Scintillation Proximity Assay (SPA): Custom Assay Development and Membrane Validation

G protein-coupled receptors (GPCRs) represent attractive drug targets because they participate in a wide range of physiological processes and are believed to play a role in a variety of disease states. At least a third of all prescription drugs on the market today are molecules acting as agonists or antagonists of the GPCR. Receptor-ligand interaction studies are pivotal in the successful identification of drug candidates. Despite numerous advances in nonradioactive technologies, radioligand binding assays remain one of the most commonly used technologies for analysis of ligand-receptor interaction in High Throughput Screening (HTS) and Structure Activity Relationship (SAR) studies. Among the different radioligand binding assays developed, Scintillation Proximity Assay (SPA) is a well established technology, offering the advantage of being homogenous (no separation of the bound and unbound radiotracer), and therefore easily amenable for miniaturization and automation. In addition to traditional filtration and FlashPlate® assays, PerkinElmer has also developed SPA binding conditions for a large number of receptors (see list below). Custom development of SPA assays can be performed utilizing PerkinElmer’s OnPoint Reagent Service team.