CLONING AND CHARACTERIZATION OF THE GENE ENCODING RABBIT CARDIAC CALSEQUESTRIN

A cDNA encoding rabbit cardiac calsequestrin was isolated and characterized. The deduced nascent cardiac calsequestrin contains 409 amino acids of which 26% are acidic residues, and had 93% and 67% aa identity with canine cardiac calsequestrin and rabbit fast-twitch skeletal muscle calsequestrin, respectively. RNA blot analyses indicate that this mRNA is expressed in atrium, ventricle and to a lesser amount in slow-twitch skeletal muscle. This mRNA transcript is not expressed in adult fast-twitch skeletal muscle, smooth muscle, or nonmuscle tissues. Analysis of in vitro skeletal muscle myogenesis using a mouse myoblast cell line C2C12, demonstrates that both cardiac and skeletal calsequestrin isoforms are coproduced during muscle differentiation.