Myosin isoenzymes as molecular markers for muscle physiology.

Myosin is a major component of skeletal muscle and it plays a central role in determining the physiological performance of adult tissue. Developing muscles contain myosin molecules which are different from the adult forms, and these isoenzymes have been found to be characteristic markers of the diverse physiological and pathological states of muscle tissue. The differences between these isoenzymes may be demonstrated by protein chemical, immunochemical and genetic evidence. The study of the sequential transitions between isoenzymes represents a means for characterizing the dynamic nature of muscle development, and neuronal and hormonal influences have been identified which contribute to the regulation of these transitions. The perspectives for future work include genetic studies, elucidation of the pathways relating extracellular signals to changes in gene expression, and the possibility that studies of myosin isoenzymes might further understanding of muscle pathology.