Atypical Chemokine Receptors

The chemokine system includes a set of G protein-uncoupled receptors characterized by arrestin-biased signaling, recently named atypical chemokine receptors (ACKRs). ACKRs are emerging as a distinct subfamily of chemokine receptors with a significant impact on the leukocyte recruitment in vivo in face of their inability to support cell migration. ACKRs control chemokine distribution in tissues by different mechanisms, including degradation, transcytosis, and presentation to typical chemokine receptors. The unbalanced activation of the β-arrestin signaling module provides a new conceptual element in the understanding of the molecular mechanisms underlying their loss of chemotactic activity and gain of chemokine gradient-shaping functions.