4URG:
reference: Structure of a Diguanylate Cyclase from Thermotoga maritima: Insights into Activation, Feedback Inhibition and Thermostability., Deepthi A, Liew CW, Liang ZX, Swaminathan K, Lescar J, PLoS One. 2014 Oct 31;9(10):e110912. doi: 10.1371/journal.pone.0110912., eCollection 2014. PMID: 25360685

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