| abstract |
XC chemokine receptor 1, member of the class A family of seven-transmembrane G protein-coupled receptors. XCR1 is a chemokine receptor specific for XCL1 and XCL2 (previously called lymphotactin alpha/beta), which differ in only two amino acids. XCL1/2 is the only member of the C chemokine subfamily, which is unique as containing only two of the four cysteines that are found in other chemokine families. Human XCL1/2 has been shown to be secreted by activated CD8+ T cells and upon activation of the innate immune system. Chemokines are principal regulators for leukocyte trafficking, recruitment, and activation. Chemokine family membership is defined on the basis of sequence homology and on the presence of variations on a conserved cysteine motif, which allows the family to further divide into four subfamilies (CC, CXC, XC, and CX3C). Chemokines interact with seven-transmembrane receptors which are typically coupled to G protein for signaling. |