Dimerization of G protein-coupled purinergic receptors: increasing the diversity of purinergic receptor signal responses and receptor functions.

It is well accepted that G protein-coupled receptors (GPCRs) arrange into dimers or higher-order oligomers that may modify various functions of GPCRs. GPCR-type purinergic receptors (i.e. adenosine and P2Y receptors) tend to form heterodimers with GPCRs not only of the different families but also of the same purinergic receptor families, leading to alterations in functional properties. In the present review, we focus on current knowledge of the formation of heterodimers between metabotropic purinergic receptors that activate novel functions in response to extracellular nucleosides/nucleotides, revealing that the dimerization seems to be employed for 'fine-tuning' of purinergic signaling. Thus, the relationship between adenosine and adenosine triphosphate is likely to be more and more intimate than simply being a metabolite of the other.