4BWF:
reference: A disulphide bond in the E2 enzyme Pex4p modulates ubiquitin-conjugating activity., Williams C, van den Berg M, Stanley WA, Wilmanns M, Distel B, Sci Rep. 2013 Jul 30;3:2212. doi: 10.1038/srep02212. PMID: 23896733

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