G Protein–Coupled Receptor Multimers: A Question Still Open Despite the Use of Novel Approaches

Heteromerization of G protein-coupled receptors (GPCR) can significantly change the functional properties of involved receptors. Various biochemical and biophysical methodologies have been developed the last two decades to identify and functionally evaluate GPCR heteromers in heterologous cells, with recent approaches focusing on GPCR complex stoichiometry and stability. Yet, validation of these observations in native tissues is still lacking behind for the majority of GPCR heteromers. Remarkably, recent studies, particularly some involving advanced fluorescence microscopy techniques, are contributing to our current knowledge on aspects that were not well known till now such as GPCR complex stoichiometry and stability. In parallel, a growing effort is being applied to move the field forward into native systems. This short review will highlight recent developments to study stoichiometry and stability of GPCR complexes and methodologies to detect native GPCR dimers.