1NBJ:
reference: Twists, knots, and rings in proteins. Structural definition of the cyclotide framework., Rosengren KJ, Daly NL, Plan MR, Waine C, Craik DJ, J Biol Chem 2003 Mar 7;278(10):8606-16. Epub 2002 Dec 12. PMID: 12482868

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