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

Spindle Assembly02:50

Spindle Assembly

3.7K
Spindle assembly occurs through three, often coexisting, pathways – the centrosome-mediated pathway, the chromatin-mediated pathway, and the microtubule-mediated pathway – collectively contributing to form a robust spindle apparatus.
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a...
3.7K
Generation of Straight or Branched Actin Filaments01:14

Generation of Straight or Branched Actin Filaments

3.0K
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...
3.0K
The Spindle Assembly Checkpoint02:19

The Spindle Assembly Checkpoint

3.2K
The spindle assembly checkpoint is a molecular surveillance mechanism ensuring the fidelity of chromosome segregation during anaphase. The checkpoint monitors the completion of all the prerequisite steps before chromosome segregation to determine whether the segregation process should proceed or be delayed.
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
3.2K
The Contractile Ring02:15

The Contractile Ring

6.4K
Contractile rings are composed of microfilaments and are responsible for separating the daughter cells during cytokinesis. Contractile ring assembly proceeds along with other cell cycle events; however, very few mechanistic details are known about the timing and coordination of the contractile rings with the cell cycle.
A small GTPase, RhoA, controls the function and assembly of the contractile ring. RhoA belongs to the Ras superfamily of proteins. The activation of formins by RhoA promotes...
6.4K
Assembly of Complex Microtubule Structures01:32

Assembly of Complex Microtubule Structures

1.9K
Complex microtubule structures are present in resting cells and in dividing cells. In resting cells, they are responsible for maintaining the cellular architecture, tracks for intracellular transport, positioning of organelles, assembly of cilia and flagella. They mediate the bipolar spindle assembly for chromosomal segregation and positioning of the cell division plate in dividing cells. The formation of microtubule complex structures depends on the cell type, cell stage, and cell function.
1.9K
Microtubule Instability02:17

Microtubule Instability

5.2K
Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated...
5.2K

You might also read

Related Articles

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

Sort by
Same author

Capillary bundling of microtubules by condensates.

bioRxiv : the preprint server for biology·2026
Same author

Molecular insight into microtubule nucleation by the XMAP215/γ-TuRC module.

Nature communications·2026
Same author

Sperm hyperactivation drives a circling-and-wandering swimming behavior.

Nature communications·2026
Same author

Molecular grammars of predicted intrinsically disordered regions that span the human proteome.

Cell·2025
Same author

How augmin establishes the angle of the microtubule branch site.

Nature communications·2025
Same author

Single-fluorogen imaging reveals distinct environmental and structural features of biomolecular condensates.

Nature physics·2025
Same journal

Wanted and unwanted modifications of mRNA, and their effect on gene expression and signaling.

The Journal of biological chemistry·2026
Same journal

TGF-β2 drives lipid droplet accumulation in chondrocytes through the TβRI/p-Smad3/Fabp5 axis.

The Journal of biological chemistry·2026
Same journal

Macrophage-specific targeting of histone demethylases with small-molecule inhibitors suppresses inflammatory response in vivo.

The Journal of biological chemistry·2026
Same journal

Substrate and target selectivity of 4'-fluoroadenosine against viral and host polymerases.

The Journal of biological chemistry·2026
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
See all related articles

Related Experiment Video

Updated: Aug 2, 2025

Reconstitution of Basic Mitotic Spindles in Spherical Emulsion Droplets
10:52

Reconstitution of Basic Mitotic Spindles in Spherical Emulsion Droplets

Published on: August 13, 2016

9.8K

Augmin is a Ran-regulated spindle assembly factor.

Jodi Kraus1, Sophie M Travis1, Matthew R King1

  • 1Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA.

The Journal of Biological Chemistry
|April 22, 2023
PubMed
Summary
This summary is machine-generated.

Researchers found that augmin is a key spindle assembly factor regulated by Ran. This discovery reveals a new mechanism for how Ran controls microtubule nucleation and spindle assembly, even without TPX2.

Keywords:
Ran pathwayTPX2augminbranching microtubule nucleationimportinsspindle assembly factor

More Related Videos

Use of Primary Cultured Hippocampal Neurons to Study the Assembly of Axon Initial Segments
06:53

Use of Primary Cultured Hippocampal Neurons to Study the Assembly of Axon Initial Segments

Published on: February 12, 2021

5.1K
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

8.0K

Related Experiment Videos

Last Updated: Aug 2, 2025

Reconstitution of Basic Mitotic Spindles in Spherical Emulsion Droplets
10:52

Reconstitution of Basic Mitotic Spindles in Spherical Emulsion Droplets

Published on: August 13, 2016

9.8K
Use of Primary Cultured Hippocampal Neurons to Study the Assembly of Axon Initial Segments
06:53

Use of Primary Cultured Hippocampal Neurons to Study the Assembly of Axon Initial Segments

Published on: February 12, 2021

5.1K
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

8.0K

Area of Science:

  • Cell Biology
  • Molecular Biology

Background:

  • Mitotic spindles, essential for cell division, are built from microtubules (MTs).
  • Ran GTPase regulates spindle assembly by controlling the localization of spindle assembly factors (SAFs).
  • Branching MT nucleation, crucial for spindle formation, typically requires the augmin complex.

Purpose of the Study:

  • To investigate how Ran regulates branching MT nucleation independently of TPX2.
  • To determine if augmin is a direct target of Ran regulation.

Main Methods:

  • In vitro pulldown assays to assess protein interactions.
  • Total internal reflection fluorescence microscopy to visualize MT nucleation dynamics.
  • Experiments conducted in Xenopus egg extract and in vitro.

Main Results:

  • Augmin was identified as a Ran-regulated SAF.
  • Augmin directly interacts with importin-α and importin-β via its Haus8 subunit.
  • Ran controls the localization of augmin to microtubules.

Conclusions:

  • Ran directly regulates augmin, providing a novel mechanism for controlling branching MT nucleation.
  • This pathway is critical for spindle assembly in both the presence and absence of TPX2.