REGULATION IN STRIATED, SMOOTH, AND CARDIAC MUSCLES

横纹肌、平滑肌和心肌的调节

• 批准号: 3481416
• 负责人: ANDREW G SZENT-GYORGYI
• 金额: $ 29.66万
• 依托单位: BRANDEIS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1977
• 资助国家: 美国
• 起止时间: 1977-05-01 至 1992-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3481416
• 关键词: Bivalvia; Malacostraca; X ray crystallography; actins; biological information processing; calcium binding protein; crosslink; electron microscopy; horseshoe crabs; immunochemistry; laboratory rabbit; molecular genetics; muscle contraction; mutagens; myocardium; myofibrils; myosins; nucleic acid probes; phosphorylation; protein structure; radiotracer; saltwater environment; smooth muscle; species difference; striated muscles; thiols; tropomyosin; troponin

The control of muscle contraction by myosin is studied at the molecular level in molluscan muscles. We have previously shown that in these muscles calcium triggers contraction by binding directly to myosin and that the regulatory components are the regulatory and essential light chains of myosin which maintain the resting state in the absence of calcium. The mechanism of this subunit regulation is most conveniently studied on scallop myosin since the regulatory light chains can be fully and reversibly dissociated from the heavy chains without denaturation. Removal of the RLCs and immobilization of the light chains at a site where the two myosin heads join locks muscle in the "on" state, losing its ability to relax. The interactions between the light chains and between the heavy and light chains are studied with the aid of photolabile, heterobifunctional cross-linkers, and with chemical and genetic modifications. We plan to identify the cross-linked products formed with various foreign light chains in rest and rigor. Since cross-linkers introduced into the various foreign light chains are located differently in the sequence, the experiments will help to ascertain the polarity, colinearity and relative position of the light chains in myosin in its different functional states. Cross-linkers introduced via the fast reacting heavy chain thiols will relate the heavy chains to light chain movement. Fragmentation of the heavy chain with proteolytic enzymes may identify regions within the molecule responsible for particular functions. Light chains modified by site-directed mutagenesis will help to identify residues responsible for binding to the heavy chain, calcium binding and calcium regulation of contractile functions. Introduction of thiol groups in predetermined positions of the sequence will allow for a more precise localization of the light chains in myosin, and a more accurate description of their rearrangement. The findings will clarify the basic mechanisms of thick-filament regulation They may also be extended to vertebrate smooth and non-muscle myosins, which are also regulated by light chains but triggered by phosphorylation instead of calcium binding.

在分子上研究了肌球蛋白对肌肉收缩的控制 软体动物肌肉的水平。 我们以前已经表明，在这些肌肉中 钙通过直接与肌球蛋白结合而触发收缩 调节组件是监管和基本的轻链 在没有钙的情况下维持静息状态的肌球蛋白。 这 最方便地研究了该亚基调节的机制 扇贝肌球蛋白，因为调节轻链可以完全 不可逆地与重链分离而不会变性。 移动 RLCS的固定在两个位置的位置 肌球蛋白头在“ ON”状态下连接锁肌肉，失去了其能力 放松。 轻链之间以及沉重和光线之间的相互作用 借助光值，异常功能研究链条 交联，以及化学和遗传修饰。 我们计划 识别由各种外国轻链形成的交联产品 休息和严峻。 由于交联引入了各种外国 轻链在序列中的位置不同，实验将 有助于确定极性，分类性和相对位置 肌球蛋白在其不同功能状态下的光链。 交联 通过快速反应重链硫醇引入将与重型 链条到轻链运动。 重链的破碎 蛋白水解酶可以鉴定负责分子内的区域 对于特定功能。 通过站点定向修改的光链 诱变将有助于确定负责结合的残基 重链，钙结合和收缩的钙调节 功能。 引入硫醇基团在预定位置 序列将使光链中的更精确定位 肌球蛋白，以及对其重排的更准确描述。 这些发现将阐明厚丝调节的基本机制 它们也可能扩展到脊椎动物光滑和非肌肉肌球蛋白， 它也受光链调节，但由磷酸化触发 而不是钙结合。