The Molecular Transitions that Initiate EC Coupling in Skeletal Muscle

项目摘要/摘要 这些研究的动机是需要了解基本的生物物理学 骨骼肌电压门控L型钙通道CaV1.1的特性而离子传导是一种 绝大多数离子通道的关键特征(通常也是唯一的职责)，CaV1.1在某种程度上 独一无二的：它的电压传感器的激活打开了它的毛孔，但不需要钙离子进入来触发 肌肉收缩。相反，Cav1.1电压传感器的构象变化直接门控 兰尼定受体(RyR1)通过这两个通道之间的物理耦合来触发释放 肌浆网钙离子。在此背景下，Cav1.1的四个电压传感元件确实是 RyR1通道的电压传感器。由于在卵母细胞中表达Cav1.1通道的可能性 最近由于发现了一种重要的适配器蛋白(Stac3)，Olcese变得可行 实验室处于有利地位，可以直接研究电压调节的机制 蛋白质，具有实现尖端电压钳荧光测量的独特能力(到目前为止) 进近CAV航道。 在接下来的五年里，利用电生理、光学和计算技术， 研究人员将描绘CaV1.1通道中电压依赖的基础，在成人和 胚胎剪接变体。他们将询问这种电压依赖是如何由 辅助亚基(β，α2δ和γ)参与CaV1.1大分子复合体的形成。他们会 确定四个同源但不相同的CaV1.1电压感应域中的哪个授予 电压对RyR1介导的钙释放的敏感性。最后，调查人员将解决分子 一种引起恶性高热的突变对电压敏感产生特异性影响的机制 CAV1.1的仪器。所收集的知识对于理解 肌肉生理学和对收缩的电压依赖控制。

PROJECT SUMMARY/ABSTRACT The motivation for these studies is the need to gain an understanding of the fundamental biophysical properties of the skeletal voltage-gated L-type Calcium channel CaV1.1. While ion conduction is a critical feature (and often the only duty) of the vast majority of ion channels, CaV1.1 is somewhat unique: the activation of its voltage sensors opens its pore, but Ca2+ entry is not required to trigger muscle contraction. Instead, the conformational changes of Cav1.1 voltage sensors directly gate Ryanodine receptors (RyR1) via a physical coupling between these two channels, to trigger the release of sarcoplasmic reticulum Ca2+. In this context, the four voltage-sensing elements of Cav1.1 are indeed the voltage sensors of RyR1 channels. As the possibility to express Cav1.1 channel in oocytes has recently become feasible thanks to the discovery of an essential adaptor protein (Stac3), the Olcese laboratory is in a privileged position to directly address the mechanism of voltage regulation in this protein, with a unique capability (to date) to implement the cutting-edge voltage clamp fluorometry approach to CaV channels. During the next five years, using electrophysiological, optical and computational techniques, the investigators will delineate the basis of voltage dependence in CaV1.1 channels, in both adult and embryonic splice variants. They will interrogate how this voltage dependence is modulated by the participation of auxiliary subunits (β, α2δ, and γ) in the CaV1.1 macromolecular complex. They will determine which of the four homologous, but non-identical CaV1.1 Voltage Sensing Domains confer voltage sensitivity to RyR1-mediated Ca release. Finally, the investigators will address the molecular mechanism of a malignant-hyperthermia-causing mutation that specifically affects the voltage-sensing apparatus of CaV1.1. The knowledge gathered by is critical to understand fundamental aspects of muscle physiology and the voltage-dependent control of contraction.