Single-Molecule Fluorescence Microscopy for the Analysis of Fast Receptor Dynamics

Assessing the dynamics of individual membrane proteins in living cells is a powerful approach to investigate their assembly, mobility, and function. Here, we describe how to image single G protein-coupled receptors (GPCRs), both in the active and inactive state. This is achieved by combining labeling of GPCRs with bright organic fluorophores and fluorescent imaging by total internal reflection fluorescence microscopy. Using this method, individual tracks of single molecules can be analyzed in parallel with high spatial precision and with frame rates up to 50/s.