Isoform-specific differences in the size of desmosomal cadherin/catenin complexes

Via their integration of the intermediate filament cytoskeleton into the ce ll membrane, desmosomes facilitate the maintenance of cell shape and tissue integrity as well as intercellular communication. The transmembrane compon ents of the desmosome, the desmogleins and desmocollins, are members of the cadherin family of cell-cell adhesion molecules. Each of these proteins ex ists as three distinct isoforms, which are the products of individual genes and expressed in a cell-type and differentiation-specific manner. Previous work has suggested that desmoglein 1 binds to its catenin partner, plakogl obin, in an approximately 6:1 stoichiometry. In this study, the molecular o rganization of complexes formed by plakoglobin and desmoglein 1, 2, or 3 ar e further examined through immunoprecipitation, size exclusion chromatograp hy and sucrose density sedimentation analysis. It is shown that the complex formed between plakoglobin and desmoglein 1 has an overall molecular weigh t greater than that of plakoglobin/desmoglein 2 or plakoglobin/desmoglein 3 ; however, the stoichiometry of the plakoglobin/desmoglein I complex does n ot appear to exceed 2:1.