1QO3:
reference: Crystal structure of a lectin-like natural killer cell receptor bound to its MHC class I ligand., Tormo J, Natarajan K, Margulies DH, Mariuzza RA, Nature. 1999 Dec 9;402(6762):623-31. PMID: 10604468

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