4BWI:
reference: Structure of the cyanobacterial phytochrome 2 photosensor implies a tryptophan switch for phytochrome signaling., Anders K, Daminelli-Widany G, Mroginski MA, von Stetten D, Essen LO, J Biol Chem. 2013 Oct 30. PMID: 24174528

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