Lateral Membrane Heterogeneity Probed by FRET Spectroscopy and Microscopy

Abstract

Förster resonance energy transfer (FRET) is a photophysical process highly dependent on interchromophore distance. Due to this feature, it is very sensitive to membrane lateral heterogeneity, as the donor and acceptor fluorophores involved in FRET tend to have different preference for distinct types of lipid bilayer domains. In this chapter, the basic formalisms of FRET in situations of increasing complexity (from a single donor-acceptor pair at a fixed distance to non-random probe distribution) are presented and illustrated with selected examples from the literature. The importance of time-resolved fluorescence data is emphasized. It is shown that FRET can be used to study the occurrence of domain formation, allowing their detection as well as size estimation. Lateral lipid distribution hetero- geneity may also result from peptide- or protein-lipid interaction. Formalisms that apply to these situations are also presented, as well as selected examples of their use. Applications of FRET under the microscope have recently come to the fore, and representative studies are mentioned. Keywords