CHARACTERIZATION OF THE INTERACTIONS OF ALPHA-CATENIN WITH ALPHA-ACTININ AND BETA-CATENIN PLAKOGLOBIN/

Cadherins are calcium-dependent, cell surface glycoproteins involved i n cell-cell adhesion, To function in cell-cell adhesion, the transmemb rane cadherin molecule must be associated with the cytoskeleton via cy toplasmic proteins known as catenins. Three catenins, alpha-catenin, b eta-catenin and gamma-catenin (also known as plakoglobin), have been i dentified, beta-catenin or plakoglobin is associated directly with the cadherin; alpha-catenin binds to beta-catenin/plakoglobin and serves to link the cadherin/catenin complex to the actin cytoskeleton, The do mains on the cadherin and beta-catenin/plakoglobin that are responsibl e for protein-protein interactions have been mapped, However, little i s known about the molecular interactions between alpha-catenin and bet a-catenin/plakoglobin or about the interactions between alpha-catenin and the cytoskeleton, In this study we have used the yeast two-hybrid system to map the domains on alpha-catenin that allow it to associate with beta-catenin/plakoglobin and with alpha-actinin. We also identify a region on alpha-actinin that is responsible for its interaction wit h alpha-catenin. The yeast two-hybrid data were confirmed with biochem ical studies.