The Characterization of a Transmembrane Receptor Protein by Fluorescence Correlation Spectroscopy

Fluorescence Correlation Spectroscopy (FCS) is a powerful technique for the in vivo and in vitro investigation of biomolecular interactions. It was first described almost three decades ago [8, 13, 14] and has found, especially in the last ten years, increased interest as a tool for screening of ligand—receptor interactions in fundamental research [18, 12, 24, 31] and in drug development [19, 20, 1, 30]. In this contribution, we use FCS for the characterization of a transmembrane receptor protein. Determined parameters include the molecular mass of the protein, the stoichiometry of binding, equilibrium constants of receptor—ligand interactions, and the lateral diffusion and organization of proteins on the surface of living cells.