Xarvcf, Xenopus Member of the p120 Catenin Subfamily Associating with Cadherin Juxtamembrane Region*

The catenin ARVCF is a member of the p120ctn subfamily of Armadillo proteins. A number of catenins directly bind cadherin cytoplasmic tails, contributing to the modulation of cell-cell adhesion and motility processes. Some catenins, such as β-catenin (and likely p120ctn), have additional roles within signaling pathways regulating gene transcription. We have isolated the Xenopushomolog of human ARVCF. Utilizing the cadherin membrane proximal region known to bind p120ctn and δ-catenin, coimmunoprecipitation experiments demonstrate that Xarvcf, likewise, binds cadherin in this region and that corresponding point mutations within conserved residues abrogate the Xarvcf-cadherin association. Western blot analysis of Xarvcf protein across a series of developmental stages reveals changes in protein mobility, likely due to changes in phosphorylation. Xarvcf is a maternally provided transcript and expressed in the embryo throughout all stages of development. Interestingly, Xarvcf mRNA is differentially spliced to produce several isoforms, one of which is developmentally regulated. In common with the putative post-translational modifications of the Xarvcf protein, the presence of alternative splice isoforms suggests that Xarvcf possesses the capacity to effect developmental functions in a regulatable manner.