Ohlendieck K, Briggs F N, Lee K F, Wechsler A W, Campbell K P
Howard Hughes Medical Institute, University of Iowa College of Medicine, Iowa City.
Eur J Biochem. 1991 Dec 18;202(3):739-47. doi: 10.1111/j.1432-1033.1991.tb16428.x.
The chronic stimulation of predominantly fast-twitch mammalian skeletal muscle causes a transformation to physiological characteristics of slow-twitch skeletal muscle. Here, we report the effects of chronic stimulation on the protein components of the sarcoplasmic reticulum and transverse tubular membranes which are directly involved in excitation-contraction coupling. Comparison of protein composition of microsomal fractions from control and chronically stimulated muscle was performed by immunoblot analysis and also by staining with Coomassie blue or the cationic carbocyanine dye Stains-all. Consistent with previous experiments, a greatly reduced density was observed for the fast-twitch isozyme of Ca(2+)-ATPase, while the expression of the slow-twitch Ca(2+)-ATPase was found to be greatly enhanced. Components of the sarcolemma (Na+/K(+)-ATPase, dystrophin-glycoprotein complex) and the free sarcoplasmic reticulum (Ca(2+)-binding protein sarcalumenin and a 53-kDa glycoprotein) were not affected by chronic stimulation. The relative abundance of calsequestrin was slightly reduced in transformed skeletal muscle. However, the expression of the ryanodine receptor/Ca(Ca2+)-release channel from junctional sarcoplasmic reticulum and the transverse tubular dihydropyridine-sensitive Ca2+ channel, as well as two junctional sarcoplasmic reticulum proteins of 90 kDa and 94 kDa, was greatly suppressed in transformed muscle. Thus, the expression of the major protein components of the triad junction involved in excitation-contraction coupling is suppressed, while the expression of other muscle membrane proteins is not affected in chronically stimulated muscle.
对主要为快肌型的哺乳动物骨骼肌进行长期刺激会使其转变为慢肌型骨骼肌的生理特征。在此，我们报告长期刺激对肌浆网和横管膜中直接参与兴奋 - 收缩偶联的蛋白质成分的影响。通过免疫印迹分析以及考马斯亮蓝或阳离子碳菁染料“全染剂”染色，对来自对照肌肉和长期刺激肌肉的微粒体部分的蛋白质组成进行了比较。与先前的实验一致，观察到钙（2 +） - ATP酶的快肌型同工酶密度大幅降低，而慢肌型钙（2 +） - ATP酶的表达则大幅增强。肌膜成分（钠/钾（+） - ATP酶、肌营养不良蛋白 - 糖蛋白复合物）和游离肌浆网（钙（2 +）结合蛋白肌钙网蛋白和一种53 kDa糖蛋白）不受长期刺激的影响。在转变后的骨骼肌中，肌集钙蛋白的相对丰度略有降低。然而，来自连接肌浆网的兰尼碱受体/钙（Ca2 +）释放通道和横管二氢吡啶敏感钙通道，以及两种90 kDa和94 kDa的连接肌浆网蛋白的表达在转变后的肌肉中受到极大抑制。因此，在长期刺激的肌肉中，参与兴奋 - 收缩偶联的三联体连接主要蛋白质成分的表达受到抑制，而其他肌膜蛋白的表达不受影响。
