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Signal transduction of Small GTP-binding proteins

小 GTP 结合蛋白的信号转导

基本信息

批准号：
06404021
负责人：
TAKAI Yoshimi
金额：
$ 19.58万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06404021/
关键词：
Small GTP-binding Ras B-Raf Rho The ERM family CD44 Rab3A Rabphilin-3A Doc2 Ras Rho Rab3A MAPキナーゼ ERM-CD44系 Rabphi7in-3A

项目摘要

There is the small GTP-binding protein (G protein) superfamily which consists of over sixty members. All the members are monomeric proteins with Mrs between 20,000 and 30,000 which exhibit both GDP/GTP-binding and GTPase activities. In the present research project, we studied the functions and modes of activation and action of small G proteins. Ras is the representative of this superfamily and is well known to regulate gene expression at least through the MAP kinase cascade consisting of MAP kinase, MAP kinase kinase (MEK), and MEK kinase. We purified from bovine brain a MEK kinase which activated MEK in a GTPgammaS-Ki-Ras-dependent manner in a cell-free system and identified it as B-Raf complexed with 14-3-3 proteins. We also found that Rapl, which has the same amino acid sequence at its effector domain as that of Ras, is also involved in the activation of the B-Raf-dependent MAP kinase cascade. Rho regulates reorganization of actin filaments and is implicated in at least maintenance … More of cell morphology, cell motility, and cytokinesis in mammalian cells. We found that Rho is translocated to a membrane ruffling area when cells are stimulated by HGF and TPA.Rho was also observed at the contractile ring produced during cytokinesis. The ERM family (Ezrin, Radixin, and Moesin), which directly interacts with actin filaments through its C-terminal region and with a transmembrane protein, CD44, through its N-terminal region, is located at these areas. Therefore, Rho may regulate reorganization of the ERM family-dependent association of actin filaments with the plasma membrane. We also found that Rho GDI directly interacts with ERM,initiating the activation of Rho by reducing the Rho GDI activity. Rho also exists in the yeast Saccharomyces cerevisiae, and we found that Rho is essential for budding process. We genetically and biochemically isolated the regulatory proteins (RDI1 and ROM1/ROM2) and target proteins (PKC1, BNI1/BNR1, glucan synthase) for Rho. BNI1 and BNR1 directly interact with profilin at the FH1 domains, suggesting that Rho regulates the reorganization of actin filaments through the BNI1/BNR1-profilin system. Rab3A is a member of the Rab family which is particularly implicated in neurotransmitter release from the nerve terminal. We had isolated its regulatory protein, named Rab GDI,and its target protein, named Rabphilin-3A.In this research project, we isolated other regulatory proteins for Rab3A,Rab3 GEP and Rab3 GAP. Less

有一个小的gtp结合蛋白（G蛋白）超家族，由60多个成员组成。所有成员均为单体蛋白，Mrs值在2万~ 3万之间，具有GDP/ gtp结合和gtp酶活性。在本课题中，我们研究了小G蛋白的功能和激活和作用方式。Ras是该超家族的代表，至少通过MAP激酶、MAP激酶（MEK）和MEK激酶组成的MAP激酶级联来调节基因表达。我们从牛脑中纯化了一个MEK激酶，该激酶在无细胞系统中以依赖gtpgammas - ki - ras的方式激活MEK，并鉴定其为B-Raf与14-3-3蛋白络合。我们还发现，Rapl在其效应域具有与Ras相同的氨基酸序列，也参与b - raf依赖性MAP激酶级联的激活。Rho调节肌动蛋白丝的重组，至少与维持哺乳动物细胞的细胞形态、细胞运动和细胞分裂有关。我们发现，当细胞受到HGF和TPA刺激时，Rho会转移到膜褶区。在细胞分裂过程中产生的收缩环上也观察到Rho。ERM家族（Ezrin， Radixin和Moesin）通过其c端区域直接与肌动蛋白丝相互作用，并通过其n端区域与跨膜蛋白CD44相互作用，位于这些区域。因此，Rho可能调节ERM家族依赖的肌动蛋白丝与质膜结合的重组。我们还发现Rho GDI直接与ERM相互作用，通过降低Rho GDI活性来启动Rho的激活。Rho也存在于酿酒酵母中，我们发现Rho在出芽过程中是必不可少的。我们通过遗传和生化分离了Rho的调控蛋白（RDI1和ROM1/ROM2）和靶蛋白（PKC1, BNI1/BNR1，葡聚糖合成酶）。BNI1和BNR1在FH1结构域直接与profilin相互作用，表明Rho通过BNI1/BNR1-profilin系统调控肌动蛋白丝的重组。Rab3A是rabb家族的一员，特别涉及神经末梢的神经递质释放。我们分离出了它的调节蛋白，命名为rabb GDI，以及它的靶蛋白，命名为Rabphilin-3A。在本课题中，我们分离了Rab3A、Rab3 GEP和Rab3 GAP的其他调控蛋白。少