Alpha-catenin can form asymmetric homodimeric complexes and/or heterodimeric complexes with beta-catenin

J Biol Chem. 1997 Oct 24;272(43):27301-6. doi: 10.1074/jbc.272.43.27301.

Abstract

The cadherin-based transmembrane cell-cell adhesive complex is thought to be composed of a cadherin molecule, a beta-catenin, and an alpha-catenin, which connects the complex to the cytoskeleton. The precise stoichiometry of this complex remains uncertain. We have used a series of recombinant molecules and biophysical techniques to assess the multimeric state of human alpha- and beta-catenin in vitro and then visualized them by electron microscopy after rotary shadowing. Calculated solution molecular masses are 213 kDa for alpha-catenin, 73 kDa for beta-catenin, and 186 kDa for both. This suggests that alpha-catenin exists as a homodimer in solution, beta-catenin is a monomer, and when both are present, they form alpha/beta-catenin heterodimers. Co-precipitation and surface plasmon resonance assays localize the site of alpha-catenin dimerization to the NH2-terminal 228 amino acids. This region encompasses a high-affinity (Kd = 100 nM) binding site for beta-catenin that lies between residues 54 and 157. We anticipate that the oligomeric state of alpha-catenin and the relative stoichiometry of the components in the membrane adhesion complex will be dynamic and regulated by beta-catenin, cell adhesion, and probably other factors as well.

Publication types

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

MeSH terms

  • Binding Sites
  • Cadherins / chemistry
  • Cadherins / metabolism
  • Chromatography, Affinity
  • Cytoskeletal Proteins / chemistry*
  • Cytoskeletal Proteins / isolation & purification
  • Cytoskeletal Proteins / metabolism*
  • Dimerization
  • Glutathione Transferase
  • Humans
  • Kinetics
  • Macromolecular Substances
  • Molecular Weight
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / isolation & purification
  • Recombinant Fusion Proteins / metabolism
  • Regression Analysis
  • Trans-Activators*
  • alpha Catenin
  • beta Catenin

Substances

  • CTNNA1 protein, human
  • CTNNB1 protein, human
  • Cadherins
  • Cytoskeletal Proteins
  • Macromolecular Substances
  • Recombinant Fusion Proteins
  • Trans-Activators
  • alpha Catenin
  • beta Catenin
  • Glutathione Transferase