4FMT:
reference: Branched signal wiring of an essential bacterial cell-cycle phosphotransfer protein., Blair JA, Xu Q, Childers WS, Mathews II, Kern JW, Eckart M, Deacon AM, Shapiro L, Structure. 2013 Sep 3;21(9):1590-601. doi: 10.1016/j.str.2013.06.024. Epub 2013, Aug 8. PMID: 23932593

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