CALCIUM MOVEMENTS IN EXCITATION-CONTRACTION COUPLING

动作电位对肌肉收缩的传导 耦合）是细胞膜之间快速通信的一个例子 事件和代谢状态。 正如在许多系统中一样， 这种耦合是钙，在肌肉中，钙是从肌肉中释放出来的。 肌浆网（SR）激活收缩蛋白。 的 SR的释放通道由在所述电极处的电势变化控制。 血浆和T管膜。 该项目的长期目标是 理解这种控制。 自上次更新该补助金以来， 两个关键分子的身份，T的电压传感器， 膜和SR的释放通道，成为已知的。 中央 EC耦合的问题-以及该建议-现在可以表述为 了解二氢吡啶受体之间的相互作用， DHPr分子（电压传感器）和兰尼碱受体或R Yr （释放频道） 对这个问题的简化方法是 使用，包括完整系统及其部分的研究。 完整系统中的测量将包括膜内 电荷移动（电压传感器的表现）和Ca释放 单个骨骼肌细胞中的通量。 一种新的电压钳位技术， 改进以前的测量。 了解前向传输将 需要阐明一个新发现的反向传输： 释放反馈到电压传感器上。 电荷移动，钙释放， 传播机制将统一在一个综合模型中 EC耦合。 在这个框架中，将有可能测试 从数量上讲，有两种可能的前向传播机制： 机械的，通过DHPr和RYr之间的直接或间接接触，或 化学物质，通过一个可扩散的发射器。 为了分别研究系统的各个部分， 将使用：双层DHPr和RYr的单通道记录 和测量心脏细胞中的Ca通道门控电流。 一 比较系统及其部件的特性， 属性，并帮助确定 传输是机械的。 有希望的初步工作，其中 通过将组分置于双层中， 将继续并延长。 E-C耦合的分子机制基本上是 与膜生物物理学的其他现象相似， players是在别处发现的通道蛋白的相似同种型。 因此在 除了本研究报告应具有的必要相关性之外， 对肌肉功能障碍和治疗的理解， EC偶联对中枢神经系统的研究将产生更广泛的影响 心脏和平滑肌的问题

The transduction of action potential to muscle contraction (EC coupling) is an example of fast communication between cell membrane events and metabolic state. As in many systems, the central messenger of this coupling is calcium, which in muscle is released from the Sarcoplasmic Reticulum (SR) to activate contractile proteins. The release channels of the SR are controlled by changes in potential at the plasma and T-tubular membrane. The long term goal of this project is to understand this control. Since the last renewal of this grant, the identity of two key molecular players, the voltage sensor of the T membrane and the release channel of the SR, became known. The central problem of EC coupling -and of this proposal- can now be formulated as understanding the interaction between the dihydropyridine receptor or DHPr molecule (voltage sensor) and the ryanodine receptor or R Yr (release channel). A reductionist approach to this question will be used, consisting of studies of the complete system and its parts. Measurements in the complete system will include intramembrane charge movement (a manifestation of the voltage sensor) and Ca release flux in single skeletal muscle cells. A new voltage clamp technique will improve previous measurements. Understanding forward transmission will require the elucidation of a newly found backward transmission: Ca release feeds back on the voltage sensor. Charge movement, Ca release, and mechanisms of transmission will be unified in a comprehensive model of EC coupling. In this framework it will be possible to test quantitatively two possible mechanisms of forward transmission: mechanical, by direct or indirect contact between DHPr and RYr, or chemical, via a diffusible transmitter. To study the parts of the system separately, two preparations will be used: single channel recording with DHPrs and RYrs in bilayers and measurement of Ca channel gating currents in heart cells. A comparison of the properties of the system and its parts will identify properties that depend on the interaction, and help decide whether the transmission is mechanical. Promising preliminary work, in which an interaction was demonstrated in bilayers by putting the components together, will be continued and extended. The molecular mechanisms in E-C coupling are fundamentally similar to other phenomena of membrane biophysics, and the key molecular players are close isoforms of channel proteins found elsewhere. Thus, in addition to the obligatory relevance that the present studies should have to the understanding of muscle dysfunction and therapeutics, findings in Ec coupling should have a more general impact, on research of CNS problems, heart and smooth muscle.