Understanding G protein-coupled receptor (GPCR) structure–function relationship and its activation mechanism has been broadly explored using mutational strategy due to problems in GPCR crystallization. Probing into GPCR: effector (G protein/β-arrestin) interactions and downstream signaling are important aspects of GPCR research. Among the G proteins, though there are some approaches to investigate Gq-mediated signaling, they involve the use of radioactivity and are qualitative in nature. Our method described here makes use of the cell permeable nature of fluorescent Ca2 + indicator dye, fura2AM, that binds with the Ca2 + released in response to GPCR: Gq interaction on ligand treatment. Using this spectrophotometric method, EC50 values of the GPCR: ligand binding can be calculated and the binding affinity can be analyzed. © 2017 Elsevier Inc.