCAGCAGCAA TGTGGAGGGT AGAAGGGATG 2050 AGCAGGTACA AGGAACTCCT TCAAAGGCCA TGCTGCGACT CCTACAAAGT 2100 GCTTTTAGCA AGAATGCACT TTCAAAACAA TCACCAAAGA AGTCTCCAAG 2150 TGCAAAGCTC AGCATCCCTT ATGAAAGTTT CTATGAAGCC TTGGAAAAGC 2200 TTAACAAGCC CTCCAAGCTT GAAGGCTCTG AAGACAGTCT GTACAGTGAC 2250 TATGTTGATG TATTCTATAA CACAAAACCT TATAAGCATA GAGATGACAG 2300 GCTGCTGCAA GCTCTCATGG ACATCCTAAA TGAGGAGAAT TAAAATAAGG 2350 AGCTC 2355 (2) INFORMATION FOR SEQ ID NO:2: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 2012 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2 : TCTAGATGCA TCTTCCCTCT TCGTCCCCTG CTCCACCACC CTGCGCGCCT 50 CACAGCCCCG • CTTTTCACTC CCAAAGAAGG ATGGAGGGCG GTTGTGGATC 100 CCAGTGGAAG GCGGCCGGGT TCCTCTTCTG TGTGATGGTT TTTGCGTCTG 150 CCGAGAGACC CGTCTTCACG AATCATTTTC TTGTGGAGTT GCATAAAGAC 200 GGAGAGGAAG AGGCTCGCCA AGTTGCAGCA GAACACGGCT TTGGAGTCCG 250 AAAGCTCCCC TTTGCAGAAG GCCTGTATCA CTTTTATCAC AATGGGCTTG 300 CAAAGGCCAA AAGAAGACGC AGCCTACACC ATAAGCGGCA GCTAGAGAGA 350 GACCCCAGGA TAAAGATGGC GCTGCAACAA GAAGGATTTG ACCGTAAAAA 400 GAGAGGGTAC AGGGACATCA ATGAGATTGA CATCAACATG AATGATCCTC 450 TCTTTACAAA GCAATGGTAC CTGTTCAACA CTGGGCAAGC CGATGGAACT 500 CCTGGGCTAG ACTTGAACGT GGCCGAAGCC TGGGAGCTGG GATACACAGG 550 AAAAGGAGTG ACCATTGGAA TTATGGATGA TGGAATTGAC TATCTCCACC 600 CAGACCTGGC CTACAACTAC AACGCTGATG CAAGTTATGA CTTCAGCAGC 650 AATGACCCCT ACCCATACCC TCGATACACA GATGACTGGT TCAACAGCCA 700 TGGAACTAGG TGTGCAGGAG AAGTTTCTGC TGCAGCCAGC AACAATATCT 750 GTGGAGTCGG CGTAGCATAC AACTCCAAGG TGGCAGGGAT CCGGATGCTG 800 GACCAGCCCT TTATGACAGA CATCATCGAA GCCTCCTCCA TCAGCCACAT 850 GCCTCAACTG ATCGACATCT ACAGTGCAAG CTGGGGCCCC ACAGACAATG 900 GGAAGACGGT TGATGGGCCC CGAGAGCTCA CACTCCAGGC CATGGCTGAT 950 GGCGTGAACA AGGGCCGTGG GGGCAAAGGC AGCATCTATG TGTGGGCCTC 1000 TGGGGACGGT GGCAGCTACG ATGACTGCAA CTGTGACGGC TATGCTTCAA 1050 GCATGTGGAC CATCTCCATC AACTCAGCCA TCAATGATGG CAGGACTGCC 1100 TTGTATGATG AGAGTTGCTC TTCCACCTTA GCATCCACCT TCAGCAATGG 1150 GAGGAAGAGG AATCCTGAGG CTGGTGTGGC TACCACAGAC TTGTATGGCA 1200 ACTGTACTCT GAGACACTCT GGGACATCTG CAGCTGCTCC GGAGGCAGCT 1250 GGCGTGTTTG CATTAGCTTT GGAGGCTAAC CTGGATCTGA CCTGGAGAGA 1300 CATGCAACAT CTGACTGTGC TCACCTCCAA GCGGAACCAG CTTCATGATG 1350 AGGTTCATCA GTGGCGACGG AATGGGGTTG GCCTGGAATT TAATCACCTC 1400 TTTGGCTACG GAGTCCTTGA TGC GGTGCC ATGGTGAAAA TGGCTAAAGA 1450 CTGGAAAACT GTTCCGGAGA GATTCCATTG TGTGGGAGGC TCTGTGCAGA 1500 ACCCTGAAAA AATACCACCC ACCGGCAAGC TGGTACTGAC CCTCAAAACA 1550 AATGCATGTG AGGGGAAGGA AAACTTCGTC CGCTACCTGG AGCACGTCCA 1600 AGCTGTCATC ACAGTCAACG CGACCAGGAG AGGAGACCTG AACATCAACA 1650 TGACCTCCCC AATGGGCACC AAGTCCATTT TGCTGAGCCG GCGTCCCAGA 1700 GACGACGACT CCAAGGTGGG CTTTGACAAG TGGCCTTTCA TGACCACCCA 1750 CACCTGGGGG GAGGATGCCC GAGGGACCTG GACCCTGGAG CTGGGGTTTG 1800 TGGGCAGTGC ACCACAGAAG GGGTTGCTGA AGGAATGGAC CCTGATGCTT 1850 CACGGCACAC AGAGCGCCCC ATACATCGAT CAGGTGGTGA GGGATTACCA 1900 GTCTAAGCTG GCCATGTCCA AGAAGCAGGA GCTGGAGGAA GAGCTGGATG 1 50 AGGCTGTGGA GAGAAGCCTG CAAAGTATCC TGAGAAAGAA CTAGGGCCAC 2000 GCTTCCGAAT TC 2012 (2) INFORMATION FOR SEQ ID NO:3 : (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 753 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3 : Met Glu Gin Arg Gly Trp Thr Leu Gin Cys Thr Ala Phe Ala Phe 1 5 10 15 Phe Cys Val Trp Cys Ala Leu Ser Ser Val Lys Ala Lys Arg Gin 20 25 30 Phe Val Asn Glu Trp Ala Ala Glu He Pro Gly Gly Gin Glu Ala 35 40 45 Ala Ser Ala He Ala Glu Glu Leu Gly Tyr Asp Leu Leu Gly Gin 50 55 60 He Gly Ser Leu Glu Asn His Tyr Leu Phe Lys His Lys Ser His 65 70 75 Pro Arg Arg Ser Arg Arg Ser Ala Leu His He Thr Lys Arg Leu 80 85 90 Ser Asp Asp Asp Arg Val Thr Trp Ala Glu Gin Gin Tyr Glu Lys 95 100 105 Glu Arg Ser Lys Arg Ser Val Gin Lys Asp Ser Ala Leu Asp Leu 110 115 120 Phe Asn Asp Pro Met Trp Asn Gin Gin Trp Tyr Leu Gin Asp Thr 125 ' 130 135 Arg Met Thr Ala Ala Leu Pro Lys Leu Asp Leu His Val He Pro 140 145 150 Val Trp Glu Lys Gly He Thr Gly Lys Gly Val Val He Thr Val 155 160 165 Leu Asp Asp Gly Leu Glu Trp Asn His Thr Asp He Tyr Ala Asn 170 175 180 Tyr Asp Pro Glu Ala Ser Tyr Asp Phe Asn Asp Asn Asp His Asp 185 190 195 Pro Phe Pro Arg Tyr Asp Leu Thr Asn Glu Asn Lys His Gly Thr 200 205 210 Arg Cys Ala Gly Glu He Ala Met Gin Ala Asn Asn His Lys Cys 215 220 225 Gly Val Gly Val Ala Tyr Asn Ser Lys Val Gly Gly He Arg Met 230 235 240 Leu Asp Gly He Val Thr Asp Ala He Glu Ala Ser Ser He Gly 245 250 255 Phe Asn Pro Gly His Val Asp He Tyr Ser Ala Ser Trp Gly Pro 260 265 270 Asn Asp Asp Gly Lys Thr Val Glu Gly Pro Gly Arg Leu Ala Gin 275 280 285 Lys Ala Phe Glu Tyr Gly Val Lys Gin Gly Arg Gin Gly Lys Gly 290 295 300- Ser He Phe Val Trp Ala Ser Gly Asn Gly Gly Arg Gin Gly Asp 305 310 315 Asn Cys Asp Cys Asp Gly Tyr Thr Asp Ser He Tyr Thr He Ser 320 325 330 He Ser Ser Ala Ser Gin Gin Gly Leu Ser Pro Trp Tyr Ala Glu 335 340 345 Lys Cys Ser Ser Thr Leu Ala Thr Ser Tyr Ser Ser Gly Asp Tyr 350 355 360 Thr Asp Gin Arg He Thr Ser Ala Asp Leu His Asn Asp Cys Thr 365 370 375 Glu Thr His Thr Gly Thr Ser Ala Ser Ala Pro Leu Ala Ala Gly 380 385 390 ' He Phe Ala Leu Ala Leu Glu Ala Asn Pro Asn Leu Thr Trp Arg 395 400 405 Asp Met Gin His Leu Val Val Trp Thr Ser Glu Tyr Asp Pro Leu 410 415 420 Ala Ser Asn Pro Gly Trp Lys Lys Asn Gly Ala Gly Leu Met Val 425 430 435 Asn Ser Arg Phe Gly Phe Gly Leu Leu Asn Ala Lys Ala Leu Val 440 445 450 Asp Leu Ala Asp Pro Arg Thr Trp Arg Asn Val Pro Glu Lys Lys 455 460 465 Glu Cys Val Val Lys Asp Asn Asn Phe Glu Pro Arg Ala Leu Lys 470 475 480 Ala Asn Gly Glu Val He Val Glu He Pro Thr Arg Ala Cys Glu 485 490 495 Gly Gin Glu Asn Ala He Lys Ser Leu Glu His Val Gin Phe Glu 500 505 510 Ala Thr He Glu Tyr Ser Arg Arg Gly Asp Leu His Val Thr Leu 515 520 525 Thr Ser Ala Val Gly Thr Ser Thr Val Leu Leu Ala Glu Arg Glu 530 535 540 Arg Asp Thr Ser Pro Asn Gly Phe Lys Asn Trp Asp Phe Met Ser 545 550 555 Val His Thr Trp Gly Glu Asn Pro Val Gly Thr Trp Thr Leu Lys 560 565 570 He Thr Asp Met Ser Gly Arg Met Gin Asn Glu Gly Arg He Val 575 580 585 Asn Trp Lys Leu He Leu His Gly Thr Ser Ser Gin Pro Glu His 590 595 600 Met Lys Gin Pro Arg Val Tyr Thr Ser Tyr Asn Thr Val Gin Asn 605 610 615 Asp Arg Arg Gly Val Glu Lys Met Val Asn Val Val Glu Lys Arg 620 625 630 Pro Thr Gin Lys Ser Leu Asn Gly Asn Leu Leu Val Pro Lys Asn 635 640 645 Ser Ser Ser Ser Asn Val Glu Gly Arg Arg Asp Glu Gin Val Gin 650 655 660 Gly Thr Pro Ser Lys Ala Met Leu Arg Leu Leu Gin Ser Ala Phe 665 670 675 Ser Lys Asn Ala Leu Ser Lys Gin Ser Pro Lys Lys Ser Pro Ser 680 685 690 Ala Lys Leu Ser He Pro Tyr Glu Ser Phe Tyr Glu Ala Leu Glu 695 700 705 Lys Leu Asn Lys Pro Ser Lys Leu Glu Gly Ser Glu Asp Ser Leu 710 715 720 Tyr Ser Asp Tyr Val Asp Val Phe Tyr Asn Thr Lys Pro Tyr Lys 725 730 735 His Arg Asp Asp Arg Leu Leu Gin Ala Leu Met Asp He Leu Asn 740 745 750 Glu Glu Asn 753 (2) INFORMATION FOR SEQ ID NO:4: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 637 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4: Met Glu Gly Gly Cys Gly Ser Gin Trp Lys Ala Ala Gly Phe Leu 1 5 10 15 Phe Cys Val Met Val Phe Ala Ser Ala Glu Arg Pro Val Phe Thr 20 25 30 Asn His Phe Leu Val Glu Leu His Lyε Asp Gly Glu Glu Glu Ala 35 40 45 Arg Gin Val Ala Ala Glu His Gly Phe Gly Val Arg Lys Leu Pro 50 55 60 Phe Ala Glu Gly Leu Tyr His Phe Tyr His Asn Gly Leu Ala Lys 65 70 75 Ala Lys Arg Arg Arg Ser Leu His His Lys Arg Gin Leu Glu Arg 80 85 90 Asp Pro Arg He Lys Met Ala Leu Gin Gin Glu Gly Phe Asp Arg 95 100 . 105 Lys Lys Arg Gly Tyr Arg Asp He Asn Glu He Asp He Asn Met 110 115 120 Asn Asp Pro Leu Phe Thr Lys Gin Trp Tyr Leu Phe Asn Thr Gly 125 130 135 Gin Ala Asp Gly Thr Pro Gly Leu Asp Leu Asn Val Ala Glu Ala 140 145 150 Trp Glu Leu Gly Tyr Thr Gly Lys Gly Val Thr He Gly He Met 155 160 165 Asp Asp Gly He Asp Tyr Leu His Pro Asp Leu Ala Tyr Asn Tyr 170 175 180 Asn Ala Asp Ala Ser Tyr Asp Phe Ser Ser Asn Asp Pro Tyr Pro 185 190 195 Tyr Pro Arg Tyr Thr Asp Asp Trp Phe Asn Ser His Gly Thr Arg 200 205 210 Cys Ala Gly Glu Val Ser Ala Ala Ala Ser Asn Asn He Cys Gly 215 220 225 Val Gly Val Ala Tyr Asn Ser Lys Val Ala Gly He Arg Met Leu 230 235 240 Asp Gin Pro Phe Met Thr Asp He He Glu Ala Ser Ser He Ser 245 250 255 His Met Pro Gin Leu He Asp He Tyr Ser Ala Ser Trp Gly Pro 260 265 270 Thr Asp Asn Gly Lys Thr Val Asp Gly Pro Arg Glu Leu Thr Leu 275 280 285 Gin Ala Met Ala Asp Gly Val Asn Lys Gly Arg Gly Gly Lys Gly 290 295 300 Ser He Tyr Val Trp Ala Ser Gly Asp Gly Gly Ser Tyr Asp Asp 305 310 315 Cys Asn Cys Asp Gly Tyr Ala Ser Ser Met Trp Thr He Ser He 320 325 330 Asn Ser Ala He Asn Asp Gly Arg Thr Ala Leu Tyr Asp Glu Ser 335 340 345 Cys Ser Ser Thr Leu Ala Ser Thr Phe Ser Asn Gly Arg Lys Arg 350 355 360 Asn Pro Glu Ala Gly Val Ala Thr Thr Asp Leu Tyr Gly Asn Cys 365 370 375 Thr Leu Arg His Ser Gly Thr Ser Ala Ala Ala Pro Glu Ala Ala 380 385 390 Gly Val Phe Ala Leu Ala Leu Glu Ala Asn Leu Asp Leu Thr Trp 395 400 405 Arg Asp Met Gin His Leu Thr Val Leu Thr Ser Lys Arg Asn Gin 410 415 420 Leu His Asp Glu Val His Gin Trp Arg Arg Asn Gly Val Gly Leu 425 430 435 Glu Phe Asn His Leu Phe Gly Tyr Gly Val Leu Asp Ala Gly Ala 440 445 450 Met Val Lys Met Ala Lys Asp Trp Lys Thr Val Pro Glu Arg Phe 455 460 465 His Cys Val Gly Gly Ser Val Gin Asn Pro Glu Lys He Pro Pro 470 475 480 Thr Gly Lys Leu Val Leu Thr Leu Lys Thr Asn Ala Cys Glu Gly 485 490 495 Lys Glu Asn Phe Val Arg Tyr Leu Glu His Val Gin Ala Val He 500 505 510 Thr Val Asn Ala Thr Arg Arg Gly Asp Leu Asn He Asn Met Thr 515 520 525 Ser Pro Met Gly Thr Lys Ser He Leu Leu Ser Arg Arg Pro Arg 530 535 540 Asp Asp Asp Ser Lys Val Gly Phe Asp Lys Trp