5OXA:
reference: Chromophore Isomer Stabilization Is Critical to the Efficient Fluorescence of Cyan Fluorescent Proteins., Gotthard G, von Stetten D, Clavel D, Noirclerc-Savoye M, Royant A, Biochemistry. 2017 Nov 27. pii: 10.1021/acs.biochem.7b01088. doi:, 10.1021/acs.biochem.7b01088. PMID: 29148725

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