| Primary Identifier | IPR005393 | Type | Family |
| Short Name | Chemokine_XCR1 |
| description | Chemokines (chemotactic cytokines) are a family of chemoattractant molecules. They attract leukocytes to areas of inflammation and lesions, and play a key role in leukocyte activation. Originally defined as host defense proteins, chemokines are now known to play a much broader biological role []. They have a wide range of effects in many different cell types beyond the immune system, including, for example, various cells of the central nervous system [], and endothelial cells, where they may act as either angiogenic or angiostatic factors [].The chemokine family is divided into four classes based on the number and spacing of their conserved cysteines: 2 Cys residues may be adjacent (the CC family); separated by an intervening residue (the CXC family); have only one of the first two Cys residues (C chemokines); or contain both cysteines, separated by three intervening residues (CX3C chemokines).Chemokines exert their effects by binding to rhodopsin-like G protein-coupled receptors on the surface of cells. Following interaction with their specific chemokine ligands, chemokine receptors trigger a flux in intracellular calcium ions, which cause a cellular response, including the onset of chemotaxis. There are over fifty distinct chemokines and least 18 human chemokine receptors []. Although the receptors bind only a single class of chemokines, they often bind several members of the same class with high affinity. Chemokine receptors are preferentially expressedon important functional subsets of dendritic cells, monocytes and lymphocytes, including Langerhans cells and T helper cells [, ]. Chemokines and their receptors can also be subclassified into homeostatic leukocyte homing molecules (CXCR4, CXCR5, CCR7, CCR9) versus inflammatory/inducible molecules (CXCR1, CXCR2, CXCR3, CCR1-6, CX3CR1).Chemokine XC receptor 1 (XCR1), which this entry represents is a receptor for lymphotactin []. Lymphotactin is the only known member of the C (or XC) chemokine family, and is produced by certain subsets of T cells and natural killer cells and is also chemotactic for these cell types []. XCR1 is strongly expressed in placenta and at lower levels in the spleen and thymus and detected only at very low levels in peripheral blood leukocytes []. Within these tissues, expression is restricted to CD8+ T cells and natural killer cells [, ]. Binding of lymphotactin to XCR1 stimulates calcium mobilisation and migration in a pertussis toxin-sensitive manner, indicating coupling of the receptor to Gi type proteins [, ]. The matching expression patterns of both lymphotactin and its receptor suggest a role for the chemokine in self-recruitment of leukocytes []. |
