A NOVEL TUNICATE (BOTRYLLUS-SCHLOSSERI) PUTATIVE C-TYPE LECTIN FEATURES AN IMMUNOGLOBULIN DOMAIN

We have cloned a putative C-type lectin of Botryllus schlosseri [Ascid iacea], whose deduced protein of 333 amino acids features three buildi ng blocks: (i) a Creek-key moth signature at the amino-terminus, (ii) a C-type lectin domain signature, and (iii) an immunoglobulin (Ig) dom ain at the carboxyl terminus, This C-type lectin was termed BSCLT, Sim ilarity searches revealed that the Ig domain in BSCLT, which is eviden tly not polymorphic, is best classified as an Intermediate-type Ig dom ain. Rabbit antibodies, raised against recombinant BSCLT, cross-reacte d in a Western blot with a 38-kD polypeptide in tunicate crude extract , Presumably, this bimodal tunicate protein is the first description o f a soluble lectin that features besides the carbohydrate recognition domain also a complete Ig domain.