Fig. 3. -catenin complexes in cell adhesion. Crystal structures of the -catenin armadillo repeat domain (yellow) in complex with the E-cadherin cytoplasmic domain (red) and the dimerization and -catenin-binding domain of -catenin (green) were superimposed on the basis of shared -catenin residues 145-148. Note the disruption of the first helix in the armadillo repeat domain upon -catenin binding, which potentially produces a hinge, allowing structural flexibility between -catenin and -catenin. -catenin Y142, which disrupts -catenin binding upon phosphorylation, and Y654, which modulates the interaction between -catenin and E-cadherin upon phosphorylation, are shown in purple. Red dashes indicate flexible regions of E-cadherin.