title: Oestrogen-inducible uterine progesterone receptors. characteristics in the ovariectomized immature and adult hamster.
abstract: In order to characterize the uterine progesterone-binding proteins of oestrogen-primed and unprimed, ovariectomized immature and adult golden hamsters, cytosols were incubated with [3H]progesterone and/or other steroids and analyzed by sucrose-glycerol density gradient ultracentrifugation. Progesterone-binding components with sedimentation coefficients of 7S and 4.5S were found in the uterine cytosols, but not in the cytosols from the hypothalamus, pituitary, diaphragm, or small intestine. Oestradiol-17beta markedly elevated the level of 7S uterine receptor and this increase appeared to be due to new receptor synthesis, since actinomycin D and cycloheximide blocked this response. Fifty to 100 mug of oestradiol-17beta per kg body weight was found to promote a maximum increase in the 7S macromolecular component. The 7S receptor showed a tendency to saturate at 1 X 10(-7) M [1,2-3H]progesterone, indicating limited capacity. At a molar ratio of 100:1, unlabeled progesterone competed effectively for 7S and 4,5S [3H]progesterone binding, whereas 5alpha-pregnane-3,20-dione, oestradiol-17beta and testosterone did not. Moreover, [1,2-3H]cortisol and [1,2-3H]corticosterone did not bind to the 7S receptor, implying steroid specificity. CI-628, a non-steroid oestrogen antagonist, completely prevented [6,7-3H]oestradiol-17beta binding to its 8.5S uterine cytosol receptor, but was entirely without effect on 7S and 4.5S [3H]progesterone binding. Pronase, but not DNase or RNase, abolished 7S and 4.5S progesterone binding, suggesting that the binders are at least in part protein. Protamine sulphate and p-hydroxymercuribenzoate also obliterated 7S binding, implying that this receptor may be an acidic protein which contains sulfhydryl groups that are necessary for progesterone binding.
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D003345:Corticosterone / Q000494:pharmacology; D006224:Cricetinae; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D003851:Deoxyribonucleases / Q000494:pharmacology; D003864:Depression, Chemical; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006854:Hydrocortisone / Q000494:pharmacology; D006902:Hydroxymercuribenzoates / Q000494:pharmacology; D011277:Pregnanediones / Q000494:pharmacology; D011374:Progesterone / Q000378:metabolism* / Q000494:pharmacology; D011402:Pronase / Q000494:pharmacology; D011479:Protamines / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000187:drug effects*; D012260:Ribonucleases / Q000494:pharmacology; D013268:Stimulation, Chemical; D013739:Testosterone / Q000494:pharmacology; D014599:Uterus / Q000378:metabolism*
chemical_list: D006902:Hydroxymercuribenzoates; D011277:Pregnanediones; D011479:Protamines; D011956:Receptors, Cell Surface; D003609:Dactinomycin; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D003513:Cycloheximide; D003851:Deoxyribonucleases; D012260:Ribonucleases; D011402:Pronase; D003345:Corticosterone; D006854:Hydrocortisone