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Updated: May 12, 2026
08:57
Aip1p Dynamics Are Altered by the R256H Mutation in Actin
Published on: July 30, 2014
Unconventional actin configurations step into the limelight.
Unai Silván1, Brigitte M Jockusch, Cora-Ann Schoenenberger
1Focal Area Structural Biology and Biophysics, Biozentrum, University of Basel, Basel, Switzerland.
Advances in Protein Chemistry and Structural Biology
|April 16, 2013
Summary
Actin
Area of Science:
- Cell Biology
- Biochemistry
- Structural Biology
Background:
- Actin polymerization into microfilaments is conserved across life.
- Eukaryotes have highly conserved actins despite diverse functions.
- Actin research traditionally focuses on G-actin and F-actin states.
Purpose of the Study:
- To review current knowledge on actin structure and polymerization.
- To highlight less-studied actin conformations and structures.
- To explore the role of diverse actin forms in cellular functions.
Main Methods:
- Literature review of actin structure and function.
- Analysis of actin-binding protein influence on actin conformation.
- Examination of supramolecular actin assemblies beyond F-actin.
Main Results:
- Actin exhibits significant structural plasticity beyond G-actin and F-actin.
- Over 200 actin-binding proteins modulate actin conformation and function.
- Emerging research reveals unconventional actin conformations and higher-order structures.
Conclusions:
- Actin's functional diversity arises from its complex structural plasticity.
- Understanding non-classical actin forms is crucial for cell biology.
- Further research into novel actin structures will uncover new cellular roles.
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01:14Generation 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...
01:11Formation 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...
01:26Introduction 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.
01:42Actin 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...
01:18Actin Treadmilling
Actin filaments undergo polymerization and depolymerization from either end. The polymerization and depolymerization rates depend on the cytosolic concentration of free G-actins. The polymerization rate is generally higher at the plus or barbed end, while the depolymerization rate is higher at the minus or pointed end. At a steady state, critical concentration describes the concentration of free G-actin monomers at which the polymerization rate at the plus end is equal to that of the...
01:13Actin Polymerization and Cell Motility
Actin is a family of globular proteins that are highly abundant in eukaryotic cells. It makes up approximately 1-5% of total cell protein concentration. Actin monomers polymerize to form a complex network of polarized filaments, the actin cytoskeleton, that plays a crucial role in many cellular processes, including cell motility, division, endocytosis, and metastasis of cancer cells.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.