6NL9:
reference: Design of High-Affinity Metal-Controlled Protein Dimers., Maniaci B, Lipper CH, Anipindi DL, Erlandsen H, Cole JL, Stec B, Huxford T, Love JJ, Biochemistry. 2019 Apr 30;58(17):2199-2207. doi: 10.1021/acs.biochem.9b00055., Epub 2019 Apr 12. PMID: 30938154

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