3B0M:
reference: Structure-function relationship of assimilatory nitrite reductases from the leaf and root of tobacco based on high-resolution structures., Nakano S, Takahashi M, Sakamoto A, Morikawa H, Katayanagi K, Protein Sci. 2012 Mar;21(3):383-95. doi: 10.1002/pro.2025. Epub 2012 Jan 31. PMID: 22238192

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