Structure of Arp2/3 complex in its activated state and in actin filament branch junctions

N Volkmann, KJ Amann, S Stoilova-McPhie, C Egile… - science, 2001 - science.org
N Volkmann, KJ Amann, S Stoilova-McPhie, C Egile, DC Winter, L Hazelwood, JE Heuser
science, 2001science.org
The seven-subunit Arp2/3 complex choreographs the formation of branched actin networks
at the leading edge of migrating cells. When activated by Wiskott-Aldrich Syndrome protein
(WASp), the Arp2/3 complex initiates actin filament branches from the sides of existing
filaments. Electron cryomicroscopy and three-dimensional reconstruction of Acanthamoeba
castellanii and Saccharomyces cerevisiae Arp2/3 complexes bound to the WASp carboxy-
terminal domain reveal asymmetric, oblate ellipsoids. Image analysis of actin branches …
The seven-subunit Arp2/3 complex choreographs the formation of branched actin networks at the leading edge of migrating cells. When activated by Wiskott-Aldrich Syndrome protein (WASp), the Arp2/3 complex initiates actin filament branches from the sides of existing filaments. Electron cryomicroscopy and three-dimensional reconstruction of Acanthamoeba castellanii andSaccharomyces cerevisiae Arp2/3 complexes bound to the WASp carboxy-terminal domain reveal asymmetric, oblate ellipsoids. Image analysis of actin branches indicates that the complex binds the side of the mother filament, and Arp2 and Arp3 (for actin-related protein) are the first two subunits of the daughter filament. Comparison to the actin-free, WASp-activated complexes suggests that branch initiation involves large-scale structural rearrangements within Arp2/3.
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