Progesterone-binding properties of the microsomal fraction from chick oviduct.
Progesterone binds to specific high-affinity and limited-capacity binding sites of chick-oviduct microsomes of estrogen-primed chicks. The dissociation constant is 2 x 10(-9) M (range 1.6--3.0) and the number of binding sites 500 femtomoles/mg microsomal protein (range 464--551). Treatment of the estrogen-primed chicks by progesterone had no apparent effect on the progesterone-binding capacity or affinity. Competition studies showed that testosterone, R-5020, Org-2058, D-norgestrel, 5 alpha-dihydrotestosterone and R-2323 were effective competitors of progesterone, in that order, whereas cortisol, estradiol and estrone exhibited only minimal displacement. No displacement of microsome-bound [3H]progesterone was found with fenoterol or prostaglandin F2 alpha. No high-affinity progesterone-binding sites were found in the microsomal fractions of liver, muscle, intestine or brain. On the basis of steroid-binding affinity and steroid-specificity determinations, the microsomal progesterone-binding components seem to be different from the progesterone receptor previously described in chick oviduct cytosol.
D000818:Animals; D002645:Chickens; D004054:Diethylstilbestrol / Q000378:metabolism; D013196:Dihydrotestosterone / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D004970:Estrone / Q000378:metabolism; D005867:Gestrinone / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D009644:Norgestrel / Q000378:metabolism; D010057:Oviducts / Q000378:metabolism*; D011397:Promegestone / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism
D011980:Receptors, Progesterone; D013196:Dihydrotestosterone; D005867:Gestrinone; D004970:Estrone; D009644:Norgestrel; D013739:Testosterone; D004958:Estradiol; D004054:Diethylstilbestrol; D011397:Promegestone