Myosin, light chain 2 (MYL2) encodes the regulatory light chain associated with cardiac myosin beta heavy chain. It is an important protein involved in the regulation of myosin ATPase activity in smooth muscle and Ca+ triggers the phosphorylation of regulatory light chain that in turn triggers contraction. Mutations in MYL2 are associated with mid-left ventricular chamber type hypertrophic cardiomyopathy.