Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 54: Biomaterials and Biopolymers II (Joint CPP/BP/MM)
MM 54.4: Vortrag
Donnerstag, 10. März 2016, 12:30–12:45, H52
Mechanical properties of branched actin filaments — •Mohammadhosein Razbin1, Martin Falcke3,4, Panayotis Benetatos5, and Annette Zippelius1,2 — 1Georg August University — 2Max Planck Institute for Dynamics and Selforganization — 3Humboldt University — 4Max Delbrueck Center for Molecular Medicine — 5Kyungpook National University
Motile cells on a 2dimensional substrate generate motion by flat membrane protrusion called lamellipodia. Within lamellipodia, actin filaments are generated by branching off existing ones, giving rise to branched network structures. We investigate the force-extension relation of branched actin filaments, grafted on an elastic substrate at one end and pushing with the free ends against a flat and stiff wall. We compute the thermal fluctuation of the endpoints and the resulting entropic forces on a membrane, restricting the fluctuations of the endpoints. The entropic forces are shown to depend sensitively not only on the persistence length but also on the geometry of the structure. It depends on branch point position and filament orientation, being most pronounced for intermediate tilt angles and intermediate branch point positions. We describe filament networks without cross-linkers to focus on the effect of branching. We compare properties of branched and unbranched networks. The ratio of the network average of the force per branched filament to the average force per unbranched filament exhibits compression dependence and may go up to about 4.5 in networks with a narrow orientation distribution. With orientation distributions measured in lamellipodia, it is about 2.