Related Experiment Video

Updated: Aug 13, 2026

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

Tropomyosin inhibits ADF/cofilin-dependent actin filament dynamics

Shoichiro Ono1, Kanako Ono

  • 1Department of Pathology, Emory University, Atlanta, Georgia 30322, USA. sono@emory.edu

The Journal of Cell Biology
|March 20, 2002
PubMed

Insights

Tropomyosin (CeTM) inhibits actin filament dynamics driven by ADF/cofilin (UNC-60B) in C. elegans. This interaction is crucial for maintaining actin organization and muscle function.

Area of Science:

  • Cell Biology
  • Biochemistry
  • Molecular Biology

Background:

  • Tropomyosin stabilizes actin filaments, a key component of the cytoskeleton.
  • Actin dynamics are regulated by proteins like ADF/cofilin, influencing cellular processes.

Purpose of the Study:

  • To investigate the biochemical and cell biological roles of Caenorhabditis elegans tropomyosin (CeTM).
  • To determine the relationship between CeTM and ADF/cofilin-dependent actin filament dynamics.

Main Methods:

  • Purification of CeTM, actin, and UNC-60B from C. elegans.
  • In vitro binding assays to assess CeTM and UNC-60B interactions with F-actin.
  • Analysis of native thin filaments and salt-extracted filaments.
  • RNA interference (RNAi) to suppress CeTM in different genetic backgrounds.
  • Assessment of actin organization and worm motility.

Main Results:

  • CeTM and UNC-60B bind to F-actin mutually exclusively.
  • CeTM inhibits UNC-60B-induced actin depolymerization and polymerization.
  • CeTM is a major component of native thin filaments, while UNC-60B is present in trace amounts.
  • Suppression of CeTM disrupts actin organization and causes paralysis in wild-type worms but not in ADF/cofilin mutants.

Conclusions:

  • Tropomyosin acts as a physiological inhibitor of ADF/cofilin-dependent actin dynamics.
  • CeTM plays a critical role in regulating actin organization and muscle function in C. elegans.

More Related Videos

Using Microfluidics and Fluorescence Microscopy to Study the Assembly Dynamics of Single Actin Filaments and Bundles08:02

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

Published on: May 5, 2022

Optogenetic Inhibition of Rho1-Mediated Actomyosin Contractility Coupled with Measurement of Epithelial Tension in Drosophila Embryos12:35

Optogenetic Inhibition of Rho1-Mediated Actomyosin Contractility Coupled with Measurement of Epithelial Tension in Drosophila Embryos

Published on: April 14, 2023

Related Concept Videos

Adaptability of Cytoskeletal Filaments01:12

Adaptability of Cytoskeletal Filaments

The cytoskeleton is a complex dynamic structure performing varied functions based on cellular requirements. The adaptability of the individual filaments in the cytoskeleton determines their ability to perform various functions within the cell. It can undergo rapid reorganization during processes like cell division or remain stable for several hours as in the interphase. The adaptability of these filaments depends on stringent regulatory mechanisms. The microfilament and microtubules of the...
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...
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...
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 and Myosin in Muscle Contraction01:16

Actin and Myosin in Muscle Contraction

Actin and myosin are contractile proteins that form the sarcomere found in skeletal muscle tissues for regulating muscle contraction. Actin, a globular contractile protein, interacts with myosin for muscle contraction. The skeletal tissue appears striped or striated under a microscope due to the repeated arrangement of contractile proteins actin and myosin along the length of myofibrils. Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell causes...
Actin Treadmilling01:18

Actin 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...