title: Study of a proline-rich polypeptide bound to the prostatic binding protein of rat ventral prostate.
abstract: A proline-rich polypeptide is associated with prostatic binding protein, a major androgen-dependent protein described previously in the rat ventral prostate. This polypeptide has been purified. Its molecular weight estimated by gel filtration is about 8500, but a markedly lower value (3300) is obtained by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis. Isoelectric focusing on thin layer polyacrylamide gels yields two major forms with isoelectric points of, respectively, 7.75 and 7.05. The amino acid composition of proline-rich polypeptide is characterized by a high (19.5%) proline content and its NH2-terminal amino acid is glycine. Like prostatic binding protein, proline-rich polypeptide is a characteristic component of the rat ventral prostate and localized primarily in the intraluminal secretion of this gland. In intact adult male rats the cytosol of a whole gland contains 0.70 +/- 0.15 (S.D.) mg of the polypeptide, as measured by radial immunodiffusion or 2.6 +/- 0.5% of (S.D.) of the total protein. This amount decreases gradually after castration and becomes undetectable after 8 days. Androgen treatment, on the other hand, results in a rapid stimulation, while estradiol and progesterone are ineffective. Proline-rich polypeptide is markedly more androgen-dependent than prostatic binding protein, and promises to be an interesting end point for studies on the mechanism of action of androgens.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000727:Androgen-Binding Protein / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002369:Castration; D003600:Cytosol / Q000378:metabolism; D008297:Male; D010455:Peptides / Q000378:metabolism*; D011392:Proline / Q000378:metabolism*; D055232:Proline-Rich Protein Domains; D011467:Prostate / Q000378:metabolism*; D060789:Prostatein; D051381:Rats; D011919:Rats, Inbred Strains; D012471:Salivary Proteins and Peptides / Q000378:metabolism*; D060765:Secretoglobins; D014598:Uteroglobin; D060788:Mammaglobin B
chemical_list: D000596:Amino Acids; D000727:Androgen-Binding Protein; D002352:Carrier Proteins; D010455:Peptides; D011392:Proline; D060789:Prostatein; D012471:Salivary Proteins and Peptides; D060765:Secretoglobins; D014598:Uteroglobin; C511484:Scgb1d2 protein, rat; C511483:Scgb1d4 protein, rat; C556468:Scgb2a1 protein, rat; D060788:Mammaglobin B