Molecular recognition of the atypical chemokine receptor CXCR7/ACKR3 by chemokines

Over the last years, the field of research on chemokines and their receptors has made significant progresses. As the crystallography techniques improve, the number of difficult-to-obtain three-dimensional chemokine receptor structures begins to increase. In parallel many, sometimes groundbreaking, functional data have recently been reported. As a consequence, the convictions within the chemokine-receptor community evolve considerably as the previously widely accepted models fail now to withstand the weight of both structural and functional evidences pointing out their oversimplification. The two-site/two-step binding model for chemokine-receptor interactions is being replaced with a more complex, multistep one, the concept of biased signalling is gaining ground and the growing number of novel unsuspected non-chemokine ligands for chemokine receptors regularly refine our understanding on how these receptors work and how they are regulated, bringing about new paradigms. CXCR7, for which two new ligands have recently been discovered and for which the signalling potential, 10 years after its identification as a chemokine receptor, remains a debatable subject, integrates really well in the current changing landscape of the chemokine-receptor field.