The Arp2/3 complex branches filament barbed ends: functional antagonism with capping proteins.
The Arp2/3 complex is an essential regulator of actin polymerization in response to signalling and generates a dendritic array of filaments in lamellipodia. Here we show that the activated Arp2/3 complex interacts with the barbed ends of filaments to initiate barbed-end branching. Barbed-end branching by Arp2/3 quantitatively accounts for polymerization kinetics and for the length correlation of the branches of filaments observed by electron microscopy. Filament branching is visualized at the surface of Listeria in a reconstituted motility assay. The functional antagonism between the Arp2/3 complex and capping proteins is essential in the maintenance of the steady state of actin assembly and actin-based motility.
Pantaloni
D
D
Laboratoire d'Enzymologie et Biochimie Structurale, CNRS, Gif-sur-Yvette, France.
Boujemaa
R
R
Didry
D
D
Gounon
P
P
Carlier
M F
MF
D008841:Actin Cytoskeleton / Q000737:chemistry / Q000378:metabolism*; D051339:Actin Depolymerizing Factors; D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism; D003598:Cytoskeletal Proteins; D051345:Destrin; D018260:Gelsolin / Q000378:metabolism; D007700:Kinetics; D008089:Listeria monocytogenes / Q000502:physiology*; D008840:Microfilament Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008854:Microscopy, Electron; D008954:Models, Biological; D009068:Movement; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011817:Rabbits; D012996:Solutions; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal
D051339:Actin Depolymerizing Factors; D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins; D001704:Biopolymers; D003598:Cytoskeletal Proteins; D051345:Destrin; D018260:Gelsolin; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D012996:Solutions; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal