TROPOMYOSIN AND THE REGULATION OF MUSCLE CONTRACTION

描述：(逐字摘自申请者的摘要)广泛的、长期的 目的是阐明肌肉调节的分子基础。 通过确定每个肌肉成分的作用来收缩：肌动蛋白、原肌球蛋白 (TM)、肌钙蛋白组分、TnI、TnT、TnC和肌球蛋白。与健康相关： 这些信息将有助于理解肌肉疾病，例如， TM、TnT、TnI和肌球蛋白基因突变引起的肥厚型心肌病 以及冠状动脉疾病引起的心肌顿抑。 在与肌动蛋白的相互作用中，TM在决定 肌肉细丝的三种状态之间的平衡， 阻止/关闭/打开(收缩在打开状态下发生)。通过互动 通过肌动蛋白Tm，肌钙蛋白复合体和肌球蛋白头部改变了平衡 在各州之间，从而打开和关闭收缩。 其具体目的是检验如下假设：(A)钙离子和肌球蛋白诱导 TM在肌动蛋白上的位置和构象的变化导致 朝向开放生化状态的平衡，从而允许 收缩；(B)在没有钙离子的情况下，TnI除了与TM相互作用外，还 肌动蛋白，用于在封闭状态下稳定细丝；(C)TNT：(I) 通过改变TM构象抑制ActinTm-S1 ATPase，(Ii)增加 ActinTm单元之间的协作性，(Iii)与TM在 3种生化状态中的每一种；(D)TM向细丝运动 钙离子诱导后肌球蛋白结合时的开启状态(Open-State) TnI与肌动蛋白解离；(E)HMM的两个头部协同作用以 将actinTm从闭合状态转变为开放状态；(F)在 FHC患者体内3种生化状态之间的平衡发生改变 细丝，从而影响收缩。 方法：除了对溶液中的3种状态进行表征外 ATPase、肌球蛋白滴定和停流技术，将得到广泛应用 由高分辨率的组件之间的距离测量组成，具有 时间分辨荧光能量转移。

Description: (Verbatim from the applicant's abstract) The broad, long-term objective is to elucidate the molecular basis of the regulation of muscle contraction by defining the role of each muscle component: actin, tropomyosin (Tm), the troponin components, TnI, TnT, TnC, and myosin. Health Relatedness: This information will help in the understanding of muscle diseases e.g., hypertrophic cardiomyopathy resulting from mutations in Tm, TnT, TnI and myosin and stunned myocardium resulting from coronary artery disease. Tm, in its interaction with actin, plays a key role in determining the equilibria between the 3 states of the muscle thin filament, Blocked/Closed/Open (contraction takes place in the Open state). By interacting with actinTm, the troponin complex and myosin heads change the equilibrium between the states, thereby turning contraction on and off. The specific aims are to test the hypotheses that: (a) Ca2+ and myosin induce changes in position and conformation of Tm on actin which results in a shift of the equilibrium toward the Open biochemical state, thereby allowing contraction; (b) in the absence of Ca2+, TnI, interacts with Tm in addition to actin, to stabilize the thin filament in the Blocked-state; (c) TnT: (i) inhibits actinTm-S1 ATPase by altering Tm conformation, (ii) increases the cooperativity between actinTm units, (iii) interacts differently with Tm in each of the 3 biochemical states; (d) Tm movement to the thin filament On-activity state (Open-state) occurs during myosin binding after Ca2+-induced TnI dissociation from actin; (e) the two heads of HMM act cooperatively to shift actinTm from the Closed to the Open-state; (f) mutants of Tm found in patients with FHC alter the equilibria between the 3 biochemical states of the thin filament thereby affecting contraction. Methods: In addition to characterization of the 3 states in solution with ATPase, myosin titrations and stopped-flow techniques, extensive use will be made of high resolution distance measurements between components with time-resolved fluorescence energy transfer.