2GBL:
reference: Analysis of KaiA-KaiC protein interactions in the cyano-bacterial circadian clock using hybrid structural methods., Pattanayek R, Williams DR, Pattanayek S, Xu Y, Mori T, Johnson CH, Stewart PL, Egli M, EMBO J. 2006 May 3;25(9):2017-28. Epub 2006 Apr 20. PMID: 16628225

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