1HKO:
reference: The solution structure of bovine ferricytochrome b5 determined using heteronuclear NMR methods., Muskett FW, Kelly GP, Whitford D, J Mol Biol. 1996 Apr 26;258(1):172-89. PMID: 8613986

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