ISOLATION AND CDNA CLONING OF KSP-CADHERIN, A NOVEL KIDNEY-SPECIFIC MEMBER OF THE CADHERIN MULTIGENE FAMILY

Cadherins are recognized as the principal mediators of homotypic cellular recognition and, play a demonstrated role in the morphogenic direction of tissue development. We report here the identification of a structurally unique, kidney-specific member of the cadherin multigene family (Ksp-cadherin). cDNA cloning and molecular analysis of the 130-kDa protein confirmed that it was novel and indicated that it most closely resembled members of the LI-cadherin/HPT-1 cadherin subgroup. The predicted protein possesses the definitive cadherin-specific sequence motifs LDRE, DXND, and DXD in well conserved sequential arrangement, and the characteristic cysteine residues found in the last ectodomains of almost all known cadherins. Like LI-cadherin and HPT-1, Ksp-cadherin lacks the prosequence and HAV adhesion recognition sequence typical of most classical cadherins, and possesses a truncated cytoplasmic domain (18-22 amino acids). When expressed in a transient Vaccinia/T7 expression system, Ksp-cadherin displayed the classic calcium sensitivity to trypsin proteolysis that is observed in all cadherins. Immunolocalization studies and Northern analysis indicated that expression of Ksp-cadherin was kidney-specific and limited to the basolateral membranes of renal tubular epithelial cells. In summary, we have identified and cloned a novel, kidney-specific member of the cadherin multigene family that we propose be designated Ksp-cadherin.