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 electrophor eses. 2. Depending on the species, three or four myosin isoforms were detected in the white muscle, one or two isoforms in the pure red musc le, and four isomyosins were found in the red muscle composed of red a nd pink (intermediate) fibres.3. It is suggested that all main types o f fish muscle fibre (red, intermediate and white) differ in myosin iso form content. 4. Myosin heavy chain of the red muscle is a distinct pr otein from that of the white muscle. However, structural differences b etween these proteins vary among species.