GO:0030891 VCB complex: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0030891 (VCB complex) is a pentameric ubiquitin ligase complex composed of pVHL, elongin B, elongin C, cullin-2 (Cul2), and Rbx1.
• The VCB complex is best known for targeting hypoxia-inducible factor alpha (HIF-alpha) for ubiquitin-mediated degradation under normoxic conditions.
• Germline mutations in VHL or ELOC (encoding elongin C) cause von Hippel-Lindau disease, a hereditary cancer syndrome.
• The complex is a validated target for PROTAC design, with macrocyclic PROTACs exploiting VCB substrate recognition.
• Small-molecule inducers of protein-protein associations can modulate VCB complex assembly and activity.
• Research models include knockout, point-mutation, knock-in, and overexpression cell lines to dissect VCB subunit functions.
Description
The VCB complex (GO:0030891) is a cellular component defined as a protein complex that possesses ubiquitin ligase activity, typically pentameric, and in mammals comprises pVHL, elongin B, elongin C, cullin-2 (Cul2), and Rbx1. This complex is a founding member of the Cullin-RING ligase (CRL) family and plays a central role in oxygen sensing and protein homeostasis. The VCB complex is essential for the ubiquitination and subsequent proteasomal degradation of hypoxia-inducible factor alpha (HIF-alpha) under normoxic conditions, thereby regulating angiogenesis, metabolism, and cell survival. Dysregulation of the VCB complex due to mutations in VHL or ELOC leads to von Hippel-Lindau disease, a hereditary cancer syndrome characterized by tumors in multiple organs. Beyond its physiological roles, the VCB complex has emerged as a versatile tool in chemical biology, particularly for targeted protein degradation via PROTACs. Understanding the structure, assembly, and regulation of the VCB complex is therefore critical for both basic research and therapeutic development.
VCB complex At A Glance
| GO ID | GO:0030891 |
|---|---|
| GO term | VCB complex |
| Ontology | cellular_component |
| Synonym | pVHL-elongin C-elongin B complex, VHL complex, von Hippel-Lindau tumor suppressor complex |
| Major function | Ubiquitin ligase activity; targets HIF-alpha for degradation |
| Subunits | pVHL, elongin B, elongin C, cullin-2 (Cul2), Rbx1 |
| Disease relevance | von Hippel-Lindau disease, renal cell carcinoma, hemangioblastoma |
| Research applications | PROTAC design, small-molecule modulators, CRISPR models |
What Is GO:0030891?
The VCB complex is a pentameric ubiquitin ligase complex that in mammals consists of pVHL (von Hippel-Lindau tumor suppressor), elongin B, elongin C, cullin-2 (Cul2), and Rbx1. It functions as a substrate recognition module within Cullin-RING ligases, where pVHL binds to hydroxylated HIF-alpha, leading to its ubiquitination and degradation. The complex is also known as the pVHL-elongin C-elongin B complex, VHL complex, or von Hippel-Lindau tumor suppressor complex.
Why Is VCB complex Important in Cell Biology?
The VCB complex is a critical regulator of the cellular response to oxygen availability and a key tumor suppressor pathway. Its dysfunction leads to von Hippel-Lindau disease, a hereditary cancer syndrome with diverse manifestations including renal cell carcinoma, hemangioblastoma, and pheochromocytoma. The complex is also a prime target for therapeutic intervention, as it can be hijacked by PROTACs to degrade disease-causing proteins. Understanding its assembly and regulation is essential for developing targeted therapies and for interpreting genetic variants in VHL and ELOC.
• Regulates HIF-alpha stability and oxygen sensing.
• Mutations in VHL or ELOC cause von Hippel-Lindau disease.
• Involved in renal cell carcinoma, hemangioblastoma, and pheochromocytoma.
• Target for PROTAC-based targeted protein degradation.
• Modulated by small-molecule inducers of protein-protein interactions.
• Essential for proper angiogenesis and metabolic adaptation.
• Provides a model for Cullin-RING ligase assembly and function.
• Enables study of genotype-phenotype correlations in hereditary cancer.
• Facilitates development of CRISPR models for functional genomics.
