糖皮质激素受体（GR）配体结合域的第8螺旋对于配体结合至关重要。

Helix 8 of the ligand binding domain of the glucocorticoid receptor (GR) is essential for ligand binding.

作者信息

Deng Qiong, Waxse Bennett, Riquelme Denise, Zhang Jiabao, Aguilera Greti

机构信息

Section on Endocrine Physiology, PDEGEN, NICHD, NIH, Bethesda, Maryland, USA; College of Animal Sciences, Jilin University, China.

Section on Organelle Biology, CBMP, NICHD, NIH, Bethesda, Maryland, USA.

出版信息

Mol Cell Endocrinol. 2015 Jun 15;408:23-32. doi: 10.1016/j.mce.2015.01.044. Epub 2015 Feb 9.

Membrane association of estrogen receptors (ER) depends on cysteine palmitoylation and two leucines in the ligand binding domain (LBD), conserved in most steroid receptors. The role of this region, corresponding to helix 8 of the glucocorticoid receptor (GR) LBD, on membrane association of GR was studied in 4B cells, expressing endogenous GR, and Cos-7 cells transfected EGFP-GR constructs. 4B cells preloaded with radiolabeled palmitic acid showed no radioactivity incorporation into immunoprecipitated GR. Moreover, mutation C683A (corresponding to ER palmitoylation site) did not affect corticosterone-induced membrane association of GR. Mutations L687-690A, L682A, E680G and K685G prevented membrane and also nuclear localization through reduced ligand binding. L687-690A mutation decreased association of GR with heat shock protein 90 and transcriptional activity, without overt effects on receptor protein stability. The data demonstrate that palmitoylation does not mediate membrane association of GR, but that the region 680-690 (helix 8) is critical for ligand binding and receptor function.

雌激素受体（ER）与膜的结合依赖于半胱氨酸棕榈酰化以及配体结合域（LBD）中的两个亮氨酸，这在大多数类固醇受体中是保守的。对应于糖皮质激素受体（GR）LBD螺旋8的这一区域在GR与膜结合中的作用，在表达内源性GR的4B细胞和转染了EGFP - GR构建体的Cos - 7细胞中进行了研究。预先加载放射性标记棕榈酸的4B细胞在免疫沉淀的GR中未显示放射性掺入。此外，突变C683A（对应于ER棕榈酰化位点）不影响皮质酮诱导的GR与膜的结合。L687 - 690A、L682A、E680G和K685G突变通过降低配体结合阻止了膜和核定位。L687 - 690A突变降低了GR与热休克蛋白90的结合以及转录活性，而对受体蛋白稳定性没有明显影响。数据表明棕榈酰化不介导GR与膜的结合，但680 - 690区域（螺旋8）对于配体结合和受体功能至关重要。