Phosphorylation of CPI-17 by Rho-associated kinase (Rho-kinase) and its effect on myosin phosphatase (MP) activity were investigated. CPI-17 was phosphorylated by Rho-kinase to 0.92 mol of P/mol of CPI-17 in vitro. The inhibitory phosphorylation site was Thr 38 (as reported previously) and was identified using a point mutant of CPI-17 and a phosphorylation state- specific antibody. Phosphorylation by Rho-kinase dramatically increased the inhibitory effect of CPI-17 on MP activity. Thus, CPI-17 as a substrate of Rho-kinase could be involved in the Ca 2+ sensitization of smooth muscle contraction as a downstream effector of Rho-kinase. (C) 2000 Federation of European Biochemical Societies.
Koyama, M., Ito, M., Feng, J., Seko, T., Shiraki, K., Takase, K., … Nakano, T. (2000). Phosphorylation of CPI-17, an inhibitory phosphoprotein of smooth muscle myosin phosphatase, by Rho-kinase. FEBS Letters, 475(3), 197–200. https://doi.org/10.1016/S0014-5793(00)01654-9