Molecular cloning, characterisation and mRNA expression analysis of the sheep myosin light chain 1 gene

• We cloned the full-length cDNA of sheep MYL1 gene firstly.
• Sheep MYL1 gene has two alternative splicing isoforms.
• The main secondary structure of MYL1 protein was predicted to be α-helical.
• The sheep MYL1 protein was highly similar to other mammals.
• MYL1 gene was highly expressed in sheep longissimus dorsi.

The complete cDNA sequence of the sheep MYL1 (Myosin light chain 1) gene was cloned using RT-PCR, 5′ RACE and 3′ RACE. We obtained two alternatively spliced isoforms of the MYL1 gene, MYL1a and MYL1b, which are 849 and 1046 bp in length and encode proteins composed of 150 and 192 amino acid residues, respectively. And the GenBank accession numbers of MYL1a and MYL1b full-length cDNA sequences that we cloned are KJ700419 and KJ710701, respectively. Neither protein was predicted to have a signal peptide, but both were predicted to have several N-glycosylation and phosphorylation sites. More than half of the secondary structure of these proteins was predicted to be α-helical. The human MYL2 protein (1m8q.1.C) is the most similar in tertiary structure. Sequence alignment showed that the sheep MYL1a protein shares more than 92% amino acid sequence similar with Mus musculus, Homo sapiens, Rattus norvegicus, Sus scrofa and Gallus gallus and that the MYL1b protein shares more than 93% amino acid sequence similar with M. musculus, H. sapiens, R. norvegicus, Bos taurus and Oryctolagus cuniculus. Transcription profile analyses of various tissues indicated that the sheep MYL1a and MYL1b mRNAs were highly but differentially expressed in the longissimus dorsi. Moreover, the expression levels of these genes in the longissimus dorsi differed between Dorper and Small-tailed Han sheep. These results serve as a foundation for further investigations of the function of the sheep MYL1 gene.