CC chemokine receptor types 5 and 2, member of the class A family of seven-transmembrane G protein-coupled receptors
CCR2 and CCR5 share very high amino acid sequence identity. Both receptors play important roles in the trafficking of monocytes/macrophages and are implicated in the pathogenesis of immunologic diseases (rheumatoid arthritis, celiac disease, and transplant rejection) and cardiovascular diseases (atherosclerosis and autoimmune hepatitis). CCR2 is a receptor specific for members of the monocyte chemotactic protein family, including CCL2, CCL7, and CCL13. Conversely, CCR5 is a major co-receptor for HIV infection and binds many CC chemokine ligands, including CC chemokine ligands including CCL2, CCL3, CCL4, CCL5, CCL11, CCL13, CCL14, and CCL16. CCR2 is expressed primarily on blood monocytes and memory T cells, whereas CCR5 is expressed on antigen-presenting cells (macrophages and dendritic cells) and activated T effector cells. 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.
Comment:Small-molecule chemical ligands tend to bind deeper within the receptor core, compared to a peptide ligand neurotensin, which binds towards the extracellular surface of its receptor.
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