6FHT:
reference: Structure-guided design and functional characterization of an artificial red light-regulated guanylate/adenylate cyclase for optogenetic applications., Etzl S, Lindner R, Nelson MD, Winkler A, J Biol Chem. 2018 Apr 25. pii: RA118.003069. doi: 10.1074/jbc.RA118.003069. PMID: 29695503

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