DIVERSITY OF NATIVE MYOSIN AND MYOSIN HEAVY-CHAIN IN FISH SKELETAL-MUSCLES

1. Polymorphism of native myosin and myosin heavy chain (MHC) of fish skeletal muscles was analysed by pyrophosphate and SDS-gel electrophoreses. 2. Depending on the species, three or four myosin isoforms were detected in the white muscle, one or two isoforms in the pure red muscle, and four isomyosins were found in the red muscle composed of red and pink (intermediate) fibres. 3. It is suggested that all main types of fish muscle fibre (red, intermediate and white) differ in myosin isoform content. 4. Myosin heavy chain of the red muscle is a distinct protein from that of the white muscle. However, structural differences between these proteins vary among species.