Comparison of adult, embryonic, and dystrophic myosin heavy chains from chicken muscle by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and peptide mapping.

Abstract

Chicken myosin heavy chains from adult fast white muscle fibers (both normal and dystrophic), adult slow red fibers, and embryonic presumptive fast white fibers were compared by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and by peptide mapping. The heavy chain of slow red myosin migrated electrophoretically more slowly than the heavy chains of the other myosins and differed markedly from them in its peptide maps. The heavy chain of dystrophic fast white myosin was similar to its normal counterpart by peptide mapping but showed slight differences. The peptide map of the heavy chain of embryonic presumptive fast white myosin had the general features of that of the heavy chain of fast white, not slow red, fibers but contained definite differences from the former. The results are consistent with the existence of a separate gene for the heavy chain of embryonic presumptive fast white myosin.

Immunofluorescence analysis of the primordial myosin detectable in embryonic striated muscle.

“…These results could also be consistent with the expression of a distinct embryonic isomyosin (1)(2)(3)(4)(5)(6)(7)(8), because our anti-skeletal antibodies cross-react with embryonic as well as adult skeletal myosins. However, our results indicate that these patterns of myosin expression do not apply to the initial developmental program for the myotome.…”

“…However, there has been considerable controversy as to the nature of both the heavy-chain and light-chain subunit composition of the myosin isozymes expressed in embryonic muscle. With respect to heavy-chain composition, there are several lines of evidence to suggest that skeletal muscle development is characterized by the expression of a distinct embryonic isomyosin (1)(2)(3)(4)(5)(6)(7)(8). Other evidence has suggested that the developmental program for embryonic skeletal muscle involves either the expression of fast skeletal myosin initially (10), the coexpression offast and slow skeletal isomyosins (7,9), or the expression of cardiac as well as skeletal isomyosins (11,17,18).…”

“…There is abundant evidence that myosin expression undergoes transitions during the development of both skeletal (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) and cardiac muscle (1,(12)(13)(14)(15)(16) in a number of species. However, there has been considerable controversy as to the nature of both the heavy-chain and light-chain subunit composition of the myosin isozymes expressed in embryonic muscle.…”

Molecular cloning of mRNA sequences for cardiac alpha- and beta-form myosin heavy chains: expression in ventricles of normal, hypothyroid, and thyrotoxic rabbits.

“…This enzymatic activity is correlated with contractile velocity in skeletal muscle (1) and thus appears to be an important determinant of contractile function. Numerous polymorphic forms of myosin HC exist, not only in different types of muscle-e.g., fast and slow skeletal and cardiac-but also within each muscle type (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Expression of these forms follows a developmental pattern (12)(13)(14)(15)(16)(17)(18) that may be altered by changes in the physiological (19)(20)(21) and hormonal (10)(11)(12)(13) milieu ofthe cell.…”

“…The specific activity ofthe probe was 1-5 X 10r' cpm/yg. Hybridization and nuclease S1 digestion were carried.out by the method of Orkin and Goff (38), except that the probe (0.5-1 X 105 cpm, 10-50 ng) was hybridized in a sealed capillary tube with either 5 ,ug of cardiac poly(A)+RNA or 30-50 pg of cardiac total RNA. The digested products were analyzed on 5% sequencing gels (33,38).…”