Control of actin assembly and disassembly at filament ends

Department of Cell Biology, Washington University, Box 8228, St Louis, MO 631110, USA.
Current Opinion in Cell Biology (Impact Factor: 8.47). 03/2000; 12(1):97-103. DOI: 10.1016/S0955-0674(99)00062-9
Source: PubMed


The most important discovery in the field is that the Arp2/3 complex nucleates assembly of actin filaments with free barbed ends. Arp2/3 also binds the sides of actin filaments to create a branched network. Arp2/3's nucleation activity is stimulated by WASP family proteins, some of which mediate signaling from small G-proteins. Listeria movement caused by actin polymerization can be reconstituted in vitro using purified proteins: Arp2/3 complex, capping protein, actin depolymerizing factor/cofilin, and actin. actin depolymerizing factor/cofilin increases the rate at which actin subunits leave pointed ends, and capping protein caps barbed ends.

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Available from: Dorothy A Schafer, Feb 05, 2014
    • "If G-actin levels fall below the critical concentration, no more polymerization takes place. The maintenance of the actin pool necessitates the depolymerization of existing actin filaments which appears to be facilitated by different supporting proteins such as ADF and cofilin [124] [125]. "
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    • "Cell migration requires a number of changes, e.g. the reorganization of the actin cytoskeleton (Mogilner and Edelstein-Keshet, 2002), changes in cell shape and in activity of various cytokines and growth factors. On the other hand, proper organization of the cell cytoskeleton is essential for a number of fundamental processes in cells including proliferation, migration, differentiation, signal transmission or regeneration (Cooper and Schafer, 2000; Mogilner and Edelstein-Keshet, 2002; Pollard and Borisy, 2003). There are several reports indicating significant disruption of the hepatocyte actin cytoskeleton caused by MC-LR (Runnegar et al., 1995; Toivola and Eriksson, 1999; Batista et al., 2003). "
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    • "The dendritic nucleation treadmilling model proposes several steps whereby actin filament formation and turnover are coupled in order to generate and sustain the growing lamellipodial structure [9], [10]. This includes rapid elongation of barbed ends through the addition of profilin-ATP-actin [11], which pushes the membrane forward and termination of F-actin growth through the binding of F-actin capping proteins [12]. In addition, cofilin, an actin depolymerizing factor-homology (ADF-H) family member severs ADP-F-actin via conformational changes in filament structure and depolymerizes aged filaments at the pointed ends [13]. "
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