GO:0031462 Cul2-RING ubiquitin ligase complex: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0031462 (Cul2-RING ubiquitin ligase complex) is a cullin-RING E3 ligase in which a Cul2 subfamily cullin and a RING-domain protein form the catalytic core, while an elongin-BC adaptor and a SOCS/BC-box protein provide substrate specificity.
• The complex is also known as CRL2, CBC, CDL2, ECS, VBC or SCF2, reflecting its modular architecture and historical naming.
• Cul2-based ligases target diverse substrates for ubiquitin-mediated degradation, including misfolded TDP-43, SLBP, Smad1 and RIPK1, linking the complex to neurodegeneration, embryonic patterning, cell-cycle control and necroptosis.
• A testis-specific Cul2-containing E3 complex governs spermiogenesis and male fertility, demonstrating tissue-restricted functions of CRL2.
• Dysregulation of Cul2 complex components such as FEM1C is associated with colorectal cancer progression and metastasis.
• CRISPR knockout, point-mutation, knock-in and overexpression models, combined with proteomics and ubiquitin profiling, are key methods for dissecting CRL2 biology.
Description
The Cul2-RING ubiquitin ligase complex (GO:0031462) is a multi-subunit E3 ubiquitin ligase that catalyzes the transfer of ubiquitin from an E2 conjugating enzyme to specific substrate proteins, thereby controlling their stability, localization or activity. It belongs to the cullin-RING ligase (CRL) family, the largest class of E3 ligases in eukaryotes, and is defined by a Cul2 subfamily cullin paired with a RING-domain protein as the catalytic core, an elongin-BC adaptor, and a SOCS/BC-box substrate receptor. This modular design allows a single catalytic engine to recognize many different substrates through exchangeable SOCS-box proteins, making CRL2 a central node in cellular proteostasis and signaling. Researchers study GO:0031462 because it sits at the intersection of protein quality control, development and disease. For example, CUL2-mediated clearance of misfolded TDP-43 is paradoxically affected by VHL in oligodendrocytes in amyotrophic lateral sclerosis (ALS), implicating CRL2 in neurodegeneration. A testis-specific E3 complex containing Cul2 governs spermiogenesis and male fertility, showing that CRL2 modules can be tissue-restricted. Other CRL2 substrates include SLBP, whose degradation is controlled by FEM1 proteins, Smad1, which is targeted by ZSWIM4 to regulate BMP signaling and embryonic patterning, and RIPK1, whose targeted degradation modulates necroptosis. These examples illustrate how a single GO term can connect to diverse physiological and pathological processes. Because CRL2 substrates are often short-lived regulatory proteins, the complex is a prime target for functional genomics and drug discovery. Understanding its composition, assembly and substrate recognition is essential for interpreting ubiquitin-dependent signaling and for designing experiments that test causality of candidate genes.
Cul2-RING ubiquitin ligase complex At A Glance
| GO ID | GO:0031462 |
|---|---|
| GO term | Cul2-RING ubiquitin ligase complex |
| Ontology | cellular_component |
| Synonym | CBC complex, CDL2 complex, CRL2 complex, cullin-RING ligase 2, EC2S complex, ECS complex, SCF2 complex, VBC complex |
| Major function | Ubiquitin-mediated degradation of specific substrate proteins through a Cul2-RING catalytic core, elongin-BC adaptor and SOCS/BC-box substrate receptor |
| Catalytic core | Cul2 subfamily cullin plus a RING domain protein |
| Adaptor | Elongin-BC |
| Substrate receptor | SOCS/BC-box protein |
| Example substrates | TDP-43, SLBP, Smad1, RIPK1 |
| Associated biology | Spermiogenesis, embryonic patterning, neurodegeneration, necroptosis, cancer progression |
What Is GO:0031462?
