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Related Concept Videos

Generation of Straight or Branched Actin Filaments01:14

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...
Introduction to Actin01:26

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.
Assembly of Cytoskeletal Filaments01:18

Assembly of Cytoskeletal Filaments

Cytoskeletal filaments are polymeric forms of smaller protein subunits. However, individual cytoskeletal filaments may easily disassemble or associate with other similar filaments to form rigid structures. Microfilaments, made of actin monomers, rely on actin-binding proteins to form bundles and create networks of individual actin filaments. Microtubules rely on microtubule-associated proteins (MAPs) to form sturdy cylindrical structures. However, the proteins involved in forming complex...
Formation of Higher-order Actin Filaments01:11

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...
Actin Polymerization01:42

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...
Cytoskeletal Proteins in Bacteria01:29

Cytoskeletal Proteins in Bacteria

Bacterial cells were initially considered simple, randomly organized structures lacking a cytoskeleton. However, the discovery of cytoskeleton homologs in bacteria led to the change of this opinion. Bacterial cytoskeletal filaments regulate the cell shape, cell polarity, cell division, and partitioning of plasmids during cell division. It was later discovered that bacterial cytoskeletal proteins, mainly actin and tubulin homologs, are diverse compared to their eukaryotic counterparts. On the...

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Related Experiment Video

Updated: May 23, 2026

Using Microfluidics and Fluorescence Microscopy to Study the Assembly Dynamics of Single Actin Filaments and Bundles
08:02

Using Microfluidics and Fluorescence Microscopy to Study the Assembly Dynamics of Single Actin Filaments and Bundles

Published on: May 5, 2022

FtsA forms actin-like protofilaments.

Piotr Szwedziak1, Qing Wang, Stefan M V Freund

  • 1MRC Laboratory of Molecular Biology, Cambridge, UK.

The EMBO Journal
|April 5, 2012
PubMed
Summary
This summary is machine-generated.

FtsA protein, crucial for bacterial cell division, tethers FtsZ to the membrane and forms filaments. Disrupting FtsA polymerization impairs cell division, highlighting its essential role in the Z-ring structure.

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Visualizing Actin and Microtubule Coupling Dynamics In Vitro by Total Internal Reflection Fluorescence (TIRF) Microscopy
08:44

Visualizing Actin and Microtubule Coupling Dynamics In Vitro by Total Internal Reflection Fluorescence (TIRF) Microscopy

Published on: July 20, 2022

Reconstitution of Actin-Based Motility with Commercially Available Proteins
08:40

Reconstitution of Actin-Based Motility with Commercially Available Proteins

Published on: October 28, 2022

Related Experiment Videos

Last Updated: May 23, 2026

Using Microfluidics and Fluorescence Microscopy to Study the Assembly Dynamics of Single Actin Filaments and Bundles
08:02

Using Microfluidics and Fluorescence Microscopy to Study the Assembly Dynamics of Single Actin Filaments and Bundles

Published on: May 5, 2022

Visualizing Actin and Microtubule Coupling Dynamics In Vitro by Total Internal Reflection Fluorescence (TIRF) Microscopy
08:44

Visualizing Actin and Microtubule Coupling Dynamics In Vitro by Total Internal Reflection Fluorescence (TIRF) Microscopy

Published on: July 20, 2022

Reconstitution of Actin-Based Motility with Commercially Available Proteins
08:40

Reconstitution of Actin-Based Motility with Commercially Available Proteins

Published on: October 28, 2022

Area of Science:

  • Bacteriology
  • Cell Biology
  • Structural Biology

Background:

  • FtsA is an essential early component of the bacterial Z-ring, responsible for cell division.
  • The Z-ring is primarily formed by the tubulin-like FtsZ protein.
  • FtsA, an actin family protein, exhibits a unique subdomain architecture.

Purpose of the Study:

  • To investigate the mechanism of FtsZ membrane tethering by FtsA.
  • To determine the structural basis of the FtsA:FtsZ interaction.
  • To explore the polymerization of FtsA and its role in Z-ring formation.

Main Methods:

  • In vitro reconstitution of FtsZ membrane tethering using purified proteins.
  • X-ray crystallography to determine the FtsA:FtsZ complex structure.
  • Electron cryotomography to visualize FtsA polymerization in vivo.
  • Site-directed mutagenesis to assess the function of FtsA polymerization.

Main Results:

  • FtsA tethers FtsZ to the membrane via its C-terminal helix.
  • Crystal structure reveals FtsZ tail binding to FtsA subdomain 2B.
  • FtsA forms actin-like protofilaments with a characteristic 48 Å repeat.
  • FtsA polymerization occurs on lipid surfaces and in vivo, and is essential for cell division.

Conclusions:

  • FtsA's filament formation is critical for its function in the Z-ring.
  • The structural insights provide a basis for understanding bacterial cell division mechanisms.
  • FtsA polymerization is a conserved mechanism essential for bacterial cytokinesis.