Pro Phe Met Thr 545 550 555 Thr His Thr Trp Gly Glu Asp Ala Arg Gly Thr Trp Thr Leu Glu 560 565 570 Leu Gly Phe Val Gly Ser Ala Pro Gin Lys Gly Leu Leu Lys Glu 575 580 585 Trp Thr Leu Met Leu His Gly Thr Gin Ser Ala Pro Tyr He Asp 590 595 600 Gin Val Val Arg Asp Tyr Gin Ser Lys Leu Ala Met Ser Lys Lys 605 610 615 Gin Glu Leu Glu Glu Glu Leu Asp Glu Ala Val Glu Arg Ser Leu 620 625 630 Gin Ser He Leu Arg Lys Asn 635 637 (2) INFORMATION FOR SEQ ID NO:5: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 32 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5: GCAAAATCTA GAYKGCNATY GTNGAYGAKG GN 32 (2) INFORMATION FOR SEQ ID NO:6: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NOr6: AAGCATGAGC TCNGGRGCRG CRGCNGANCC 30 (2) INFORMATION FOR SEQ ID NO:7: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7: GATATCACTC AGATCGATGA ATTCGAGCTC 30 (2) INFORMATION FOR SEQ ID NO:8: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 33 bases (B) TYPE: nucleic acid ' (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8 : AAGCTTTCTA GAGGATCCCT CTGGTGGATT TGG 33 (2) INFORMATION FOR SEQ ID NO:9 : (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9 AAGCTTGAAT TCTCCAACCC CACACTTGTG 30 (2) INFORMATION FOR SEQ ID NO:10 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 20 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 10 AGATCGATGA ATTCGAGCTC 20 (2) INFORMATION FOR SEQ ID NO:11: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 21 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11; CATTCTCGAA AAAAGAGACA A 21 (2) INFORMATION FOR SEQ ID NO:12: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 21 bases (B) TYPE: nucleic acid . (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12: CATTCTGTAA AAAAGAGACA A 21 (2) INFORMATION FOR SEQ ID NO:13: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 21 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13: CATTCTAGAG CAAAGAGACA A 21 (2) INFORMATION FOR SEQ ID NO:14: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 21 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:14: CATTCTAGAA AAGCAAGACA A 21 (2) INFORMATION FOR SEQ ID NO-.15: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 21 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:15: CATTCTAGAA AAAGAGCACA A 21 (2) INFORMATION FOR SEQ ID NO:16: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 21 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:16: ACCTGGAGCA AAGCTTCTCT G 21 (2) INFORMATION FOR SEQ ID NO: 17: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 21-bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 17: ACCTGGAGCG CTAGGTCTCT G 21 (2) INFORMATION FOR SEQ ID NO:18: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:18: CATAAGCTTA CCATGGCCCT GTGGATGCGC 30 (2) INFORMATION FOR SEQ ID NO:19: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:19: CATTCTAGAC TAGTTGCAGT AGTTCTCCAG 30 (2) INFORMATION FOR SEQ ID NO:20: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 4 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:20: Lys Thr Arg Arg 1 4 (2) INFORMATION FOR SEQ ID NO:21: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 4 