2D1U:
reference: Nuclear magnetic resonance solution structure of the periplasmic signalling domain of the TonB-dependent outer membrane transporter FecA from Escherichia coli., Garcia-Herrero A, Vogel HJ, Mol Microbiol. 2005 Dec;58(5):1226-37. PMID: 16313612

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