Ohtsuki Iwao, Morimoto Sachio
Department of Cell Physiology, Jikei University School of Medicine, 3-25-8, Nishi-shimbashi, Minato-ku, Tokyo 105-8461, Japan.
Biochem Biophys Res Commun. 2008 Apr 25;369(1):62-73. doi: 10.1016/j.bbrc.2007.11.187. Epub 2007 Dec 26.
Study of the molecular biology of the calcium regulation of muscle contraction was initiated by Professor Ebashi's discovery of a protein factor that sensitized actomyosin to calcium ions. This protein factor was separated into two proteins: tropomyosin and a novel protein named troponin. Troponin is a Ca(2+)-receptive protein for the Ca(2+)-regulation of muscle contraction and, in association with tropomyosin, sensitizes actomyosin to Ca(2+). Troponin forms an ordered regulatory complex with tropomyosin in the thin filament. Several regulatory properties of troponin, which is composed of three different components, troponins C, I, and T, are discussed in this article. Genetic studies have revealed that many mutations of genes for troponin components, especially troponins T and I, are involved in the three types of inherited cardiomyopathy. Results of functional analyses indicate that changes in the Ca(2+)-sensitivity caused by troponin mutations are the critical functional consequences leading to these disorders. Recent results of this pathophysiological aspect of troponin are also discussed.
肌钙蛋白对肌肉收缩钙调节的分子生物学研究始于江桥教授发现一种使肌动球蛋白对钙离子敏感的蛋白质因子。这种蛋白质因子被分离成两种蛋白质：原肌球蛋白和一种名为肌钙蛋白的新蛋白质。肌钙蛋白是一种用于肌肉收缩钙调节的钙受体蛋白，与原肌球蛋白一起，使肌动球蛋白对钙离子敏感。肌钙蛋白在细肌丝中与原肌球蛋白形成有序的调节复合物。本文讨论了由三种不同成分肌钙蛋白C、I和T组成的肌钙蛋白的几种调节特性。遗传学研究表明，肌钙蛋白成分的许多基因突变，尤其是肌钙蛋白T和I的突变，与三种遗传性心肌病有关。功能分析结果表明，肌钙蛋白突变引起的钙敏感性变化是导致这些疾病的关键功能后果。本文还讨论了肌钙蛋白这一病理生理学方面的最新研究结果。
