Probe dependence of allosteric enhancers on the binding affinity of adenosine A1 -receptor agonists at rat and human A1 -receptors measured using NanoBRET.

These results demonstrate the power of the NanoBRET ligand-binding approach to study the effect of allosteric ligands on the binding of fluorescent agonists to the adenosine A1 -receptor in intact living cells. Furthermore, our studies suggest that VCP171 and PD 81,723 may switch a proportion of A1 -receptors to an active agonist conformation (R*).