GO:0071797 LUBAC complex: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0071797 (LUBAC complex) is a cellular_component term describing a ubiquitin ligase complex that catalyzes linear head-to-tail polyubiquitin conjugation on its targets.
• In humans, LUBAC is composed of RBCK1 (HOIL-1L), RNF31 (HOIP), and SHARPIN, with an estimated molecular weight of approximately 600 kDa, suggesting a heteromultimeric assembly.
• LUBAC regulates key signaling pathways including NF-kB, autophagy, and T-cell receptor signaling, making it central to immunity and inflammation.
• Dysregulation of LUBAC is linked to autoinflammatory syndromes, atopic disorders, cancer, and neuroinflammation.
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) are essential for dissecting LUBAC subunit functions and substrate specificity.
• Studying LUBAC requires integrated methods such as proteomics, imaging, and ubiquitin chain profiling to capture its dynamic assembly and signaling roles.
Description
The LUBAC complex (GO:0071797) is a cellular_component defined as a ubiquitin ligase complex that catalyzes linear head-to-tail polyubiquitin conjugation on its targets. In humans, it consists of RBCK1, RNF31, and SHARPIN, forming a heteromultimeric assembly of approximately 600 kDa. This unique mode of ubiquitination distinguishes LUBAC from other E3 ligases and enables it to regulate diverse signaling cascades. Researchers study LUBAC because it is a critical regulator of NF-kB activation, autophagy, and immune cell function, with direct implications for inflammatory diseases and cancer. Understanding its assembly and substrate specificity is essential for developing targeted therapies.
LUBAC complex At A Glance
| GO ID | GO:0071797 |
|---|---|
| GO term | LUBAC complex |
| Ontology | cellular_component |
| Synonym | None |
| Major function | Catalyzes linear head-to-tail polyubiquitin conjugation on target proteins |
| Subunits | RBCK1, RNF31, SHARPIN |
| Molecular weight | Approximately 600 kDa |
| Assembly | Heteromultimeric assembly of subunits |
| Associated processes | NF-kB signaling, autophagy, T-cell receptor signaling |
What Is GO:0071797?
GO:0071797 (LUBAC complex) is a cellular component ontology term describing a ubiquitin ligase complex that catalyzes linear head-to-tail polyubiquitin conjugation on its targets. In human cells, the complex is composed of RBCK1, RNF31, and SHARPIN, and has an estimated molecular weight of approximately 600 kDa, suggesting a heteromultimeric assembly of its subunits. LUBAC stands for Linear Ubiquitin Chain Assembly Complex.
Why Is LUBAC complex Important in Cell Biology?
The LUBAC complex is critically important because it generates linear ubiquitin chains, a unique post-translational modification that regulates key signaling pathways such as NF-kB, autophagy, and immune responses. Dysregulation of LUBAC subunits is associated with severe human diseases, including autoinflammatory syndromes, atopic disorders, and cancer, making it a high-priority target for both basic research and therapeutic development.
• Regulates NF-kB activation downstream of TNF and IL-1 receptors, controlling inflammation and immunity.
• Modulates T-cell receptor signaling via the CBM complex downstream of TRAF6.
• Controls autophagy initiation and maturation by stabilizing ATG13 through linear ubiquitination.
• Mutations in LUBAC subunits cause autoinflammatory syndromes such as OTULIN-related autoinflammatory syndrome.
• Implicated in primary atopic disorders, highlighting its role in allergic inflammation.
• Promotes tumor-promoting LT-beta receptor signaling by activating canonical NF-kB.
• Linked to neuroinflammation through Ripk-dependent pathways.
• Essential for B-cell development and immune homeostasis.
• Potential therapeutic target for cancers with aberrant NF-kB activation.
• Provides a model system for studying linear ubiquitination and its crosstalk with other ubiquitin linkages.
Structure and Composition of LUBAC complex
Submit composition and stoichiometry
In simple terms: LUBAC is made of three main proteins that stick together to form a larger machine.
The human LUBAC complex consists of three core subunits: RBCK1 (also known as HOIL-1L), RNF31 (also known as HOIP), and SHARPIN. The complex has an estimated molecular weight of approximately 600 kDa, suggesting a heteromultimeric assembly of its subunits. RNF31 is the catalytic subunit containing the RING-between-RING (RBR) domain responsible for ubiquitin ligation, while RBCK1 and SHARPIN are regulatory subunits that stabilize the complex and modulate its activity.
