| abstract |
CC chemokine receptor type 6, member of the class A family of seven-transmembrane G protein-coupled receptors. CCR6 is the only known receptor identified for the chemokine CCL20 (also known as macrophage inflammatory protein-3alpha, MIP-3alpha). CCR6 is expressed by all mature human B cells, effector memory T-cells, and dendritic cells found in the gut mucosal immune system. CCL20 contributes to recruitment of CCR6-expressing cells to Peyer's patches and isolated lymphoid follicles in the intestine, thereby promoting the assembly and maintenance of organized lymphoid structures. Also, CCL20 expression is highly inducible in response to inflammatory signals. Thus, CCL20 is involved in both inflammatory and homeostatic functions in the 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. Currently, there are ten known receptors for CC chemokines, seven for CXC chemokines, and single receptors for the XC and CX3C chemokines. The CC chemokine receptors are all activating the G protein Gi. |