This family contains Cass2 from Vibrio cholerae, an integron-associated protein that has been shown [1] to bind cationic drug compounds with submicromolar affinity. Cass2 has been proposed to be representative of a larger family of independent effector-binding proteins associated with lateral gene transfer within Vibrio and other closely-related species.

1: Crystal structure of an integron gene cassette-associated protein from Vibrio cholerae identifies a cationic drug-binding module. Deshpande CN, Harrop SJ, Boucher Y, Hassan KA, Di Leo R, Xu X, Cui H, Savchenko A, Chang C, Labbate M, Paulsen IT, Stokes HW, Curmi PM, Mabbutt BC; PLoS One. 2011;6:e16934. PMID:21390267