Invariance and heterogeneity in the major structural and regulatory proteins of chick muscle cells revealed by two-dimensional gel electrophoresis.

Abstract

A-2 dimensional gel electrophoresis system was used to investigate some of the properties of desmin, the major subunit of the 100 .ANG. 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 was resolved into 2 isoelectric variants, .alpha. and .beta., which possessed slightly different electrophoretic mobilities in sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Both the .alpha. and .beta. variants from all 6 preparations appeared identical in isoelectric variants of desmin served as the structural subunits of the 100 .ANG. filaments in chick muscle cells. Tropomyosin was also resolved into 2 subunits, .alpha. and .beta., in all 3 types of muscle. In each type of muscle both subunits differed from their counterparts in the other types of muscle, either by MW or by isoelectric point [pI]. With regard to apparent pI and MW, desmin, a major muscle regulatory protein, exhibited heterogeneity in the 3 types of muscle.