3CIQ:
reference: A regulatable switch mediates self-association in an immunoglobulin fold., Calabrese MF, Eakin CM, Wang JM, Miranker AD, Nat Struct Mol Biol. 2008 Sep;15(9):965-71. PMID: 19172750

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