Related Experiment Video
Updated: Jun 4, 2026
08:47
Monitoring eIF4F Assembly by Measuring eIF4E-eIF4G Interaction in Live Cells
Published on: May 1, 2020
Not4 E3 ligase contributes to proteasome assembly and functional integrity in part through Ecm29
Olesya O Panasenko1, Martine A Collart
1Department of Microbiology and Molecular Medicine, University of Geneva, Faculty of Medicine, Geneva, Switzerland.
Molecular and Cellular Biology
|February 16, 2011
Summary
The E3 ligase Not4 is crucial for proteasome integrity, preventing protein buildup. Its absence destabilizes proteasome components and impairs Ecm29 chaperone function.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Degradation
Background:
- The proteasome is a vital cellular machine responsible for protein degradation.
- E3 ligases play critical roles in protein ubiquitination and turnover.
- Proteasome integrity is essential for maintaining cellular homeostasis.
Purpose of the Study:
- To investigate the role of the Not4 E3 ligase in proteasome integrity.
- To elucidate the relationship between Not4, Ecm29, and proteasome function.
- To understand the mechanism by which Not4 influences proteasome subunit stability.
Main Methods:
- Proteasome purification and complex analysis.
- Co-immunoprecipitation assays to study protein interactions.
- Ubiquitination and degradation assays.
- Analysis of proteasome subunit stability in Not4-deficient cells.
Main Results:
- Deletion of Not4 leads to accumulation of polyubiquitinated proteins and reduced free ubiquitin.
- Not4-deficient cells exhibit salt-resistant proteasome regulatory particle (RP) and core particle (CP) complexes.
- Not4 associates with RP in the proteasome holoenzyme and interacts with the proteasome stabilizer Ecm29.
- In the absence of Not4, Ecm29 interaction with the proteasome is reduced, leading to its ubiquitination and degradation.
Conclusions:
- Not4 is essential for maintaining proteasome integrity and stability.
- Not4 regulates the stability and function of the proteasome chaperone Ecm29.
- Ecm29 requires Not4 for proper interaction with the proteasome, highlighting a novel regulatory pathway.
Related Concept Videos
01:13The Proteasome
Eukaryotic cells can degrade proteins through several pathways. One of the most important among these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...
02:18The Proteasome
Eukaryotic cells can degrade proteins through several pathways. One of the most important amongst these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. A series of enzymes carry out the ubiquitination of the target proteins - E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3...
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. A series of enzymes carry out the ubiquitination of the target proteins - E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3...
02:58Regulated Protein Degradation
It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
02:41Protein Complex Assembly
Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types. Most protein complexes self-assemble spontaneously via ordered pathways, while some proteins need assembly factors that guide their proper assembly. Despite the crowded intracellular environment, proteins usually interact with their correct partners and form functional complexes.
Many viruses self-assemble into a fully functional unit using the infected host cell to...
Many viruses self-assemble into a fully functional unit using the infected host cell to...
01:17The Proteasome Structure
The ubiquitin-proteasome pathway is a well-known mechanism utilized by eukaryotic cells to remove cytoplasmic proteins that are misfolded, damaged, or no longer needed. In this pathway, the protein that needs to be eliminated undergoes a process called ubiquitination, where a chain of ubiquitin molecules is attached to the 48th lysine residue of the target protein. This ubiquitin modification helps the proteasome distinguish between a target protein and a healthy protein.
The proteasome is an...
The proteasome is an...
01:57Protein Complexes with Interchangeable Parts
Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex’s function. Often some of the proteins in the complex can be replaced by a closely related variant to give a complex that contains many of the same components yet is functionally distinct.
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...