Oral Presentation 2014 International Biophysics Congress

A tool for study membrane protein association in model membranes (#201)

Vladimir Adrien 1 , Gamal Rayan 1 , Myriam Reffay 1 , Martin Picard 2 , Arnaud Ducruix 2 , Wladimir Urbach 1 , Nicolas Taulier 3
  1. Laboratoire de Physique Statistique de l École Normale Supérieure, Paris, France
  2. Laboratoire de Cristallographie et R.M.N. Biologiques, Paris, France
  3. Laboratoire d'Imagerie Biomédicale, Paris, France

So far, most experimental techniques are limited to probing interactions between membrane proteins embedded into a bilayer and another protein solubilized in micelles. However when associations of membrane proteins are studied in micellar systems by techniques designed for soluble proteins, the results do not reflect what happens in reality. Indeed in bilayers, the anchorage to a membrane modifies the dynamics of the association by imposing a preferential orientation of the molecules and this reduces the dimensionality of the space to explore. We present here an approach that combines the Fluorescence Recovery After fringe Pattern Photobleaching technique and the use of a versatile sponge phase that makes possible to extract crucial information about interactions between membrane proteins embedded in the same bilayers or in facing ones. Indeed when the membranes are far apart, the only possible interactions occur laterally between proteins embedded within the same bilayer, whereas when membranes get closer to each other, interactions between proteins embedded in facing membranes may occur as well. The size of the protein complex, its stoichiometry and the mode of interaction can be thus determined. Furthermore the membrane proteins' associations can be studied in both 3-D and 2-D geometries and the kinetic rates for association and dissociation as well as the dissociation constant can be easily obtained. Our method opens a new and wide range of experiments to understand membrane proteins' associations. Additionally, we believe that it can be extended to other techniques such as FRET or FCS.