Homogeneous Techniques for Monitoring ReceptorLigand Interactions

Radioligand binding is a well-established technique that has been used to study the interactions of extracellular ligands and their corresponding cell-surface receptors (1 ). The initial studies relied on laborious, vacuum-filtration techniques that are cumbersome and difficult to automate. Despite these limitations, filtration-based radioligand binding assays were adequate to probe the kinetics of receptor-ligand interactions and to screen small libraries of compounds in search of receptor-binding antagonists. A number of reviews are available that described this methodology in detail (2 ,3 ).