Sequence conservation among fish myostatin orthologues and the characterization of two additional cDNA clones from Morone saxatilis and Morone americana

Myostatin (MSTN) negatively regulates mammalian skeletal muscle growth and development by inhibiting myoblast proliferation. Mice and cattle possessing mutant MSTN alleles display a 'double muscling' phenotype characterized by extreme skeletal muscle hypertrophy and/or hyperplasia. MSTN orthologues have been previously characterized in 12 vertebrate species, including the white bass Morone chrysops. Presented herein is the identification and characterization of novel cDNA clones from two additional Morone species: saxatilis (striped bass) and americana (white perch), which were obtained by PCR amplification and subsequent TA-cloning. The predicted amino acid sequence of each cDNA clone contains a putative signal sequence, conserved cysteine residues and a RXXR proteolytic processing site. The different Morone proteins were 97-99% identical to each other and approximately 91, 81, 68 and 67% identical to the tilapia, zebrafish, mammalian and avian proteins, respectively. However, the bioactive domains, which lie downstream of each processing site, were considerably more conserved. They were 99-100% identical within the genus and were approximately 99, 95, 88 and 88% identical to the tilapia, zebrafish, mammalian and avian domains, respectively. This high level of sequence conservation among all known MSTN orthologues suggests that the structure/function relationship of each is equally well conserved among vertebrates.