GO:0070534 protein K63-linked ubiquitination: Signaling Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0070534 (protein K63-linked ubiquitination) describes the addition of K63-linked ubiquitin polymers to substrate proteins, a non-degradative signal that regulates DNA repair, autophagy, immune signaling, and stress responses.
• K63-linked ubiquitination is catalyzed by an enzymatic cascade involving E1, E2, and E3 enzymes, with E3 ligases such as TRIM16, TRIM26, TRIM32, STUB1, and ARIH1 conferring substrate specificity.
• Dysregulation of K63-linked ubiquitination is implicated in cancer, neurodegeneration, vascular calcification, and ferroptosis-related pathologies.
• Key substrates include GPX4, DAB2, UHRF1, PHB1, G3BP1, and p62, linking K63-linked ubiquitination to ferroptosis, DNA methylation, mitochondrial function, and stress granule dynamics.
• K63-linked ubiquitination is distinct from K48-linked ubiquitination, which primarily targets proteins for proteasomal degradation; K63 chains instead serve as scaffolds for signal transduction and selective autophagy.
• CRISPR-based knockout, point-mutation, knock-in, and overexpression models are essential for dissecting the causal roles of E3 ligases and ubiquitin chain types in K63-linked ubiquitination pathways.
Description
Protein K63-linked ubiquitination (GO:0070534) is a post-translational modification in which a ubiquitin polymer formed through isopeptide linkages at lysine 63 of ubiquitin monomers is conjugated to a substrate protein. Unlike K48-linked polyubiquitination, which typically targets proteins for proteasomal degradation, K63-linked chains serve non-degradative functions, acting as signaling platforms that promote error-free DNA postreplication repair, autophagy, and immune signaling. This process is orchestrated by a hierarchical enzymatic cascade comprising E1 activating enzymes, E2 conjugating enzymes, and E3 ligases that determine substrate specificity. Researchers study GO:0070534 because it sits at the intersection of genome stability, cell death, and disease. For example, TRIM16 mediates K63-linked ubiquitination of DAB2 to facilitate vascular calcification, while TRIM26 catalyzes K63-linked ubiquitination of GPX4 to suppress ferroptosis in glioma. STUB1-mediated K63-linked ubiquitination of UHRF1 promotes cholangiocarcinoma progression by maintaining DNA hypermethylation of PLA2G2A, and TRIM32 enhances K63-linked ubiquitination and autophagic degradation of GPX4 to promote neuronal ferroptosis. These findings underscore the broad physiological and pathological relevance of K63-linked ubiquitination. The pathway also modulates stress granule homeostasis through TRIM21-mediated ubiquitination of G3BP1, and ARIH1 facilitates colorectal cancer progression by promoting mitochondrial translocation of K63-linked ubiquitinated PHB1. Collectively, these studies highlight K63-linked ubiquitination as a critical regulatory mechanism in cancer, neurodegeneration, and metabolic disorders.
protein K63-linked ubiquitination At A Glance
| GO ID | GO:0070534 |
|---|---|
| GO term | protein K63-linked ubiquitination |
| Ontology | biological_process |
| Synonym | protein K63-linked polyubiquitination |
| Major function | Non-degradative ubiquitination that regulates DNA repair, autophagy, immune signaling, and stress responses |
| Enzymatic cascade | E1 activating enzyme, E2 conjugating enzyme, and E3 ligase (e.g., TRIM16, TRIM26, TRIM32, STUB1, ARIH1) |
| Key substrates | GPX4, DAB2, UHRF1, PHB1, G3BP1, p62 |
| Associated diseases | Cancer, neurodegeneration, vascular calcification, ferroptosis-related pathologies |
What Is GO:0070534?
GO:0070534, protein K63-linked ubiquitination, is a biological process in which a polymer of ubiquitin, formed by linkages between lysine residues at position 63 of the ubiquitin monomers, is added to a target protein. This modification does not target the substrate for degradation but instead serves as a signal in pathways such as error-free DNA postreplication repair, autophagy, and immune signaling.
Why Is protein K63-linked ubiquitination Important in Cell Biology?
Protein K63-linked ubiquitination is a central regulatory mechanism that controls diverse cellular processes without causing protein degradation. It is essential for error-free DNA postreplication repair, selective autophagy, and immune signaling, and its dysregulation contributes to cancer, neurodegeneration, and metabolic diseases. Understanding this pathway provides mechanistic insights into disease pathogenesis and identifies potential therapeutic targets, such as E3 ligases and deubiquitinases that modulate K63-linked chains.
