title: Comparative binding specificity of methyltrienolone in human and rat prostate.
abstract: The binding of methyltrienolone (R 1881) in crude human hyperplastic prostate cytosol was determined by a charcoal assay. Maximum binding was observed after 2-3 h of incubation at 0 degrees C. This binding decreased steadily thereafter and reached 41% of the 2-hour values after 96 h of incubation. In human hyperplastic prostate, the binding of 3H-R 1881 was competed by low concentrations of R 1881, R 5020 and progesterone and by high concentrations of dihydrotestosterone (DHT) and 17 alpha-methyl-DHT. In the rat prostate, on the other hand, this binding was competed by low concentrations of DHT and 17 alpha-methyl-DHT and only by high concentrations of progesterone and R 5020. The apparent association constant (Ka) of R 1881 was determined in three human prostates and found to be 0.2-0.4 X 10(9) liters/mol; the number of binding sites ranged from 101 to 158 fmol per mg of protein. These findings constitute further evidence for the existence of relatively large amounts of a progesterone-binding component in human hyperplastic prostate.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D003600:Cytosol / Q000378:metabolism; D004963:Estrenes / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008297:Male; D011467:Prostate / Q000378:metabolism*; D011470:Prostatic Hyperplasia / Q000378:metabolism; D051381:Rats; D011944:Receptors, Androgen / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*; D013045:Species Specificity; D045165:Testosterone Congeners / Q000378:metabolism*
chemical_list: D004963:Estrenes; D011944:Receptors, Androgen; D011987:Receptors, Steroid; D045165:Testosterone Congeners