4JGQ:
reference: Insight into the sporulation phosphorelay: Crystal structure of the sensor domain of Bacillus subtilis histidine kinase, KinD., Wu R, Gu M, Wilton R, Babnigg G, Kim Y, Pokkuluri PR, Szurmant H, Joachimiak A, Schiffer M, Protein Sci. 2013 May;22(5):564-76. doi: 10.1002/pro.2237. Epub 2013 Mar 18. PMID: 23436677

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