Fluorescence correlation spectroscopy for detecting submicroscopic clusters of fluorescent molecules in membranes

The formation of cell surface receptor clusters has been implicated or confirmed in the mechanism of signal transduction across biological membranes for a variety of processes, including receptor-mediated phagocytosis and endocytosis and cellular response to hormones and neurotransmitters. Fluorescence correlation spectroscopy (FCS) is one technique that may provide insight into the kinetics and extent of receptor aggregation. Recent theoretical and experimental developments in FCS for the investigation of submicroscopic clusters of fluorescent molecules are described and the potential applications of the technique to receptor aggregation are reviewed.