<p> The beta catenins and homologues, plakoglobin and the Drosophila Armadillo protein [<cite idref="PUB00000843"/>], are implicated in cell adhesion and Wnt signalling [<cite idref="PUB00017308"/>]. Originally identified as downstream elements (armadillo phenotype) of the Wnt signalling pathway (wingless phenotype) [<cite idref="PUB00017324"/>, <cite idref="PUB00017318"/>], these proteins have also been shown to be components of adherens junctions, joining classical cadherins to the actin cytoskeleton in cell adhesion [<cite idref="PUB00017310"/>]. The beta-catenin structure has been determined [<cite idref="PUB00000951"/>, <cite idref="PUB00011781"/>]. Beta catenin family proteins contain several ARM repeats, sequences of approximately 50 amino acids involved in protein-protein interactions. Each repeat consists of three helices [<cite idref="PUB00000951"/>, <cite idref="PUB00011781"/>, <cite idref="PUB00017323"/>], with helix 1 and 3 antiparallel to each other and perpendicular to helix 2 [<cite idref="PUB00000951"/>, <cite idref="PUB00011781"/>, <cite idref="PUB00017323"/>]. A conserved glycine residue allows the sharp turn between helices 1 and 2 [<cite idref="PUB00000951"/>, <cite idref="PUB00011781"/>, <cite idref="PUB00017323"/>]. </p>