• Regulates error-free DNA postreplication repair and genome stability.
• Controls selective autophagy and stress granule clearance.
• Modulates ferroptosis by targeting GPX4 for autophagic degradation.
• Promotes cancer progression via substrates such as UHRF1 and PHB1.
• Facilitates vascular calcification through DAB2 ubiquitination.
• Implicated in neurodegeneration and neuronal ferroptosis.
• Serves as a non-degradative signal distinct from K48-linked ubiquitination.
• Provides potential therapeutic targets in oncology and neurology.
• Involved in immune signaling and stress responses.
• Enables research using CRISPR models to dissect E3 ligase-substrate relationships.
What Happens During protein K63-linked ubiquitination?
Activation and Conjugation Cascade
In simple terms: A chain of enzymes passes ubiquitin to the target protein.
K63-linked ubiquitination begins with the ATP-dependent activation of ubiquitin by an E1 enzyme, followed by transfer to an E2 conjugating enzyme. An E3 ligase then catalyzes the formation of an isopeptide bond between the C-terminal glycine of ubiquitin and a lysine residue on the substrate, and subsequently extends the chain through lysine 63 of ubiquitin monomers. This hierarchical cascade ensures substrate specificity and spatial-temporal control.
Chain Elongation and Linkage Specificity
In simple terms: Ubiquitin molecules are linked together at a specific position (K63).
The K63 linkage is generated when the C-terminal glycine of a donor ubiquitin is conjugated to lysine 63 of the acceptor ubiquitin. This linkage geometry prevents recognition by proteasomal degradation machinery and instead creates a docking platform for ubiquitin-binding domains that activate downstream signaling. E3 ligases such as TRIM16, TRIM26, TRIM32, STUB1, and ARIH1 have been shown to catalyze K63-linked chains on specific substrates.
Substrate Recognition and Functional Outcomes
In simple terms: The tagged protein gets a new job instead of being destroyed.
K63-linked ubiquitination alters the function, localization, or interaction of the substrate. For example, TRIM16-mediated K63-linked ubiquitination of DAB2 facilitates vascular calcification, while TRIM26-catalyzed K63-linked ubiquitination of GPX4 suppresses ferroptosis in glioma. STUB1-mediated K63-linked ubiquitination of UHRF1 promotes cholangiocarcinoma progression by maintaining DNA hypermethylation, and TRIM32 enhances K63-linked ubiquitination and autophagic degradation of GPX4 in neurons. ARIH1 promotes mitochondrial translocation of K63-linked ubiquitinated PHB1 in colorectal cancer.
Autophagy and Stress Granule Regulation
In simple terms: K63 chains help cells clean up damaged proteins and stress granules.
K63-linked ubiquitination serves as a signal for selective autophagy. TRIM21-mediated ubiquitination of G3BP1 modulates stress granule homeostasis and promotes autophagy-dependent elimination of stress granules. Similarly, K63-linked ubiquitination of GPX4 by TRIM32 leads to p62-selective autophagic degradation. These examples illustrate how K63 chains target substrates to autophagic adaptors such as p62.
Reversal by Deubiquitinases
In simple terms: Enzymes can remove the K63 chains to switch off the signal.
Deubiquitinases (DUBs) hydrolyze K63-linked ubiquitin chains, providing a reversible layer of regulation. Although specific DUBs for each substrate are not detailed in the provided literature, the dynamic balance between E3 ligases and DUBs is critical for maintaining cellular homeostasis.
Key Genes Involved in GO:0070534 protein K63-linked ubiquitination
The following genes and proteins are experimentally validated components or regulators of K63-linked ubiquitination pathways.
