5JRV:
reference: Structural and Functional Evidence Indicates Selective Oxygen Signaling in Caldanaerobacter subterraneus H-NOX., Hespen CW, Bruegger JJ, Phillips-Piro CM, Marletta MA, ACS Chem Biol. 2016 Jun 30. PMID: 27328180

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