CXC chemokine receptor type 5, member of the class A family of seven-transmembrane G protein-coupled receptors
CXCR5 is a B-cell selective receptor that binds specifically to the homeostatic chemokine CXCL13 and regulates adaptive immunity. The receptor is found on all peripheral blood and tonsillar B cells and is involved in lymphocyte migration (homing) to specific tissues and development of normal lymphoid tissue. 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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