Fortunati N, Fissore F, Fazzari A, Berta L, Varvello L, Frairia R
Dipartimento di Fisiopatologia Clinica, Università di Torino, Italy.
Steroids. 1992 Sep;57(9):464-70. doi: 10.1016/0039-128x(92)90102-f.
The sex steroid-binding protein (SBP) receptor was solubilized from the membranes of human premenopausal endometrium with the zwitterionic detergent CHAPS. The binding activity of the soluble receptor was studied, allowing it to interact with [125I]SBP and precipitating the complex with polyethylene glycol 8,000. The interaction of SBP with the soluble receptor was specific, saturable, and at high affinity. Indeed, the specific binding was definitely improved on the solubilized form of the receptor. The effect exerted by sex steroids on the interaction of SBP with receptor was also examined on both the soluble and membrane-bound forms. At physiologic doses (10(-8) M) estradiol inhibits the binding at a significant extent on the soluble receptor, but not on membrane-bound form. The dose of estradiol required to significantly inhibit the SBP-specific binding was dependent on the form of receptor. In membrane-bound receptor the inhibiting dose of estradiol was higher than its physiologic concentration. Thus, it is likely that, while soluble receptor cannot recognize the complex steroid-SBP, membrane-bound receptor can interact both with "unliganded" SBP and with the estradiol-SBP complex (but not with androgen-SBP complexes) in an estrogen-dependent tissue like human endometrium.
用两性离子去污剂CHAPS从人绝经前子宫内膜膜中溶解出性类固醇结合蛋白（SBP）受体。研究了可溶性受体的结合活性，使其与[125I]SBP相互作用，并用聚乙二醇8000沉淀复合物。SBP与可溶性受体的相互作用具有特异性、饱和性且亲和力高。实际上，受体的溶解形式确实明显提高了特异性结合。还在可溶性和膜结合形式上研究了性类固醇对SBP与受体相互作用的影响。在生理剂量（10^(-8) M）下，雌二醇在很大程度上抑制了可溶性受体上的结合，但对膜结合形式没有影响。显著抑制SBP特异性结合所需的雌二醇剂量取决于受体形式。在膜结合受体中，雌二醇的抑制剂量高于其生理浓度。因此，在像人子宫内膜这样的雌激素依赖性组织中，虽然可溶性受体不能识别复合类固醇-SBP，但膜结合受体可能既能与“未结合配体的”SBP相互作用，也能与雌二醇-SBP复合物（但不能与雄激素-SBP复合物）相互作用。
