Chemokine receptor dimerization: two are better than one

The chemokines participate in an exceptional range of physiological and pathological processes, including the control of lymphocyte trafficking, tumor growth, wound healing, allograft rejection, regulation of T-cell differentiation, asthma, infection with HIV and atherosclerosis. This vast array of activities is triggered by the interaction of nearly 50 different chemokines with a relatively modest number of 20 G-protein-coupled receptors. The asymmetry between the number of receptors and ligands suggests an underlying, shared control mechanism activated at a very early stage of the response. One of the first events triggered by the binding of chemokines is the homo- and hetero-dimerization of their receptors; here, we outline these events and their consequences in chemokine signaling.