1R8J:
reference: Crystal structure of circadian clock protein KaiA from Synechococcus elongatus., Ye S, Vakonakis I, Ioerger TR, LiWang AC, Sacchettini JC, J Biol Chem 2004 May 7;279(19):20511-8. Epub 2004 Mar 8. PMID: 15007067

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