| Gene | Major Role | Research Relevance |
|---|---|---|
| TRIM16 | E3 ligase mediating K63-linked ubiquitination of DAB2 | Vascular calcification |
| TRIM26 | E3 ligase catalyzing K63-linked ubiquitination of GPX4 | Ferroptosis suppression in glioma |
| TRIM32 | E3 ligase enhancing K63-linked ubiquitination of GPX4 | Neuronal ferroptosis and autophagic degradation |
| STUB1 | E3 ligase mediating K63-linked ubiquitination of UHRF1 | Cholangiocarcinoma progression |
| ARIH1 | E3 ligase promoting K63-linked ubiquitination of PHB1 | Colorectal cancer and oxidative phosphorylation |
| TRIM21 | E3 ligase mediating ubiquitination of G3BP1 | Stress granule homeostasis |
| GPX4 | Substrate; K63-linked ubiquitination regulates ferroptosis | Cancer and neurodegeneration |
| DAB2 | Substrate; K63-linked ubiquitination facilitates vascular calcification | Vascular calcification |
| UHRF1 | Substrate; K63-linked ubiquitination maintains DNA methylation | Cholangiocarcinoma |
| PHB1 | Substrate; K63-linked ubiquitination promotes mitochondrial translocation | Colorectal cancer |
| G3BP1 | Substrate; ubiquitination modulates stress granule dynamics | Stress granule homeostasis |
| p62 | Autophagic adaptor recognizing K63-linked ubiquitinated substrates | Selective autophagy |
| E1 ubiquitin-activating enzyme | Activates ubiquitin in an ATP-dependent manner | Core cascade component |
| E2 ubiquitin-conjugating enzyme | Transfers ubiquitin to E3 ligases | Core cascade component |
| E3 ubiquitin ligases | Confer substrate specificity for K63-linked ubiquitination | Therapeutic targets |
| Deubiquitinases | Remove K63-linked ubiquitin chains | Regulation of pathway |
How Is protein K63-linked ubiquitination Regulated?
K63-linked ubiquitination is regulated at multiple levels, including the availability of E1, E2, and E3 enzymes, the activity of deubiquitinases, and the presence of ubiquitin-binding domains that interpret the signal. Specific E3 ligases such as TRIM16, TRIM26, TRIM32, STUB1, and ARIH1 are themselves subject to regulation by cellular stress, cytokines, and oncogenic signals. For instance, TRIM32-mediated K63-linked ubiquitination of GPX4 is linked to neuronal ferroptosis, suggesting that oxidative stress modulates this pathway. Additionally, TRIM21-mediated ubiquitination of G3BP1 is involved in stress granule homeostasis, indicating that stress conditions regulate K63-linked ubiquitination.
protein K63-linked ubiquitination and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| TRIM26 | Glioma (ferroptosis suppression) | Knockout glioma cell lines |
| STUB1 | Cholangiocarcinoma (DNA hypermethylation) | Knockout cholangiocarcinoma cells |
| ARIH1 | Colorectal cancer (oxidative phosphorylation) | Knockout colorectal cancer cells |
| TRIM32 | Neurodegeneration (neuronal ferroptosis) | Knockout neuronal cells |
| TRIM16 | Vascular calcification | Knockout vascular smooth muscle cells |
Cancer
Dysregulated K63-linked ubiquitination promotes tumorigenesis through multiple mechanisms. TRIM26-catalyzed K63-linked ubiquitination of GPX4 suppresses ferroptosis in glioma, supporting cancer cell survival. STUB1-mediated K63-linked ubiquitination of UHRF1 maintains DNA hypermethylation of PLA2G2A, promoting cholangiocarcinoma progression. ARIH1 facilitates colorectal cancer progression by promoting oxidative phosphorylation via mitochondrial translocation of K63-linked ubiquitinated PHB1. These findings highlight K63-linked ubiquitination as a potential therapeutic target in oncology.
Neurodegeneration
K63-linked ubiquitination is implicated in neurodegeneration, where it regulates protein aggregation and neuronal survival. TRIM32 promotes neuronal ferroptosis by enhancing K63-linked ubiquitination and autophagic degradation of GPX4, suggesting a role in neurodegenerative diseases associated with ferroptosis. The balance between K63-linked ubiquitination and degradation pathways is critical for neuronal homeostasis.
Vascular Calcification
TRIM16 mediates K63-linked ubiquitination of DAB2 to facilitate vascular calcification, linking this ubiquitination pathway to cardiovascular pathology. This suggests that targeting K63-linked ubiquitination could modulate vascular calcification.
Ferroptosis-Related Pathologies
K63-linked ubiquitination of GPX4 by TRIM26 and TRIM32 regulates ferroptosis in glioma and neurons, respectively. This connects K63-linked ubiquitination to ferroptosis-related diseases, including cancer and neurodegeneration.