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear ( i) SEQUENCE DESCRIPTION: SEQ ID NO:21: Leu Gin Lyε Arg 1 4 (2) INFORMATION FOR SEQ ID NO:22: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 4 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear ( i) SEQUENCE DESCRIPTION: SEQ ID NO:22: Arg Thr Lyε Arg 1 4 (2) INFORMATION FOR SEQ ID NO:23: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 4 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (Xi) SEQUENCE DESCRIPTION: SEQ ID NO:23: Arg Gin Lyε Arg 1 4 (2) INFORMATION FOR SEQ ID NO-.24: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 4 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (Xi) SEQUENCE DESCRIPTION: SEQ ID NO:24r Lys Thr Lys Arg 1 4 (2) INFORMATION FOR SEQ ID NO:25: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 31 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear ( i) SEQUENCE DESCRIPTION: SEQ ID NO:25: CTCTGCCTCC CGCTTGGTCC TGGGTGTGTA G 31 (2) INFORMATION FOR SEQ ID NO:26: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 22 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:26: CACGCTTCTG CCGGGATCCC TC 22 (2) INFORMATION FOR SEQ ID NO:27: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 31 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear ( i) SEQUENCE DESCRIPTION: SEQ ID NO:27 CTCTGCCTCC CGCTTGGTCT TCGGTGTGTA G 31 (2) INFORMATION FOR SEQ ID NO:28: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 36 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:28: GATATGAAGA GCAGATCTTT TGGACCTCCG AGGATG 36 (2) INFORMATION FOR SEQ ID NO:29: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 39 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:29: CTTATGGTGT AAGCTTCGTT TTGCTCTGGC CTTTGCAAG 39 (2) INFORMATION FOR SEQ ID NO:30: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 21 bases (B) TYPE: nucleic acid ' (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:30: TACAACTCAC CGCGGGTCCT G 21 (2) INFORMATION FOR SEQ ID NO:31: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 38 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear ( i) SEQUENCE DESCRIPTION: SEQ ID NO:31: AAGATGGGAT GGGATGATGA CCGTTTCCGC CTTGATGT 38 (2) INFORMATION FOR SEQ ID NO:32: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 38 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (Xi) SEQUENCE DESCRIPTION: SEQ ID NO:32: ACATCACGGC GGAAACGGTC ATCATCCCAT CCCATCTT 38 (2) INFORMATION FOR SEQ ID NO:33: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 28 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:33: GATATAAGCT TGAGAGTGTA GAAGGGGC 28 (2) INFORMATION FOR SEQ ID NO:34: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 40 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:34: GGCTTGACAT CATTGGCTGA CACTTTCGAA CACATGATAG 40 (2) INFORMATION FOR SEQ ID NO:35: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 41 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:35: AAGATGGGAT GGGATGATGA GCGCCGGACC CTCATGGACA T 41 (2) INFORMATION FOR SEQ ID NO:36: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 41 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:36: ATGTCCATGA