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Updated: Jul 5, 2026
08:57
Aip1p Dynamics Are Altered by the R256H Mutation in Actin
Published on: July 30, 2014
X-ray scattering study of activated Arp2/3 complex with bound actin-WCA
Malgorzata Boczkowska1, Grzegorz Rebowski, Maxim V Petoukhov
1Department of Physiology, University of Pennsylvania School of Medicine, 3700 Hamilton Walk, A507 Richards Building, Philadelphia, PA 19104-6085, USA.
Structure (London, England : 1993)
|May 9, 2008
Summary
Researchers stabilized the activated Arp2/3 complex with N-WASP's WCA region and an actin monomer. Small angle X-ray scattering (SAXS) revealed actin binds to Arp2, supporting a new activation model.
Area of Science:
- Cell biology
- Biochemistry
- Structural biology
Background:
- The Arp2/3 complex is crucial for actin nucleation, but its activated structure is difficult to study.
- Previous structural studies captured the inactive conformation of the Arp2/3 complex.
Purpose of the Study:
- To determine the structure of the activated Arp2/3 complex in solution.
- To elucidate the mechanism of Arp2/3 complex activation by N-WASP.
Main Methods:
- Engineered a stable activated complex of Arp2/3, N-WASP WCA region, and actin monomer.
- Utilized small angle X-ray scattering (SAXS) to study the complex in solution.
Main Results:
- Scattering data support a model where the first actin monomer binds to the barbed end of Arp2.
- This binding position disqualifies models placing actin at the Arp3 barbed end.
- Constrained binding sites for N-WASP motifs (W, C, A) were identified, consistent with biochemical data.
Conclusions:
- The study provides structural evidence for a specific model of Arp2/3 complex activation.
- The findings reconcile structural data with existing biochemical observations of actin polymerization.
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Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
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Actin polymerization occurs through the head-to-tail association of binding sites on monomeric actin or G-actin to form filamentous or F-actin. The polymerization can be divided into three phases ̶ nucleation, elongation, and steady-state phase.
The nucleation phase involves forming a stable nucleus consisting of three actin monomers to form a new actin filament. Actin-binding proteins such as formins and Arp2/3 complex help filament growth post-nucleation. The Formins form straight actin...
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In F-actin, the ADF/cofilin proteins...
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The high-order actin networks...
The high-order actin networks...
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