1PV6:
reference: Structure and mechanism of the lactose permease of Escherichia coli., Abramson J, Smirnova I, Kasho V, Verner G, Kaback HR, Iwata S, Science 2003 Aug 1;301(5633):610-5. PMID: 12893935

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