Measurement of Agonist-Stimulated [35S]GTPS Binding to Cell Membranes

This chapter describes a functional assay which measures the increase in guanine nucleotide exchange at G-proteins in cell membranes, resulting from agonist binding to G-protein-coupled receptors (GPCRs), by monitoring the binding of [³⁵ S]GTPγS, a radiolabeled, hydrolysis-resistant analog of GTP (guanosine triphosphate), in the presence of unlabeled GDP (guanosine triphosphate).