The enzyme is composed of three subunits. The holoenzyme dephosphorylates myosin light chains and EC 188.8.131.52, myosin-light-chain kinase, but not myosin; the catalytic subunit acts on all three substrates.
Pato, M.D. and Adelstein, R.S. Purification and characterization of a multisubunit phosphatase from turkey gizzard smooth muscle. The effect of calmodulin binding to myosin light chain kinase on dephosphorylation. J. Biol. Chem.258 (1983) 7047–7054. [PMID: 6304072]