GGGTCCGGCG CTCATCATCC CATCCCATCT T 41 (2) INFORMATION FOR SEQ ID NO:37; (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 28 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:37: GATATAAGCT TGAGAGTGTA GAAGGGGC 28 (2) INFORMATION FOR SEQ ID NO:38 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 51 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:38; TGAGCGACAG CACCCCCTTG GAGCCCCCGC CCTTGTATCT CATGGAGGAT 50 T 51 (2) INFORMATION FOR SEQ ID NO:39: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 51 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:39: TCAGCTCCCC TCGTCGGGCG GGGTCCGAGT GCCGTTTCCG CCGTGATGTT 50 C 51 (2) INFORMATION FOR SEQ ID NO: 0: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 48 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:40: ACGTGGGCAG CCCCGTGGTG GCGAACAGAA CATCACGGCG GAAACGGC 48 (2) INFORMATION FOR SEQ ID NO:41: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 48 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:41: TGTTCGCCAC CACGGGGCTG CCCACGTAAT CCTCCATGAG ATACAAGG 48 (2) INFORMATION FOR SEQ ID NO:42: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 26 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:42: CTCGGACCCC GCCCGACGAG GGGAGC 26 (2) INFORMATION FOR SEQ ID NO:43: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 27 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:43 GCGGGGGCTC CAAGGGGGTG CTGTCGC 27 (2) INFORMATION FOR SEQ ID NO:44 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 54 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:44: GTAGAACAAC ATGGACATGG TGGCAATATT GTCGACTCTG GAGTCGACCT 50 GCAG 54 (2) INFORMATION FOR SEQ ID NO:45: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 48 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:45: CACATAAAAC AAGATGGACA TGGTCTTGTT CACCTGTAGG ATCCCCGG 48 (2) INFORMATION FOR SEQ ID NO:46: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 53 bases (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (Xi) SEQUENCE DESCRIPTION: SEQ ID NO:4« AGTAAGGAAA AGGATGGTCA TGGTGGAGGT CGACAAGCTT GAGAATTCAA 50 TCG 53 (2) INFORMATION FOR SEQ ID NO:47: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 4 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:47: Xaa Xaa Xaa Arg 1 4 (2) INFORMATION FOR SEQ ID NO:48: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:48: His Ser Arg Lys Lys Arg Gin 1 5 7 (2) INFORMATION FOR SEQ ID NO:49: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:49: His Ser Val Lys Lys Arg Gin 1 5 7 (2) INFORMATION FOR SEQ ID NO:50: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:50: His Ser Arg Ala Lys Arg Gin 1 5 7 (2) INFORMATION FOR SEQ ID NO:51: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:51: His Ser Arg Lys Ala Arg Gin 1 5 7 (2) INFORMATION FOR SEQ ID NO:52: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:52 His Ser Arg Lys Arg Ala Gin 1 5 7 (2) INFORMATION FOR SEQ ID NO:53: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:53: Thr Trp Ser Lys Ala Ser Gin 1 5 7 (2) INFORMATION FOR SEQ ID NO:54: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:54 Thr Trp Ser Ala Arg Ser Gin 1 5 7

