Institute of Cell Biology and Immunology, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany.
J Biol Chem. 2012 Oct 5;287(41):34604-13. doi: 10.1074/jbc.M112.374652. Epub 2012 Aug 13.
The continuous assembly and disassembly of focal adhesions is required for efficient cell spreading and migration. The G-protein-coupled receptor kinase-interacting protein 1 (GIT1) is a multidomain protein whose dynamic localization to sites of cytoskeletal remodeling is critically involved in the regulation of these processes. Here we provide evidence that the subcellular localization of GIT1 is regulated by protein kinase D3 (PKD3) through direct phosphorylation on serine 46. GIT1 phosphorylation on serine 46 was abrograted by PKD3 depletion, thereby identifying GIT1 as the first specific substrate for this kinase. A GIT1 S46D phosphomimetic mutant localized to motile, paxillin-positive cytoplasmic complexes, whereas the phosphorylation-deficient GIT1 S46A was enriched in focal adhesions. We propose that phosphorylation of GIT1 on serine 46 by PKD3 represents a molecular switch by which GIT1 localization, paxillin trafficking, and cellular protrusive activity are regulated.
黏着斑的不断组装和拆卸是细胞有效铺展和迁移所必需的。G 蛋白偶联受体激酶相互作用蛋白 1（GIT1）是一种多功能蛋白，其动态定位到细胞骨架重塑部位对于这些过程的调节至关重要。在这里，我们提供的证据表明，GIT1 的亚细胞定位受蛋白激酶 D3（PKD3）通过丝氨酸 46 上的直接磷酸化调节。PKD3 耗竭使 GIT1 丝氨酸 46 上的磷酸化受到抑制，从而鉴定 GIT1 是该激酶的第一个特异性底物。GIT1 S46D 磷酸模拟突变体定位于运动的、含有桩蛋白的细胞质复合物中，而磷酸化缺陷的 GIT1 S46A 在黏着斑中富集。我们提出，PKD3 对 GIT1 丝氨酸 46 的磷酸化代表了一种分子开关，通过该开关调节 GIT1 定位、桩蛋白运输和细胞伸出活性。
