1R84:
reference: The structures of the active center in dark-adapted bacteriorhodopsin by solution-state NMR spectroscopy., Patzelt H, Simon B, terLaak A, Kessler B, Kuhne R, Schmieder P, Oesterhelt D, Oschkinat H, Proc Natl Acad Sci U S A 2002 Jul 23;99(15):9765-70. Epub 2002 Jul 15. PMID: 12119389

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