The cadherin-based transmembrane cell-cell adhesive complex is thought to be composed of a cadherin molecule, a -catenin, and an ␣-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 ␣-and -catenin in vitro and then visualized them by electron microscopy after rotary shadowing. Calculated solution molecular masses are 213 kDa for ␣-catenin, 73 kDa for -catenin, and 186 kDa for both. This suggests that ␣-catenin exists as a homodimer in solution, -catenin is a monomer, and when both are present, they form ␣/-catenin heterodimers. Co-precipitation and surface plasmon resonance assays localize the site of ␣-catenin dimerization to the NH 2 -terminal 228 amino acids. This region encompasses a high-affinity (K d ؍ 100 nM) binding site for -catenin that lies between residues 54 and 157. We anticipate that the oligomeric state of ␣-catenin and the relative stoichiometry of the components in the membrane adhesion complex will be dynamic and regulated by -catenin, cell adhesion, and probably other factors as well.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.