Muscle contraction. 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). Identified by mass spectrometry in melanosome fractions from stage I to stage IV. Thick filaments of the myofibrils. Smooth muscle; expressed in the umbilical artery, bladder, esophagus and trachea. Isoform 1 is mostly found in slowly contracting tonic muscles. 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. 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). A chromosomal aberration involving MYH11 is found in acute myeloid leukemia of M4EO subtype. Pericentric inversion inv(16)(p13;q22). The inversion produces a fusion protein consisting of the 165 N-terminal residues of CBF-beta (PEPB2) and the tail region of MYH11. 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. This isoform with a 7 AA insert in the head domain is predominantly expressed in rapidly contracting phasic muscles. This isoform with a 7 AA insert in the head domain is predominantly expressed in rapidly contracting phasic muscles. Belongs to the TRAFAC class myosin-kinesin ATPase superfamily. Myosin family.