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In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones
Published on: July 25, 2019
Non-canonical ubiquitylation: mechanisms and consequences
Gary S McDowell1, Anna Philpott
1Department of Oncology, University of Cambridge, Hutchison/Medical Research Council (MRC) Research Centre, Cambridge, UK.
Summary
Non-canonical ubiquitylation modifies proteins at non-lysine sites, impacting cellular processes. This review explores these unusual modifications and their consequences on protein activity and fate.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Post-translational modifications regulate cellular events.
- Ubiquitylation typically targets lysine residues, marking proteins for degradation or signaling.
- Emerging evidence suggests ubiquitylation can occur at non-lysine sites.
Purpose of the Study:
- To highlight the process of non-canonical ubiquitylation.
- To discuss the consequences of non-canonical ubiquitylation on protein activity and fate.
- To underscore the overlooked importance of modifications at non-lysine residues.
Main Methods:
- Literature review of existing studies on ubiquitylation.
- Analysis of chemical principles underlying ubiquitylation.
- Compilation of evidence for non-canonical ubiquitylation sites.
Main Results:
- Ubiquitylation can occur at N-terminal amines, serine, threonine, and cysteine residues.
- Non-canonical ubiquitylation represents a significant, yet underappreciated, regulatory mechanism.
- These modifications can alter protein function and cellular localization.
Conclusions:
- Non-canonical ubiquitylation expands the known regulatory mechanisms of protein function.
- Further research is needed to fully understand the scope and impact of these modifications.
- Recognizing non-canonical ubiquitylation is crucial for a comprehensive understanding of cellular signaling and protein homeostasis.
Keywords:
ERADHECTHOMOLUMONon-canonical ubiquitylationProtein degradationRINGSCFSUMOSkp-Cullin-F-boxUFDUPSUbUbiquitinUbiquitin ligaseUbiquitinomicsendoplasmic reticulum-associated degradationhighest occupied molecular orbitalhomologous to E6 carboxyl terminuslowest unoccupied molecular orbitalreally Interesting New Genesmall ubiquitin-like modifierubiquitinubiquitin fusion degradationubiquitin proteasome systemRelated Concept Videos
Covalently 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.
Regulated 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.
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The 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...
The 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...
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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...
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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...
Endocytosis
In endocytosis, the cell membrane takes up macromolecules and particles from the surrounding medium. Clathrin-mediated...

