cDNAs and antibodies for small GTP-binding proteins

有一个小的GTP结合蛋白(G蛋白)超家族，由50多个成员组成。所有成员都有MRS在20,000到30,000之间的单体蛋白，既显示GDP/GTP结合活性，又显示GTP酶活性。在本研究项目中，我们对小G蛋白的功能和激活方式进行了研究，并试图制备与小G蛋白相关的cDNA和抗体作为治疗某些疾病的工具。RAS是这一超家族的代表，调节细胞的增殖、分化和转化是众所周知的，但其激活和作用方式尚不清楚。我们鉴定了三种RAS的GDP/GTP交换蛋白，包括SMG GDS、CDC25Mm和MSO。我们鉴定了RAS的一个靶蛋白，并将其命名为REKS，它使MAP激酶磷酸化，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胞外酶和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、胞质分裂和平滑肌收缩。已知RAB家族调节细胞内的囊泡运输，如胞吐、内吞和跨细胞作用。Rab3A是RAB家族的成员，与突触释放的神经递质密切相关。我们克隆了编码Rab3A靶蛋白的cDNA，该蛋白选择性地与Rab3A的GTP结合形式相互作用，命名为RabPhilin-3A。这些结果表明，小G蛋白在多种细胞功能中发挥着关键作用，其cDNA和抗体可用于某些疾病的诊断和治疗。

There is the small GTP-binding protein (G protein) superfamily which consists of over fifty members. All members have 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 of small G proteins and tried to prepare concerning cDNAs and antibodies as tools for certain diseases. Ras is the representative of this superfamily 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 Smg GDS, CDC25Mm, and mSos. We indentified a target protein for Ras and named it REKS, which phosphorylated MAP kinase 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 morphology, cell motility, membrane ruffling, cytokinesis, and smooth muscle contraction through an actomyosin system. Rab 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 interacted with the GTP-bound form of Rab3A, and named it rabphilin-3A.These results suggest that small G proteins play crucial roles in various cell functions and that their cDNA and antibodies can be used at tools for diagnosis and treatment of certain diseases.