1EFX:
reference: Crystal structure of an NK cell immunoglobulin-like receptor in complex with its class I MHC ligand., Boyington JC, Motyka SA, Schuck P, Brooks AG, Sun PD, Nature 2000 Jun 1;405(6786):537-43. PMID: 10850706

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