Characterization of cadherin-24, a novel alternatively spliced type II cadherin

Cadherins comprise a superfamily of calcium-dependent cell-cell adhesion molecules. Within the superfamily are six subfamilies including type I and type II cadherins. Both type I and type II cadherins are composed of five extracellular repeat domains with conserved calcium-binding motifs, a single pass transmembrane domain, and a highly conserved cytoplasmic domain that interacts with β-catenin and p120 catenin. In this study, we describe a novel cadherin, cadherin-24. It is a type II cadherin with a 781-codon open reading frame, which encodes a type II cadherin protein complete with five extracellular repeats containing calcium-binding motifs, a transmembrane domain, and a conserved cytoplasmic domain. Cadherin-24 has the unusual feature of being alternatively spliced in extracellular repeat 4. This alternative exon encodes 38 in-frame amino acids, resulting in an 819-amino-acid protein. Sequence analysis suggests the presence of β-catenin and p120 catenin-binding sequences, and immunoprecipitation experiments confirm the ability of both forms of the novel cadherin to associate with α-catenin, β-catenin, and p120 catenin. In addition, aggregation assays show that both forms of cadherin-24 mediate strong cell-cell adhesion.