1AAR:
reference: Structure of a diubiquitin conjugate and a model for interaction with ubiquitin conjugating enzyme (E2)., Cook WJ, Jeffrey LC, Carson M, Chen Z, Pickart CM, J Biol Chem 1992 Aug 15;267(23):16467-71. PMID: 1322903

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