Whelly S M
Biochim Biophys Acta. 1986 Feb 19;880(2-3):179-88. doi: 10.1016/0304-4165(86)90078-4.
Rat uterine nuclei contain two types of estrogen binding sites (I and II). Type I is the classical high-affinity, low-capacity binding component, while Type II has lower affinity and higher capacity. Investigation of the presence and number of estrogen-binding proteins in isolated uterine nucleoli, and the possible role of the estrogen-binding protein(s) in the stimulation of nucleolar RNA synthesis was undertaken. Isolated uterine nucleoli contain a large number of lower-affinity binding sites (Type II) but are devoid of a significant number of high-affinity binding protein(s) (Type I). Following in vivo treatment with estradiol the number of detectable Type II estradiol-binding sites in isolated uterine nucleoli increased with time of estrogen treatment, peaking between 16 and 24 h after hormone administration and gradually decreasing to control levels between 48 and 72 h. The estrogen-activated binding activity but not the basal activity is sensitive to dithiothreitol and insensitive to beta-mercaptoethanol during the in vitro assay, suggesting that important disulfide bonds may be involved in the estrogen-induced nucleolar binding sites. The in vivo activation of nucleolar estradiol-binding sites exhibits steroid specificity. Data indicate that a strong correlation exists between activation of uterine nucleolar transcriptional and estradiol-binding activities.
大鼠子宫核含有两种类型的雌激素结合位点（I和II）。I型是典型的高亲和力、低容量结合成分，而II型具有较低的亲和力和较高的容量。本研究对分离的子宫核仁中雌激素结合蛋白的存在和数量，以及雌激素结合蛋白在刺激核仁RNA合成中的可能作用进行了调查。分离的子宫核仁含有大量低亲和力结合位点（II型），但缺乏大量高亲和力结合蛋白（I型）。经雌二醇体内处理后，分离的子宫核仁中可检测到的II型雌二醇结合位点数量随雌激素处理时间增加，在激素给药后16至24小时达到峰值，并在48至72小时之间逐渐降至对照水平。在体外测定中，雌激素激活的结合活性而非基础活性对二硫苏糖醇敏感，对β-巯基乙醇不敏感，这表明重要的二硫键可能参与雌激素诱导的核仁结合位点。核仁雌二醇结合位点的体内激活表现出类固醇特异性。数据表明，子宫核仁转录激活与雌二醇结合活性之间存在很强的相关性。
