2P4V:
reference: The carboxy-terminal coiled-coil of the RNA polymerase beta'-subunit is the main binding site for Gre factors., Vassylyeva MN, Svetlov V, Dearborn AD, Klyuyev S, Artsimovitch I, Vassylyev DG, EMBO Rep. 2007 Nov;8(11):1038-43. Epub 2007 Oct 5. PMID: 17917675

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