UNIT 1.22 Quantification of Allosteric Interactions at G Protein–Coupled Receptors Using Radioligand Binding Assays

  1. Katie Leach,
  2. Patrick M. Sexton,
  3. Arthur Christopoulos

Published Online: 1 MAR 2011

DOI: 10.1002/0471141755.ph0122s52

Current Protocols in Pharmacology

Current Protocols in Pharmacology

How to Cite

Leach, K., Sexton, P. M. and Christopoulos, A. 2011. Quantification of Allosteric Interactions at G Protein–Coupled Receptors Using Radioligand Binding Assays. Current Protocols in Pharmacology. 52:1.22:1.22.1–1.22.41.

Author Information

  1. Drug Discovery Biology, Monash Institute of Pharmaceutical Science and Department of Pharmacology, Monash University, Parkville, Victoria, Australia

Publication History

  1. Published Online: 1 MAR 2011
  2. Published Print: MAR 2011


Allosteric interactions involve the simultaneous binding of two ligands to the same receptor. An allosteric modulator causes a conformational change in the receptor protein that yields a change in the binding or signaling of an orthosteric agent, i.e., an agonist or competitive antagonist that binds to the endogenous agonist binding site. Because of the complex nature of allosteric phenomena, the detection and quantification of their effects on orthosteric ligand binding relies on the use of both equilibrium and non-equilibrium assays to ensure proper interpretation of the findings. Outlined in this unit are the most common experimental approaches for measuring allosteric effects on orthosteric ligand affinity at G protein-coupled receptors. There is also a discussion of the analysis of experimental data derived from such assays. Curr. Protoc. Pharmacol. 52:1.22.1-1.22.41. © 2011 by John Wiley & Sons, Inc.


  • allosterism;
  • allosteric interaction;
  • cooperativity;
  • radioligand binding;
  • G protein coupled-receptors;
  • dissociation kinetics;
  • non-equilibrium