Myosin heavy chain isoforms expressed in bovine skeletal muscles

Nucleotide sequences including the full coding region for three types of myosin heavy chain (MyHC) isoforms were determined from bovine adult skeletal muscles. The deduced amino acid sequences were 1940, 1938, and 1935 residues for the MyHC-2a, -2x, and -slow, respectively. Like other mammalian MyHC isoforms, the bovine MyHC isoforms had homologous sequences except for substitutions concentrated on the loop 1, loop 2, and light chain binding regions. RT-PCR amplifications showed that the adult bovine skeletal muscles expressed the MyHC-2a, -2x, and -slow isoforms but no -2b isoform. The absence of the MyHC-2b isoform and substitutions on the loop2 region could explain some differences in meat quality between beef and pork.