Characterization of the plasma membrane dynamics during cell signaling processes investigated by spot variation fluorescence correlation spectroscopy ( svFCS )

Abstract

The plasma membrane organization is highly heterogeneous as a result of the intrinsic molecular Brownian agitation and the vast diversity of membrane components. Selective interactions take place in the formation of local complex multicomponent assemblies of lipids and proteins on different time scales. Still, deciphering this lateral organization on living cells and on the appropriate length and temporal scales has been challenging but is crucial to advance our knowledge on the biological function of the plasma membrane. Among the methodological developments made during the last decade, the spot variation FCS (svFCS), a fluorescent correlation spectroscopy (FCS)‐based method, has allowed the significant progress in the characterization of cell membrane lateral organization at the sub‐optical level, including to providing compelling evidence for the in vivo existence of lipid‐dependent nanodomains (see for review ) 1 .This method provides particular insight to identify possible molecular confinement occurring at the plasma membrane 1, 2 . The svFCS is performed by changing the spot of illumination underfilling the back aperture of the objective 3 . Theoretical models have been developed to predict how geometrical constraints such as the presence of adjacent or isolated domains affect the svFCS observations 4, 5 . We will illustrate how the investigations based on svFCS have provided compelling evidence for the in vivo existence of lipid‐dependent nanodomains 2, 6, 7 and have allowed significant progress in the characterization of cell membrane lateral organization for different kind of receptors 8‐10 .