Atypical Chemokine Receptors

The chemokine family encompasses forty-seven proteins which interacts with less than twenty receptors. Chemokine receptors are seven transmembrane spanning molecules that after ligand binding activate a complex G protein-dependent signaling cascade leading to a variety of functions, including cell activation and migration. Over the last two decades a set of atypical chemokine receptors (ACKR) was defined. ACKRs share the ability to bind chemokines in a rather promiscuous manner in the absence of G protein coupling. Nevertheless, ACKRs have a significant impact on the leukocyte recruitment and in several pathological conditions based on their ability to control chemokine distribution in tissues by different mechanisms, including degradation, transcytosis, and presentation to classic chemokine receptors. The ACKR family consists of five members (ACKR1-5) characterized by different tissue distribution, regulation and role in biology.