関連する実験動画
Updated: Jun 28, 2026

08:57
Aip1p Dynamics Are Altered by the R256H Mutation in Actin
Published on: July 30, 2014
活性化状態のArp2/3複合体の構造とアクチンフィラメントの枝接点における構造
N Volkmann1, K J Amann, S Stoilova-McPhie
1The Burnham Institute, La Jolla, CA 92037, USA.
まとめ
Arp2/3複合体は,細胞移動に不可欠な枝分かれしたアクチンネットワークを開始します. 構造分析により,ウィスコット・オールドリッヒ症候群タンパク質 (WASp) によって活性化されたこの複合体が,新しいアクチン繊維を形成するためにどのように再編成されるかが明らかになります.
科学分野:
- 細胞生物学 細胞生物学
- バイオケミストリー バイオケミストリー
- 構造生物学 構造生物学とは
背景:
- Arp2/3複合体は,アクチン細胞骨格の重要な調節体である.
- アクチンネットワークは,細胞の運動性と形状に不可欠です.
- ウィスコット・オールドリッヒ症候群のタンパク質 (WASp) は,Arp2/3複合体を活性化させます.
研究 の 目的:
- Arp2/3 複合媒介アクチン分岐開始の構造的メカニズムを解明する.
- Arp2/3複合体の活性化におけるWASpの役割を理解する.
主な方法:
- 高解像度イメージングのための電子冷凍顕微鏡 (cryo-EM).
- タンパク質複合体の3次元 (3D) 再構築.
- アクチンフィラメントの分岐の画像分析.
主要な成果:
- Arp2/3複合体は,非対称で,平らな円形の構造を持っています.
- 複合体は,既存の (母) アクチンフィラメントの側面に結合します.
- アクチン関連タンパク質Arp2とArp3は,新しい (子) 糸の初期サブユニットを形成する.
- Arp2/3複合体内で,WASpの活性化とアクチン結合により構造的再編成が発生する.
結論:
- Arp2/3複合体は,アクチン分岐を開始するために重要な構造変化を経験しています.
- このメカニズムは,Acanthamoeba castellaniiとSaccharomyces cerevisiaeを含むさまざまな種で保存されています.
- Arp2/3の複雑な構造と機能を理解することで,細胞の移動と関連する疾患の洞察が得られます.
関連する概念動画
Introduction to Actin
Actin is a highly conserved cytoskeletal protein found abundantly in eukaryotic cells. It constitutes 10% weight of the total cellular protein in muscle cells, while in non-muscle cells, it is lower and makes up around 1–5 percent of the total cell protein. Actin found in the unicellular amoebae and complex multicellular animals is around 80% similar, demonstrating their conservation over a billion years of evolution. Actin coding genes are conserved within species and across different species.
Actin Polymerization
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...
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...
Generation of Straight or Branched Actin Filaments
The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
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...
Actin Filament Depolymerization
Actin filaments (F-actin) are composed of actin subunits. The dissociation of actin monomers can occur from either end of F-actin. The rate of dissociation is faster from the minus-end or the pointed end, where the actin subunits exist with a bound ADP, together known as ADP-actin. The depolymerization of F-actin is aided by proteins, including the actin-depolymerizing factor (ADF) and cofilin family of proteins, gelsolin, and glia maturation factor (GMF).
In F-actin, the ADF/cofilin proteins...
In F-actin, the ADF/cofilin proteins...
Formation of Higher-order Actin Filaments
The polymerization of G-actin monomers into filamentous F-actin is a multi-step process. Once the F-actins are formed, they can bundle together in different arrangements to form higher-order networks and regulate cellular functions. Common examples include the formation of lamellipodia and filopodia at the cell's leading edge by actin reorganization in a migrating cell. The microvilli on the brush border epithelial cells are also formed through the F-actin network.
The high-order actin networks...
The high-order actin networks...
Mechanism of Filopodia Formation
Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, length, and positioning in different cell types, suggesting their diverse roles.
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...

