Principles: a model for the allosteric interactions between ligand binding sites within a dimeric GPCR.

Increasing evidence suggests that most, if not all, G-protein-coupled receptors have the propensity to dimerize. The dimerization process can lead to crosstalk between the protomers and can result in cooperative binding of ligands to these protomers. However, many results suggest that the crosstalk between protomers within a dimer is not permanent. Receptors oscillate between two states: one that enables binding sites to crosstalk and another that does not enable such crosstalk. In this article, the consequences of the equilibrium between these two states on the binding properties of a receptor are analyzed using the predictions of two mathematical models.