ADHESIVE BUT NOT LATERAL E-CADHERIN COMPLEXES REQUIRE CALCIUM AND CATENINS FOR THEIR FORMATION

We examined intercadherin interactions in epithelial A-431 cells produ cing endogenous E-cadherin and recombinant forms of E-cadherin tagged either by myc or by flag epitopes. Three distinct E-cadherin complexes were found. The first is a conventional E-cadherin-catenin complex co nsisting of one E-cadherin molecule linked either to beta-catenin/alph a-catenin or to plakoglobin/alpha-catenin dimers. The second is a late ral E-cadherin complex incorporating two E-cadherin-catenin convention al complexes combined in parallel fashion via dimerization of the NH2- terminal extracellular domain of E-cadherin, The third complex is like ly to contain two E-cadherin-catenin conventional complexes derived fr om two opposing cells and arranged in an antiparallel fashion. Formati on of the antiparallel but not lateral complex strictly depends on ext racellular calcium and E-cadherin binding to catenins, Double amino ac id substitution Trp156Ala/Val157Gly within the extracellular NH2-termi nal E-cadherin domain completely abolished both lateral and antiparall el inter-E-cadherin association. These data support an idea that the a ntiparallel complex has the adhesion function. Furthermore, they allow us to suggest that antiparallel complexes derive from lateral dimers and this complex process requires catenins and calcium ions.