The estrogen cytosol receptor of female ovine pituitary.
The biochemical parameters of estrone and estradiol binding to the cytosol fraction of ovine anterior pituitary were investigated. When increasing amounts of [3H]estrone or [3H]estradiol were incubated with the 105,000 g fraction from the pituitary, both hormones bound to a receptor with the same apparent KD (mean +/- S.E., estrone = 1.40 +/- 0.30 X 10(-10) M, estradiol = 1.03 +/- 0.11 X 10(-10)M) and the same concentration of binding sites (estrone = 3.22 +/- 0.58 X 10(-14) moles/mg protein, estradiol = 3.92 +/- 0.19 X 10(-14)). No conversion of [3H]estrone to [3H]estradiol under the experimental conditions used could be demonstrated. The receptor-estrogen complex exhibited identical sedimentation coefficients (7-8 S) with either hormone. The receptor was specific only for estrogens; neither 500-fold excess of testosterone nor progesterone affected binding. Competitive inhibition using increasing amounts of non-radioactive estrone or estradiol with [3H]estrone or [3H]estradiol resulted in parallel displacement of the radioactive hormone. These results strongly suggest that both hormones bind to the same pituitary cytosol receptor.
D000818:Animals; D001665:Binding Sites; D003600:Cytosol / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism*; D004970:Estrone / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D010902:Pituitary Gland / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism; D011956:Receptors, Cell Surface; D012756:Sheep
D011506:Proteins; D011956:Receptors, Cell Surface; D004970:Estrone; D004958:Estradiol