The G protein-coupled receptor kinase 2 is a microtubule-associated protein kinase that phosphorylates tubulin
The G protein-coupled receptor kinase 2 is a microtubule-associated protein kinase that phosphorylates tubulin
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DOI：
10.1074/jbc.273.20.12316
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发表时间：
1998-05-15
影响因子：
4.8
通讯作者：
Barak, LS
中科院分区：
文献类型：
--
作者：
Pitcher, JA;Hall, RA;Barak, LS
G蛋白偶联受体激酶2(GRK2)是一种丝氨酸/苏氨酸激酶，可使激动剂占据的G蛋白偶联受体(GPCRs)磷酸化和脱敏。在这里，我们证明了GRK2是一种微管相关蛋白，并将微管蛋白确定为一种新的GRK2底物。GRK2与从牛脑中提纯的微管结合，与细胞提取物中的微管蛋白形成复合体，并与活细胞中的微管蛋白共存。此外，与微管结合的内源性微管蛋白激酶活性具有类似于GRK2的性质，并被抗GRK2单抗抑制。事实上，GRK2在体外磷酸化微管蛋白的动力学参数非常类似于激动剂占据的β(2)-肾上腺素能受体的磷酸化，表明这种磷酸化事件在功能上是相关的。在细胞环境中，GPCRs的激动剂占据导致GRK2被募集到质膜并随后被激活，从而促进GRK2-微管蛋白复合体的形成和微管蛋白的磷酸化。这些发现提示了GRK2作为GPCR信号转导分子的新作用，该信号转导分子介导了GPCR激活对细胞骨架的影响。
The G protein-coupled receptor kinase 2 (GRK2) is a serine/threonine kinase that phosphorylates and desensitizes agonist-occupied G protein-coupled receptors (GPCRs). Here we demonstrate that GRK2 is a microtubule-associated protein and identify tubulin as a novel GRK2 substrate. GRK2 is associated with microtubules purified from bovine brain, forms a complex with tubulin in cell extracts, and colocalizes with tubulin in living cells. Furthermore, an endogenous tubulin kinase activity that copurifies with microtubules has properties similar to GRK2 and is inhibited by anti-GRK2 monoclonal antibodies. Indeed, GRK2 phosphorylates tubulin in vitro with kinetic parameters very similar to those for phosphorylation of the agonist-occupied beta(2)-adrenergic receptor, suggesting a functionally relevant role for this phosphorylation event. In a cellular environment, agonist occupancy of GPCRs, which leads to recruitment of GRK2 to the plasma membrane and its subsequent activation, promotes GRK2-tubulin complex formation and tubulin phosphorylation. These findings suggest a novel role for GRK2 as a GPCR signal transducer mediating the effects of GPCR activation on the cytoskeleton.