Smooth Muscle Thin Filament

描述（由申请人提供）：平滑肌，围绕 中空器官的外周，收缩以改变器官形状或保持张力 以固定形状，从而控制重要流体的流动， 对心血管，呼吸， 消化和生殖系统。如果平滑肌的调节 收缩功能不正常，它可能有助于这些疾病， 高血压哮喘和早产我们工作的目标是 了解收缩正常调节的分子基础。光滑 肌肉收缩主要由Ca 2+控制的 粗肌丝中肌球蛋白的磷酸化。然而，没有严格的 磷酸化水平和所产生的磷酸化水平之间的耦合 收缩力有证据表明，有额外的规定， 肌动蛋白细丝可能涉及原肌球蛋白（Tm）。然而 这种功能的机制知之甚少。这个项目的长期目标是 该项目是揭示Tm的分子机制， 其他细丝蛋白，调节平滑肌收缩。主要 该建议的假设是，细丝调节主要通过以下方式发生： 通过肌球蛋白在粗肌丝上控制Tm在细肌丝上的运动， 和其他细丝蛋白，钙调素和钙调蛋白， 反过来又受磷酸化和Ca 2+结合蛋白的调节。这将是 通过监测Tm的位置进行测试，并通过测量Tm-肌动蛋白 通过荧光作为肌球蛋白、钙调蛋白和钙调蛋白的函数的距离 共振能量转移与肌动球蛋白ATP酶活性相关， 收缩的体外模拟物。这些研究的结果， 进行重组厚和薄长丝，将有助于进一步我们的 了解平滑肌收缩的开启/关闭， 平滑肌，尤其是血管肌， 张力，从而器官的形状，在成本非常少的能量。这些研究 我将比较血管和胃肠道平滑肌的肌球蛋白， 以更好地了解血管肌肉维持这种张力的能力。

DESCRIPTION (provided by the applicant): Smooth muscles, which surround the periphery of hollow organs, contract to change organ shape or maintain tension to fix the shape and thereby control the flow of vital fluids, which are essential to the normal functioning of the cardiovascular, respiratory, digestive, and reproductive systems. If the regulation of smooth muscle contraction does not function properly, it could contribute to such diseases as high blood pressure, asthma, and premature birth. The goal of our work is to understand the molecular basis of the normal regulation of contraction. Smooth muscle contraction is primarily regulated by the Ca2+ controlled phosphorylation of myosin in the thick filament. However there is not a strict coupling between phosphorylation levels and the level of the resulting contractile force. Evidence indicates that there is additional regulation in the actin thin filament possibly involving tropomyosin (Tm). However the mechanism of this function is poorly understood. The long-range goal of this project is to uncover the molecular mechanisms whereby Tm, in concert with other thin filament proteins, regulates smooth muscle contraction. The main hypothesis of this proposal is that thin filament regulation occurs mainly by controlling the movement of Tm on the thin filament by myosin in the thick filament and by the other thin filament proteins, caldesmon and calponin, which are in turn regulated by phosphorylation and Ca2+binding proteins. This will be tested by monitoring Tm's position, and movement by measuring the Tm-actin distances as a function of myosin, caldesmon and calponin by fluorescence resonance energy transfer and correlated with actomyosin ATPase activity, an in vitro analogue of contraction. The results of these studies, which will be conducted on reconstituted thick and thin filaments, will help to further our understanding of the switching on/off of smooth muscle contraction and of smooth muscle's unique ability, especially vascular muscle, to maintain tension, and thus organ shape, at the cost of very little energy. These studies will compare myosin from vascular and gastrointestinal smooth muscles in order to better understand the ability of vascular muscle to maintain this tension.