3DRF:
reference: The structural basis for peptide selection by the transport receptor OppA., Berntsson RP, Doeven MK, Fusetti F, Duurkens RH, Sengupta D, Marrink SJ, Thunnissen AM, Poolman B, Slotboom DJ, EMBO J. 2009 Mar 19. PMID: 19300437

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