2LB9:
reference: Solution structure of a cyanobacterial phytochrome GAF domain in the red-light-absorbing ground state., Cornilescu G, Ulijasz AT, Cornilescu CC, Markley JL, Vierstra RD, J Mol Biol. 2008 Nov 7;383(2):403-13. Epub 2008 Aug 22. PMID: 18762196

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