Detection of G Protein-Coupled Receptors by Immunofluorescence Microscopy

G protein-coupled receptors (GPCRs) are activated by a wide array of signals, which include light, neurotransmitters, hormones, cytokines, and drugs. Knowledge of the subcellular distribution of GPCRs is required in many experimental situations. Most GPCR signaling occurs in response to activators that interact with receptors localized on the cell surface. GPCRs must move from their site of synthesis to the plasma membrane, often undergoing redistribution in response to ligand binding. Endocytosis and recycling of receptors are important for desensitization and resensitization. Furthermore, mutations in GPCRs can alter receptor trafficking and prevent normal receptor function. This chapter describes a widely applicable method for visualizing a GPCR by indirect immunofluorescence microscopy.