Izant J G, Lazarides E
Proc Natl Acad Sci U S A. 1977 Apr;74(4):1450-4. doi: 10.1073/pnas.74.4.1450.
A two-dimensional gel electrophoresis system is used to investigate some of the properties of desmin, the major subunit of the 100-A filaments from chick muscle cells, and to compare these properties to those of the other major contractile and regulatory proteins of muscle. Desmin from embryonic and adult smooth, skeletal, and cardiac muscle cells is resolved into two isoelectric variants, alpha and beta, which possess slightly different electrophoretic mobilities in sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Both the alpha and the beta variants from all six preparations appear to be identical in isoelectric point and apparent molecular weight. The alpha and beta desmin are present in approximately equal amounts in all three types of muscle, suggesting that both isoelectric variants of desmin serve as the structural subunits of the 100-A filaments in chick muscle cells. Tropomyosin also can be resolved into two subunits, alpha and beta, in all three types of muscle. However, in each type of muscle both subunits differ from their counterparts in the other types of muscle, either by molecular weight or by isoelectric point. These results indicate that, with regard to apparent isoelectric point and molecular weight, desmin, a major muscle structural protein, is invariant, while tropomyosin, a major muscle regulatory protein, exhibits heterogeneity in the three types of muscle.
二维凝胶电泳系统用于研究结蛋白（鸡肌肉细胞中100埃细丝的主要亚基）的一些特性，并将这些特性与肌肉的其他主要收缩和调节蛋白的特性进行比较。来自胚胎和成年平滑肌、骨骼肌和心肌细胞的结蛋白可分离为两种等电变体，α和β，它们在十二烷基硫酸钠/聚丙烯酰胺凝胶电泳中具有略有不同的电泳迁移率。所有六种制剂中的α和β变体在等电点和表观分子量上似乎都是相同的。α和β结蛋白在所有三种类型的肌肉中含量大致相等，这表明结蛋白的两种等电变体均作为鸡肌肉细胞中100埃细丝的结构亚基。原肌球蛋白在所有三种类型的肌肉中也可分离为两个亚基，α和β。然而，在每种类型的肌肉中，这两个亚基在分子量或等电点方面均与其在其他类型肌肉中的对应物不同。这些结果表明，就表观等电点和分子量而言，作为主要肌肉结构蛋白的结蛋白是不变的，而作为主要肌肉调节蛋白的原肌球蛋白在三种类型的肌肉中表现出异质性。
