Activated G Protein Gαs Samples Multiple Endomembrane Compartments
Activated G Protein Gαs Samples Multiple Endomembrane Compartments
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DOI：
10.1074/jbc.m116.729731
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发表时间：
2016-09-23
影响因子：
4.8
通讯作者：
Lambert, Nevin A.
中科院分区：
文献类型：
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作者：
Martin, Brent R.;Lambert, Nevin A.
异三聚体G蛋白定位于质膜，在那里它们将细胞外信号传递给细胞内效应器。G蛋白也作用于细胞内，并可在细胞间转运。例如，G(s)在活化后可以离开质膜进入细胞内部。然而，G(s)易位的机制及其细胞内目的地尚不清楚。在这里，我们使用生物发光共振能量转移（BRET）来显示激活后，G(s)迅速与内质网、线粒体和核内体结合，这与从细胞质溶胶中任意取样细胞膜而不是通过特定的囊泡途径运输一致。内体室G(s)的主要来源是组成性内吞作用，而不是活性依赖性内化。停止刺激后25分钟，G(s)到质膜的再循环就完成了。我们还表明，酰化-去酰化循环对G(s)在质膜上的稳态定位很重要，但我们的结果不支持去酰化在活性依赖性G(s)内化中的作用。
Heterotrimeric G proteins are localized to the plasma membrane where they transduce extracellular signals to intracellular effectors. G proteins also act at intracellular locations, and can translocate between cellular compartments. For example, G(s) can leave the plasma membrane and move to the cell interior after activation. However, the mechanism of G(s) translocation and its intracellular destination are not known. Here we use bioluminescence resonance energy transfer (BRET) to show that after activation, G(s) rapidly associates with the endoplasmic reticulum, mitochondria, and endosomes, consistent with indiscriminate sampling of intracellular membranes from the cytosol rather than transport via a specific vesicular pathway. The primary source of G(s) for endosomal compartments is constitutive endocytosis rather than activity-dependent internalization. Recycling of G(s) to the plasma membrane is complete 25 min after stimulation is discontinued. We also show that an acylation-deacylation cycle is important for the steady-state localization of G(s) at the plasma membrane, but our results do not support a role for deacylation in activity-dependent G(s) internalization.