SIGNAL TRANSDUCTION VIA RECEPTORS AND G PROTEINS

调节荷尔蒙和其他物质的主要信号模式 细胞外刺激是细胞对异源三聚体G蛋白的利用 表面受体。除了直接调节各种酶 产生细胞内的第二信使，这些受体/G蛋白 通路影响RAS超家族的几个成员的行为 依赖于GTP的单体蛋白。这个家族的成员，如RAS 和Rho蛋白，调节细胞的生长、分化、形状 和粘附力。最近，p115 Rhogef被证明直接连接到 刺激鸟嘌呤交换的两个G蛋白家族 当被异三聚体G13蛋白激活时，Rho上的核苷酸。 由于Rho可以调节磷脂酶D(PLD)，这表明 遵循一些信号通路调节该酶 荷尔蒙。 Hormone--&gt；Receptor--&gt；G13--&gt；p115RhoGEF--&gt；Rho--&gt；PLD 拟议的研究审查了以下各组成部分之间的调节机制 这条途径，并将探索假设p115罗基环境基金 举例说明了异三聚体之间通信的一般机制 和单体G蛋白。用于隔离的各种亲和方法 以类似的方式工作的新分子将检验这一点 假设。P115 Rhogef的功能域将由以下定义 截短分子的表达。P115罗氏环境基金的重组 上游(受体/G13)和下游(Rho效应器)组件将 定义监管机制。功能突变和抑制突变 结构域将被用来探索体内功能。继续进修 PLD试图定义分子的调节机制和 它在监管中的作用。特别感兴趣的是 磷脂酰肌醇4，5-二磷酸和磷脂酸，产品 PLD活性，调节这种酶和蛋白质的运输。 进展将增加我们对这些关键途径的理解 调节，并更好地了解荷尔蒙是如何 异三聚体G蛋白对RAS的调控作用 GTP酶超家族及其后遗症。

A major signaling paradigm for modulation of hormonal and other extracellular stimuli is the use of heterotrimeric G proteins by cell surface receptors. Besides direct regulation of a variety of enzymes that produces intracellular second messengers, these receptor/Gprotein pathways influence the action of several members of the Ras superfamily of monomeric GTP-dependent proteins. Members of this family, such as Ras and the Rho proteins, regulate cellular growth, differentiation, shape and adhesion. Recently, p115 RhoGEF was shown to directly connect the two families of G proteins by stimulating exchanges of guanine nucleotides on Rho when activated by the heterotrimeric G13 protein. Since Rho can regulate phospholipase D (PLD), this suggests the following signaling pathway for regulation of this enzyme by some hormones. Hormone-->Receptor-->G13-->p115RhoGEF-->Rho-->PLD The proposed studies examine regulatory mechanisms among components of this pathway and will explore the hypothesis that p115 RhoGEF exemplifies a general mechanism for communication between heterotrimeric and monomeric G proteins. A variety of affinity approaches for isolation of new molecules that would act in a analogous fashion will test this hypothesis. The functional domains of p115 RhoGEF will be defined by expression of truncated molecules. Reconstitution of p115 RhoGEF with upstream (receptor/G13) and downstream (Rho effectors) components will define mechanisms of regulation. Mutants in function and inhibitory domains will be used to explore in vivo function. Continuing studies with PLD attempt to define regulatory mechanisms for the molecule and its role in regulation. Special interest is focused on the roles of phosphatidylinositol 4,5-bisphosphate and phosphatidic acid, the product of PLD activity, in regulation of this enzyme and protein trafficking. Progress will increase our understanding of these key pathways for regulation and provide a better understanding of how hormones liked to heterotrimeric G proteins impart regulatory control on the Ras superfamily of GTPases and their sequelae.