肌球蛋白结构和功能变化与运动的影响

Influence of exercise on the structure and function of myosin

目的:从肌球蛋白的一级结构、二级结构、分子生物学水平综述运动对肌球蛋白结构及功能的影响,及运动对肌球蛋白重链表达的影响。资料来源:应用计算机检索Pubmed数据库1999-06/2006-06相关运动与肌球蛋白的文献,检索词"myosin,myosin heavy chain,myosin light chain,aerobic exercise",限定文献语言种类为English。同时检索CNKI中国期刊全文数据库1999-06/2006-06相关运动与肌球蛋白的文章,检索词"肌球蛋白,肌球蛋白重链,肌球蛋白轻链,运动",限定文章语言种类为中文。资料选择:对资料进行初审,选取包括运动与肌球蛋白的文献,开始查找全文。纳入标准:①有关肌球蛋白的结构研究及临床研究。②运动与肌球蛋白运动与肌球蛋白关系的实验研究。③影响肌球蛋白重链表达的运动因素和其他因素。排除标准:重复或类似的同一研究、个案报道、偏重于临床医学的研究。资料提炼:共检索到132篇关于运动与肌球蛋白的文献,最终纳入33篇符合标准的文献。资料综合:①肌球蛋白是各类肌细胞中含量最多的结构蛋白和收缩蛋白,是构成肌肉肌原纤维粗丝的基本组成蛋白,是横纹肌细胞表达最丰富的蛋白,肌球蛋白不仅是骨骼肌重要的结构蛋白和收缩蛋白,而且还有ATP酶活性,故通常也称之为肌球蛋白ATP酶。肌肉收缩的直接能量来源是肌球蛋白对ATP的水解。肌球蛋白由两条Mr约为220000的重链和两条Mr为16000～27000的轻链组成。在哺乳动物的横纹肌中,至少有9种肌球蛋白重链的异形体被发现(包括心肌和骨骼肌里的)。②不同运动模式和运动负荷可导致肌纤维类型发生不同转变,一般认为,耐力性训练可观察到Ⅱb型向Ⅱa型转变,但是由Ⅱa型转变为Ⅰ型是非常困难的,目前许多研究证实,耐力训练、阻力训练和速度训练后Ⅱ型肌纤维的Ⅱb向Ⅱa转化,而在停止训练或肌肉废用后,Ⅱ型肌纤维出现相反的变化,即Ⅱa向Ⅱb转变。③除运动训练外,减少神经-肌肉的活动如太空飞行、后肢悬吊、制动、脊髓横切或脊髓损伤和增加神经-肌肉的活动(如电刺激)等以及一些激素如甲状腺素的变化也能引起肌纤维肌球蛋白重链异形体表达的变化。结论:不同运动模式和运动负荷可导致肌纤维类型发生不同转变;其他因素也能引起肌纤维肌球蛋白重链异形体表达的变化。

OBJECTIVE： In terms of pnmary structure, secondary structure and molecular biology of myosin, this paper is designed to review the influence of exercise on the structure and function of myosin, as well the expression of myosin heavy chain （MHC）. DATA SOURCES： A computer-based online search of Pubmed database was undertaken to identify the articles related to the exercise and myosin published from June 1999 to June 2006 with the key words ＂myosin, myosin heavy chain, myosin light chain, aerobic exercise＂, and language was limited to English. Meanwhile, the related Chinese articles were retrieved in CNKI China Journal Full-text Database between June 1999 and June 2006, with the key words ＂myosin, myosin heavy chain, myosin light chain, exercise＂. STUDY SELECTION： All the data were checked primarily to search for the articles of exercise and myosin and look up for full-texts. Inclusive criteria： ①structure research and clinical study of myosin. ②experiments on the relationship between exercise and myosin.③exercise factor and other factors affecting MHC expression. Exclusive criteria： repetitive or similar investigations for the same study, case report and clinical medicine. DATA EXTRACTION： A total of 132 articles related to the exercise and myosin were screened out, and 33 of them met the criteda were included. DATA SYNTHESIS： ①Myosin is one kind of structural protein and spectrin which present the most content among various muscle cells, one basic protein of constituting myoflbril thick filament, and one protein that expresses the most stnated muscle cell. Myosin is crucial for skeletal muscle, moreover it is named myosin ATPase due to ATP activity. The ATP hydrolysis of myosin may result in the muscle contraction directly. Myosin includes two MHCs in which Mr is about 220 000 and two myosin light chains in which Mr was 16 000-27 000. There are over 9 isoforms found in striated muscle of mammals （myocardium and skeletal muscle）.②The different exercise patterns and exercise loadings may induce the different types of muscle fiber. Generally Ⅱb type muscle fiber transforms to Ⅱ a type fiber by endurance exercise, but it is extremely formidable for the transformation from Ⅱ a type to Ⅰ type. Many present researches confirm that, endurance exercise, resistance exercise and velocity exercise can conduce to the transformation from Ⅱ b to Ⅱ a, however, the exercise or muscle disuse may arise the contrary variation, that is the transformation from Ⅱ a to Ⅱ b.③ Except exercise, the cause of the varied expression of MHC isoform includes the activities of reducing nerve-muscle （such as space flight, hindlimb suspend, braking, spinal cord transection or spinal cord injury）, the activities of increasing nerve-muscle （such as electric stimulation）, and some hormones （such as thyroxin）. CONCLUSION： Muscle fiber type differs from the exercise pattern and exercise loading; the variation of MHC expression may result from other factors.