Identification of the Axin and Frat binding region of glycogen synthase kinase-3

J Biol Chem. 2002 Jan 18;277(3):2176-85. doi: 10.1074/jbc.M109462200. Epub 2001 Nov 13.

Abstract

Glycogen synthase kinase-3 (GSK-3) is a key component of several signaling pathways including those regulated by Wnt and insulin ligands. Specificity in GSK-3 signaling is thought to involve interactions with scaffold proteins that localize GSK-3 regulators and substrates. This report shows that GSK-3 forms a low affinity homodimer that is disrupted by binding to Axin and Frat. Based on the crystal structure of GSK-3, we have used surface-scanning mutagenesis to identify residues that differentially affect GSK-3 interactions. Mutations that disrupt Frat and Axin cluster at the dimer interface explaining their effect on homodimer formation. Loss of the Axin binding site blocks the ability of dominant negative GSK-3 to cause axis duplication in Xenopus embryos. The Axin binding site is conserved within all GSK-3 proteins, and its loss affects both cell motility and gene expression in the nonmetazoan, Dictyostelium. Surprisingly, we find no genetic interaction between a non-Axin-binding GSK-3 mutant and T-cell factor activity, arguing that Axin interactions alone cannot explain the regulation of T-cell factor-mediated gene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Amino Acid Substitution
  • Animals
  • Axin Protein
  • Binding Sites
  • Calcium-Calmodulin-Dependent Protein Kinases / chemistry
  • Calcium-Calmodulin-Dependent Protein Kinases / genetics
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Carrier Proteins*
  • Cell Line
  • Crystallography, X-Ray
  • Glycogen Synthase Kinase 3
  • Glycogen Synthase Kinases
  • Humans
  • Immunohistochemistry
  • Intracellular Signaling Peptides and Proteins
  • Models, Molecular
  • Mutagenesis
  • Neoplasm Proteins*
  • Protein Conformation
  • Proteins / metabolism*
  • Proto-Oncogene Proteins / metabolism*
  • Repressor Proteins*
  • Xenopus
  • Xenopus Proteins*

Substances

  • Adaptor Proteins, Signal Transducing
  • Axin Protein
  • Carrier Proteins
  • FRAT1 protein, human
  • Intracellular Signaling Peptides and Proteins
  • Neoplasm Proteins
  • PIAS1 protein, Xenopus
  • Proteins
  • Proto-Oncogene Proteins
  • Repressor Proteins
  • Xenopus Proteins
  • axin1 protein, Xenopus
  • Glycogen Synthase Kinases
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Glycogen Synthase Kinase 3