Assembly and domain architecture
In simple terms: The three proteins assemble in a specific order using specialized domains that act like Velcro.
Assembly of LUBAC is driven by specific protein-protein interaction domains. RNF31 contains multiple domains including the PUB domain, which interacts with RBCK1, and the RBR domain for catalysis. SHARPIN binds to RNF31 through its N-terminal region, forming a stable heterotrimer. The complex can also associate with other proteins such as OTULIN, which removes linear ubiquitin chains and regulates LUBAC activity.
Subcellular localization
In simple terms: LUBAC is found in different parts of the cell depending on the signal it receives.
LUBAC is primarily cytosolic but translocates to receptor complexes at the plasma membrane upon stimulation, such as TNF receptor 1 (TNFR1) or T-cell receptor (TCR) signaling. It also localizes to autophagosomes during autophagy induction. This dynamic localization is essential for its function in distinct signaling pathways.
Regulatory subunits and interacting proteins
In simple terms: Other proteins can join or leave the complex to fine-tune its activity.
Beyond the core subunits, LUBAC interacts with accessory proteins such as OTULIN, which hydrolyzes linear ubiquitin chains and acts as a negative regulator. In T cells, LUBAC modulates the CBM complex downstream of TRAF6, integrating TCR signals. These interactions allow LUBAC to respond to diverse cellular contexts.
Key Genes Involved in GO:0071797 LUBAC complex
The following genes encode the core subunits and key regulators of the LUBAC complex, each with distinct roles in its assembly, catalysis, and regulation.
| Gene | Major Role | Research Relevance |
|---|---|---|
| RNF31 (HOIP) | Catalytic subunit with RBR domain; catalyzes linear ubiquitin chain formation | Central to LUBAC activity; target for knockout and point mutation studies |
| RBCK1 (HOIL-1L) | Regulatory subunit; stabilizes complex and modulates substrate specificity | Mutations cause autoinflammation; used in knockout models |
| SHARPIN | Regulatory subunit; essential for complex stability and NF-kB activation | Knockout leads to severe inflammatory phenotypes |
| OTULIN | Deubiquitinase that removes linear ubiquitin chains; negative regulator | Mutations cause autoinflammatory syndrome; studied with knock-in models |
| TRAF6 | E3 ligase that cooperates with LUBAC in T-cell signaling | Knockout models reveal crosstalk with LUBAC |
| ATG13 | Substrate of LUBAC; stabilized by linear ubiquitination during autophagy | Used to study LUBAC role in autophagy |
| NFKB1 | Transcription factor activated downstream of LUBAC | Readout for LUBAC activity in NF-kB assays |
| RELA | NF-kB subunit; activated by LUBAC-mediated signaling | Commonly monitored in LUBAC studies |
| LTBR | Receptor that signals through LUBAC to activate NF-kB | Model for tumor-promoting signaling |
| GPX4 | Ferroptosis regulator; stability influenced by LUBAC-related pathways | Studied in osteoarthritis models |
| RIPK1 | Kinase regulated by linear ubiquitination; involved in neuroinflammation | Knockout models link LUBAC to neuroinflammation |
| RIPK3 | Kinase in necroptosis; modulated by LUBAC | Used in neuroinflammation research |
| CBM complex | Signaling complex downstream of TCR; modulated by LUBAC | Studied in T-cell activation |
| IKBKG (NEMO) | Regulatory subunit of IKK; binds linear ubiquitin chains | Key downstream effector of LUBAC |
| TNF | Cytokine that triggers LUBAC recruitment to TNFR1 | Stimulus for LUBAC activation |
| IL1B | Cytokine that activates LUBAC via IL-1 receptor | Used in inflammation studies |
| P21 (CDKN1A) | Cell cycle inhibitor; linked to GPX4 stability and ferroptosis | Studied in osteoarthritis chondrocytes |
How Is LUBAC complex Regulated?
LUBAC activity is tightly regulated by its interacting partners and post-translational modifications. OTULIN directly binds to LUBAC and removes linear ubiquitin chains, acting as a negative regulator to prevent excessive NF-kB activation. In T cells, LUBAC function is modulated downstream of TRAF6, integrating signals from the T-cell receptor. Additionally, LUBAC regulates autophagy by stabilizing ATG13, and this process is subject to feedback regulation by autophagy machinery. The complex also crosstalks with other ubiquitin linkages, and its localization is controlled by receptor stimulation such as TNF or IL-1.
