Brock Binkowski, Frank Fan, Pete Stecha, Braeden Butler and Keith Wood
Promega Corporation, 2800 Woods Hollow Rd., Madison, WI 53711
Cell-based assays provide biologically relevant context for drug screening and have increased in importance in recent years. Bioluminescence is uniquely suited for developing cell-based assays, especially for high-throughput screening, owing to the inherent high sensitivity, wide dynamic range and low susceptibility to compound interference. Here we present the use of a novel biosensor construct composed of a genetic fusion of a cAMP binding domain to a circularly permuted form of firefly luciferase. This biosensor can be used to rapidly interrogate changes in the concentration of intracellular cAMP using a live cell, nonlytic assay format. This format enables direct screens for allosteric modulators of Gs- and Gi-coupled 7-TM receptors and improved hit identification through multiple measurements. Moreover, the enhanced sensitivity of the assay allows detection of inverse agonists and the activation of Gi-coupled receptors in the absence of forskolin.