Myosin regulatory subunit that plays an essential to maintain muscle integrity during early development (By similarity). Plays a role in muscle contraction (PubMed:15256600). Myosin is a hexamer of 2 heavy chains and 4 light chains. The N-terminus is blocked. N,N,N-trimethylalanine, found in other myosin light chains would not have been detected in the N-terminal tryptic peptide in PubMed:7358336 because it would remain trimethylated and ninhydrin negative after hydrolysis. This chain binds calcium.