LUBAC complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| OTULIN | Autoinflammatory syndrome | Knock-in of patient mutations in cell lines |
| RNF31 | Cancer (NF-kB-driven) | Knockout in cancer cell lines |
| RBCK1 | Immunodeficiency and autoinflammation | Point mutation knock-in |
| SHARPIN | Chronic proliferative dermatitis | Knockout mouse models |
| GPX4 | Osteoarthritis and ferroptosis | Overexpression and knockout in chondrocytes |
Autoinflammatory syndromes
Mutations in LUBAC subunits or its regulator OTULIN cause severe autoinflammatory syndromes. Dominant negative OTULIN-related autoinflammatory syndrome is characterized by systemic inflammation, and LUBAC dysfunction contributes to pathology. Rapid genomic sequencing has identified LUBAC-related primary atopic disorders, highlighting its role in allergic inflammation.
Cancer
LUBAC promotes tumor-promoting LT-beta receptor signaling by activating canonical NF-kB, suggesting that LUBAC inhibition could be therapeutic in cancers with aberrant NF-kB activation. Its role in T-cell signaling also implicates LUBAC in immune evasion and lymphoma development.
Neuroinflammation
LUBAC regulates RIPK1 and RIPK3, kinases central to neuroinflammation and necroptosis. Dysregulation of linear ubiquitination contributes to inflammatory damage in neurodegenerative conditions.
Osteoarthritis and ferroptosis
LUBAC-related pathways influence GPX4 stability and ferroptosis in osteoarthritic chondrocytes, linking LUBAC to cartilage degeneration and potential therapeutic targets.
From LUBAC complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does RNF31 catalytic activity drive NF-kB activation? | Point mutation (catalytic dead) knock-in |
| What is the role of SHARPIN in complex stability? | Knockout cell lines |
| How does OTULIN regulate LUBAC in autoinflammation? | Knock-in of patient mutations |
| Does LUBAC modulate autophagy via ATG13? | Knockout and overexpression of ATG13 |
| Can LUBAC be targeted in cancer? | Knockout in tumor cell lines |
| How does LUBAC affect T-cell signaling? | Knockout in primary T cells |
How to Study the LUBAC complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Co-immunoprecipitation | Protein-protein interactions | Confirm LUBAC subunit assembly |
| Mass spectrometry | Protein identification and modifications | Identify LUBAC interactors |
| Ubiquitin chain-specific antibodies | Linear ubiquitin chain levels | Quantify LUBAC activity |
| Fluorescence microscopy | Subcellular localization | Track LUBAC recruitment |
| NF-kB luciferase reporter | NF-kB transcriptional activity | Assess LUBAC signaling |
| LC3 flux assay | Autophagic flux | Measure LUBAC role in autophagy |
| CRISPR knockout | Gene function loss | Study LUBAC subunit necessity |
| RNA-seq | Transcriptional changes | Identify LUBAC-dependent gene expression |
Proteomic analysis of LUBAC assembly
Affinity purification coupled with mass spectrometry can identify LUBAC subunits and interacting proteins, confirming the heteromultimeric assembly and post-translational modifications.
Ubiquitin chain profiling
Linear ubiquitin chains generated by LUBAC can be detected using chain-specific antibodies or mass spectrometry, allowing quantification of LUBAC activity in cells.
Imaging of LUBAC localization
Fluorescence microscopy with tagged subunits (e.g., GFP-RNF31) reveals dynamic recruitment of LUBAC to receptor complexes and autophagosomes upon stimulation.
Functional assays for NF-kB and autophagy
Luciferase reporter assays for NF-kB and LC3 flux assays for autophagy are standard readouts to assess LUBAC function in knockout or overexpression models.
How CRISPR Can Be Used to Study GO:0071797 LUBAC complex
Knockout
CRISPR knockout of RNF31, RBCK1, or SHARPIN in cell lines abolishes LUBAC activity, leading to impaired NF-kB activation and autophagy, and is used to define subunit-specific functions.
Point Mutation
Point mutations in the catalytic RBR domain of RNF31 (e.g., catalytic dead) can be introduced to separate LUBAC enzymatic activity from scaffolding functions, revealing substrate specificity.
Knock-in
Knock-in of patient-derived mutations in OTULIN or RBCK1 recapitulates autoinflammatory phenotypes, enabling study of disease mechanisms and drug testing.
