The major protein phosphatase-1 (PP1) is composed of 3 subunits with apparent molecular mass of 110-130, 37 & 20 kDa. The 110-130 kDa component act as a regulatory subunit known as myosine binding (MBS) or myosine phosphatae targeting subunit (MYPT). The N-terminal portion of MYPT binds to both PP1c-delta and phosphorylated myosin, thereby increasing myosin phosphatase activity. Two isoform of MYPT have been identified (MYPT1 & MYPT2) and share 61% sequence identity. While MYPT1 is widely distributed in human tissues, MYPT2 is mostly detected in brain and heart.
