Members of this family are found in Pseudomonas aeruginosa exotoxin A, and are responsible for binding of the toxin to the alpha-2-macroglobulin receptor, with subsequent internalisation into endosomes. The domain adopts a thirteen-strand antiparallel beta jelly roll topology, which belongs to the Concanavalin A-like lectins/glucanases fold superfamily [1].

1: Refined crystallographic structure of Pseudomonas aeruginosa exotoxin A and its implications for the molecular mechanism of toxicity. Wedekind JE, Trame CB, Dorywalska M, Koehl P, Raschke TM, McKee M, FitzGerald D, Collier RJ, McKay DB; J Mol Biol. 2001;314:823-837. PMID:11734000