Involved in the transport of the toxin RTX-III. Homodimer. The sequence shown is that of serotype 2. Belongs to the ABC transporter superfamily. Protein-1 exporter (TC 3.A.1.109) family. Tyr-13 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.