2IXE:
reference: Distinct structural and functional properties of the ATPase sites in an asymmetric ABC transporter., Procko E, Ferrin-O'Connell I, Ng SL, Gaudet R, Mol Cell. 2006 Oct 6;24(1):51-62. PMID: 17018292

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).