4NLP:
reference: Distinct Conformations of a Putative Translocation Element in Poliovirus Polymerase., Sholders AJ, Peersen OB, J Mol Biol. 2014 Jan 11. pii: S0022-2836(14)00020-5. doi:, 10.1016/j.jmb.2013.12.031. PMID: 24424421

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