Molecular cloning and mRNA expression analysis of sheep MYL3 and MYL4 genes

Using longissimus dorsi muscles of Dorper sheep as the experimental materials, the complete cDNAs of ovine MYL3 (Myosin light chain 3) and MYL4 (Myosin light chain 4) genes were cloned using RT-PCR, 5' RACE and 3' RACE. We obtained 925-bp and 869-bp full-length cDNAs and submitted their sequences to GenBank as accession numbers of KJ710703 and KJ768855, respectively. The cDNAs contained 600-bp and 582-bp open reading frames (ORFs) and encoded proteins comprising 199 and 193 amino acid residues, respectively. Neither protein was predicted to have a signal peptide, but both were predicted to have several N-glycosylation, O-glycosylation, and phosphorylation sites. The secondary structures of MYL3 and MYL4 were predicted to be 40.70% and 48.70% α- helical, respectively. Sequence alignment showed that the MYL3 and MYL4 proteins of Ovis aries both shared more than 91% amino acid sequence similarity with those of Mus musculus, Homo sapiens, Rattus norvegicus, Bos taurus, and Sus scrofa. The levels of MYL3 and MYL4 mRNA in various sheep tissues were determined using qRT-PCR. The results showed that both mRNAs were highly expressed in the heart. This study has established a foundation for further investigation of the ovine MYL3 and MYL4 genes.