Cell adhesion and signal transduction: the Armadillo connection.

The products of the Drosophila segment polarity gene armadillo and its vertebrate homologue beta-catenin are components of the signal transduction pathway for Wingless/Wnt-1; this signal regulates cell-fate choices in embryos of the fruit fly Drosophila and vertebrates. Armadillo/beta-catenin is also a component of cell-cell adherens junctions in epithelia. How can these two seemingly distinct roles be reconciled? Evidence suggests that Armadillo has distinct functions: one in the adherens junction and one or more in the cytoplasm. The biochemical role of Armadillo may be to serve as a scaffold upon which different multiprotein complexes are assembled.