2XUR:
reference: The G157C mutation in the Escherichia coli sliding clamp specifically affects initiation of replication., Johnsen L, Flatten I, Morigen, Dalhus B, Bjoras M, Waldminghaus T, Skarstad K, Mol Microbiol. 2011 Jan;79(2):433-46. doi:, 10.1111/j.1365-2958.2010.07453.x. Epub 2010 Nov 23. PMID: 21219462

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