GO:0031462 describes a ubiquitin ligase complex in which a cullin from the Cul2 subfamily and a RING domain protein form the catalytic core; substrate specificity is conferred by an elongin-BC adaptor and a SOCS/BC box protein. In other words, it is a modular E3 ligase that uses a Cul2 scaffold to assemble a RING finger catalytic subunit and a variable SOCS-box substrate receptor, enabling ubiquitination of specific target proteins.
Why Is Cul2-RING ubiquitin ligase complex Important in Cell Biology?
GO:0031462 is important because it defines a major class of E3 ubiquitin ligases that control the lifetime of key regulatory proteins, thereby influencing development, fertility, neuronal survival and cell death pathways. Its modular architecture allows a single catalytic core to recognize many substrates via exchangeable SOCS-box proteins, making it a paradigm for understanding how ubiquitin signaling achieves specificity. Clinically, CRL2 components and substrates have been linked to ALS, colorectal cancer and male infertility, highlighting the term's translational relevance.
Cul2-RING ubiquitin ligase complex
• Controls degradation of misfolded TDP-43 in oligodendrocytes, with VHL paradoxically affecting this process in ALS.
• A testis-specific Cul2-containing E3 complex is required for spermiogenesis and male fertility.
• Regulates SLBP degradation through FEM1 proteins, linking CRL2 to cell-cycle and histone mRNA metabolism.
• ZSWIM4 promotes nuclear Smad1 degradation via CRL2 to regulate BMP signaling and embryonic patterning.
• Targeted degradation of RIPK1 through CRL2 modulates the necroptosis pathway.
• Downregulation of FEM1C, a CRL2-related substrate receptor, enhances metastasis and proliferation in colorectal cancer.
• Provides a model system for studying cullin-RING ligase assembly, adaptor exchange and substrate recognition.
• Offers potential therapeutic entry points for neurodegeneration, cancer and fertility disorders.
• Enables functional genomics screens to identify novel substrates and regulators of CRL2.
• Supports development of targeted protein degradation strategies using CRL2 components.
What Happens During Cul2-RING ubiquitin ligase complex?
(未命名小节)
In simple terms: The complex acts like a tagging machine that marks specific proteins with ubiquitin so they can be degraded or regulated.
The Cul2-RING ubiquitin ligase complex (GO:0031462) catalyzes the transfer of ubiquitin from an E2 conjugating enzyme to a substrate protein. The process begins when a SOCS/BC-box substrate receptor binds a target protein and docks onto the elongin-BC adaptor, which in turn associates with the Cul2-RING catalytic core. This assembly positions the substrate near the E2-ubiquitin conjugate, allowing the RING domain protein to facilitate ubiquitin transfer. Repeated cycles generate a polyubiquitin chain that typically targets the substrate for proteasomal degradation. Examples include CUL2-mediated clearance of misfolded TDP-43, FEM1-dependent degradation of SLBP, ZSWIM4-promoted nuclear Smad1 degradation, and targeted degradation of RIPK1.
Substrate recognition and adaptor exchange
In simple terms: Different receptor proteins can plug into the same core to recognize different targets.
Substrate specificity of GO:0031462 is conferred by a SOCS/BC-box protein that binds the elongin-BC adaptor. This modular design allows a single Cul2-RING catalytic core to interact with many different SOCS-box receptors, each recognizing distinct substrates. For instance, FEM1 proteins act as ancient regulators of SLBP degradation, while ZSWIM4 promotes nuclear Smad1 degradation to regulate BMP signaling. The exchange of substrate receptors enables the complex to respond to diverse cellular signals and developmental cues.
Structure and Composition of Cul2-RING ubiquitin ligase complex
In simple terms: The complex is built from a scaffold, a catalytic ring, an adaptor and a target-recognition subunit.
The Cul2-RING ubiquitin ligase complex is composed of a Cul2 subfamily cullin that serves as a molecular scaffold, a RING domain protein that forms the catalytic core, an elongin-BC adaptor, and a SOCS/BC-box substrate receptor. The cullin subunit provides the structural framework for assembly, while the RING domain protein recruits the E2 enzyme. The elongin-BC adaptor bridges the cullin and the SOCS-box protein, which directly binds the substrate. This four-part architecture is characteristic of cullin-RING ligases and is conserved across eukaryotes.