Claims: We claim: 1. A method for the production of a heterologous polypeptide factor in a polypeptide factor-dependent host cell comprising: a) introducing into the polypeptide factor-dependent host cell nucleic acid encoding a heterologous polypeptide factor precursor comprising a cleavage site heterologous to the polypeptide factor and recognizable by a host cell enzyme and wherein said host cell is dependent on the cleavage product of said polypeptide factor precursor; and b) culturing said host cell under conditions wherein the polypeptide factor precursor is expressed and cleaved at said cleavage site by the host cell enzyme, thereby producing said polypeptide factor 2. The method of claim 1, wherein said cleavage site recognizable by said host cell is a prohormone hormone convertase cleavage site. 3. The method of claim 2 wherein said prohormone convertase cleavage site is ZXZR (Seq ID #47) , wherein Z is LYS or ARG; X is any amino acid; and R is ARG. 4. The method of claim 1 wherein said host cell is mammalian. 5. The method of claim 4 wherein said host cell is a Chinese hamster ovary cell. 6. The method of claim 1 further comprising introducing into said host cell nucleic acid encoding a selectable gene. 7. The method of claim 1 wherein said polypeptide factor precursor is proinsulin and said polypeptide factor is insulin. 8. The method of claim 7 wherein said nucleic acid encoding proinsulin is operably linked to a promoter. 9. The method of claim 8 wherein said promoter is inducible. 10. The method of claim 1 wherein said nucleic acid encoding a polypeptide factor precursor is proins.RTKR.Ip/RQKR.Up. 11. The method of claim 1 wherein said nucleic acid encoding a polypeptide factor precursor is proins.RTKR. Ip/RQKR.lip.BIO H>D. 12. The method of claim 1 comprising the additional stepε: a) further introducing into the hoεt cell nucleic acid encoding a deεired polypeptide; and b) culturing εaid host cell under conditions wherein said desired polypeptide is expressed. 13. The method of claim 12 wherein said desired polypeptide is selected from the group comprising: relaxin, insulin-like growth factor I and II, growth hormone; factor VIII; factor IX; tumor necrosis factor-alpha and -beta; tissue factor protein; inhibin; activin; vascular endothelial growth factor; thrombopoietin; nerve growth factor; platelet-derived growth factor; fibroblast growth factor; epidermal growth factor; transforming growth factor; insulin-like growth factor-I and -II; interferon; GM-CSF; G-CSF; interleukin; decay accelerating factor; and atrial natriuretic peptides A, B or C. 14. The method of claim 12 further comprising recovering said desired polypeptide 15. The method of claim 12 wherein said desired polypeptide further comprises a precursor region having a second cleavage site recognizable by a host cell enzyme and wherein the precursor is cleaved at said second cleavage site by the host cell enzyme, thereby producing said desired polypeptide. 16. The method of claim 1 comprising the additional steps: a) further introducing into the host cell nucleic acid encoding said host cell enzyme; and b) culturing said host cell under conditions wherein said host cell enzyme is expressed. 