4XHA:
reference: The Structure of the RNA-Dependent RNA Polymerase of a Permutotetravirus Suggests a Link between Primer-Dependent and Primer-Independent Polymerases., Ferrero DS, Buxaderas M, Rodriguez JF, Verdaguer N, PLoS Pathog. 2015 Dec 1;11(12):e1005265. doi: 10.1371/journal.ppat.1005265., eCollection 2015 Dec. PMID: 26625123

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