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。所有成员都具有Mrs在20，000和30，000之间的单体蛋白质，其表现出GDP/GTP结合和GTP酶活性。在本研究项目中，我们研究了小G蛋白的功能和激活模式，并试图制备相关的cDNA和抗体作为某些疾病的工具。Ras是该超家族的代表，众所周知可以调节细胞增殖、分化和转化，但其激活和作用方式仍有待阐明。我们表征了Ras的三种GDP/GTP交换蛋白，包括Smg GDS，CDC 25 Mm和mSos。我们确定了Ras的靶蛋白，并将其命名为REKS，其磷酸化MAP激酶激酶，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外切酶和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、膜皱褶、胞质分裂和平滑肌收缩。已知Rab家族调节胞内囊泡转运，如胞吐、胞吞和胞转。Rab 3A是Rab家族的成员，其特别涉及从突触释放神经递质。本研究从Rab 3A基因中克隆了一个靶蛋白，并将其命名为rabphilin-3A，该蛋白能与Rab 3A的GTP结合形式发生特异性相互作用，提示小G蛋白在多种细胞功能中起着重要作用，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.