6FNN:
reference: Rpn11-mediated ubiquitin processing in an ancestral archaeal ubiquitination system., Fuchs ACD, Maldoner L, Wojtynek M, Hartmann MD, Martin J, Nat Commun. 2018 Jul 12;9(1):2696. doi: 10.1038/s41467-018-05198-1. PMID: 30002364

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