Myosin Hinge Region In Contraction

超出所提供的空间。我们提出了一种多方面和综合的方法来确定肌球蛋白重链蛋白的“铰链”区域在肌肉收缩中的功能。虽然很多努力都集中在肌球蛋白头在决定肌肉收缩特性中的作用上，但我们的新结果表明，杆的铰链对肌肉功能也至关重要。我们采用黑腹果蝇，这是适用于基因，转基因和肌肉机械方法。它的单个肌球蛋白基因编码不同的肌球蛋白铰链区域，一个在慢抽搐的胚胎肌肉中表达，另一个在快速抽搐和振荡的成人肌肉中表达。我们制造了一种转基因系，在通常表达成年铰链（间接飞行和跳跃肌肉）的肌肉中表达带有胚胎铰链的肌球蛋白。转基因肌肉组装正常的肌原纤维，但肌肉功能严重受损。我们建议通过测试以下假设来确定铰链功能在完整生物体、分离纤维、单个肌原纤维、粗丝和/或肌球蛋白分子水平上是否至关重要：1)肌球蛋白铰链在肌原纤维组装中不重要；2)铰链影响肌纤维和肌原纤维的机械性能[分别与David Maughan博士（佛蒙特大学）和Gerald Pollack博士（华盛顿大学）合作，分别是肌纤维和肌原纤维的生物物理测量专家]；3)铰链对肌凝蛋白分子和粗丝的物理特性有重要贡献，特别是对分离的肌凝蛋白分子的缩短或完整的粗丝的弹性的差异（与Pollack博士合作）；4)形成盘绕线圈的倾向对于定义不同铰链域之间的差异至关重要；5)铰链特异性蛋白相互作用会导致不同铰链区域之间的功能差异[我们将测试与厚丝蛋白飞行蛋白的相互作用（与佛蒙特大学的Jim Vigoreaux博士合作），并在果蝇中进行基因抑制研究]。我们的综合方法应该阐明肌球蛋白铰链在肌肉功能中的作用及其作用机制。我们的工作与人类疾病有关，因为肌球蛋白突变可引起心肌肥厚性心肌病和骨骼肌中央核心疾病。此外，由于间接飞行肌具有类似于人类心肌的振荡和拉伸激活特性，了解肌球蛋白参与产生这些特性可能有助于了解人类心脏功能。网站性能 ======================================== 节结束 ===========================================

EXCEED THE SPACE PROVIDED. We propose a multifaceted and integrative approach to determine the function of the "hinge" region of the myosin heavy chain protein in muscle contraction. While much effort has focused on the role of the myosin head in dictating muscle contractile properties, our novel results indicate that the hinge of the rod also is critical for muscle function. We employ Drosophila melanogaster, which is amenable to genetic, transgenic and muscle mechanical approaches. Its single myosin gene encodes alternative myosin hinge regions, one expressed in slow twitch embryonic muscles and one expressed in fast twitch and oscillatory adult muscles. We produced a transgenic line that expresses myosin with the embryonic hinge in muscles that normally express the adult hinge (indirect flight and jump muscles). Transgenic muscles assemble normal-looking myofibrils, but muscle function is severely compromised. We propose to determine if hinge function is critical at the level of the intact organism, the isolated fiber, the single myofibril, the thick filament and/or the myosin molecule, by testing the following hypotheses: 1) the myosin hinge is not important in myofibril assembly; 2) the hinge influences the mechanical properties of muscle fibers and myofibrils [in collaboration with Dr. David Maughan (U. Vermont) and Dr. Gerald Pollack (U. Washington),experts in biophysical measurements of muscle fibers and myofibrils, respectively]; 3) the hinge contributes significantly to physical properties of myosin molecules and thick filaments, specifically to differences in the shortening of isolated myosin molecules or elasticity of intact thick filaments (in collaboration with Dr. Pollack); 4) the propensity to form a coiled-coil is critical to defining the differences between alternative hinge domains; 5) hinge-specific protein interactions impart functional differences between alternativehinge regions [we will test for interaction with the thick filament protein flightin (in collaboration with Dr. Jim Vigoreaux, U. Vermont) and perform genetic suppression studies in flies]. Out integrative approach should elucidate the role of the myosin hinge in muscle function and the mechanism by which it acts. Our work is relevant to human disease since mutations in myosin can cause hypertrophic cardiomyopathy in heart muscle and central core disease in skeletal muscle. Further, since the indirect flight muscle has oscillatory and stretch-activated properties similar to human cardiac muscle, understanding myosin' involvement in generating these properties may lead to insights into human heart function. PERFORMANCE SITE ========================================Section End===========================================