3LX2:
reference: Crystal structures of two active proliferating cell nuclear antigens (PCNAs) encoded by Thermococcus kodakaraensis., Ladner JE, Pan M, Hurwitz J, Kelman Z, Proc Natl Acad Sci U S A. 2011 Feb 15;108(7):2711-6. Epub 2011 Jan 26. PMID: 21270332

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