1IHR:
reference: Crystal structure of the dimeric C-terminal domain of TonB reveals a novel fold., Chang C, Mooser A, Pluckthun A, Wlodawer A, J Biol Chem 2001 Jul 20;276(29):27535-40. PMID: 11328822

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