2VEA:
reference: The structure of a complete phytochrome sensory module in the Pr ground state., Essen LO, Mailliet J, Hughes J, Proc Natl Acad Sci U S A. 2008 Sep 23;105(38):14709-14. Epub 2008 Sep 17. PMID: 18799745

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