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Published April 1, 1977 | public
Journal Article Open

Invariance and Heterogeneity in the Major Structural and Regulatory Proteins of Chick Muscle Cells Revealed by Two-Dimensional gel Electrophoresis


A two-dimensional gel electrophoresis system is used to investigate some of the properties of desmin, the major subunit of the 100- angstrom 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 ß , which possess slightly different electrophoretic mobilities in sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Both the alpha and the ß variants from all six preparations appear to be identical in isoelectric point and apparent molecular weight. The alpha and ß 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- angstrom filaments in chick muscle cells. Tropomyosin also can be resolved into two subunits, alpha and ß , 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.

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Copyright © 1977 by the National Academy of Sciences Communicated by William B. Wood, January 17, 1977 We are grateful to Dr. J. R. McIntosh for the use of his laboratory facilities during this work. We also thank Drs. J. R. McIntosh, W. B. Wood, D. I. Hirsh, and L. E. Hood for their valuable comments on the manuscript. This work was supported by Grant no. NSFBMS-75-03939 from the National Science Foundation to Dr. J. R. McIntosh and by Grant no. GM06965 from the National Institutes of Health to E.L. E.L. was supported also by a postdoctoral fellowship from the Muscular Dystrophy Association of America.


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