Myosin polymorphism in muscles of the toadfish, Opsanus tau.

The superfast swimbladder muscle of Opsanus tau differs from the corresponding fast skeletal muscle not only by its greater sarcoplasmic reticulum and parvalbumin content but also by a genuine myosin LC2. The study of light chains has been extended here to other striated muscles. Myosins from fast (trunk muscle), superfast (swimbladder muscle), slow (lateral-line muscle) and cardiac (ventricle muscle) were compared, using one- and two-dimensional polyacrylamide gel electrophoresis. The results showed that the light chains all appear distinct in isoelectric point and molecular weight, except for the two LC1 and two LC3 from fast and superfast muscles. Striated muscles from the toadfish Opsanus tau exhibited at least four isoenzymic forms of the myosin, related to the light chains and corresponding to different physiological properties.