Résumé:

Biomimetic systems such as giant unilamellar vesicles (GUVs) are increasingly used for studying protein/lipid interactions due to their size (similar to that of cells) and to their ease of observation by light microscopy techniques. We use GUVs to understand in vitro, using purified proteins and biomimetic membranes, the interplay between specific proteins and lipids with actin in the organisation of the linkage between the cytoskeleton and the plasma membrane. These components contribute to the anchoring of a cell in its environment as they are localized in membrane protrusions. The protein Ezrin, a membrane cytoskeleton linker involved in the cellular morphogenesis and motility, provides a direct link between the plasmic membrane of cells and the actin cytoskeleton through its interaction with phosphatidylinositol(4,5) bisphosphate (PIP2), a lipid which plays important physiological roles in cellulo. We will first show zeta potential measurements and confocal microscopy images that quantify the incorporation of PIP2 in the membrane of GUVs, and then present results on the interaction of ezrin with PIP2-containing GUVs.