LANCE Ultra cAMP: A New TR-FRET cAMP Assay for Gs- and Gi-Coupled Receptors

Guanosine triphosphate binding proteincoupled receptors (GPCRs) represent one of the largest and most important classes of pharmaceutical drug targets. Approximately 48% of all GPCRs couple through adenylate cyclase making the need for a robust cAMP detection method critical. We have developed a secondgeneration LANCE® time-resolved fluorescence resonance energy transfer (TR-FRET) immunoassay designed to measure cAMP produced upon modulation of adenylyl cyclase activity by activated GPCRs. Here we present data comparing the performance in 384-well plate format of the new LANCE Ultra cAMP kit with that of two other commercially available cAMP kits, namely an alternative TR-FRET assay (dynamic 2) from Company C and two Enzyme Fragment Complementation (EFC) assays (XS+ and HS+) from Company D. These three cAMP assay technologies were evaluated for their ability to detect agonistor antagonist-induced cAMP responses in suspension cells expressing either endogenous (Gs-β-adrenergic) or recombinant receptors (Gs-MC4; Gi-CXCR3; Gi-CB1). The assay principle of the LANCE Ultra cAMP kit is shown in Figure 1. Time-Resolved Fluorescence Resonance Energy Transfer a p p l i c a t i o n n o t e