Radioligand Binding Studies: Pharmacological Profiles of Cloned Y-Receptor Subtypes

Radioligand binding is an extremely powerful technique that can provide detailed information about receptor-ligand interactions both in vitro and in vivo. Several types of binding assay can be performed, including studies of the kinetics of association or dissociation of the radiolabeled ligand, and equilibrium binding experiments such as saturation and competition binding assays. Data obtained from such studies generate accurate information regarding receptor number, ligand affinity, the existence of receptor subtypes, and allosteric interactions between binding sites and/or receptors. Generally receptorligand interactions are studied using membrane preparations since these give highly reproducible results. However, the technique can also be adapted to other preparations such as whole cells, tissue slices, solubilized receptors, and even whole animals. The techniques used and problems associated with radioligand binding studies are reviewed in ref. 1 .