G Protein-Coupled Receptor-Mediated ERK1/2 Phosphorylation: Towards a Generic Sensor of GPCR Activation

The development of new analytical methods, aimed at profiling G protein-coupled receptor (GPCR) ligands, regardless of the G protein-coupling pattern of their respective receptor, remains a key goal in drug discovery. Considerable evidence has recently revived the central role that could be played by extracellular-signal-regulated kinase (ERK), the cornerstone protein kinase of the first tyrosine kinase receptor-mediated pathway identified, in response to the activation of various types of GPCRs. Here we reveal a conceptual study in which the potential of ERK phosphorylation is evaluated as a generic readout in response to three different receptors activating three main classes of G proteins: Gα_s, Gα_i and Gα _q. GPCR-mediated ERK phosphorylation was compared with different readouts such as GTPγ S, CAMP, or Ca^{2 +}. We propose the measurement of GPCR-activated ERK phosphorylation as an alternative assay to better understand the molecular pharmacology of ligands of promiscuous GPCRs.