Regensburg 2010 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 9: Physics of Cells I

BP 9.5: Vortrag

Dienstag, 23. März 2010, 10:45–11:00, H43

Structural transitions in growing actin networks — •Julian Weichsel and Ulrich Schwarz — University of Heidelberg, Institute for Theoretical Physics

The directed polymerization of a branched actin network is a universal propulsion system used in many different contexts of biological relevance, including the migration of animal cells and the motility of intracellular pathogens like Listeria. It also can be reconstituted in cell-free assays, for example to propel plastic beads or vesicles. Despite the universal nature of the underlying mechanisms of filament growth, branching and capping, conflicting results have been reported for the force-velocity relation of growing actin networks. Using a relatively simple theoretical model, we show that the interplay between filament and network growth leads to structural transitions in the network which can explain the experimental observations. Using a rate equation approach, we analytically calculate a phase diagram which is in excellent agreement with stochastic simulations of network growth.