The unliganded mineralocorticoid receptor is associated with heat shock proteins 70 and 90 and the immunophilin FKBP-52.
The unliganded mineralocorticoid receptor is associated with heat shock proteins 70 and 90 and the immunophilin FKBP-52.
复制标题
DOI：
--
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Bruner Kl;A. Derfoul;N. Robertson;Giulia Guerriero;T. Fernandes‐Alnemri;Emad S. Alnemri;Gerald Litwack
中科院分区：
文献类型：
--
作者：
Bruner Kl;A. Derfoul;N. Robertson;Giulia Guerriero;T. Fernandes‐Alnemri;Emad S. Alnemri;Gerald Litwack
人类矿物皮质激素受体（MR）是类固醇-甲状腺激素受体超家族的一员，该家族包括维甲酸、维生素D和其他类固醇的受体，如糖皮质激素（与糖皮质激素受体结合，GR）。皮质类固醇受体MR和GR具有显著的同源性，并被类固醇结合激活，导致构象变化、核易位和DNA结合。尽管与GR有这些相似之处，MR的特征仍然不太明确。然而，已知存在于无配体GR中的蛋白质组分也可能是异聚体MR复合物的组分。在目前的研究中，我们研究了hsp70、hsp90和亲免疫蛋白FKBP-52是否存在于非类固醇结合的MR复合物中，因为已知这些蛋白存在于未配体的GR复合物中。在体外用网织细胞裂解液组装无配体MR复合物，在体内用杆状病毒过表达系统和狐尾蛾（Spodoptera frugiperda, Sf9）细胞组装。Western blot分析显示，hsp70、hsp90和FKBP-52在非配体复合物中存在，但暴露于醛固酮后未检测到hsp90和FKBP-52。电泳迁移迁移分析表明，MR的DNA结合仅在醛固酮处理后发生。这些研究表明，与无配体GR相关的蛋白质也存在于无配体MR复合物中，并且hsp90和FKBP-52在DNA结合之前以与GR相似的方式解离。最后，对异聚体MR复合物中存在的蛋白质的化学计量学分析表明，该受体与GR之间存在差异。
The human mineralocorticoid receptor (MR) is a member of the steroid-thyroid hormone receptor superfamily, which includes receptors for retinoic acid, vitamin D, and other steroids, such as the glucocorticoids (which bind the glucocorticoid receptor, GR). MR and GR, the corticosteroid receptors, share significant homology and are activated by steroid binding, resulting in a conformational change, nuclear translocation, and DNA binding. Despite these similarities with GR, the MR remains less well characterized. However, protein components known to be present in the unliganded GR are also likely to be components of the heteromeric MR complex. In the current study, we investigated whether or not hsp70, hsp90, and the immunophilin FKBP-52 are present in the nonsteroid-bound MR complex, because these proteins are known to be present in the unliganded GR complex. The unliganded MR complex was assembled in vitro using reticulocyte lysate and in vivo using the baculovirus overexpression system and Spodoptera frugiperda (Sf9) cells. Western blot analysis revealed the presence of hsp70, hsp90, and FKBP-52 in the unliganded complexes, but hsp90 and FKBP-52 were not detected following exposure to aldosterone. Electrophoretic mobility shift analysis demonstrated that DNA binding of MR occurred only after treatment with aldosterone. These studies indicate that proteins associated with the unliganded GR are also present in the unliganded MR complex, and that hsp90 and FKBP-52 dissociate prior to DNA binding in a manner similar to that described for GR. Finally, the stoichiometric analysis of the proteins present within the heteromeric MR complex suggests a divergence between this receptor and the GR.