• Serves as a paradigm for ubiquitin ligase substrate recognition.
What Happens During VCB complex?
Substrate Recognition and Binding
In simple terms: The VCB complex recognizes specific target proteins that need to be degraded.
The VCB complex recognizes substrates through the pVHL subunit, which binds to hydroxylated proline residues on target proteins such as HIF-alpha. This recognition is oxygen-dependent, as prolyl hydroxylases modify HIF-alpha only in the presence of oxygen. The binding of pVHL to HIF-alpha is mediated by the elongin C subunit, which acts as an adaptor.
Ubiquitin Transfer and Chain Formation
In simple terms: The complex attaches ubiquitin molecules to the target protein, marking it for destruction.
Once the substrate is bound, the RING finger protein Rbx1 recruits ubiquitin-conjugating enzymes (E2s) and facilitates the transfer of ubiquitin to the substrate. Cullin-2 (Cul2) serves as a scaffold, bringing together the substrate recognition module and the catalytic RING domain. Polyubiquitin chains are formed on the substrate, leading to its recognition by the proteasome.
Proteasomal Degradation
In simple terms: The tagged protein is destroyed by the proteasome, a cellular recycling machine.
Polyubiquitinated substrates are rapidly degraded by the 26S proteasome, thereby terminating their signaling functions. This process is crucial for maintaining low levels of HIF-alpha under normoxic conditions. Dysregulation of this step leads to accumulation of HIF-alpha and activation of hypoxia-responsive genes.
Assembly of the VCB Complex
In simple terms: The five subunits come together to form a functional complex.
The VCB complex assembles through sequential interactions: elongin B and elongin C form a heterodimer that binds to pVHL, and this trimeric module associates with Cul2 and Rbx1. The assembly is regulated by post-translational modifications and chaperones. Proper assembly is essential for ubiquitin ligase activity.
Regulation by Oxygen and Hydroxylation
In simple terms: Oxygen levels control whether the complex can bind its targets.
Under normoxia, prolyl hydroxylases hydroxylate HIF-alpha, enabling pVHL binding and subsequent degradation. Under hypoxia, hydroxylation is inhibited, HIF-alpha escapes recognition, and the VCB complex cannot target it. This oxygen-sensing mechanism is central to the complex's physiological role.
Key Genes Involved in GO:0030891 VCB complex
The VCB complex comprises several key genes and proteins that are essential for its structure and function.
| Gene | Major Role | Research Relevance |
|---|---|---|
| VHL | Encodes pVHL, substrate recognition subunit | Mutations cause von Hippel-Lindau disease |
| ELOC | Encodes elongin C, adaptor linking pVHL to Cul2 | Mutations cause VHL disease |
| ELOB | Encodes elongin B, stabilizes elongin C | Component of VCB complex |
| CUL2 | Encodes cullin-2, scaffold protein | Essential for ubiquitin ligase activity |
| RBX1 | Encodes Rbx1, RING finger protein | Recruits E2 enzymes |
| HIF1A | Substrate of VCB complex | Degraded under normoxia |
| EPAS1 | Substrate of VCB complex | Regulates hypoxia response |
| VHL | Tumor suppressor | Target for PROTAC design |
| ELOC | Adaptor protein | Target for small-molecule modulators |
| CUL2 | Scaffold | Potential therapeutic target |
| RBX1 | Catalytic subunit | Target for inhibitor development |
| UBE2D1 | E2 ubiquitin-conjugating enzyme | Interacts with VCB complex |
| UBE2D2 | E2 ubiquitin-conjugating enzyme | Interacts with VCB complex |
| UBE2D3 | E2 ubiquitin-conjugating enzyme | Interacts with VCB complex |
| NEDD8 | Ubiquitin-like modifier | Regulates cullin-2 activity |
| CAND1 | Cullin-associated protein | Regulates complex assembly |
| TCEB1 | Alternative name for ELOC | Mutations in VHL disease |
How Is VCB complex Regulated?
