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BP: Fachverband Biologische Physik

BP 2: Protein Structure \& Dynamics

BP 2.4: Talk

Monday, March 14, 2011, 11:15–11:30, ZEU 260

Lateral Diffusion and Correlation of Membrane Anchored Proteins — •Wasim Abuillan¹, Andreas Hartel², Nicola Jones², Markus Engstler², and Motomu Tanaka¹ — ¹Institute for Physical Chemistry, Heidelberg University, Germany — ²Department of Cell and Developmental Biology, Würzburg University, Germany

Many Glycosylphosphatidylinositol (GPI) - anchored proteins are found on the plasma membrane.e.g. ~ 0.5 % of cellular proteins in eukaryotes are GPI-anchored. For example, GPI-anchored Variant Surface Glycoprotein (VSG) is among the most abundant cell-surface proteins in trypanosoma protozoa, playing important roles in viability and defense against the host immune system. The lateral mobility of lipids and membrane proteins is essential for them to maintain their function. The lateral correlation and coupling of membrane proteins are studied by Grazing Incidence Small Angle X-ray Scattering (GISAXS) and high energy X-ray reflectivity (XRR) at the air/water and solid/water interfaces. Although this has been a challenge due to the low contrast in the scattering length density of proteins, we have successfully detect the two membrane anchored proteins using XRR and GISAXS: (i) engineered recombinant avidin coupled to biotinylated lipids, and (ii) GPI-anchored VSG purified from trypanosoma. XRR results revealed the uniform coupling/incorporation of proteins to the membrane surface, while the form- and structure factors of the proteins in the plane of membranes have been determined by GISAXS.