Primary structure of myosin heavy chain from fast skeletal muscle of Chum salmon Oncorhynchus keta

Abstract

The nucleotide sequence of the cDNA encoding myosin heavy chain of chum salmon Oncorhynchus keta fast skeletal muscle was determined. The sequence consists of 5994 bp, including 5814 bp of translated region deducing an amino acid sequence of 1937 residues. The deduced sequence showed 79% homology to that of rabbit fast skeletal myosin and 84–87% homology to those of fast skeletal myosins from walleye pollack, white croaker and carp. The putative binding-sites for ATP, actin and regulatory light-chains in the subfragment-1 region of the salmon myosin showed high homology with the fish myosins (78–100% homology). However, the Loop-1 and Loop-2 showed considerably low homology (31–60%). On the other hand, the deduced sequences of subfragment-2 (533 residues) and light meromyosin (564 residues) showed 88–93% homology to the corresponding regions of the fish myosins. It becomes obvious that several specific residues of the rabbit LMM are substituted to Gly in the salmon LMM as well as the other fish LMMs. This may be involved in the structural instability of the fish myosin tail region.