The murine atrial myosin light chain-2 gene: a member of an evolutionarily conserved family of contractile proteins.

Recently the near complete cDNA of the regulatory atrial myosin light chain (MLC-2a) was cloned. The atrial specific isoform has been shown to be a useful molecular marker for cardiac chamber specification. Therefore, the regulatory sequence of the gene will provide clues on cardiomyocyte differentiation and atrial specific transcription regulation. Here we report the identification of the murine genomic sequence of the MLC-2a gene (Mylc2a). The entire 5' flanking region was identified and sequenced. In addition, the exon-intron boundaries and 3' flanking region were determined. Sequence comparison revealed the presence of the final exon (11) of the mouse glucokinase gene on chromosome 11, 2.0 kb upstream of the Mylc2a transcription start site. In addition, we compared the structure of the gene to other myosin light chains to show evolutionary conservation. The intron-exon boundaries turned out to be highly conserved and an increasing intron size in more complex mammalian species was found. At the amino acid level there is 95% homology between the human and mouse MLC-2a sequence.