MYL2(myosin, light chain 2, regulatory, cardiac, slow), also known as MLC-2, MLC2v. Entrez protein NP_000423. MYL2 associated with cardiac myosin beta (or slow) heavy chain. Ca+ triggers the phosphorylation of regulatory light chain that in turn triggers contraction. It is an hexamer of two heavy chains and four light chains that is predominantly expressed in adult cardiac ventricle muscle. Mutations in MYL2 are associated with mid-left ventricular chamber type hypertrophic cardiomyopathy.