G protein-coupled receptor oligomerization provides the framework for signal discrimination

The idea that G protein-coupled receptors (GPCRs) may undergo homo- or hetero-oligomerization, although highly controversial up to a few years ago, has recently gained wide acceptance. The recognition that GPCRs may exhibit either dimeric or oligomeric structures is based upon a large body of biochemical and biophysical evidence. While much effort has been spent to demonstrate the mechanism(s) by which GPCRs interact with each other, the physiological relevance of this phenomenon remains rather elusive. GPCR oligomerization has been proposed to play a role in receptor ontogeny by either chaperoning protein folding or controlling trafficking to the cell surface. However, the acquisition of these roles does not rule out the possibility that oligomeric receptors may have additional functions, once they are brought to the cell surface. Herein, we propose that protein-protein as well as protein-lipid interactions may provide the structural basis for organizing distinct cell compartments along the plasma membrane where different extracellular signals may be perceived and discriminated.