From protein K63-linked ubiquitination-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of TRIM26 affect glioma ferroptosis? | TRIM26 knockout glioma cell line |
| Does STUB1-mediated UHRF1 ubiquitination promote cholangiocarcinoma? | STUB1 knockout or UHRF1 point-mutant cholangiocarcinoma cells |
| Does ARIH1-mediated PHB1 ubiquitination drive colorectal cancer? | ARIH1 knockout colorectal cancer cells |
| Does TRIM32-mediated GPX4 ubiquitination regulate neuronal ferroptosis? | TRIM32 knockout neuronal cells |
| Does TRIM16-mediated DAB2 ubiquitination facilitate vascular calcification? | TRIM16 knockout vascular smooth muscle cells |
| Does TRIM21-mediated G3BP1 ubiquitination modulate stress granules? | TRIM21 knockout cells with stress granule induction |
How to Study the protein K63-linked ubiquitination Process
| Method | What It Measures | Typical Application |
|---|---|---|
| In vitro ubiquitination assay | K63-linked chain formation on substrate | Reconstitution of E3 ligase activity |
| Mass spectrometry | Ubiquitination sites and linkage types | Mapping K63-linked substrates |
| CRISPR knockout screening | Genes required for K63-linked ubiquitination | Identifying pathway components |
| Co-immunoprecipitation | Interaction between E3 ligase and substrate | Validating TRIM16-DAB2 or TRIM26-GPX4 interactions |
| Fluorescence microscopy | Subcellular localization of ubiquitinated proteins | Mitochondrial translocation of PHB1 |
| Western blot with linkage-specific antibodies | K63-linked ubiquitin chain abundance | Quantifying pathway activity |
| Autophagy flux assays | Autophagic degradation of ubiquitinated substrates | GPX4 degradation by TRIM32 |
| Stress granule isolation | Stress granule composition and clearance | TRIM21-mediated G3BP1 ubiquitination |
Ubiquitination Assays
In vitro ubiquitination assays using recombinant E1, E2, E3, and ubiquitin can reconstitute K63-linked chain formation on substrates. These assays, combined with mass spectrometry, identify linkage-specific ubiquitination sites.
Proteomics and Mass Spectrometry
Mass spectrometry-based proteomics can map K63-linked ubiquitination sites and quantify changes in response to genetic perturbations. This approach is useful for identifying substrates of specific E3 ligases such as TRIM16, TRIM26, TRIM32, STUB1, and ARIH1.
CRISPR Screening
Genome-wide CRISPR knockout screens can identify genes required for K63-linked ubiquitination pathways, such as E3 ligases and deubiquitinases. Follow-up validation using targeted knockouts of TRIM family members or STUB1 can confirm their roles.
Imaging and Co-localization
Fluorescence microscopy can visualize K63-linked ubiquitin chains and substrate co-localization, as shown for PHB1 mitochondrial translocation and stress granule dynamics. These methods provide spatial insights into K63-linked ubiquitination functions.
How CRISPR Can Be Used to Study GO:0070534 protein K63-linked ubiquitination
Knockout
CRISPR knockout of E3 ligases such as TRIM16, TRIM26, TRIM32, STUB1, or ARIH1 can abolish K63-linked ubiquitination of specific substrates, revealing loss-of-function phenotypes in cancer, ferroptosis, and vascular calcification models. Knockout of substrate genes (e.g., GPX4, DAB2, UHRF1, PHB1) can confirm their roles in downstream pathways.
Point Mutation
Point mutations at the ubiquitination acceptor site (e.g., lysine-to-arginine) in substrates such as GPX4 or UHRF1 can prevent K63-linked ubiquitination and test its functional significance. Similarly, mutations in the catalytic domain of E3 ligases can separate ligase activity from scaffolding functions.
Knock-in
Knock-in of tagged ubiquitin or substrate (e.g., HA-ubiquitin or GFP-GPX4) allows tracking of K63-linked ubiquitination dynamics in live cells. Knock-in of disease-associated mutations can model pathological states linked to K63-linked ubiquitination.
Overexpression
Overexpression of E3 ligases such as TRIM26 or TRIM32 can enhance K63-linked ubiquitination of substrates and drive phenotypes like ferroptosis suppression or neuronal ferroptosis. Overexpression of substrate mutants can act as dominant-negative inhibitors of the pathway.
How EDITGENE Supports protein K63-linked ubiquitination Research
Researchers studying protein K63-linked ubiquitination-related genes often need to determine whether a candidate gene is causally involved in a specific biological process or disease. EDITGENE provides comprehensive CRISPR-based services to generate knockout, point-mutation, knock-in, and overexpression cell models, as well as CRISPR library screening and bioinformatics support, enabling rigorous functional validation of K63-linked ubiquitination components.
Contact EDITGENE today to design your custom CRISPR model for protein K63-linked ubiquitination research.
Frequently Asked Questions About protein K63-linked ubiquitination
What is protein K63-linked ubiquitination?
Protein K63-linked ubiquitination (GO:0070534) is a post-translational modification where a ubiquitin polymer linked at lysine 63 is attached to a substrate protein, serving non-degradative signaling roles in DNA repair, autophagy, and immune responses.
