signal transduction of small GTP binding proteins

有一个小的GTP结合蛋白（G蛋白）超家族，由超过50个成员组成。所有成员都具有Mrs值在20,000到30,000之间的单体蛋白，具有GDP/ gto结合和GTP酶活性。在本课题中，我们研究了小G蛋白的功能和激活方式。Ras是该苏家族的代表，众所周知，它调节细胞增殖、分化和转化，但其激活模式和作用仍不清楚。我们鉴定了三种Ras的GDP/GTP交换蛋白，包括Smq GDS、CDC25Mm和msos。我们发现了一个Ras的靶蛋白，并将其命名为REKS，它磷酸化MAP激酶，从而以Ras依赖的方式激活它。越来越多的证据表明，Rho通过肌动球蛋白系统调节某些功能。通过使用C3外泌酶和Rho GDI，我们发现Rho通过肌动球蛋白系统调节细胞形态、细胞运动、膜褶皱、细胞运动和平滑肌收缩。已知红色家族调节细胞内囊泡运输，如胞吐作用、胞吞作用和胞吞作用。Rab3A是rabb家族的一员，特别涉及突触的神经递质释放。我们分离出Rab3A的靶蛋白cDNA，该蛋白选择性地与Rab3A的gtp结合形式相互作用，并将其命名为rabphilin-3A。

There is the small GTP- binding protein (G protein) superfamily which consists of over fiftu members. All members have monomeric proteins with Mrs between 20,000 and 30,000 which exhibit both GDP/GTO-binding and GTP ase activities. In the present research project, we studied the functions and modes of activation of small G proteins. Ras is the representative of this su perfamily and is well known to regulate cell proliferation, differentiation, and transformation, but its modes of activation and action remain to be clarified. We characterized three GDP/GTP exchange proteins for Ras including Smq GDS, CDC25Mm, and msos. We identified a target protein for Ras and named it REKS, which phosphorylated MAP kinase and thereby activated it in a Ras-dependent manner. Accumulating evidence suggests that Rho regulates certain functions through an actomyosin system. By use of C3 exoenzyme and Rho GDI, we showed that Rho regulated cell morphogy, cell motility, membrane ruffling, cy-tokinesis, and smooth muscle contraction through an actomyosin system. Red family is known to regulate intracellular vesicle transport, such as exocytosis, endocytosis, and transcytosis. Rab3A is a member of Rab family which is particularly implicated in neurotransmitter release from the synapse. We isolated the cDNA encoding a target protein for Rab3A, which selectively in-teracted with the GTP-bound form of Rab3A, and named it rabphilin-3A.