Zheng C, Xing Z, Bian Z C, Guo C, Akbay A, Warner L, Guan J L
Department of Pathology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
J Biol Chem. 1998 Jan 23;273(4):2384-9. doi: 10.1074/jbc.273.4.2384.
Pyk2 is a recently described cytoplasmic tyrosine kinase that is related to focal adhesion kinase (FAK) and can be activated by a variety of stimuli that elevate intracellular calcium. In this report, we showed that Pyk2 and FAK tyrosine phosphorylation are regulated differentially by integrin-mediated cell adhesion and soluble factors both in rat aortic smooth muscle cells, which express endogenous Pyk2 and FAK, and in transfected Chinese hamster ovary cells. We also found that Pyk2 is diffusely present throughout the cytoplasm, while FAK is localized in focal contacts as expected, suggesting that the different localization may account for their differential regulation. By analyzing a chimeric protein contain N-terminal and kinase domains of Pyk2 and C-terminal domain of FAK, we provided evidence that the distinctive C-terminal domains of Pyk2 and FAK were responsible for their differential regulation by integrins and soluble stimuli as well as their subcellular localization. Finally, we correlated FAK, Pyk2, and the chimeric protein binding to talin, but not paxillin, with their regulation by integrins and focal contact localization. These results demonstrate that the distinctive C-terminal domain of Pyk2 and FAK confer their differential regulation by different subcellular localization and association with the cytoskeletal protein talin.
Pyk2是一种最近被描述的胞质酪氨酸激酶，它与粘着斑激酶（FAK）相关，并且可被多种能升高细胞内钙的刺激所激活。在本报告中，我们表明，在表达内源性Pyk2和FAK的大鼠主动脉平滑肌细胞以及转染的中国仓鼠卵巢细胞中，整合素介导的细胞粘附和可溶性因子对Pyk2和FAK酪氨酸磷酸化的调节存在差异。我们还发现，Pyk2广泛分布于整个细胞质中，而FAK如预期那样定位于粘着斑，这表明不同的定位可能解释了它们的差异调节。通过分析一种包含Pyk2的N端和激酶结构域以及FAK的C端结构域的嵌合蛋白，我们提供了证据，证明Pyk2和FAK独特的C端结构域负责它们受整合素和可溶性刺激的差异调节以及它们的亚细胞定位。最后，我们将FAK、Pyk2以及与桩蛋白无相互作用但与踝蛋白结合的嵌合蛋白与它们受整合素的调节和粘着斑定位联系起来。这些结果表明，Pyk2和FAK独特的C端结构域通过不同的亚细胞定位以及与细胞骨架蛋白踝蛋白的结合赋予它们差异调节。
