Myosin phosphatase inactivation by ROCK

Stable Identifier
Reaction [transition]
Homo sapiens
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The activity of nonmuscle myosin II (NMM2) is suppressed by dephosphorylation of myosin regulatory light chains (MRLC), MYL9 and MYL12B, by the MLC phosphatase. The MLC phosphatase is composed of a catalytic subunit (PPP1CB) and two regulatory subunits, myosin phosphatase-targeting subunit 1 (MYPT1, PPP1R12A) and M20 (MYPT2, PPP1R12B). MYPT1 binds directly to myosin II. Myosin phosphatase is inhibited by ROCKs. ROCKs phosphorylate MYPT1 subunit of the myosin phosphatase at two inhibitory sites, Thr696 and Ser852, resulting in a decrease in MRLC phosphatase activity and an increase in phosphorylated MRLC (Kimura et al. 1996, Nakai et al. 1997, Katoh et al. 2001, Iwasaki et al. 2001), which promotes binding to filamentous actin and stress fibre formation. This effect is synergistic with the direct phosphorylation of MRLC by ROCKs.

Literature References
PubMed ID Title Journal Year
8662509 Regulation of myosin phosphatase by Rho and Rho-associated kinase (Rho-kinase)

Fukata, Y, Kaibuchi, K, Ito, M, Feng, J, Nakano, T, Yamamori, B, Chihara, K, Kimura, K, Nakafuku, M, Amano, M, Okawa, K, Iwamatsu, A

Science 1996
9354661 Regulation of myosin phosphatase through phosphorylation of the myosin-binding subunit in platelet activation

Nakai, K, Suzuki, Y, Wada, H, Kaibuchi, K, Fujioka, M, Nishikawa, M, Ito, M, Kihira, H, Nakano, T, Shiku, H

Blood 1997
11942626 Diphosphorylated MRLC is required for organization of stress fibers in interphase cells and the contractile ring in dividing cells

Ishitobi, S, Iwasaki, T, Murata-Hori, M, Hosoya, H

Cell Struct. Funct. 2001
11331307 Rho-kinase--mediated contraction of isolated stress fibers

Onishi, H, Kano, Y, Kaibuchi, K, Fujiwara, K, Amano, M, Katoh, K

J. Cell Biol. 2001
Catalyst Activity

protein serine/threonine kinase activity of Activated ROCK:RhoA/B/C:GTP [plasma membrane]

Inferred From
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