Related Experiment Video

Updated: Jun 26, 2026

Cell-Based Drug Screening for Inhibitors of Autophagy Related 4B Cysteine Peptidase
09:51

Cell-Based Drug Screening for Inhibitors of Autophagy Related 4B Cysteine Peptidase

Published on: June 30, 2023

Atg4B(C74A) hampers autophagosome closure: a useful protein for inhibiting autophagy

Naonobu Fujita1, Takeshi Noda, Tamotsu Yoshimori

  • 1Department of Cellular Regulation, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan.

Autophagy
|December 24, 2008
PubMed

Insights

Overexpression of an inactive Atg4B mutant blocks autophagic degradation by sequestering LC3 proteins, providing a new tool for autophagy research.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Autophagy Research

Background:

  • Autophagy is a cellular degradation process involving LC3 proteins.
  • Atg4B protease processes pro-LC3 paralogues, a key step in autophagy.
  • Dysregulation of autophagy is implicated in various diseases.

Purpose of the Study:

  • To investigate the mechanism by which an inactive Atg4B mutant affects autophagy.
  • To explore the utility of this mutant as a research tool.

Main Methods:

  • Overexpression of an inactive Atg4B mutant in mammalian cells.
  • Mechanistic analysis of LC3 lipidation and autophagic degradation.
  • Observation of Atg5-positive autophagic structures.

Main Results:

  • Inactive Atg4B mutant overexpression inhibited LC3 lipidation and autophagic degradation.
  • The mutant sequestered LC3 paralogues, blocking Atg7-LC3 intermediate formation.
  • Accumulated Atg5-positive structures showed defects in autophagosome closure.

Conclusions:

  • Excess inactive Atg4B mutant effectively inhibits autophagy by disrupting LC3 processing and autophagosome formation.
  • This provides a novel tool for studying the LC3 system and autophagy.

More Related Videos

Imaging ATG9A, a Multi-Spanning Membrane Protein07:20

Imaging ATG9A, a Multi-Spanning Membrane Protein

Published on: June 16, 2023

Study of Protein-protein Interactions in Autophagy Research14:08

Study of Protein-protein Interactions in Autophagy Research

Published on: September 9, 2017

Related Concept Videos

Autophagy01:27

Autophagy

Autophagy is a self-digesting process by which a cell protects itself from threats both within and outside the cell, ranging from abnormal proteins to invading bacteria. In this process, obsolete components of the cell and invading microbes are degraded by hydrolytic enzymes active in an acidic environment of the lysosomal lumen.
An autophagic pathway consists of a series of signaling events activated in response to diverse stress and physiological conditions such as food deprivation,...
Delivery Pathways to the Lysosome01:36

Delivery Pathways to the Lysosome

Eukaryotic cells use different mechanisms to eliminate toxic waste obsolete and worn-out substances. Lysosomes play a pivotal role in this, and hence, these substances are carried to the lysosome from other parts of the cell and extracellular space through different pathways. The most elaborately studied pathways to the lysosome are the endocytic pathways.
Endocytosis
In endocytosis, the cell membrane takes up macromolecules and particles from the surrounding medium. Clathrin-mediated...
Autophagic Cell Death01:18

Autophagic Cell Death

Christian de Duve discovered “autophagy,” a process in which cellular components are engulfed by membrane-bound organelles called autophagosomes. The autophagosomes then fuse with lysosomes to digest the enclosed contents. Autophagy is generally activated in cells to prevent cell death. However, cell death is triggered when the damage is beyond repair.
Autophagy and Apoptosis
Autophagy can activate apoptosis. In normal conditions, the autophagy activating protein Beclin-1 and pro-apoptotic...
Allosteric Proteins-ATCase01:19

Allosteric Proteins-ATCase

Binding sites linkages can regulate a protein's function.  For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to  N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
DNA Damage can Stall the Cell Cycle02:36

DNA Damage can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
Export of Misfolded Proteins out of the ER01:32

Export of Misfolded Proteins out of the ER

After folding, the ER assesses the quality of secretory and membrane proteins. The correctly folded proteins are cleared by the calnexin cycle for transport to their final destination, while misfolded proteins are held back in the ER lumen. The ER chaperones attempt to unfold and refold the misfolded proteins but sometimes fail to achieve the correct native conformation. Such terminally misfolded proteins are then exported to the cytosol by ER-associated degradation or ERAD pathway for...