An empirical basis for the competition by dexamethasone to progesterone receptors as estimated with the synthetic progestin R5020.
An empirical basis for the competition by dexamethasone to progesterone receptors as estimated with the synthetic progestin R5020.
复制标题
用合成孕激素 R5020 估计的地塞米松与孕酮受体竞争的经验基础。
DOI：
10.3109/107998981809038877
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
G. Shyamala
中科院分区：
文献类型：
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作者：
S. Haslam;W. McBlain;G. Shyamala
小鼠的正常乳腺含有孕酮和糖皮质激素受体，并且这两种受体的水平作为发育的函数被调节。使用合成的孕激素受体R5020测量孕激素受体导致了关于在乳腺的某些发育阶段孕激素受体的存在和糖皮质激素竞争特定R5020结合位点的能力的相互矛盾的数据。在这份报告中，我们已经确定了实验条件，允许单独测量的孕酮和糖皮质激素受体在相同的胞质溶胶。如果从测定缓冲液中排除巯基还原剂如二硫苏糖醇，则R5020仅与未交配小鼠乳腺胞质溶胶中的单一类别的高亲和力位点结合，并且这些结合位点表现出孕酮受体的严格类固醇特异性特征。相反，如果缓冲液中包含二硫苏糖醇，R5020不仅与高亲和力位点结合，而且与某些可饱和的较低亲和力位点结合; R5020的这些较低亲和力位点也与糖皮质激素如地塞米松结合。这些发现将有助于更准确地定量正常和肿瘤组织中的孕酮和糖皮质激素受体，也适用于孕酮作用机制的研究。
Normal mammary glands of mice contain both progesterone and glucocorticoid receptors and the levels of both these receptors are modulated as a function of development. Measurement of progesterone receptors using the synthetic progestin, R5020, has led to conflicting data both with regard to the presence of progesterone receptor during certain developmental stages of the mammary gland and the ability of the glucocorticoids to compete for specific R5020 binding sites. In this report we have identified experimental conditions which allow for the separate measurements of the progesterone and glucocorticoid receptors in the same cytosol. If sulfhydryl reducing agents such as dithiothreitol are excluded from the assay buffer, R5020 binds to only a single class of high affinity sites in mammary cytosol of virgin mice and these binding sites exhibit a strict steroid specificity characteristic of progesterone receptors. In contrast, if dithiothreitol is included in the buffers, R5020 binds not only to the high affinity sites but also to certain saturable lower affinity sites; these lower affinity sites for R5020 also bind glucocorticoids such as dexamethasone. These findings should facilitate more accurate quantitation of both progesterone and glucocorticoid receptors in normal and neoplastic tissues and also be applicable to studies on the mechanism(s) of progesterone action.