Regulation of Phospholipase C

13种不同的哺乳动物磷脂酶C（PLC）同工酶整合 来自多个上游调节器的信号， 了解许多激素作用的信号节点， 神经递质、生长因子和其他细胞外刺激。我们最近 PLC-<$同工酶在G蛋白存在和不存在下的结构 激活剂导致发现这些信号蛋白基本上是 由催化TIM筒的X/Y连接体区域自抑制。源自我们的 生物化学研究也与以下假设一致： GTP结合蛋白和可能的其他调节剂通过膜介导的 通过激活剂促进的募集和定向， 膜表面的脂肪酶活性位点。我们最近确定了 PLC-b的结构绑定到Gaq，并使用此信息提出了一个“捕获- 并释放”飞投机制来解释这个复杂的快速循环 包括G蛋白偶联受体在内的功能性支架。这里 （具体目标1）我们建议采用创新方法的组合， 包括分子动力学模拟、肽模拟和生物传感器， 进一步了解这种支架及其生物学分支。PLC-b 同工酶也可通过从异源三聚体释放Gbg二聚体而被直接激活 G蛋白。这种情况发生的机制尚不清楚， 具体目标2将是确定结合至以下的PLC-b同工酶的结构： Gbg.

The thirteen different mammalian phospholipase C (PLC) isozymes integrate signals from multiple upstream regulators acting as highly organized but poorly understood signaling nodes central to the action of many hormones, neurotransmitters, growth factors, and other extracellular stimuli. Our recent structures of PLC-¿ isozymes in the absence and presence of G protein activators led to the discovery that these signaling proteins are basally autoinhibited by the X/Y linker region of the catalytic TIM barrel. Results from our biochemical studies also are consistent with the hypothesis that activation by GTP-binding proteins and likely other modulators occurs by membrane-mediated removal of this autoinhibition by activator-promoted recruitment and orientation of the lipase active site at the membrane surface. We recently determined the structure of PLC-b bound to Gaq and used this information to propose a "catch- and-release" fly-casting mechanism to interpret the rapid cycling of this complex within functional scaffolds that include G protein-coupled receptors. Here (Specific Aim 1) we propose to use a combination of innovative approaches, including molecular dynamics simulations, peptidomimetics, and biosensors to further understand this scaffolding and its biological ramifications. PLC-b isozymes also are directly activated by release of Gbg dimers from heterotrimeric G proteins. The mechanism whereby this occurs is unknown, and the goal of Specific Aim 2 will be to determine the structure of a PLC-b isozyme bound to Gbg.