17. A method for producing a desired polypeptide in a host cell, comprising: a) introducing into the host cell nucleic acid encoding the desired polypeptide precursor having a cleavage site not recognizable by any endogenous host cell enzyme and recognizable by enzyme heterologous to said host cell; b) introducing into said host cell nucleic acid encoding the enzyme heterologous to said host cell and wherein said enzyme heterologous to said host cell further comprises a precursor having a cleavage site recognizable by a host cell enzyme, and c) culturing said host cell under conditions wherein said precursor of enzyme heterologous to said host cell is expressed and cleaved at said cleavage site by host cell enzyme thereby producing said heterologous enzyme and wherein said desired polypeptide precursor is expressed and cleaved at said cleavage site by said enzyme heterologous to said host cell thereby producing said desired polypeptide. 18. The method of claim 17 further comprising recovering said desired polypeptide. 19. The method of claim 17 wherein the desired polypeptide is relaxin, growth hormone; factor VIII; factor IX; tumor necrosis factor-alpha and -beta; tissue factor protein; inhibin; activin; vascular endothelial growth factor; thrombopoie in; nerve growth factor; platelet-derived growth factor; fibroblast growth factor; epidermal growth factor; transforming growth factor; insulin-like growth factor-I and -II; interferon; GM-CSF; G-CSF; interleukin; decay accelerating factor; and atrial natriuretic peptideε A, B or C. 20. The method of claim 17 wherein the enzyme heterologouε to said hoεt cell is a prohormone convertase. 21. The method of claim 20 wherein said prohormone convertase is mammalian prohormone convertase 1 or mammalian prohormone convertase 2. 22. The method of claim 17 wherein said host cell is a polypeptide-factor dependent host cell. 23. The method of claim 22 further comprising introducing into the polypeptide factor-dependent host cell nucleic acid encoding a heterologous polypeptide factor precursor further comprising a cleavage site recognizable by a host cell enzyme or a heterologous enzyme added to said host cell, and culturing said host cell under conditions wherein the polypeptide factor precurεor iε cleaved at the cleavage site thereby producing said polypeptide factor. 24. The method of claim 23 wherein εaid polypeptide factor precursor is encoded by proins.RTKR.Ip/RQKR.Up.BIO H>D. 25. The method of claim 17 further comprising introducing into the host cell nucleic acid encoding a selectable gene. 26. The method of claim 17 wherein said host cell iε mammalian. 27. The isolated proinsulin encoded by the nucleic acid, proins.RTKR. Ip/RQKR.Up.B10 H>D. 28. The isolated nucleic acid proins.RTKR.Ip/RQKR.Up.B10 H>D.

Inventors: GORMAN CORNELIA M, GROSKREUTZ DEBYRA J, MARRIOTT DAVID, GORMAN, CORNELIA, M., GROSKREUTZ, DEBYRA, J., MARRIOTT, DAVID
Applicants: GENENTECH INC, GENENTECH, INC.
Application year: 1992
Main classification: C12N15
IPC codes: C07K14, C12N9, C12N15, C12P21, C12R1