The VCB complex is regulated at multiple levels, including oxygen-dependent hydroxylation of substrates, neddylation of cullin-2, and interaction with regulatory proteins such as CAND1. Small molecules can modulate the assembly and activity of the complex, as demonstrated by inducers of protein-protein associations. Additionally, the complex is subject to regulation by ubiquitin-like modifications and chaperones.
VCB complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| VHL | Von Hippel-Lindau disease, renal cell carcinoma | VHL knockout cell lines |
| ELOC | Von Hippel-Lindau disease | ELOC point-mutation knock-in |
| HIF1A | Hypoxia signaling, cancer | HIF1A overexpression |
| CUL2 | Cancer, hypoxia | CUL2 knockout |
| RBX1 | Cancer | RBX1 knockout |
Von Hippel-Lindau Disease
Germline mutations in VHL or ELOC cause von Hippel-Lindau disease, an autosomal dominant disorder characterized by hemangioblastomas, renal cell carcinomas, pheochromocytomas, and pancreatic tumors. The VCB complex is inactivated, leading to HIF-alpha accumulation and activation of hypoxia-inducible genes. Recent studies have identified pathogenic ELOC variants in multigenerational families, with responses to belzutifan.
Renal Cell Carcinoma
Loss of VHL function is a hallmark of clear cell renal cell carcinoma, where VCB complex dysfunction leads to constitutive HIF activation. This drives angiogenesis and tumor growth. Targeting the VCB complex or its downstream effectors is a therapeutic strategy.
Other Cancers
Dysregulation of the VCB complex has been implicated in other cancers, including hemangioblastoma and pheochromocytoma. The complex is also being explored as a target for PROTAC-based degradation of oncoproteins.
From VCB complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of VHL in HIF degradation? | VHL knockout cell line |
| How do ELOC mutations affect VCB assembly? | ELOC point-mutation knock-in |
| Can PROTACs target VCB substrates? | Tagged knock-in of substrate |
| What is the effect of VCB overexpression? | Overexpression cell line |
| How does VCB complex regulate gene expression? | CRISPR library screening |
| What are the interactors of VCB complex? | Bioinformatics analysis |
How to Study the VCB complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Co-immunoprecipitation | Protein-protein interactions | VCB subunit assembly |
| Mass spectrometry | Complex composition | Interactome analysis |
| Cryo-EM | 3D structure | Drug design |
| CRISPR knockout | Gene function | Functional genomics |
| RNA-seq | Transcriptional changes | Hypoxia response |
| PROTAC degradation assay | Target protein levels | Drug discovery |
| Small-molecule screening | Compound activity | Chemical biology |
Proteomics and Interactomics
Affinity purification coupled with mass spectrometry can identify VCB complex subunits and interactors. This approach reveals dynamic changes in complex composition under different conditions.
Structural Biology
Cryo-EM and X-ray crystallography provide high-resolution structures of the VCB complex, informing drug design. Structural studies have elucidated the binding interface between pVHL and elongin C.
CRISPR Screening
Genome-wide CRISPR knockout screens can identify genes that modulate VCB complex activity or synthetic lethality. These screens are powerful for discovering new components and regulators.
Small-Molecule Screening
High-throughput screening for small molecules that induce or inhibit VCB complex assembly can yield chemical probes. Rational screening for cooperativity in protein-protein association inducers has been demonstrated.
How CRISPR Can Be Used to Study GO:0030891 VCB complex
Knockout
CRISPR knockout of VHL, ELOC, CUL2, or RBX1 can abolish VCB complex function, leading to HIF-alpha stabilization. These models are valuable for studying hypoxia signaling and tumorigenesis.
Point Mutation
Point mutations in ELOC or VHL can mimic disease-associated variants, allowing study of genotype-phenotype correlations. Such models help assess the impact of specific mutations on complex assembly and activity.
Knock-in
Knock-in of tagged subunits (e.g., HA-tagged pVHL) enables affinity purification and imaging of the VCB complex. This approach facilitates tracking of complex dynamics in live cells.
Overexpression
Overexpression of VCB subunits can enhance complex formation and substrate degradation, useful for biochemical assays. It can also reveal dose-dependent effects on HIF signaling.
