1VGL:
reference: Functionally important substructures of circadian clock protein KaiB in a unique tetramer complex., Iwase R, Imada K, Hayashi F, Uzumaki T, Morishita M, Onai K, Furukawa Y, Namba K, Ishiura M, J Biol Chem. 2005 Dec 30;280(52):43141-9. Epub 2005 Oct 13. PMID: 16227211

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