Myosin light-chain phosphatase

EC number CAS number IntEnz BRENDA ExPASy KEGG MetaCyc metabolic pathway
PRIAM PDB structures PDBsum
Gene Ontology EGO

In chemical reaction

[myosin light-chain] phosphate + H2O \rightleftharpoons [myosin light-chain] + phosphate

Thus, the two substrates of this enzyme are myosin light-chain phosphate and H2O, whereas its two products are myosin light-chain and phosphate.

This enzyme belongs to the family of hydrolases, specifically those acting on phosphoric monoester bonds. The systematic name of this enzyme class is [myosin-light-chain]-phosphate phosphohydrolase. Other names in common use include myosin light chain kinase phosphatase, myosin phosphatase, myosin phosphatase, protein phosphatase 2A, and myosin-light-chain-phosphatase.

Structural studies

MLCP is composed of three subunits: a PP1c catalytic subunit, a myosin targeting subunit called MYPT1, and a small subunit of unknown function called M20.

As of late 2007, only one 1S70.


MLCP is important for regulating contraction in smooth muscle, which lacks the troponin binding system. It inhibits contraction by dephosphorylating myosin light-chain fibers. It counters the myosin light-chain kinase (MLCK), which promotes contraction by phosphorylating myosin light-chain proteins. MLCP is present in smaller amounts compared with MLCK, but compensates for this lack of mass by rapid movement along actin fibers. MLCP activity is inhibited by Rhoa and Rho kinase, components of the Ca2+ independent pathway for maintaining muscle contraction.[1] This can result in Ca2+ sensitization.

See also


Further reading

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