Identification and partial characterization of the cytoplasmic androgen receptor in bovine ovarian capsule

Abstract

[3H]Dihydrotestosterone (DHT) binding to a specific protein in the cytosol of bovine ovarian capsule was studied in vitro. The specific androgen-binding protein in the cytosol was analyzed by chromatographic and ultracentrifugal techniques. From Scatchard analysis, the dissociation constant was 7.4 nM and the number of binding sites was 58.8 fmol/mg protein. Testosterone and 17 alpha-methyltrienolone (R1881) compete for [3H]DHT binding. In the presence of sodium molybdate and at low salt concentrations, the steroid-protein complex sediments as a 9S form, while in the presence of high salt, it sediments at 3.5S. In the absence of molybdate or in the presence of high salt, the 9S form dissociates in a temperature-dependent manner into smaller units. These properties are consistent with the presence of a typical androgen receptor in the bovine ovarian capsule.