title: Forster resonance energy transfer in liposomes: measurements of transmembrane helix dimerization in the native bilayer environment.
abstract: The lipid bilayer vesicle is a model of the cellular membrane. Even in this simple system, however, measuring the thermodynamics of membrane protein association is a challenge. Here we discuss Forster resonance energy transfer (FRET) in liposomes as a method to probe the dimerization of transmembrane helices in a membrane environment. Although the measurements are labor intensive, FRET in liposomes can be measured accurately provided that attention is paid to sample homogeneity and sample equilibration. One must also take into account statistical expectations and the FRET that results from random colocalization of donors and acceptors in the bilayer. Without careful attention to these details, misleading results are easy to obtain in membrane FRET experiments. The results that we obtain in model systems are reproducible and depend solely on the concentration of the protein in the bilayer (i.e., on the protein-to-lipid ratio), thereby yielding thermodynamic parameters that are directly relevant to processes in biological membranes.
authors.affiliation: Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
authors.forename: Min
authors.initials: M
authors.lastname: You
authors.forename: Edwin
authors.initials: E
authors.lastname: Li
authors.forename: William C
authors.initials: WC
authors.lastname: Wimley
authors.forename: Kalina
authors.initials: K
authors.lastname: Hristova
mesh_terms: D019281:Dimerization; D005453:Fluorescence; D031541:Fluorescence Resonance Energy Transfer; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism*; D050356:Lipid Metabolism; D008081:Liposomes / Q000737:chemistry* / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D013816:Thermodynamics
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes; D008565:Membrane Proteins