Editing Natural killer cell (section)

===Inhibitory receptors===
*[[Killer-cell immunoglobulin-like receptor]]s (KIRs) belong to a multigene family of more recently [[evolution|evolved]] Ig-like extracellular domain receptors; they are present in nonhuman primates, and are the main receptors for both classical MHC I ([[HLA-A]], [[HLA-B]], [[HLA-C]]) and nonclassical Mamu-G ([[HLA-G]]) in primates. Some KIRs are specific for certain HLA subtypes. Most KIRs are inhibitory and dominant. Regular cells express MHC class 1, so are recognised by KIR receptors and NK cell killing is inhibited.<ref name=Lannello2008/>
* '''[[CD94/NKG2]]''' (heterodimers), a C-type lectin family receptor, is conserved in both rodents and primates and identifies nonclassical (also nonpolymorphic) MHC I molecules such as [[HLA-E]]. Expression of HLA-E at the cell surface is dependent on the presence of nonamer peptide epitope derived from the signal sequence of classical MHC class I molecules, which is generated by the sequential action of [[signal peptide peptidase]] and the [[proteasome]]. Though indirect, this is a way to survey the levels of classical (polymorphic) HLA molecules.
*'''ILT''' or '''LIR''' (immunoglobulin-like receptor) – are recently discovered members of the Ig receptor family.	
* '''Ly49''' (homodimers) have both activating and inhibitory isoforms. They are highly polymorphic on the population level; though they are structurally unrelated to KIRs, they are the functional homologues of KIRs in mice, including the expression pattern. Ly49s are receptor for classical (polymorphic) MHC I molecules.