Rho GTPases are important regulators of cellular behavior through their effects on processes such as cytoskeletal organization. Here we show interactions between Drosophila Rho1 and the adherens junction components α-catenin and p120ctn. We find that while Rho1 protein is present throughout the cell, it accumulates apically, particularly at sites of cadherin-based adherens junctions. Cadherin and catenin localization is disrupted in Rho1 mutants, implicating Rho1 in their regulation. p120ctn

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... recently been suggested to inhibit Rho activity through an unknown mechanism. We find that Rho1 accumulates in response to lowered p120ctn activity. Significantly, we find that Rho1 binds directly to α-catenin and p120ctn in vitro, and these interactions map to distinct surface-exposed regions of the protein not previously assigned functions. In addition, we find that both α-catenin and p120ctn co-immunoprecipitate with Rho1-containing complexes from embryo lysates. Our observations suggest that α-catenin and p120ctn are key players in a mechanism of recruiting Rho1 to its sites of action.