Berlin 2005 – scientific programme

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AKB: Biologische Physik

AKB 100: Poster Session I

AKB 100.14: Poster

Saturday, March 5, 2005, 16:45–18:45, Poster TU D

Protein diffusion in living cells: anomalous is normal — •Matthias Weiss — MEMPHYS–Center for Biomembrane Physics,University of Southern Denmark, Odense, Denmark& BIOMS–Center for Modelling and Simulation in the Biosciences, Heidelberg, Germany

Using fluorescence correlation spectroscopy (FCS) it is shown that (inert) macromolecules in the cytoplasm exhibit a size- and conformation-dependent anomalous sub-diffusion, i.e. the particles’ mean square displacement v(t) grows less than linear in time (v(t)∼ t^α, α<1). By accompanying these observations with model simulations and in vitro experiments it is demonstrated that this behavior is a generic consequence of ’molecular crowding’ [1]. In other words, the anomality α of the diffusion yields a quantifiable measure for the ’crowdedness’ of a fluid on the molecular scale.

It is further highlighted that integral membrane proteins also move sub-diffusively on organellar membranes, e.g. in the endoplasmic reticulum and the Golgi apparatus [2]. Using a simulation approach, this observation is shown to be consistent with the postulated transient formation of oligomers during the process of protein sorting.

[1] Weiss et al., Biophys. J. 87, 3518 (2004).

[2] Weiss et al., Biophys. J. 84, 4043 (2003).