Overexpression
Overexpression of LUBAC subunits or tagged versions (e.g., GFP-RNF31) allows visualization of complex assembly and amplification of linear ubiquitination for biochemical assays.
How EDITGENE Supports LUBAC complex Research
Researchers studying LUBAC complex-related genes often need to determine whether a candidate gene is causally involved in linear ubiquitination, NF-kB signaling, or autophagy. EDITGENE provides tailored CRISPR services to generate precisely engineered cell models that answer these questions.
Contact EDITGENE today to design your custom CRISPR model for LUBAC complex research.
Frequently Asked Questions About LUBAC complex
What is the LUBAC complex?
The LUBAC complex (GO:0071797) is a ubiquitin ligase complex that catalyzes linear head-to-tail polyubiquitin conjugation on its targets, composed of RBCK1, RNF31, and SHARPIN in humans.
What genes are involved in the LUBAC complex?
The core genes are RNF31 (HOIP), RBCK1 (HOIL-1L), and SHARPIN, with regulators such as OTULIN and TRAF6.
What is the function of LUBAC in NF-kB signaling?
LUBAC generates linear ubiquitin chains that recruit IKK components, leading to NF-kB activation downstream of TNF, IL-1, and T-cell receptors.
How is LUBAC regulated?
LUBAC is regulated by OTULIN, which removes linear ubiquitin chains, and by its dynamic assembly and localization upon receptor stimulation.
What diseases are associated with LUBAC mutations?
Mutations in LUBAC subunits or OTULIN cause autoinflammatory syndromes, primary atopic disorders, and are implicated in cancer and neuroinflammation.
What is the molecular weight of LUBAC?
The human LUBAC complex has an estimated molecular weight of approximately 600 kDa, suggesting a heteromultimeric assembly.
How can I study LUBAC complex assembly?
Use co-immunoprecipitation, mass spectrometry, and fluorescence microscopy with tagged subunits to analyze assembly and localization.
What CRISPR models are available for LUBAC research?
Knockout, point mutation, knock-in, and overexpression models can be generated for RNF31, RBCK1, SHARPIN, and OTULIN to study function and disease.
Does LUBAC regulate autophagy?
Yes, LUBAC mediates linear ubiquitination and stabilization of ATG13, regulating autophagy initiation and maturation.
What is the role of LUBAC in T cells?
LUBAC modulates CBM complex functions downstream of TRAF6 in T cells, influencing T-cell receptor signaling.
Conclusion
The LUBAC complex (GO:0071797) is a unique ubiquitin ligase that generates linear ubiquitin chains to control NF-kB, autophagy, and immune signaling. Its core subunits RBCK1, RNF31, and SHARPIN assemble into a ~600 kDa heteromultimer, and its dysregulation causes autoinflammatory diseases and cancer. CRISPR-based models are indispensable for dissecting LUBAC biology and developing targeted therapies.
References
- 1. Graß C et al.. 2025. LUBAC modulates CBM complex functions downstream of TRAF6 in T cells.. Nat Commun 16(1):9899 PMID: 41213928
- 2. Shibata Y et al.. 2022. LUBAC.. Curr Biol 32(11):R506-R508 PMID: 35671719
- 3. Niehues T et al.. 2024. Rapid identification of primary atopic disorders (PAD) by a clinical landmark-guided, upfront use of genomic sequencing.. Allergol Select 8:304-323 PMID: 39381601
- 4. Chu Y et al.. 2021. LUBAC and OTULIN regulate autophagy initiation and maturation by mediating the linear ubiquitination and the stabilization of ATG13.. Autophagy 17(7):1684-1699 PMID: 32543267
- 5. Zheng Z et al.. 2024. P21 resists ferroptosis in osteoarthritic chondrocytes by regulating GPX4 protein stability.. Free Radic Biol Med 212:336-348 PMID: 38176476
- 6. Chen YG et al.. 2024. LUBAC enables tumor-promoting LTβ receptor signaling by activating canonical NF-κB.. Cell Death Differ 31(10):1267-1284 PMID: 39215104
- 7. Davidson S et al.. 2024. Dominant negative OTULIN-related autoinflammatory syndrome.. J Exp Med 221(6) PMID: 38630025
- 8. Xu Y et al.. 2024. Ripks and Neuroinflammation.. Mol Neurobiol 61(9):6771-6787 PMID: 38349514
