A common phosphate binding site explains the unique substrate specificity of GSK3 and its inactivation by phosphorylation

Mol Cell. 2001 Jun;7(6):1321-7. doi: 10.1016/s1097-2765(01)00253-2.


The inhibition of GSK3 is required for the stimulation of glycogen and protein synthesis by insulin and the specification of cell fate during development. Here, we demonstrate that the insulin-induced inhibition of GSK3 and its unique substrate specificity are explained by the existence of a phosphate binding site in which Arg-96 is critical. Thus, mutation of Arg-96 abolishes the phosphorylation of "primed" glycogen synthase as well as inhibition by PKB-mediated phosphorylation of Ser-9. Hence, the phosphorylated N terminus acts as a pseudosubstrate, occupying the same phosphate binding site used by primed substrates. Significantly, this mutation does not affect phosphorylation of "nonprimed" substrates in the Wnt-signaling pathway (Axin and beta-catenin), suggesting new approaches to design more selective GSK3 inhibitors for the treatment of diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arginine / metabolism
  • Axin Protein
  • Binding Sites / physiology
  • Calcium-Calmodulin-Dependent Protein Kinases / chemistry*
  • Calcium-Calmodulin-Dependent Protein Kinases / genetics
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Cell Line
  • Cytoskeletal Proteins / metabolism
  • Diabetes Mellitus, Type 2 / metabolism
  • Glycogen Synthase Kinase 3
  • Humans
  • Leucine / genetics
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Phosphates / metabolism*
  • Phosphorylation
  • Protein Structure, Tertiary
  • Proteins / metabolism
  • Repressor Proteins*
  • Serine / metabolism
  • Substrate Specificity
  • Trans-Activators*
  • beta Catenin


  • Axin Protein
  • CTNNB1 protein, human
  • Cytoskeletal Proteins
  • Phosphates
  • Proteins
  • Repressor Proteins
  • Trans-Activators
  • beta Catenin
  • Serine
  • Arginine
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Glycogen Synthase Kinase 3
  • Leucine