title: The cDNA cloning of a 55-kilodalton protein from guinea pig seminal vesicle. Evidence that the protein is the precursor of a 25-kilodalton basic secretory protein.
abstract: Guinea pig seminal vesicle epithelium synthesizes and secretes large amounts of four secretory proteins including a basic protein designated SVP-1. The latter migrates as a protein of 25 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When total cellular RNA from seminal vesicle epithelium was translated in vitro by a rabbit reticulocyte system, SVP-1 was not identifiable as a product. In contrast, a major product of the reticulocyte system was a 55-kDa protein which paradoxically could not be identified as one of the four known secretory proteins or as an abundant tissue protein. We isolated a cDNA clone which corresponded to the mRNA which coded for the 55-kDa protein. The mRNA was 1800 bases and of very high abundance; only the transcripts corresponding to the major secretory proteins SVP-3 and SVP-4 were as conspicuous. From these observations, we decided to test whether the 55-kDa protein was related to SVP-1. The 55-kDa protein was found to share properties of SVP-1, including an alkaline pI and selection by antibody against SVP-1. After proteolytic digestion of the 55-kDa protein, one fragment co-migrated with authentic SVP-1. Furthermore, detectable fragments of the 55-kDa protein smaller than SVP-1 all co-migrated with fragments generated from the proteolytic digestion of SVP-1. Finally, we show that the 55-kDa protein could be processed in vitro by seminal vesicle lumenal extracts to yield a 30-kDa protein and a protein the size of native SVP-1. The best explanation of our results is that the 55-kDa protein represents the primary translation product and precursor of SVP-1. Our proteolytic mapping and in vitro processing studies are consistent with the idea that the 55-kDa protein is a tandem repeat of two SVP-1 molecules. We used the cDNA clone to study the expression of the corresponding gene in different states of androgen depletion and repletion.
authors.forename: J T
authors.initials: JT
authors.lastname: Moore
authors.forename: M E
authors.initials: ME
authors.lastname: Norvitch
authors.forename: C M
authors.initials: CM
authors.lastname: Veneziale
mesh_terms: D000818:Animals; D004247:DNA / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism; D006168:Guinea Pigs; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000378:metabolism; D008297:Male; D008970:Molecular Weight; D010206:Papain / Q000378:metabolism; D011061:Poly A / Q000378:metabolism; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000235:genetics*; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger; D012669:Seminal Vesicles / Q000032:analysis*; D012697:Serine Endopeptidases
chemical_list: D011498:Protein Precursors; D012333:RNA, Messenger; D011061:Poly A; D012313:RNA; D004247:DNA; D010450:Endopeptidases; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D010206:Papain; D008274:Magnesium