Phosphorylation of CPI-17, an inhibitory phosphoprotein of smooth muscle myosin phosphatase, by Rho-kinase

FEBS Lett. 2000 Jun 23;475(3):197-200. doi: 10.1016/s0014-5793(00)01654-9.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Intracellular Signaling Peptides and Proteins
  • Muscle Proteins / genetics
  • Muscle Proteins / metabolism*
  • Muscle, Smooth / metabolism*
  • Myosin-Light-Chain Phosphatase
  • Phosphoprotein Phosphatases / antagonists & inhibitors*
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Point Mutation
  • Protein Serine-Threonine Kinases / metabolism*
  • rho-Associated Kinases


  • Intracellular Signaling Peptides and Proteins
  • Muscle Proteins
  • Phosphoproteins
  • Protein Serine-Threonine Kinases
  • rho-Associated Kinases
  • Phosphoprotein Phosphatases
  • Myosin-Light-Chain Phosphatase