Synonyms: CD_antigen=CD158d,CD158 antigen like family member D,CD158 antigen-like family member D,CD158d,G9P,KI2L4,Killer cell immunoglobulin like receptor 2DL4,Killer cell immunoglobulin like receptor, two domains, long cytoplasmic tail, 4,Killer cell immunoglobulin-like receptor 2DL4,Killer cell inhibitory receptor 103AS,Killer Ig receptor,KIR 103AS,KIR-103AS,KIR103,KIR103AS,KIR2DL4,MHC class I NK cell receptor KIR103AS,Natural killer cell inhibitory receptor,NK cell receptor,NK cell receptor, natural killer cell inhibitory receptor,OTTHUMP00000068612,OTTHUMP00000068614,OTTHUMP00000068615
Background: Killer cell immunoglobulin-like receptors (KIRs) are transmembrane glycoproteins expressed by natural killer cells and subsets of T cells. The KIR genes are polymorphic and highly homologous and they are found in a cluster on chromosome 19q13.4 within the 1 Mb leukocyte receptor complex (LRC). The gene content of the KIR gene cluster varies among haplotypes, although several 'framework' genes are found in all haplotypes (KIR3DL3, KIR3DP1, KIR3DL4, KIR3DL2). The KIR proteins are classified by the number of extracellular immunoglobulin domains (2D or 3D) and by whether they have a long (L) or short (S) cytoplasmic domain. KIR proteins with the long cytoplasmic domain transduce inhibitory signals upon ligand binding via an immune tyrosine-based inhibitory motif (ITIM), while KIR proteins with the short cytoplasmic domain lack the ITIM motif and instead associate with the TYRO protein tyrosine kinase binding protein to transduce activating signals. The ligands for several KIR proteins are subsets of HLA class I molecules, thus, KIR proteins are thought to play an important role in regulation of the immune response. This gene is one of the 'framework' loci that is present on all haplotypes. Alternate alleles of this gene are represented on multiple alternate reference loci (ALT_REF_LOCs). Alternative splicing results in multiple transcript variants, some of which may not be annotated on the primary reference assembly.