What genes are involved in protein K63-linked ubiquitination?
Key genes include E3 ligases such as TRIM16, TRIM26, TRIM32, STUB1, and ARIH1, as well as substrates like GPX4, DAB2, UHRF1, PHB1, and G3BP1.
How is K63-linked ubiquitination different from K48-linked ubiquitination?
K48-linked ubiquitination typically targets proteins for proteasomal degradation, whereas K63-linked ubiquitination does not cause degradation but instead acts as a signaling platform for DNA repair, autophagy, and immune signaling.
What diseases are associated with K63-linked ubiquitination?
It is implicated in cancer (glioma, cholangiocarcinoma, colorectal cancer), neurodegeneration, vascular calcification, and ferroptosis-related pathologies.
How can I study K63-linked ubiquitination using CRISPR?
CRISPR knockout, point mutation, knock-in, and overexpression models can be used to dissect the roles of E3 ligases and substrates in K63-linked ubiquitination pathways.
What is the role of TRIM26 in K63-linked ubiquitination?
TRIM26 catalyzes K63-linked ubiquitination of GPX4 to suppress ferroptosis in glioma.
What is the role of TRIM32 in K63-linked ubiquitination?
TRIM32 enhances K63-linked ubiquitination and subsequent p62-selective autophagic degradation of GPX4, promoting neuronal ferroptosis.
What is the role of STUB1 in K63-linked ubiquitination?
STUB1 mediates K63-linked ubiquitination of UHRF1, promoting cholangiocarcinoma progression by maintaining DNA hypermethylation of PLA2G2A.
What is the role of ARIH1 in K63-linked ubiquitination?
ARIH1 facilitates colorectal cancer progression by promoting oxidative phosphorylation via mitochondrial translocation of K63-linked ubiquitinated PHB1.
What is the role of TRIM21 in K63-linked ubiquitination?
TRIM21 mediates ubiquitination of G3BP1, modulating stress granule homeostasis and autophagy-dependent elimination of stress granules.
Conclusion
Protein K63-linked ubiquitination (GO:0070534) is a versatile non-degradative post-translational modification that regulates DNA repair, autophagy, immune signaling, and cell death pathways. Its dysregulation contributes to cancer, neurodegeneration, vascular calcification, and ferroptosis-related diseases, making it a compelling therapeutic target. CRISPR-based models are indispensable for dissecting the causal roles of E3 ligases and substrates in K63-linked ubiquitination. EDITGENE offers comprehensive services to accelerate this research, from knockout and point-mutation cell lines to CRISPR library screening and bioinformatics support.
References
- 1. Tracz M et al.. 2021. Beyond K48 and K63: non-canonical protein ubiquitination.. Cell Mol Biol Lett 26(1):1 PMID: 33402098
- 2. Lan Z et al.. 2025. TRIM16 Mediates K63-Linked Ubiquitination of DAB2 to Facilitate Vascular Calcification.. Circ Res 137(4):551-568 PMID: 40575853
- 3. Wang Z et al.. 2023. The E3 ligase TRIM26 suppresses ferroptosis through catalyzing K63-linked ubiquitination of GPX4 in glioma.. Cell Death Dis 14(10):695 PMID: 37872147
- 4. Chen J et al.. 2024. STUB1-mediated K63-linked ubiquitination of UHRF1 promotes the progression of cholangiocarcinoma by maintaining DNA hypermethylation of PLA2G2A.. J Exp Clin Cancer Res 43(1):260 PMID: 39267107
- 5. Zhou X et al.. 2025. TRIM32 promotes neuronal ferroptosis by enhancing K63-linked ubiquitination and subsequent p62-selective autophagic degradation of GPX4.. Int J Biol Sci 21(3):1259-1274 PMID: 39897031
- 6. Yang C et al.. 2023. Stress granule homeostasis is modulated by TRIM21-mediated ubiquitination of G3BP1 and autophagy-dependent elimination of stress granules.. Autophagy 19(7):1934-1951 PMID: 36692217
- 7. Lim KL et al.. 2011. K63-linked ubiquitination and neurodegeneration.. Neurobiol Dis 43(1):9-16 PMID: 20696248
- 8. Tong Y et al.. 2025. The E3 Ubiquitin Ligase ARIH1 Facilitates Colorectal Cancer Progression by Promoting Oxidative Phosphorylation via the Mitochondrial Translocation of K63-Linked Ubiquitinated PHB1.. Adv Sci (Weinh) 12(25):e2501017 PMID: 40285603
