NATURE OF STEROID-RECEPTOR INTERACTION

本项目的目标是定义初始的，细胞内的 类固醇激素作用的事件。 这些事件包括类固醇与 细胞内受体分子，受体类固醇的“激活”， 复合物与DNA结合和核结合物质的结合，以及复合物与DNA结合和核结合物质的结合。 激活复合物的那些核受体位点参与 调节特定基因的转录。 一种方法， 用于检查这些步骤的方法是比较激动剂和 拮抗剂受体-类固醇复合物。 使用无细胞糖皮质激素 糖皮质激素反应性大鼠肝癌组织的受体 培养（HTC）细胞，其已经被可逆的 激动剂地塞米松或亲和标记的不可逆 抗糖皮质激素地塞米松21-甲磺酸盐，我们已经发现， 受体复合物之间微小但真实的物理化学差异 糖皮质激素和抗糖皮质激素类固醇。 因此， 非共价激动剂复合物在0 ℃的活化是2倍 比共价复合物的活化速度快， 复合物结合小牛胸腺DNA的2倍高的非共价 激动剂复合物。 这种对非特异性DNA的亲和力的微小差异 在活化的非共价复合物与共价复合物的结合中没有变化 长末端重复序列（LTR）中的生物活性DNA序列 小鼠乳腺肿瘤病毒（MMTV）。 因此，整个细胞不可逆 地塞米松21-甲磺酸盐的抗糖皮质激素活性不能归因于 共价复合物对生物活性的亲和力的改变 活性或非活性DNA序列，或与 共价复合物。

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 agonist and antagonist receptor-steroid complexes. Using cell-free glucocorticoid receptors from a line of glucocorticoid responsive rat hepatoma tissue culture (HTC) cells that have been noncovalently bound by the reversible agonist dexamethasone or affinity labeled by the irreversible antiglucocorticoid dexamethasone 21-mesylate, we have found that there are minor, but real, physicochemical differences between the receptor complexes of glucocorticoid and antiglucocorticoid steroids. Thus, the rate of activation at O degrees C of the noncovalent agonist complexes was 2-fold faster than that of the covalent complexes and the strength of activated complex binding to calf thymus DNA was 2-fold higher for the noncovalent agonist complexes. This small difference in affinity for non-specific DNA was unchanged in the binding of activated noncovalent vs covalent complexes to the biologically active DNA sequences in the long termined repeat (LTR) of mouse mammary tumor virus (MMTV). Thus, the whole cell irreversible antiglucocorticoid activity of dexamethasone 21-mesylate cannot be ascribed to alterations in the affinity of the covalent complexes for biologically active or inactive DNA sequences or to changes in the rate of activation of the covalent complexes.