3AIZ:
reference: A novel heterotetrameric structure of the crenarchaeal PCNA2-PCNA3 complex., Kawai A, Hashimoto H, Higuchi S, Tsunoda M, Sato M, Nakamura KT, Miyamoto S, J Struct Biol. 2011 Jun;174(3):443-50. Epub 2011 Feb 23. PMID: 21352919

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