The vertebrate adhesive junction proteins beta-catenin and plakoglobin and the Drosophila segment polarity gene armadillo form a multigene family with similar properties |
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Authors: | M Peifer P D McCrea K J Green E Wieschaus B M Gumbiner |
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Affiliation: | Department of Biology, University of North Carolina, Chapel Hill 27599. |
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Abstract: | Three proteins identified by quite different criteria in three different systems, the Drosophila segment polarity gene armadillo, the human desmosomal protein plakoglobin, and the Xenopus E-cadherin-associated protein beta-catenin, share amino acid sequence similarity. These findings raise questions about the relationship among the three molecules and their roles in different cell-cell adhesive junctions. We have found that antibodies against the Drosophila segment polarity gene armadillo cross react with a conserved vertebrate protein. This protein is membrane associated, probably via its interaction with a cadherin-like molecule. This cross-reacting protein is the cadherin-associated protein beta-catenin. Using anti-armadillo and antiplakoglobin antibodies, it was shown that beta-catenin and plakoglobin are distinct molecules, which can coexist in the same cell type. Plakoglobin interacts with the desmosomal glycoprotein desmoglein I, and weakly with E-cadherin. Although beta-catenin interacts tightly with E-cadherin, it does not seem to be associated with either desmoglein I or with isolated desmosomes. Anti-armadillo antibodies have been further used to determine the intracellular localization of beta-catenin, and to examine its tissue distribution. The implications of these results for the structure and function of different cell-cell adhesive junctions are discussed. |
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