Miroshnichenko M L, Smirnova O V, Smirnov A N, Rozen V B
J Steroid Biochem. 1983 Apr;18(4):403-9. doi: 10.1016/0022-4731(83)90058-4.
The unusual estrogen-binding protein (UEBP) found in a male rat liver is a sex dependent protein which differs from other known receptor and transport proteins by the high lability of its complexes with estradiol (E2) and also the unique specificity of affinity for hormones. In this work values of relative binding affinity (RBA) of the UEBP for 57 steroids and their analogs were determined. The affinity of steroids was characterised by the amount of the unlabeled compound needed for 50% inhibition of [3H]-E2 binding with the UEBP. A number of derivatives of estrane and androstane possess an ability to interact with this protein, in contrast to the derivatives of pregnane, stilbene and triphenylethane. Characterized by RBA values, natural steroids are found to have the following order: estriol larger than or equal to E2 greater than 16 alpha-hydroxyestrone = 2 alpha-hydroxytestosterone greater than 16-epiestriol greater than or equal to estetrol greater than or equal to 17-epiestriol greater than or equal to 2-methoxyestradiol greater than or equal to 5 alpha-androstane-3 alpha,17 beta-diol greater than or equal to estrone greater than testosterone greater than or equal to 2 beta-hydroxytestosterone greater than 5 alpha-dihydrotestosterone. Affinity of estrogens and androgens for the UEBP diminishes abruptly after removal of 3- and 17-hydroxy groups, masking of these by ether bonds or changing of 17 beta-hydroxyl to 17 alpha. All the investigated 17 oxo-C19-steroids, 5 beta-derivatives of testosterone, its 6 beta- and 16 alpha-hydroxy metabolites as well as 5 alpha-androstane-3 beta,17 beta-diol and 19-nortestosterone exhibit no essential affinity for the protein. On the basis of the results obtained it is suggested that the binding sites for estrogens and androgens in the UEBP molecule overlap but do not completely coincide.
在雄性大鼠肝脏中发现的异常雌激素结合蛋白（UEBP）是一种性别依赖性蛋白，它与其他已知的受体和转运蛋白不同，其与雌二醇（E2）形成的复合物具有高不稳定性，并且对激素具有独特的亲和力特异性。在这项工作中，测定了UEBP对57种甾体及其类似物的相对结合亲和力（RBA）值。甾体的亲和力通过50%抑制[3H]-E2与UEBP结合所需的未标记化合物的量来表征。与孕烷、二苯乙烯和三苯乙烷的衍生物不同，许多雌甾烷和雄甾烷的衍生物具有与该蛋白相互作用的能力。以RBA值为特征，天然甾体的顺序如下：雌三醇大于或等于E2大于16α-羟基雌酮 = 2α-羟基睾酮大于16-表雌三醇大于或等于雌四醇大于或等于17-表雌三醇大于或等于2-甲氧基雌二醇大于或等于5α-雄甾烷-3α,17β-二醇大于或等于雌酮大于睾酮大于或等于2β-羟基睾酮大于5α-二氢睾酮。去除3-和17-羟基、用醚键掩盖这些基团或将17β-羟基变为17α后，雌激素和雄激素对UEBP的亲和力会突然降低。所有研究的17-氧代-C19-甾体、睾酮的5β-衍生物、其6β-和16α-羟基代谢产物以及5α-雄甾烷-3β,17β-二醇和19-去甲睾酮对该蛋白均无明显亲和力。根据所得结果表明，UEBP分子中雌激素和雄激素的结合位点重叠但不完全重合。
