Members of this family of Bordetella pertussis toxins adopt a structure consisting of an OB fold, with a closed or partly opened beta-barrel in a Greek-key topology [1].

1: The crystal structure of pertussis toxin. Stein PE, Boodhoo A, Armstrong GD, Cockle SA, Klein MH, Read RJ; Structure. 1994;2:45-57. PMID:8075982