REGULATION HETEROTRIMERIC G PROTEINS

描述：（改编自申请人的摘要）异源三聚体G蛋白 将多种信号从膜结合受体传递到细胞内 效应器低分子量GTP酶Rho家族成员控制 肌动蛋白细胞骨架的组织，并参与各种 细胞功能。本提案的目的是了解 异源三聚体G对Rho家族GTPases的调控机制 蛋白质介导的信号通路。在异源三聚体G蛋白中，Galpha 12 和Galpha 13参与细胞转化和胚胎发育， Rho似乎参与了它们的信号通路。所以， 这项建议的目的是了解调节的生化机制， 通过Galpha 12和Galpha 13对Rho家族成员的活性。Rho家族GTP酶 由鸟嘌呤核苷酸交换因子（GEF）激活。我们有 证明了Galpha 12和Galpha 13相互作用并调节活性， 罗·GEF的小说，第115页。Galpha 13刺激p115的Rho GEF活性。在 相反，Galpha 12抑制Galpha 13对p115的激活。此外，委员会认为， RhoGEF充当Galpha 12和Galpha 14的GT3活化蛋白（GAP）。 Galpha13 p115 RhoGEF的调控将进一步详细描述。 差距测定将使用选定的Ga α突变体进行改进。 蛋白质，和负责GAP活性的p115结构域将被定义。 此外，还探讨了p115蛋白表达的差异调节的分子机制。 Galpha 12和Galpha 13将被研究。Galpha 12可以在体内激活Rho。 然而，Galpha 12不刺激p115的RhoGEF活性。因此我们将 试图找到一个RhoGEF，它是由Galpha 12通过亲和力激活的 使用固定化的Galpha 12进行层析。的生理意义 Galpha 12和Galpha 13对RhoGEF活性的调节也将是 在体内研究。G12，G13-RhoGEF通路参与轴突生长 成长和指导将被描述。

DESCRIPTION: (Adaptedfrom Applicant's Abstract) Heterotrimeric G proteins transduce a variety of signals from membrane-bound receptors to intracellular effectors. Members of the Rho family of low-molecular-weight GTPases control the organization of the actin cytoskeleton and are involved in a variety of cellular functions. The objective of this proposal is to understand the mechanism of regulation of Rho family GTPases by heterotrimeric G protein-mediated signaling pathways. Among heterotrimeric G proteins, Galpha12 and Galpha13participate in cell transformation and embryonic development, and Rho appears to be involved in their signaling pathways. Thus, the immediate goal of this proposal is to understand biochemical mechanisms of regulation of the activity of Rho family members by Galpha12 and Galpha13. Rho family GTPases are activated by guanine nucleotide exchange factors (GEFs). We have demonstrated that Galpha12 and Galpha13 interact with and regulate the activity of a novel Rho GEF, p115. Galpha13 stimulates the Rho GEF activity of p115. In contrast, Galpha12 inhibits activiation of p115 by Galpha13. Furthermore, RhoGEF acts as a GTPase activating protein (GAP) for both Galpha12 and Galpha13. The regulation of p115RhoGEF will be further characterized in detail. The GAP assay will be improved using the selected mutants of the Galpha proteins, and the domain of p115 responsible for GAP activity will be defined. In addition, the molecular mechanism of differential regulation of p115 by Galpha12 and Gaalpha13 will be investigated. Galpha12 can activate Rho in vivo. However, Galpha12 does not stimulate the RhoGEF activity of p115. We will thus attempt to find a RhoGEF that is activated by Galpha12 by affinity chromatography using immobilized Galpha12. The physiological significance of regulation of RhoGEF activity by Galpha12 and Galpha13 will also be investigated in vivo. The involvement of the G12, G13-RhoGEF pathways in axonal growth and guidance will be characterized.