Chemokine receptors are a class of G protein-coupled receptors that are activated by chemokines, which are a family of small cytokines that are involved in the regulation of immune cell migration and activation. There are approximately 20 different chemokine receptors that have been identified in humans, which are classified into four subfamilies based on the arrangement of their cysteine residues: CXC, CC, CX3C, and XC.
