ICS Key Visual

Navigation und Service

GUVs (giant unilamellar vesicles)


Phase contrast image of DUPC GUVs after formation on a ITO-coated coverslide

  • Freestanding bilayer mimics cell membranes

  • Vesicle size: Ø 2µm – 20µm

  • Entrapment of single molecules/proteins under physiological conditions or
    incorporation of integral membrane proteins by fusogenic peptides (e.g. WAE-11)

  • Well defined artificial membrane systems

  • Diffusion of integral membrane proteins as well as protein-protein and protein-lipid interaction is almost unperturbed

  • Immobilisation to functionalized surface employing a biotin-streptavidin binding assay

In order to monitor membrane–protein binding in lipid bilayers at physiological protein concentrations, we employed the recently developed dual-focus fluorescence correlation spectroscopy (2fFCS) technique. In a case study on a photoreceptor (SRII from Natronomonas pharaonis) consisting of seven transmembrane helices and its cognate transducer (HtrII; two transmembrane helices), the lateral diffusion for these integral membrane proteins was analyzed in GUVs. The two-dimensional diffusion coefficients of both separately diffusing proteins differ significantly, with D = 2.2×10−8 cm2 s−1 for the photoreceptor and with D = 4.1×10−8 cm2 s−1 for the transducer. In GUVs with both membrane proteins present together, we observed significantly smaller diffusion coefficients for labelled transducer molecules; this indicates the presence of larger diffusing units and therefore intermolecular protein binding. Based on the phenomenological dependence of diffusion coefficients on the molecule's cylindrical radius, we are able to estimate the degree of membrane protein binding on a quantitative level.

Kriegsmann et al., ChemBioChem 2009, 10, 1823-1829



Single fluorescently labeled lipid molecules diffusing within the lipid bilayer of a GUV



Fusion of WAE-11 tagged proteoliposomes containing fluorescently labeled SRII with GUV

Contact: Dr. Iris v. d. Hocht