5N9J:
reference: Core Mediator structure at 3.4 A extends model of transcription initiation complex., Nozawa K, Schneider TR, Cramer P, Nature. 2017 May 11;545(7653):248-251. doi: 10.1038/nature22328. Epub 2017 May 3. PMID: 28467824

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