Rat ovary glucocorticoid receptor: identification and characterization.
A soluble, thermolabile protein with characteristics typical of glucocorticoid receptors has been identified in the ovaries of estrogen-stimulated hypophysectomized immature rats. After the incubation of 3H- dexamethasone with ovarian cytosol, fractionation on a Sephadex G-200 column reveals a peak of radioactivity which elutes at the void volume. This peak, which represents saturable 3H-dexamethasone binding, disappears following heating (4 degrees C X 15 min) or treatment of the cytosol with pronase. Scatchard analysis of the 3H-dexamethasone binding to cytosol shows it to be high affinity (Kd=5.1 nM) and saturable, with 327 fmol binding sites/mg cytosol protein. Binding site number rises linearly with increasing cytosol protein concentrations. The relative abilities of various steroids to inhibit 3H-dexamethasone binding are: triamcinolone acetonide greater than or equal to dexamethasone greater than cortisol = progesterone greater than dihydro-testosterone greater than estradiol. This binding protein sediments at 9 S on a sucrose gradient, has a mean Stokes radius of 105 A on gel exclusion chromatography, and has a calculated molecular weight of 388,000 daltons and a frictional ratio of 2.1. 3H-Dexamethasone is not metabolized and does not bind specifically to serum. We have identified a protein in the rat ovary with characteristics of a glucocorticoid receptor and propose that this protein may be responsible for mediating direct effects of glucocorticoids on the ovary.
D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002850:Chromatography, Gel; D003600:Cytosol / Q000378:metabolism; D003907:Dexamethasone / Q000378:metabolism; D005260:Female; D007700:Kinetics; D010053:Ovary / Q000378:metabolism*; D011397:Promegestone / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011965:Receptors, Glucocorticoid / Q000302:isolation & purification / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*
D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; D003907:Dexamethasone; D011397:Promegestone