CLONING AND CHARACTERIZATION OF BS-CADHERIN, A NOVEL CADHERIN FROM THE COLONIAL UROCHORDATE BOTRYLLUS-SCHLOSSERI

The genomic DNA for a novel member of the cadherin family (BS-cadherin ) was cloned and characterized from the colonial marine invertebrate, Botryllus schlosseri. Using a differential display of mRNA by means of PCR, a small cDNA fragment of 380 nucleotides was found to be specifi cally expressed in a colony undergoing allogeneic rejection processes, as compared with naive parts of the same genotype. This cDNA fragment was used as a probe to screen a genomic library of Botryllus schlosse ri. A genomic fragment containing an ORF of 2718 nucleotides, with no introns, was isolated. The encoded protein exhibits a typical structur e of cadherins; an extracellular domain with conserved repeated sequen ces (cadherin signatures), a single transmembrane domain and a conserv ed cytoplasmic tail region. The BS-cadherin amino-acid sequence shows 32-35% identity to mature classical cadherins type I, e.g., N-, P- and E-cadherin as well as mature classical cadherins type II, e.g., human cadherin-6, -8 and OB-cadherin. This cadherin represents a new cadher in gene family, evolutionarily distant to all other known classical ca dherins. (C) 1997 Elsevier Science B.V.