4PPT:
reference: Structural basis of an engineered dual-specific antibody: conformational diversity leads to a hypervariable loop metal-binding site., Fanning SW, Walter R, Horn JR, Protein Eng Des Sel. 2014 Aug 20. pii: gzu033. PMID: 25143596

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