Killer-cell immunoglobulin-like receptor
Encyclopedia
Killer-cell immunoglobulin-like receptors (KIRs), are a family of cell surface proteins found on important cells of the immune system
called natural killer (NK) cells
. They regulate the killing function of these cells by interacting with MHC class I molecules, which are expressed on all cell types. This interaction allows them to detect virally
infected cells or tumor cells that have a characteristic low level of Class I MHC on their surface. Most KIRs are inhibitory, meaning that their recognition of MHC suppresses the cytotoxic activity of their NK cell. Only a limited number of KIRs have the ability to activate cells. KIR molecules are highly polymorphic
, meaning their gene
sequences differ greatly between individuals, so that different individuals possess different arrays/repertoires of KIR genes.
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
called natural killer (NK) cells
Natural killer cell
Natural killer cells are a type of cytotoxic lymphocyte that constitute a major component of the innate immune system. NK cells play a major role in the rejection of tumors and cells infected by viruses...
. They regulate the killing function of these cells by interacting with MHC class I molecules, which are expressed on all cell types. This interaction allows them to detect virally
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
infected cells or tumor cells that have a characteristic low level of Class I MHC on their surface. Most KIRs are inhibitory, meaning that their recognition of MHC suppresses the cytotoxic activity of their NK cell. Only a limited number of KIRs have the ability to activate cells. KIR molecules are highly polymorphic
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...
, meaning their gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
sequences differ greatly between individuals, so that different individuals possess different arrays/repertoires of KIR genes.
Genes
- two domains, long cytoplasmic tail: KIR2DL1KIR2DL1Killer cell immunoglobulin-like receptor 2DL1 is a protein that in humans is encoded by the KIR2DL1 gene.-Further reading:...
, KIR2DL2, KIR2DL3, KIR2DL4KIR2DL4Killer cell immunoglobulin-like receptor 2DL4 is a protein that in humans is encoded by the KIR2DL4 gene.-Further reading:...
, KIR2DL5A, KIR2DL5B, - two domains, short cytoplasmic tail: KIR2DS1, KIR2DS2, KIR2DS3, KIR2DS4KIR2DS4Killer cell immunoglobulin-like receptor 2DS4 is a protein that in humans is encoded by the KIR2DS4 gene.-Further reading:...
, KIR2DS5 - three domains, long cytoplasmic tail: KIR3DL1KIR3DL1Killer cell immunoglobulin-like receptor 3DL1 is a protein that in humans is encoded by the KIR3DL1 gene.-Further reading:...
, KIR3DL2KIR3DL2Killer cell immunoglobulin-like receptor 3DL2 is a protein that in humans is encoded by the KIR3DL2 gene.-Further reading:...
, KIR3DL3KIR3DL3Killer cell immunoglobulin-like receptor 3DL3 is a protein that in humans is encoded by the KIR3DL3 gene.... - three domains, short cytoplasmic tail: KIR3DS1
External links
- http://www.KIRtyping.info
- The KIR Gene Cluster, NIH Bookshelf, PDF