How EDITGENE Supports VCB complex Research
Researchers studying VCB complex-related genes often need to determine whether a candidate gene is causally involved in complex assembly, substrate recognition, or disease pathogenesis. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for VCB complex research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| USP33 Knockout HEK293 Cell Line | EDJ-KQ2412 | Human | 23032 | Details Get a Quote |
| USP33 Knockout A-549 Cell Line | EDJ-KQ22913 | Human | 23032 | Details Get a Quote |
| USP33 Knockout HCT 116 Cell Line | EDJ-KQ22914 | Human | 23032 | Details Get a Quote |
| USP33 Knockout HeLa Cell Line | EDJ-KQ22915 | Human | 23032 | Details Get a Quote |
| ELOB Knockout HEK293 Cell Line | EDJ-KQ50675 | Human | 6923 | Details Get a Quote |
| ELOB Knockout HeLa Cell Line | EDJ-KQ54621 | Human | 6923 | Details Get a Quote |
| ELOB Knockout A-549 Cell Line | EDJ-KQ63104 | Human | 6923 | Details Get a Quote |
| ELOB Knockout HCT 116 Cell Line | EDJ-KQ71576 | Human | 6923 | Details Get a Quote |
Displaying Records 1 To 8 Of 8 Records
Frequently Asked Questions About VCB complex
What is the VCB complex?
The VCB complex is a pentameric ubiquitin ligase complex composed of pVHL, elongin B, elongin C, cullin-2, and Rbx1, which targets proteins like HIF-alpha for degradation.
What genes are involved in the VCB complex?
Key genes include VHL, ELOC, ELOB, CUL2, and RBX1.
What is the function of GO:0030891?
GO:0030891 represents the VCB complex, which possesses ubiquitin ligase activity and regulates protein stability.
How is the VCB complex related to von Hippel-Lindau disease?
Mutations in VHL or ELOC disrupt VCB complex function, leading to von Hippel-Lindau disease.
What are the subunits of the VCB complex?
The subunits are pVHL, elongin B, elongin C, cullin-2, and Rbx1.
How can I study the VCB complex using CRISPR?
CRISPR knockout, point mutation, knock-in, and overexpression models can be used to dissect VCB complex function.
What is the role of elongin C in the VCB complex?
Elongin C acts as an adaptor linking pVHL to cullin-2, and mutations in ELOC cause VHL disease.
Can the VCB complex be targeted by PROTACs?
Yes, the VCB complex is exploited by PROTACs to degrade target proteins.
What diseases are associated with VCB complex dysfunction?
Von Hippel-Lindau disease, renal cell carcinoma, hemangioblastoma, and pheochromocytoma.
How is the VCB complex regulated?
It is regulated by oxygen-dependent hydroxylation, neddylation, and small molecules.
Conclusion
The VCB complex (GO:0030891) is a central player in oxygen sensing and protein degradation, with critical roles in cancer and hereditary disease. Its pentameric structure and ubiquitin ligase activity make it a prime target for therapeutic intervention and a valuable subject for CRISPR-based research. Understanding its assembly, regulation, and substrate recognition continues to yield insights into basic biology and disease mechanisms.
References
- 1. Andreou A et al.. 2022. Elongin C (ELOC/TCEB1)-associated von Hippel-Lindau disease.. Hum Mol Genet 31(16):2728-2737 PMID: 35323939
- 2. Li C et al.. 2024. Structure-Based Design of "Head-to-Tail" Macrocyclic PROTACs.. JACS Au 4(12):4866-4882 PMID: 39735913
- 5. Vocke CD et al.. 2026. Multigenerational VHL family characterized by pathogenic germline ELOC variant: Response to belzutifan.. Urol Oncol 44(2):120.e21-120.e27 PMID: 41224595
- 6. Liu S et al.. 2023. Rational Screening for Cooperativity in Small-Molecule Inducers of Protein-Protein Associations.. J Am Chem Soc 145(42):23281-23291 PMID: 37816014
- 8. Liu S et al.. 2023. Rational screening for cooperativity in small-molecule inducers of protein-protein associations.. bioRxiv PMID: 37292909
