Figure 2.

Schematic illustration of identified ligands for human and mouse NKG2D. The unique human NKG2D ligands MICA and MICB have α1, α2, and α3 extracellular domains and transmembrane domains, sharing structural homology with MHCI. All other human NKG2D ligands and all mouse NKG2D ligands lack the α3 domain. Murine NKG2D ligands, RAE1 α–ε and H60c, and human ULBP1-6 are glycosylphosphatidylinositol (GPI)-linked to the membrane. Human ligands, ULBP4 and ULBP5, and mouse ligands, MULT1, and H60a and H60b, are transmembrane proteins.