Myosins are actin-based motor molecules with ATPase activity essential for muscle contraction. Forms regular bipolar thick filaments that, together with actin thin filaments, constitute the fundamental contractile unit of skeletal and cardiac muscle. Muscle myosin is a hexameric protein that consists of 2 heavy chain subunits (MHC), 2 alkali light chain subunits (MLC) and 2 regulatory light chain subunits (MLC-2). Interacts with ECPAS (PubMed:20682791). Interacts (via C-terminus) with LRRC39 (PubMed:20847312). Thick filaments of the myofibrils. Both wild type and variant Gln-403 are detected in skeletal muscle (at protein level). The rodlike tail sequence is highly repetitive, showing cycles of a 28-residue repeat pattern composed of 4 heptapeptides, characteristic for alpha-helical coiled coils (PubMed:26150528, PubMed:26573747). Four skip residues (Skip1: Thr-1188, Skip2: Glu-1385, Skip3: Glu-1582 and Skip4: Gly-1807) introduce discontinuities in the coiled-coil heptad repeats. The first three skip residues are structurally comparable and induce a unique local relaxation of the coiled-coil superhelical pitch and the fourth skip residue lies within a highly flexible molecular hinge that is necessary for myosin incorporation in the bare zone of sarcomeres (PubMed:26150528). Limited proteolysis of myosin heavy chain produces 1 light meromyosin (LMM) and 1 heavy meromyosin (HMM). HMM can be further cleaved into 2 globular subfragments (S1) and 1 rod-shaped subfragment (S2). The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting distinct genetic loci, including the gene represented in this entry. The cardiac alpha isoform is a 'fast' ATPase myosin, while the beta isoform is a 'slow' ATPase. Belongs to the TRAFAC class myosin-kinesin ATPase superfamily. Myosin family. Represents a conventional myosin. This protein should not be confused with the unconventional myosin-7 (MYO7).