Use of the DiscoveRx Hithunter cAMPII Assay for Direct Measurement of cAMP in Gs and Gi GPCRs

G protein-coupled receptors (GPCRs) are druggable targets of great interest to the pharmaceutical industry. Generally, functional cell-based assays can be employed to detect agonists (inverse, partial, and full) in addition to allosteric and classical orthosteric antagonists. Several different homogenous assay systems can be used to monitor the signaling cascades of GPCRs. This chapter details the authors’ collective experience of using the DiscoverX Hit Hunter cAMPII kit from GE Healthcare/DiscoverX Corporation for the direct quantification of cAMP levels in Gs and Gi GPCRs.