Nuclear testosterone receptors in the ovine testis.
Nuclear [3H] testosterone-receptor complexes were demonstrated in hypophysectomized ram testis after in vitro direct labelling. The nuclear binding was maximal after a 45 min incubation of the tissue. The receptors are extractable by 0.4 M KC1 or NaSCN with a 25-30% efficiency. They migrate towards the anodic region during electrophoresis on agar gel. Nuclear androgen receptors were characterized in intact lamb testis by a testosterone exchange assay. After precipitation by protamine sulphate, the receptors were labelled with [3H]testosterone during a 12 h incubation at 4 degrees C. The exchange activity was linear between 0.1 and 0.9 mg of DNA per ml of incubation buffer. The receptors bind testosterone with a limited capacity (40-180 fmoles per mg DNA) and a dissociation constant Kd of 2 x 10(-9) M. Their relative affinities for steroids are dihydrotestosterone greater than testosterone greater than estradiol greater than progesterone greater than 5 alpha-androstanediol greater than cyproterone acute greater than R5020.
D000818:Animals; D002467:Cell Nucleus / Q000032:analysis*; D008297:Male; D011944:Receptors, Androgen; D011987:Receptors, Steroid / Q000032:analysis*; D012756:Sheep; D013696:Temperature; D013737:Testis / Q000032:analysis* / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism
D011944:Receptors, Androgen; D011987:Receptors, Steroid; D013739:Testosterone