Inactivation of glycogen synthase kinase-3 beta by phosphorylation: new kinase connections in insulin and growth-factor signalling

Biochem J. 1993 Nov 15;296 ( Pt 1)(Pt 1):15-9. doi: 10.1042/bj2960015.

Abstract

The beta-isoform of glycogen synthase kinase-3 (GSK3 beta) isolated from rabbit skeletal muscle was inactivated 90-95% following incubation with MgATP and either MAP kinase-activated protein kinase-1 (MAPKAP kinase-1, also termed RSK-2) or p70 S6 kinase (p70S6K), and re-activated with protein phosphatase 2A. MAPKAP kinase-1 and p70S6K phosphorylated the same tryptic peptide on GSK3 beta, and the site of phosphorylation was identified as the serine located nine residues from the N-terminus of the protein. The inhibitory effect of Ser-9 phosphorylation on GSK3 beta activity was observed with three substrates, (inhibitor-2, c-jun and a synthetic peptide), and also with glycogen synthase provided that 0.15 M KCl was added to the assays. The results suggest that Ser-9 phosphorylation underlies the reported inhibition of GSK3 beta by insulin and that GSK3 may represent a point of convergence of two major growth-factor-stimulated protein kinase cascades.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / pharmacology
  • Amino Acid Sequence
  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
  • Calcium-Calmodulin-Dependent Protein Kinases / isolation & purification
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Chromatography, Ion Exchange
  • Enzyme Activation
  • Glycogen Synthase Kinases
  • Insulin / pharmacology*
  • Kinetics
  • Molecular Sequence Data
  • Molecular Weight
  • Muscles / enzymology
  • Peptide Fragments / isolation & purification
  • Peptides / chemical synthesis
  • Phosphopeptides / isolation & purification
  • Phosphoprotein Phosphatases / metabolism*
  • Phosphorylation
  • Protein Phosphatase 2
  • Protein Serine-Threonine Kinases / metabolism
  • Rabbits
  • Ribosomal Protein S6 Kinases, 90-kDa
  • Signal Transduction*

Substances

  • Insulin
  • Peptide Fragments
  • Peptides
  • Phosphopeptides
  • Adenosine Triphosphate
  • Glycogen Synthase Kinases
  • Protein Serine-Threonine Kinases
  • Ribosomal Protein S6 Kinases, 90-kDa
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Phosphoprotein Phosphatases
  • Protein Phosphatase 2