2QTK:
reference: Crystal Structure of the Outer Membrane Protein OpdK from Pseudomonas aeruginosa., Biswas S, Mohammad MM, Movileanu L, van den Berg B, Structure. 2008 Jul;16(7):1027-35. PMID: 18611376

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