5U4L:
reference: Using homology modeling to interrogate binding affinity in neutralization of ricin toxin by a family of single domain antibodies., Bazzoli A, Vance DJ, Rudolph MJ, Rong Y, Angalakurthi SK, Toth RT 4th, Middaugh CR, Volkin DB, Weis DD, Karanicolas J, Mantis NJ, Proteins. 2017 Nov;85(11):1994-2008. doi: 10.1002/prot.25353. Epub 2017 Aug 4. PMID: 28718923

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