title: Discontinuous unbinding transitions of filament bundles.
abstract: Bundles of semiflexible polymers such as actin filaments are studied theoretically. The bundle formation is governed by attractive filament interactions mediated by cross-linking sticker molecules. Using a combination of analytical arguments and Monte Carlo simulations, it is shown that the formation of bundles of parallel filaments requires a threshold concentration of linkers which becomes independent of the filament number for large bundles. The unbinding of bundles happens in a single, discontinuous transition. We discuss the behavior of the bundle thickness at and below the transition. In the bound phase, large bundles tend to segregate into sub-bundles due to slow kinetics. Our results are in qualitative agreement with experiments on F-actin in the presence of the cross-linking protein alpha-actinin.
authors.affiliation: Max-Planck-Institut für Kolloid- und Grenzflächenforschung, 14424 Potsdam, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Kierfeld
authors.forename: Torsten
authors.initials: T
authors.lastname: Kühne
authors.forename: Reinhard
authors.initials: R
authors.lastname: Lipowsky
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000378:metabolism; D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D003198:Computer Simulation; D003432:Cross-Linking Reagents / Q000737:chemistry; D003599:Cytoskeleton / Q000737:chemistry* / Q000378:metabolism; D004548:Elasticity; D019277:Entropy; D007700:Kinetics; D008954:Models, Biological; D008956:Models, Chemical; D009010:Monte Carlo Method; D011108:Polymers / Q000737:chemistry*
chemical_list: D000199:Actins; D003432:Cross-Linking Reagents; D011108:Polymers