Involved in the transport of the toxin RTX-I as well as that of RTX-II. Homodimer. The sequence shown is that of serotype 9. In strain CM15 (serotype 1), disruption of this gene prevents production of both RTX-I and RTX-II toxin, and no hemolytic activity in mice or pigs. Belongs to the ABC transporter superfamily. Protein-1 exporter (TC 3.A.1.109) family. Tyr-9 is present instead of the conserved Cys which is expected to be the active site residue of peptidase C39. Thus they are presumed to be without peptidase activity.