https://doi.org/10.1351/goldbook.13362
Receptor expressed on natural killer (NK) cells that binds to major histocompatibility complex (MHC) class I molecules on target cells; binding MHC class I inhibits the signaling that would otherwise lead to target cell killing.
Note: If immunoreceptor tyrosine-based inhibitory motif (ITIM) sequences are present in the KIR cytoplasmic domain, MHC class I molecule binding is inhibitory to the killer cell. KIRs lacking ITIMs can associate with immunoreceptor tyrosine-based activation motif (ITAM)-containing adaptor molecules, in which case binding of MHC class I molecules can activate the killer cell.