Regensburg 2016 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 31: Statistical Physics of Biological Systems I (Joint Session with DY)

BP 31.1: Vortrag

Dienstag, 8. März 2016, 12:00–12:15, H43

Interplay of directed transport and diffusive motion inside cellular protrusions — •Isabella Krämer and Erwin Frey — Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität, München, Deutschland

Linear cellular protrusions are characterized by their finger-like structure that is connected to the cell body at one end, the base, and extends into the surroundings at the other end, the tip. A membrane enclosing the protrusion separates the inside from the extracellular and prevents in- and outflux other than at the base. Inside the protrusion bundles of parallel actin filaments are embedded into cytoplasm so that different types of motion interact: directed transport of cargo towards the tip on the actin filaments and diffusive motion inside the cytoplasm.

Motivated by this biological process we study the steady-state behaviour of a totally asymmetric simple exclusion process (TASEP) that is weakly coupled to different diffusive environments and focus on systems that are closed at the tip of the TASEP. We derive an exact equation that relates the average total occupation on the TASEP to the average total occupation on the diffusive lattice coupled to it. This mass balance equation represents a global detailed balance for the exchange between the two lattices, where detailed balance does not hold locally for any pair of sites but for the two lattices in total. We show that the steady-state profile on the TASEP is given by a localized domain wall whose position can be determined using the mass balance equation. By further exploiting this equation we find an analytic expression for the nearest-neighbour correlations on the TASEP.