Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

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...
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...
Cytoskeletal Accessory Proteins01:13

Cytoskeletal Accessory Proteins

The cytoskeleton is an essential cell component that plays several structural and functional roles. However, the filaments that make up the cytoskeleton cannot function independently and depend on the accessory or ancillary proteins to effectively carry out their function. Accessory proteins associate with cytoskeletal filaments and their monomers, aiding filament formation and function. They also help in the cross-communication among cytoskeletal filaments. Cytoskeletal accessory proteins are...
Mechanism of Filopodia Formation01:39

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...
Actin Filament Depolymerization01:19

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...
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...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Synergistic assembly, disassembly, and protection of complex forms of bundled F-actin.

The Journal of cell biology·2026
Same author

The Cappuccino interactome reveals an intracellular role for Semaphorin-2a in <i>Drosophila</i> oogenesis.

bioRxiv : the preprint server for biology·2026
Same author

Structural evidence that RNA contributes to polymorphism of tau amyloid fibrils.

iScience·2026
Same author

In Vitro and In Vivo Evaluation of Small-Molecule Disassemblers of Pathological Tau Fibrils.

ACS chemical neuroscience·2026
Same author

The Influence of Drosophila Spire and Myosin V During Mid-Oogenesis Is Independent of Their Direct Interaction.

Cytoskeleton (Hoboken, N.J.)·2025
Same author

Genetic and structural aspects of amyloid diseases.

Science translational medicine·2025
Same journal

Correction: Characterization of Mast2 kinase defines structural features, regulation, and substrates.

The Journal of biological chemistry·2026
Same journal

Isotope-Edited ESEEM: A New Method for Probing Copper Binding Sites in Neurodegenerative Proteins.

The Journal of biological chemistry·2026
Same journal

Introduction to the Thematic Review Series on Intracellular Protein Degradation. The ubiquitous biology of intracellular protein degradation: a tribute to Alfred L. ("Fred") Goldberg.

The Journal of biological chemistry·2026
Same journal

Correction: Aromatic residue-rich amino-terminal segments of temporin L self-assemble into collagen-mimetic peptides with cell-adhesion properties.

The Journal of biological chemistry·2026
Same journal

YhbO is a DJ-1 family glyoxalase and α-oxoaldehyde hydratase that confers resistance to reactive carbonyl stress (112).

The Journal of biological chemistry·2026
Same journal

ARMH3 acts as a central scaffold at the Golgi/TGN through interactions with Arl5, GBF1, and PI4KB.

The Journal of biological chemistry·2026
See all related articles

Related Experiment Video

Updated: May 24, 2026

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

Multiple forms of Spire-actin complexes and their functional consequences.

Christine K Chen1, Michael R Sawaya1, Martin L Phillips1

  • 1Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095.

The Journal of Biological Chemistry
|February 16, 2012
PubMed
Summary
This summary is machine-generated.

Spire protein nucleates actin filaments, but also severs and sequesters them. Structural studies reveal differences in Spire constructs, suggesting complex actin interactions and structures.

More Related Videos

Aip1p Dynamics Are Altered by the R256H Mutation in Actin
08:57

Aip1p Dynamics Are Altered by the R256H Mutation in Actin

Published on: July 30, 2014

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

Related Experiment Videos

Last Updated: May 24, 2026

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

Aip1p Dynamics Are Altered by the R256H Mutation in Actin
08:57

Aip1p Dynamics Are Altered by the R256H Mutation in Actin

Published on: July 30, 2014

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

Area of Science:

  • Cell Biology
  • Biochemistry
  • Structural Biology

Background:

  • Spire is a WH2 domain-containing protein crucial for actin mesh formation in oogenesis.
  • Spire exhibits multiple in vitro functions, including actin nucleation, filament severing, and monomer sequestration.

Purpose of the Study:

  • To investigate the severing activity of Drosophila Spire on preformed actin filaments.
  • To elucidate the structural basis and functional implications of Spire's interactions with actin monomers and filaments.
  • To understand the physiological relevance of Spire's diverse actin-binding activities.

Main Methods:

  • Bulk and single actin filament assays to study Spire's effect on filament depolymerization.
  • Solution and crystal structure determination of Spire-actin complexes.
  • Comparative analysis of Spire constructs with varying numbers of WH2 domains (Spir-ABCD vs. Spir-CD).

Main Results:

  • Spire rapidly depolymerizes actin filaments, primarily through sequestration, with a minor contribution from severing.
  • Structural analysis revealed distinct features between Spir-ABCD and Spir-CD constructs.
  • Observed lateral interactions between actin monomers bound to Spir-ABCD, indicating complex structural assemblies.

Conclusions:

  • Spire's depolymerization activity is mainly driven by sequestration, augmented by weak severing.
  • Structural differences in Spire constructs provide insights into actin nucleation and sequestration mechanisms.
  • Spire-actin mixtures likely contain both nucleation and sequestration structures, with potential for complex higher-order assemblies.