title: Prostatic cytosol binding of 5 alpha-androstane-3 beta, 17 beta-diol and estradiol-17 beta.
abstract: The goal of the present research was characterization of the interaction of 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol) with prostatic estradiol-17 beta(E2) binding sites to address the role of this 5 alpha-dihydrotestosterone(DHT)a metabolite in prostatic regulation. Using dextran-charcoal assay we demonstrated specific 3 beta-diol and E2 binding sites in rat ventral prostate cytosol (RVPC) and dog prostate cytosol (DPC). In both cytosols, E2 binding is of high affinity (Ka congruent to 10(9) M-1; RVPC:68 fmol/mg protein), DPC:170 fmol/mg protein), and 3 beta-diol binding is of moderate affinity (Ka congruent to 10(8) M-1; RVPC:62 fmol/mg protein, DPC:165 fmol/mg protein). Unlabeled 3 beta-diol competes effectively for cytosolic 3H-E2 binding sites, whereas unlabeled DHT, 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol) and testosterone (T) are poor competitors for 3H-E2 binding sites. Using DNA-cellulose column chromatography, we separated prostatic androgen and estrogen binding activities. The E2 binding activity which adhered to DNA-cellulose was displaced by 100-fold excess 3 beta-diol but not by DHT. Thus data from two assay procedures show competition of 3 beta-diol for 3H-E2 binding sites in rat and dog prostate.
mesh_terms: D015113:Androstane-3,17-diol / Q000378:metabolism*; D000732:Androstanols / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D003600:Cytosol / Q000378:metabolism; D004285:Dogs; D004958:Estradiol / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D011467:Prostate / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000732:Androstanols; D015113:Androstane-3,17-diol; D004958:Estradiol