NATURE OF STEROID-RECEPTOR INTERACTIONS

这个项目的目标是定义初始的、细胞内的 类固醇激素作用事件。这些事件包括类固醇 与细胞内受体分子结合，“激活” 受体-类固醇复合体的DNA结合和核结合 物种，以及活化的复合体与这些核的结合 参与转录调控的受体位点 特定的基因。其中一种方法已经被用来检查这些 步骤是比较不同类固醇在不同条件下的性质 细胞系。因此，以前关于诱导量的研究 几种糖皮质激素对酪氨酸氨基转移酶的影响 大鼠肝癌组织培养株(HTC和Fu5-5)显示 最大TAT的50%所需的类固醇浓度 HTC细胞的诱导率约为Fu5-5细胞的6倍。 现在在TAT酶的诱导中也看到了同样的差异 通过稳定的cAMP衍生物(8-(4- 氯苯硫基)营地)。这些数据表明，一种常见的前驱 翻译事件决定了TAT的不同敏感性 糖皮质激素和cAMP对HTC和Fu5-5细胞的诱导作用。 第二种方法是检查 不可逆抗糖皮质激素(和亲和标记)地塞米松 21-甲磺酸(Dex-Mes)的分子水平。DEX-MES 与碱性水溶液中蛋白质的半胱氨酸发生特异性反应 解决办法。地塞米松与糖皮质激素受体的反应 仅出现在类固醇结合位点的Cys-656处。这 第一个与生物相关的氨基酸的鉴定 糖皮质激素受体的特性应该会促进未来 结构-功能研究。

The objective of this project is to define the initial, intracellular events of steroid hormone action. These events include steroid binding to the intracellular receptor molecule, "activation" of the receptor-steroid complex to a DNA-binding and nuclear-binding species, and binding of the activated complex to those nuclear acceptor sites involved in the regulation of transcription of specific genes. One approach that has been used to examine these steps is to compare the properties of various steroids in different cell lines. Thus previous studies of the amount of induction of tyrosine aminotransferase (TAT) by several glucocorticoids in two rat hepatoma tissue culture lines (HTC and Fu5-5) revealed that the steroid concentration required for 50% of maximal TAT induction in HTC cells was about 6-fold higher than in Fu5-5 cells. The same difference is now seen in the induction of TAT enzyme and mRNA levels by the stable cAMP derivative, (8-(4- chlorophenylthio)cAMP). These data suggest that a common pre- translational event determines the different sensitivity of TAT induction by glucocorticoids and by cAMP in HTC and Fu5-5 cells. A second approach has been to examine the properties of the irreversible antiglucocorticoid (and affinity label) dexamethasone 21-mesylate (Dex-Mes) at a molecular level. Dex-Mes specifically reacts with the cysteines of proteins in basic aqueous solutions. Dex-Mes reaction with the glucocorticoid receptor occurs uniquely at Cys-656 in the steroid binding site. This identification of the first amino acid associated with a biological property of the glucocorticoid receptor should facilitate future structure-function studies.