Non-regulatory myosin light chain required for proper formation and/or maintenance of myofibers, and thus appropriate muscle function. Myosin is a hexamer of 2 heavy chains and 4 light chains. Does not bind calcium. Expressed in fast muscle fibers during skeletal muscle differentiation. Morphant embryos have curved bodies, bent tails and a marked reduction in touch-evoked escape response. Muscle structure is altered and myofibers are sparse and disordered.