Dresden 2009 – scientific programme

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BP: Fachverband Biologische Physik

BP 22: Transport Processes and Cellular Trafficking

BP 22.8: Talk

Thursday, March 26, 2009, 16:30–16:45, ZEU 260

Diffusional properties of unfolded proteins — •Nina Malchus and Matthias Weiss — German Cancer Research Center, Heidelberg, Deutschland

The diffusion characteristics of tracer particles in complex systems reveals properties of the surrounding medium and its interaction with the tracer. Using fluorescence correlation spectroscopy (FCS), we have examined the diffusion of folded and unfolded membrane proteins in the endoplasmatic reticulum (ER) of living cells to elucidate the interactions of unfolded proteins with the chaperone machinery. Both, folded and unfolded proteins, show anomalous diffusion with a mean square displacement ∝ t^α, α<1. For unfolded proteins the anomaly was significantly stronger, i.e. α was lower. Disrupting the interaction between chaperones and unfolded proteins resulted in a shift of the anomaly to the values observed for folded proteins. Accompanying computer simulations indicate that obstructed diffusion in the ER and complex formation of chaperones and unfolded proteins are responsible for the observed phenomena. This prediction is well supported by additional experiments.