Comparison of the 90-kilodalton heat shock protein interaction with in vitro translated glucocorticoid and estrogen receptors.
Comparison of the 90-kilodalton heat shock protein interaction with in vitro translated glucocorticoid and estrogen receptors.
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DOI：
10.1210/mend.6.1.1738366
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发表时间：
1992
影响因子：
--
通讯作者：
L. K. Schlatter;K. J. Howard;M. Parker;C. Distelhorst
中科院分区：
文献类型：
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作者：
L. K. Schlatter;K. J. Howard;M. Parker;C. Distelhorst
大鼠糖皮质激素受体是一种795个氨基酸的蛋白质，其激素结合结构域位于分子的C-末端部分。在没有激素的情况下，该结构域显示蛋白失活活性，其抑制受体的核定位、DNA结合和转录调节活性。这种失活活性似乎是由90千道尔顿热休克蛋白（HSP 90）介导的，在糖皮质激素受体中比雌激素受体激素结合结构域的相应活性更强。为了分析这些差异，我们直接比较了在体外翻译的糖皮质激素和雌激素受体在其相互作用与热休克蛋白90的免疫共沉淀试验采用两种单克隆抗体，AC 88和8D 3，与不同地区的热休克蛋白90分子。完整形式的糖皮质激素受体和雌激素受体与内源性热休克蛋白90在网织红细胞裂解物中共免疫沉淀，表明这两种受体在体外翻译时能够结合热休克蛋白90。通过分析一系列受体缺失突变体，我们发现HSP 90结合所需的序列映射到两种受体的激素结合结构域内的相似区域。虽然发现激素结合结构域是HSP 90与糖皮质激素受体结合的唯一结构要求，但激素结合结构域N-末端的额外序列显示为HSP 90与雌激素受体结合所需。这些结果与糖皮质激素和雌激素受体激素结合域的蛋白失活活性的差异可能是次要的这些域与HSP 90的相互作用的差异的假设是一致的。
The rat glucocorticoid receptor is a 795-amino acid protein with the hormone binding domain located in the C-terminal portion of the molecule. In the absence of hormone, this domain displays a protein inactivation activity that represses the nuclear localization, DNA binding, and transcriptional regulatory activities of the receptor. This inactivation activity, which appears to be mediated by the 90-kilodalton heat shock protein (HSP90), is stronger in the glucocorticoid receptor than the corresponding activity of the estrogen receptor hormone binding domain. In order to analyze these differences, we have directly compared in vitro translated glucocorticoid and estrogen receptors in terms of their interaction with HSP90 by a coimmunoprecipitation assay employing two monoclonal antibodies, AC88 and 8D3, which react with different regions of the HSP90 molecule. Intact forms of both the glucocorticoid receptor and the estrogen receptor coimmunoprecipitated with endogenous HSP90 in reticulocyte lysates, indicating that both receptors were capable of binding to HSP90 when translated in vitro. By assaying a series of receptor deletion mutants, we found that the sequences required for HSP90 binding mapped to a similar region within the hormone binding domain of both receptors. While the hormone binding domain was found to be the only structural requirement for HSP90 binding to the glucocorticoid receptor, additional sequences N-terminal to the hormone binding domain were shown to be required for HSP90 binding to the estrogen receptor. These results are consistent with a postulate that differences in the protein inactivation activities of the glucocorticoid and estrogen receptor hormone binding domains may be secondary to differences in the interactions of these domains with HSP90.