MOLECULAR-CLONING AND CHARACTERIZATION OF B-CADHERIN, A NOVEL CHICK CADHERIN

Calcium-dependent cell-cell adhesion is mediated in large part by a set of homologous integral membrane glycoproteins termed cadherins. In this report, antibodies to conserved domains in previously described cadherins have been used to isolate cDNAs encoding a novel chick cadherin. The deduced primary structure of this novel molecule, assigned the name B-cadherin, contains 726 amino acid residues which include five extracellular domains characteristic of this class of adhesion molecules, a single putative transmembrane spanning region, and a cytoplasmic tail. In each domain, B-cadherin shares extensive homologies with other cadherins, but is more closely related to E-cadherin, P-cadherin, and L-CAM than to N-cadherin. It is expressed in a wide variety of chick tissues at embryonic day 13. In particular, immunohistochemical staining and in situ hybridization localize B-cadherin protein and mRNA to the epithelial lining of the choroid plexus and to cells in specific layers of the optic tectum in chick brain. Levels of the protein and RNA transcript change dramatically as development proceeds in chick brain. These results suggest that B-cadherin has important functions in neurogenesis, in at least some epithelia, and in embryogenesis.