5FML:
reference: Influenza Polymerase Can Adopt an Alternative Configuration Involving a Radical Repacking of PB2 Domains., Thierry E, Guilligay D, Kosinski J, Bock T, Gaudon S, Round A, Pflug A, Hengrung N, El Omari K, Baudin F, Hart DJ, Beck M, Cusack S, Mol Cell. 2016 Jan 7;61(1):125-37. doi: 10.1016/j.molcel.2015.11.016. Epub 2015, Dec 17. PMID: 26711008

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