Substructure and Communication in Myosin and Actin

骨骼肌、心肌和平滑肌的收缩需要两种主要肌肉蛋白--肌球蛋白和肌动蛋白之间的循环相互作用。这些相互作用的基本步骤包括肌动蛋白激活肌球蛋白ATPase活性，根据流行的观点，这些蛋白中的一个或两个上的构象变化。拟议研究的一个主要目标是阐明这些事件的分子基础。为了达到目的，肌球蛋白ATPase活性和肌动蛋白细丝运动所需的肌动蛋白位点将被绘制出来。用于绘制肌动蛋白功能位点图的实验材料将包括多肽抗体、肌动蛋白突变体和修饰肌动蛋白。这些材料将用于体外运动性分析，以及肌动球蛋白相互作用的生化和生物物理分析。在本计划的另一部分中，将通过比较肌动蛋白和肌球蛋白单体和聚合复合体的性质来阐明肌动蛋白相互作用中必要步骤的结构决定因素。在这个项目中将使用多肽、蛋白质片段、交联蛋白质复合体、多肽抗体和肌动蛋白突变体。肌动蛋白上的特定位点在肌动球蛋白相互作用中的作用将通过对这些材料进行的化学修饰、蛋白质分解、荧光和光散射测量以及其他测量来评估。通过阐明肌球蛋白聚合G-肌动蛋白的机制，可以进一步深入了解肌球蛋白与肌动蛋白的相互作用。拟议的研究应有助于阐明肌动球蛋白相互作用的基本机制，从而更好地了解肌肉的功能以及生物系统中化学能是如何转化为工作的。

The contraction of skeletal, cardiac, and smooth muscles requires cyclic interactions between the two main muscle proteins, myosin and actin. The essential steps in these interactions include the activation of the myosin ATPase activity by actin and, according to prevalent views, conformational changes on one or both of these proteins. A major goal of the proposed research is to clarify the molecular basis of these events. To achieve aim, actin sites necessary for the activation of the myosin ATPase activity and the motility of actin filaments will be mapped. The experimental materials to be used in the mapping of functional sites on actin will include peptide antibodies, actin mutants, and modified actins. These materials will be used in the in vitro motility assays, and in biochemical and biophysical assays of actomyosin interactions. In another part of this program, the structural determinants of the essential steps in actomyosin interactions will be clarified by comparing the properties of monomeric and polymeric complexes of actin and myosin. Peptides, protein fragments, cross- linked protein complexes, peptide antibodies, and actin mutants will be used in this project. The role of specific sites on actin in actomyosin interactions will be assessed via chemical modifications, proteolytic digestions, fluorescence and light scattering measurements, and other measurements carried out on these materials. Additional insight into actomyosin interactions will be obtained by clarifying the mechanism of G-actin polymerization by myosin. %%% The proposed studies should lead to the elucidation of the basic mechanism of actomyosin interactions and thus, a better understanding of how the muscle functions and how chemical energy is transduced into work in biological systems.