Thin Filaments and Muscle Regulation

超出所提供的空间。在肌肉和非肌肉细胞中，细丝相关的肌动蛋白结合蛋白控制着基于肌动球蛋白的收缩力和细胞骨架的形成。为了阐明这些机制，确定相关蛋白质的结构相互作用是至关重要的。我们解决了几个相互关联的问题，以理解肌肉细丝功能的基础：(1)骨骼肌、心肌和平滑肌中细丝的结构是什么？(2)调节肌肉活动的细丝连接蛋白的结构相互作用变化是什么？(3)这些蛋白如何与肌动蛋白相互作用形成肌肉细胞骨架？我们使用最先进的电子显微镜，图像分析和三维重建来建立结合在细丝肌动蛋白上的成分的大分子结构。使用这些技术：(A)我们的目标是通过分析肌钙蛋白和肌钙蛋白在细丝上的相互作用以及Ca2¿和肌钙蛋白交桥结合的影响来确定肌钙蛋白-原肌球蛋白调节骨骼肌和心肌活动的结构基础。(B)为了帮助理解肌细胞皮质肌动蛋白细胞骨架的组织，我们的目标是通过检查它们独特的钙钙蛋白同源（CH）结构域的结合来确定肌营养不良蛋白和肌营养不良蛋白与丝状f -肌动蛋白的结构相互作用。(C)我们的目的是评估细丝相关caldesmon作为平滑肌中基于肌动球蛋白的运动和细胞骨架组装的可能调节剂的结构作用。(D)对星云结构的研究将是我们继续研究细丝的功能设计的一部分。在每项研究中，重建将与f -肌动蛋白的原子分辨率图相匹配，以确定结合蛋白与肌动蛋白的分子接触。此外，这种“混合晶体学”将用于在EM密度图中拟合新解的肌钙蛋白、原肌球蛋白、肌营养不良蛋白和肌营养蛋白结构域的晶体结构，以获得接近原子分辨率。我们正在进行的关于肌钙蛋白-trepomyosin调节的细丝的研究将有助于阐明骨骼肌和心肌松弛和激活的分子机制。我们成功启动的肌营养蛋白和肌营养不良蛋白的结构研究将确定它们作为细胞骨架元件的独特特征，这些信息适用于设计肌营养不良的基因疗法。对平滑肌纤维的研究将有助于理解平滑肌收缩反应的微调。这种调节影响血管张力和肺气道阻力，这是高血压和哮喘等疾病的决定因素。肌动蛋白和相关蛋白的作用强调了我们的目标的更广泛的意义，这些蛋白在恶性肿瘤中可能成为异常的重要细胞机制。网站性能 ======================================== 节结束 ===========================================

EXCEED THE SPACE PROVIDED. Thin filament-associated actin-binding proteins control both actomyosin-based contractilityand cytoskeletal formation in muscle and non-muscle cells. To elucidate these mechanisms, it is crucial to determine the structural interactionsof the proteins involved. We address several interrelated questions fundamental to understanding muscle thin filament function: (1) What is the architecture of the thin filament in skeletal, cardiac and smooth muscles? (2) What are the changing structural interactionsof thin filament-linked proteinsthat regulate muscle activity? (3) How do these proteins interact with actin to form the muscle cytoskeleton? We use state-of-the-art electron microscopy, image analysis and 3-D reconstruction to establishthe macromolecular structureof components bound on thin filament actin. Using these techniques: (A) We aim to determine the structural basis of troponin-tropomyosinregulation of skeletal and cardiac muscle activity by analyzing interactions of tropomyosin and troponin on thin filaments and the effects of Ca2¿and myosin-crossbridgebinding. (B) To help understandthe organization of the cortical actin cytoskeletonof muscle cells, we aim to determine the structural interactions of dystrophin and utrophin with filamentous F-actin by examining the binding of their distinctcalponin homology (CH)-domains. (C) We aim to assess the structural role of thin filament- associated caldesmon as a possible modulator of actomyosin-based motility and cytoskeletal assembly in smooth muscle. (D) Studies of the structureof nebulin bound to actinwill be part of our continuing investigationof the functional design of thin filaments. In each study, reconstructionswill be fitted to the atomic resolution maps of F-actin to define molecular contacts of binding proteins with actin. Further, such "hybrid crystallography" will be used to fit newly solved crystal structures of troponin, tropomyosin, dystrophin and utrophin domains within EM density maps to attain near atomic resolution. Our ongoing studies on troponin-trepomyosin regulated filaments will lead to an elucidation of the molecular mechanism of relaxation and activation in skeletal and cardiac muscle. Our successfully initiated structural studies on utrophin and dystrophinwill establish their unique features as cytoskeletal elements, informationapplicable to designing genetic therapies for muscular dystrophy.Studies on smooth muscle filaments will contributeto understanding the fine-tuning of the smooth muscle contractile response. Such modulation affects vascular tone and pulmonary airway resistance, determinants in, e.g., hypertension and asthma. The wider significance of our goals is underscored by the role of actin and associated proteins indiverse and vital cellular mechanisms that can become aberrant in malignancy. PERFORMANCE SITE ========================================Section End===========================================