ARVCF localizes to the nucleus and adherens junction and is mutually exclusive with p120(ctn) in E-cadherin complexes

ARVCF is a novel Armadillo repeat domain protein that is closely related to the catenin p120(ctn). Using new ARVCF monoclonal antibodies, we have found that ARVCF associates with E-cadherin and competes with p120 for interaction with the E-cadherin juxtamembrane domain. ARVCF also localized to the nucleus in some cell types, however, and was significantly more nucleophilic than p120. Surprisingly, despite apparently ubiquitous expression, ARVCF was at least tenfold less abundant than p120 in a wide variety of cell types, and was difficult to detect by immunofluorescence unless overexpressed. Consequently, it is not likely to be abundant enough in adult tissues to functionally compete with p120. ARVCF also completely lacked the ability to induce the cell-branching phenotype associated with overexpression of p120. Expression of ARVCF/p120 chimeras confirmed previous results indicating that the branching activity of p120 maps to its Armadillo repeat domain. Surprisingly, the preferential localization of ARVCF to the nucleus required sequences in the amino-terminal end of ARVCF, suggesting that the sequences directing nuclear translocation of ARVCF are distinct from the predicted bipartite nuclear localization signal located between repeats 6 and 7. The dual localization of ARVCF to junctions and to nuclei suggests activities in different cellular compartments, as is the case for several other Armadillo repeat proteins including beta-catenin, p120 and the plakophilins.