Enhancement of smooth muscle contraction with protein phosphatase inhibitor 1: activation of inhibitor 1 by cGMP-dependent protein kinase

Biochem Biophys Res Commun. 1996 Mar 27;220(3):777-83. doi: 10.1006/bbrc.1996.0480.

Abstract

New method for purification of phosphatase inhibitor 1 (PPI-1) was developed which avoid the phosphorylation of PPI-1 during the purification and provides a high yield of highly pure preparation. Using this preparation, it was shown that PPI-1 was stoichiometrically phosphorylated by cGMP-dependent protein kinase at Thr-35 and the phosphorylated PPI-1 potently inhibited protein phosphatase 1. Addition of the phosphorylated PPI-1 to beta-escin-skinned single smooth muscle cells resulted in force development of the cells at the submaximal pCa2+. The results suggest that the phosphorylation of PPI-1 can be the mechanism for modifying the Ca2+ sensitivity of smooth muscle contractile response.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Carrier Proteins*
  • Chromatography, Ion Exchange
  • Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
  • Cyclic GMP-Dependent Protein Kinases / metabolism*
  • Enzyme Inhibitors / metabolism
  • Enzyme Inhibitors / pharmacology*
  • Gizzard, Avian
  • Intracellular Signaling Peptides and Proteins*
  • Kinetics
  • Molecular Sequence Data
  • Muscle Contraction / drug effects*
  • Muscle, Skeletal / chemistry
  • Muscle, Skeletal / physiology
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / enzymology
  • Muscle, Smooth, Vascular / physiology*
  • Myosin-Light-Chain Kinase / metabolism
  • Peptide Fragments / chemistry
  • Peptide Fragments / isolation & purification
  • Peptides / pharmacology
  • Phosphopeptides / chemistry
  • Phosphopeptides / isolation & purification
  • Phosphorylation
  • Portal Vein
  • Proteins / isolation & purification
  • Proteins / metabolism
  • Proteins / pharmacology*
  • Rabbits
  • Turkeys

Substances

  • Carrier Proteins
  • Enzyme Inhibitors
  • Intracellular Signaling Peptides and Proteins
  • Peptide Fragments
  • Peptides
  • Phosphopeptides
  • Proteins
  • protein phosphatase inhibitor-1
  • Cyclic AMP-Dependent Protein Kinases
  • Cyclic GMP-Dependent Protein Kinases
  • Myosin-Light-Chain Kinase