Formation of oligomers by G protein-coupled receptors

There is increasing evidence that G protein-coupled receptors (GPCRs) may form homo- or hetero-oligomers and that this may be important for their function. Evidence in favor of oligomerization comes from biochemical studies, studies of functional complementation and recent studies using energy transfer techniques, which provide direct evidence for receptor/receptor contacts. The oligomerization process may be regulated by ligands for some GPCRs or it may be constitutive in other cases. Homo-oligomerization may lead to cooperative behavior for the binding of ligands to some receptors. Hetero-oligomerization may generate new pharmacological properties for some receptor combinations as well as altering the signaling properties of the GPCR concerned. Additionally, the trafficking of GPCRs from the cell surface may be affected by oligomerization.