Activation-induced subcellular redistribution of Gs alpha.
Activation-induced subcellular redistribution of Gs alpha.
复制标题
激活诱导的 Gs α 亚细胞重新分布。
DOI：
10.1091/mbc.7.8.1225
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发表时间：
1996
影响因子：
3.3
通讯作者：
vonZastrow,M
中科院分区：
文献类型：
--
作者：
Wedegaertner,PB;Bourne,HR;vonZastrow,M
我们已经研究了亚细胞分布的α S，α亚基的异源三聚体G蛋白GS，通过使用免疫荧光显微镜。在瞬时转染的HEK 293细胞中，野生型α s定位于质膜。然而，突变激活的α s（α sR 201 C）弥漫分布在整个细胞质中。类似地，霍乱毒素激活α s导致其在稳定转染的细胞中从质膜重新分布到细胞质。在用α s和β 2-肾上腺素能受体（β-AR）稳定转染的HEK 293细胞中，激动剂异丙肾上腺素对β-AR的刺激也引起α s从质膜易位到细胞质。用拮抗剂代替激动剂允许α s返回质膜，证明了α s易位的可逆性。受体激活的α s不与内在化的β-AR共定位于内体。将细胞在高渗蔗糖中孵育以抑制网格蛋白包被的pit介导的激动剂激活的β-AR的内吞作用，未能阻断激动剂刺激的α s再分布。这些发现表明，激活的α s可逆地经历了从质膜到细胞质的易位，并开始解决七跨膜受体和其同源G蛋白的调节运输之间的关系。
We have examined the subcellular distribution of alpha s, the alpha subunit of the heterotrimeric G protein Gs, by using immunofluorescence microscopy. In transiently transfected HEK293 cells, wild-type alpha s localizes to the plasma membrane. However, a mutationally activated alpha s (alpha sR201C) is diffusely distributed throughout the cytoplasm. Similarly, cholera toxin activation of alpha s causes it to redistribute from the plasma membrane to cytoplasm in stably transfected cells. In HEK293 cells stably transfected with alpha s and the beta 2-adrenergic receptor (beta-AR), stimulation of the beta-AR by the agonist isoproterenol also causes a translocation of alpha s from the plasma membrane to cytoplasm. Replacing the agonist with antagonist allows alpha s to return to the plasma membrane, demonstrating the reversibility of alpha s translocation. Receptor-activated alpha s does not colocalize with internalized beta-AR at endosomes. Incubation of cells in hypertonic sucrose to inhibit clathrin-coated pit-mediated endocytosis of agonist-activated beta-AR failed to block agonist-stimulated redistribution of alpha s. These findings demonstrate that activated alpha s reversibly undergoes a translocation from the plasma membrane to cytoplasm and begin to address the relationship between regulated trafficking of a seven-transmembrane receptor and its cognate G protein.