SMOOTH MUSCLE AND NONMUSCLE CALDESMON

排列在中空器官外围的平滑肌收缩， 改变器官的形状或保持张力以固定形状。 一个 对平滑肌收缩调节的了解有助于 为理解一些疾病奠定了基础，包括 血管系统的高血压和呼吸道的哮喘 肺。 平滑肌收缩主要由 钙调蛋白依赖的肌球蛋白磷酸化 灯丝 越来越多的证据表明， 与肌动蛋白细丝有关的机制涉及钙调蛋白， 细长肌动蛋白结合蛋白和原肌球蛋白。 短得多的 钙调素同种型也存在于广泛的非肌肉组织中 包括脑、肝、肾和血小板。 非肌肉caldesmon是 被认为在调节细胞的形状和运动性方面起作用。 但对其功能知之甚少。 因此， 该项目的目标是揭示分子机制， 钙调素与原肌球蛋白一起调节平滑肌 收缩和非肌肉运动和形状。 当前的目标 是绘制平滑肌和非肌肉钙调素的排列图， 肌动蛋白丝上的原肌球蛋白。 这些研究的结果将是 与肌动球蛋白ATP酶活性相关， 收缩，以连接结构与功能。 这些目标 将采用重组和天然细丝， 肌原纤维 该项目将利用光谱和交联 特异性连接到钙调蛋白的特定结构域的探针， 原肌球蛋白，以探测这些区域的蛋白质在其 相互作用和其他收缩蛋白。 在 特别地，自旋标记物、荧光标记物、光交联剂，以及 将使用二硫化物交联剂。 电镜和 流体动力学粘度技术和分析超浓缩技术 也将被雇用。

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.