3L0X:
reference: Structure of monoubiquitinated PCNA and implications for translesion synthesis and DNA polymerase exchange., Freudenthal BD, Gakhar L, Ramaswamy S, Washington MT, Nat Struct Mol Biol. 2010 Apr;17(4):479-84. Epub 2010 Mar 21. PMID: 20305653

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