2I1A:
reference: Ddi1, a eukaryotic protein with the retroviral protease fold., Sirkis R, Gerst JE, Fass D, J Mol Biol. 2006 Dec 1;364(3):376-87. Epub 2006 Sep 3. PMID: 17010377

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