title: Stimulation of actin polymerization by filament severing.
abstract: The extent and dynamics of actin polymerization in solution are calculated as functions of the filament severing rate, using a simple model of in vitro polymerization. The model is solved by both analytic theory and stochastic-growth simulation. The results show that severing essentially always enhances actin polymerization by freeing up barbed ends, if barbed-end cappers are present. Severing has much weaker effects if only pointed-end cappers are present. In the early stages of polymerization, the polymerized-actin concentration grows exponentially as a function of time. The exponential growth rate is given in terms of the severing rate, and the latter is given in terms of the maximum slope in a polymerization time course. Severing and branching are found to act synergistically.
authors.affiliation: Department of Physics, Washington University, St. Louis, Missouri, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Carlsson
mesh_terms: D051339:Actin Depolymerizing Factors / Q000737:chemistry; D000199:Actins / Q000737:chemistry*; D000818:Animals; D001665:Binding Sites; D001703:Biophysics / Q000379:methods*; D051338:Cofilin 1 / Q000737:chemistry; D003599:Cytoskeleton / Q000737:chemistry; D004023:Dictyostelium; D008840:Microfilament Proteins / Q000737:chemistry / Q000502:physiology; D008954:Models, Biological; D008962:Models, Theoretical; D011485:Protein Binding; D013816:Thermodynamics
chemical_list: D051339:Actin Depolymerizing Factors; D000199:Actins; D051338:Cofilin 1; D008840:Microfilament Proteins; C115237:actin interacting protein 1