5JON:
reference: Structure and dynamics underlying elementary ligand binding events in human pacemaking channels., Goldschen-Ohm MP, Klenchin VA, White DS, Cowgill JB, Cui Q, Goldsmith RH, Chanda B, Elife. 2016 Nov 18;5. pii: e20797. doi: 10.7554/eLife.20797. PMID: 27858593

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