Protein phosphatase 1 regulatory subunit 12A (UniProt: Q90623; also known as 130 kDa myosin-binding subunit of smooth muscle myosin phosphatase, Myosin phosphatase-targeting subunit 1, Myosin phosphatase target subunit 1, PP1M subunit M110, Protein phosphatase myosin-binding subunit, MYPT1) is encoded by the PPP1R12A (also known as MBS, MYPT1) gene (Gene ID: 396020) in human. MYPT1 is one of the subunits and an integral component of the Myosin phosphatase. It is detected in brain, lung, aorta, heart, gizzard, stomach, oviduct, spleen, kidney, and small intestine. MYPT1 is localized on stress fibers, and is distributed close to the cell membrane and at cell-cell contacts to regulate Myosin phosphatase activity. It is phosphorylated by Rho-associated kinases on serine and threonine residues. Phosphorylation at Threonine 695 is shown to inhibit myosin phosphatase activity and phosphorylation at Threonine 850 is reported to abolish myosin binding. Two isoforms of MYPT1 have been reported that are produced by alternative splicing.
