Alkali myosin light chains in man are encoded by a multigene family that includes the adult skeletal muscle, the embryonic or atrial, and nonsarcomeric isoforms

A set of cDNA clones coding for alkali myosin light chains (AMLC) was isolated from fetal human skeletal muscle. Nucleotide sequence analysis and RNA expression patterns of individual clones revealed related sequences corresponding to (i) fast fiber type MLC ! and MLC 3 ; (ii) the embryonic MLC that is also expressed in fetal ventricle and adult atrium (MLC emb); and (iii) a nonsarcomeric MLC isoform that is found in all nonmuscle cell types and smooth muscle. The AMLC gene family in man comprises unique copies for MLC 1, MLC 3 and MLC emb, and multiple copies for the nonsarcomeric MLC genes. The gene coding for MLC 1 and MLC 3 is located on human chromosome 2.