Related Experiment Video
Updated: Jul 19, 2026
06:06
In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
Structural basis for ubiquitin recognition by the human ESCRT-II EAP45 GLUE domain
Steven L Alam1, Charles Langelier, Frank G Whitby
1Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112-5650, USA.
Nature Structural & Molecular Biology
|October 24, 2006
Summary
The ESCRT-II complex, specifically the EAP45 subunit, binds ubiquitin and endosomal lipids. This interaction is crucial for sorting ubiquitinated proteins into multivesicular bodies (MVBs).
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Trafficking
Background:
- The Endosomal Sorting Complexes Required for Transport (ESCRT) machinery, including ESCRT-I and ESCRT-II, is essential for protein sorting into multivesicular bodies (MVBs).
- Ubiquitinated proteins are key cargo molecules recognized by the ESCRT pathway for MVB formation.
Purpose of the Study:
- To elucidate the structural basis of how the ESCRT-II complex recognizes ubiquitinated proteins and endosomal lipids.
- To understand the role of the GLUE domain of the ESCRT-II EAP45 subunit in MVB protein sorting.
Main Methods:
- Crystallographic analysis of the human ESCRT-II EAP45 subunit.
- Biochemical assays to determine binding interactions.
Main Results:
- The GLUE domain of human ESCRT-II EAP45 is a split pleckstrin-homology domain.
- This domain binds ubiquitin along one edge of its beta-sandwich structure.
- The structural findings suggest a mechanism for coupling cargo recognition and lipid binding.
Conclusions:
- Human ESCRT-II EAP45 utilizes its GLUE domain to bind ubiquitin.
- This binding facilitates the recognition of ubiquitinated cargoes during MVB protein sorting.
- The study provides structural insights into the coordination of cargo and lipid recognition by ESCRT-II.
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...
01:32Export 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...
02:04Covalently Linked Protein Regulators
Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.
These groups modify specific amino acids in a protein.
01:45ER Retrieval Pathway
In the secretory pathway, vesicles transport proteins from one cellular compartment to another in forward transport to deliver the protein to its correct location. Occasionally, misfolded proteins and incorrect proteins escape their original compartments, and a retrieval pathway is used to return the escaped proteins to their original compartment.
The ER uses many checkpoints to prevent the entry of incorrectly folded or a resident protein as cargo onto a transport vesicle. These mechanisms...
The ER uses many checkpoints to prevent the entry of incorrectly folded or a resident protein as cargo onto a transport vesicle. These mechanisms...
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...