CONTRACTION AND E-C COUPLING IN STRIATED MUSCLE

肌动球蛋白跨桥特异状态之间的关系 循环和它们的构象尚未建立。 利用光解作用 笼状化合物和快速冷冻，我们将研究的结构， 通过电子显微镜和图像在各种状态下的交叉桥 分析. 在兴奋-收缩偶联过程中， 表面膜被翻译成释放钙的信号， 肌浆网（SR）。 SR钙释放通道已经被 鉴定：它是足蛋白，其胞质结构域跨越 SR表面膜和/或其内陷之间的间隙， 横（T）小管。 我们要找出 表面膜/T小管（连接四分体），L型 钙通道（或二氢吡啶受体）被认为是 电-电耦合电压传感器。 利用肌肉的电子显微镜 来自E-C偶联缺陷突变肌肉发育不全的纤维， 通过转染的基因的cDNA拯救了发育不良的肌纤维， DHPR α 1亚基，和转染的中国仓鼠卵巢细胞， 我们将确定接合四分体之间是否存在相关性， DHPR。 骨骼肌纤维膜系统的体内发育 通过几个协调良好的步骤进行。 我们将探讨 膜发育中的特定事件之间存在关系， 中间纤维系统的出现和重新排列。

A relationship between specific states of the actomyosin cross-bridge cycle and their conformation is not yet established. Using photolysis of caged compounds and rapid freezing we will examine the structure of cross-bridges in various states by electron microscopy and image analysis. In the process of excitation-contraction coupling, depolarization of the surface membrane is translated into a signal for release of calcium from the sarcoplasmic reticulum (SR). The SR calcium release channel has been identified: it is the foot protein, whose cytoplasmic domain spans the gap between the SR surface membrane and/or its invaginations, the transverse (T) tubules. We seek identification of a component of the surface membrane/T tubules (the junctional tetrads) with the L type calcium channel (or dihydropyridine receptor) which is thought to be the voltage sensor of E-C coupling. Using electron microscopy of muscle fibers from the E-C coupling defective mutation muscular dysgenesis, of dysgenic muscle fibers rescued by transfection with the cDNA for the alpha 1 subunit of DHPRs, and of transfected chinese hamster ovary cells, we will establish if a correlation exists between junctional tetrads and DHPRs. Development of the membrane systems in skeletal muscle fibers in vivo proceeds through several well coordinated steps. We will explore whether a relationship exists between specific events in membrane development and the appearance and rearrangement of the intermediate filament system.