This region represents the C-terminal 120 amino acids of a family of surface-exposed bacterial proteins. YadA, an adhesin from Yersinia, was the first member of this family to be characterised. UspA2 from Moraxella was second. The Eib immunoglobulin-binding proteins from E. coli were third, followed by the DsrA proteins of Haemophilus ducreyi and others. These proteins are homologous at their C-terminal and have predicted signal sequences, but they diverge elsewhere. The C-terminal 9 amino acids, consisting of alternating hydrophobic amino acids ending in F or W, comprise a targeting motif for the outer membrane of the Gram negative cell envelope. This region is important for oligomerisation [1].

1: Nonimmune binding of human immunoglobulin A (IgA) and IgG Fc by distinct sequence segments of the EibF cell surface protein of Escherichia coli. Sandt CH, Hill CW; Infect Immun 2001;69:7293-7303. PMID:11705900

2: Structure and sequence analysis of Yersinia YadA and Moraxella UspAs reveal a novel class of adhesins. Hoiczyk E, Roggenkamp A, Reichenbecher M, Lupas A, Heesemann J; EMBO J 2000;19:5989-5999. PMID:11080146