MOLECULAR-CLONING OF CDNA FOR XTCAD-1, A NOVEL XENOPUS CADHERIN, AND ITS EXPRESSION IN ADULT TISSUES AND EMBRYOS OF XENOPUS-LAEVIS

We have isolated from a Xenopus tailbud cDNA library a novel cadherin cDNA, denoted as XTCAD-1, which contained an open reading frame includ ing the entire coding region. XTCAD-1 codes for 714 amino acids (molec ular mass: 96 kDa), which include five characteristic extracellular ca dherin motifs, a single putative transmembrane domain, and a cytoplasm ic domain. In each domain, XTCAD-1 shared extensive homologies with ot her cadherins, and was related to EP-, E-, and P-cadherins more closel y than to N- and M-cadherins. In adult Xenopus, XTCAD-1 mRNA was stron gly expressed in intestine/stomach, kidney and skin, which are respect ively derived from endoderm, mesoderm, and ectoderm. In Xenopus embryo genesis, expression of XTCAD-1 mRNA was first detected at blastula sta ge, and the level of the expression increased gradually during gastrul a stage, reached a peak at tailbud stage and then decreased slightly a t tadpole stage. These results suggest that in Xenopus laevis XTCAD-1 plays an important role in the maintenance of adult tissues that conta in epithelial cells abundantly and also in morphogenesis in early embr yonic development.