Phosphorylation and activation of myosin by Rho-associated kinase (Rho-kinase)
Phosphorylation and activation of myosin by Rho-associated kinase (Rho-kinase)
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DOI：
10.1074/jbc.271.34.20246
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发表时间：
1996-08-23
影响因子：
4.8
通讯作者：
Kaibuchi, K
中科院分区：
文献类型：
--
作者：
Amano, M;Ito, M;Kaibuchi, K
小的GTP酶Rho与肌动蛋白-肌球蛋白细丝相关的生理功能有关，如胞质分裂、细胞运动和平滑肌收缩。我们最近发现并分子克隆了Rho相关的丝氨酸/苏氨酸激酶(Rho-kinaseRho)，它被GTP-Rho激活(Matsui，T.，Amano，M.，Yamamoto，T.，Chihara，K.，Nakafuku，M.，Ito，M.，M.，Nakano，T.，Okawa，H.，Iwamatsu，A.，and Kaibuhi，K.(1996)EMBO J.15,2208-2216)。在这里，我们发现Rho-Kinase化学计量磷酸化肌球蛋白轻链(MLC)。多肽图谱和磷酸氨基酸分析表明，Rho-Kinase对MLC的主要磷酸化位点是Ser-19，这是MLC的磷酸化位点。Rho-Kinase能磷酸化重组MLC，而不能磷酸化含有Ala的重组MLC，Ala取代了Thr-18和Ser-19。我们还发现，Rho-Kinase对MLC的磷酸化导致肌球蛋白ATPase的肌动蛋白激活更加容易。因此，很可能一旦Rho被激活，它就可以与Rho-Kinase相互作用并激活它。被激活的Rho-Kinase随后使MLC磷酸化。这可能部分解释了Rho调节细胞质分裂、细胞运动或平滑肌收缩的机制。
The small GTPase Rho is implicated in physiological functions associated with actin-myosin filaments such as cytokinesis, cell motility, and smooth muscle contraction. We have recently identified and molecularly cloned Rho-associated serine/threonine kinase (Rho-kinase), which is activated by GTP-Rho (Matsui, T., Amano, M., Yamamoto, T., Chihara, K., Nakafuku, M., Ito, M., Nakano, T., Okawa, H., Iwamatsu, A., and Kaibuchi, K. (1996) EMBO J. 15, 2208-2216). Here we found that Rho-kinase stoichiometrically phosphorylated myosin light chain (MLC). Peptide mapping and phosphoamino acid analyses revealed that the primary phosphorylation site of MLC by Rho-kinase was Ser-19, which is the site phosphorylated by MLC kinase. Rho-kinase phosphorylated recombinant MLC, whereas it failed to phosphorylate recombinant MLC, which contained Ala substituted for both Thr-18 and Ser-19. We also found that the phosphorylation of MLC by Rho-kinase resulted in the facilitation of the actin activation of myosin ATPase. Thus, it is likely that once Rho is activated, then it can interact with Rho-kinase and activate it. The activated Rho-kinase subsequently phosphorylates MLC. This may partly account for the mechanism by which Rho regulates cytokinesis, cell motility, or smooth muscle contraction.