SMOOTH MUSCLE AND NONMUSCLE CALDESMON

排列在中空器官周围的平滑肌收缩到 改变器官的形状或保持张力以固定形状。一个 了解平滑肌收缩的调节可能会有所帮助 形成了解一些疾病的基础，包括 血管系统的高血压和呼吸道的哮喘 阿龙。平滑肌收缩主要是由 钙-钙调蛋白依赖的肌球蛋白磷酸化 灯丝。正在积累额外的监管措施的证据 与肌动蛋白细丝有关的机制涉及caldesmon，a 长、薄、肌动蛋白结合蛋白和原肌球蛋白。一个短得多的 钙调蛋白的异构体也存在于多种非肌肉组织中。 包括脑、肝、肾和血小板。非肌肉的钙调蛋白是 被认为在调节细胞的形状和运动方面起作用。 然而，人们对其功能知之甚少。因此，远距离 这个项目的目标是揭示分子机制， 钙调蛋白与原肌球蛋白协同调节平滑肌 收缩和非肌肉的运动和形状。眼前的目标 是绘制平滑肌肉和非肌肉钙蛋白的排列图，以及 肌动蛋白细丝上的原肌球蛋白。这些研究的结果将是 与肌动球蛋白ATPase活性相关的试管类似物 收缩，以便将结构与功能联系起来。这些目标 将用重组的天然细丝和完好无损的 肌原纤维。该项目将利用光谱和交联剂 专门连接到caldesmon和caldesmon特定结构域的探针 原肌球蛋白，以便探索它们的这些蛋白质区域 相互作用和其他收缩蛋白。在……里面 具体地，自旋标记、荧光标记、光交联剂和 将使用二硫化物交联剂。电子显微镜和 粘度和分析性超速离心的流体力学技术 也会被雇佣。

Smooth muscle, which lines the periphery of hollow organs, contracts to change the shape of the organ or maintains tension to fix the shape. An understanding of the regulation of smooth muscle contraction could help to form the basis for understanding a number of diseases, including hypertension in the vascular system and asthma in the airways of the lung. Smooth muscle contraction is primarily regulated by Ca2+-calmodulin dependent phosphorylation of myosin in the thick filament. Evidence is accumulating for an additional regulatory mechanism associated with the actin thin filament involving caldesmon, a long, thin, actin-binding protein, and tropomyosin. A much shorter isoform of caldesmon is also found in a wide range of non-muscle tissue including brain, liver, kidney, and platelets. Non-muscle caldesmon is thought to play a role in regulating the shape and motility of cells. However very little is known about its function. Thus the long range goal of this project is to uncover the molecular mechanisms whereby caldesmon, in concert with tropomyosin, regulates smooth muscle contraction and non-muscle motility and shape. The immediate objective is to map the arrangement of smooth muscle and non-muscle caldesmon, and tropomyosin, on the actin filament. The results of such studies will be correlated with actomyosin ATPase activity, the test tube analogue of contraction, in order to connect structure with function. These aims will be pursued with reconstituted and native thin filaments and intact myofibrils. The project will make use of spectroscopic and cross-linking probes specifically attached to particular domains of caldesmon and tropomyosin in order to probe these regions of the proteins in their interaction with each other and other contractile proteins. In particular, spin labels, fluorescence labels, photocross-linkers, and disulfide cross-linkers will be used. Electron microscopy and the hydrodynamic techniques of viscosity and analytical ultracentrifugation will also be employed.