TROPOMYOSIN AND THE REGULATION OF MUSCLE CONTRACTION

描述：（申请人摘要中的逐字记录）广泛、长期 目的是阐明肌肉调节的分子基础， 收缩通过定义每个肌肉成分的作用：肌动蛋白，原肌球蛋白 (Tm)肌钙蛋白组分TnI、TnT、TnC和肌球蛋白。健康相关性： 这些信息将有助于了解肌肉疾病，例如， Tm、TnT、TnI和肌球蛋白突变导致的肥厚型心肌病 以及冠状动脉疾病导致的心肌顿抑。 Tm在与肌动蛋白的相互作用中，在决定肌动蛋白的功能中起着关键作用。 肌肉细丝的三种状态之间的平衡， 阻塞/关闭/打开（收缩发生在打开状态）。交互 肌动蛋白Tm、肌钙蛋白复合物和肌球蛋白头改变了平衡 在状态之间，从而打开和关闭收缩。 具体目的是检验以下假设：（a）Ca 2+和肌球蛋白诱导 肌动蛋白上Tm的位置和构象发生变化，导致 平衡朝向开放的生化状态，从而允许 收缩;（B）在不存在Ca 2+的情况下，TnI除了与Tm相互作用外，还与Tm相互作用。 肌动蛋白，以使细丝稳定在阻断状态;（c）TnT：（i） 通过改变Tm构象抑制actinTm-S1 ATP酶，（ii）增加 actinTm单位之间的协同性，（iii）与Tm的相互作用不同， 3种生化状态中的每一种;（d）Tm向细丝的移动 激活状态（开放状态）发生在Ca 2+诱导后的肌球蛋白结合过程中 TnI从肌动蛋白解离;（e）HMM的两个头部协同作用， 将actinTm从封闭状态转变为开放状态;（f）在以下中发现的Tm突变体： FHC患者改变了三种生化状态之间的平衡， 细丝，从而影响收缩。 方法：除了表征溶液中的3种状态外， ATP酶，肌球蛋白滴定和停流技术，广泛使用将 由组件之间的高分辨率距离测量组成， 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.