4HDI:
reference: Global structures of IgG isotypes expressing identical variable regions., Eryilmaz E, Janda A, Kim J, Cordero RJ, Cowburn D, Casadevall A, Mol Immunol. 2013 Jul 31;56(4):588-598. doi: 10.1016/j.molimm.2013.06.006. PMID: 23911417

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