4LDT:
reference: E2 ubiquitin-conjugating enzymes regulate the deubiquitinating activity of OTUB1., Wiener R, Dibello AT, Lombardi PM, Guzzo CM, Zhang X, Matunis MJ, Wolberger C, Nat Struct Mol Biol. 2013 Aug 18. doi: 10.1038/nsmb.2655. PMID: 23955022

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