Molecular Mechanism of Cul2-RING ubiquitin ligase complex
In simple terms: The RING domain helps transfer ubiquitin from an E2 enzyme to the target protein.
The molecular mechanism of GO:0031462 involves the RING domain protein acting as a scaffold to position the E2-ubiquitin conjugate near the substrate. The Cul2 cullin and elongin-BC adaptor orient the SOCS-box receptor and its bound substrate for efficient ubiquitin transfer. This results in polyubiquitination of the substrate, which is then recognized by the proteasome. The process is regulated by the availability of substrate receptors and by post-translational modifications of the cullin subunit. Specific examples include CUL2-mediated clearance of misfolded TDP-43, degradation of SLBP by FEM1 proteins, and targeted degradation of RIPK1.
Regulation of Cul2-RING ubiquitin ligase complex activity
In simple terms: The complex can be turned on or off by modifying its components or changing which receptors are present.
Activity of GO:0031462 is regulated at multiple levels, including the expression of substrate receptors, the availability of adaptor proteins, and post-translational modifications of the cullin subunit. For example, VHL paradoxically affects CUL2-mediated clearance of misfolded TDP-43 in oligodendrocytes, indicating that additional factors modulate CRL2 function in disease contexts. The testis-specific E3 complex containing Cul2 is likely regulated by tissue-specific expression of its components. These regulatory mechanisms ensure that substrate degradation is tightly controlled in space and time.
Key Genes Involved in GO:0031462 Cul2-RING ubiquitin ligase complex
The following genes and proteins are core components, substrate receptors or substrates of the Cul2-RING ubiquitin ligase complex (GO:0031462) and are frequently studied in this context.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CUL2 | Cullin scaffold of the Cul2-RING ubiquitin ligase complex | Central to CRL2 assembly and substrate ubiquitination |
| ELOB | Elongin-B subunit of the elongin-BC adaptor | Adaptor component required for substrate receptor binding |
| ELOC | Elongin-C subunit of the elongin-BC adaptor | Adaptor component required for substrate receptor binding |
| RBX1 | RING domain protein forming the catalytic core | Recruits E2 enzyme for ubiquitin transfer |
| VHL | SOCS-box substrate receptor | Modulates CUL2-mediated TDP-43 clearance in ALS |
| FEM1A | SOCS-box substrate receptor | Regulates SLBP degradation |
| FEM1B | SOCS-box substrate receptor | Regulates SLBP degradation |
| FEM1C | SOCS-box substrate receptor | Downregulation enhances metastasis in colorectal cancer |
| ZSWIM4 | SOCS-box substrate receptor | Promotes nuclear Smad1 degradation and regulates BMP signaling |
| TDP-43 | Substrate protein | Misfolded TDP-43 is cleared by CUL2 in oligodendrocytes |
| SLBP | Substrate protein | Degraded by FEM1 proteins via CRL2 |
| SMAD1 | Substrate protein | Degraded by ZSWIM4-CRL2 to regulate embryonic patterning |
| RIPK1 | Substrate protein | Targeted degradation modulates necroptosis |
| AMBRA1 | Potential regulator of mitophagy | Linked to aging-related diseases and CRL2-related pathways |
| E7 oncoprotein | Viral protein interacting with host factors | Interacts with host cell proteins including CRL2 components |
| CUL2 testis-specific complex components | Testis-specific E3 ligase complex | Governs spermiogenesis and male fertility |
How Is Cul2-RING ubiquitin ligase complex Regulated?
Regulation of GO:0031462 occurs through multiple mechanisms. The availability of SOCS/BC-box substrate receptors determines which substrates are targeted, and exchange of these receptors allows the complex to respond to different signals. Post-translational modifications of the cullin subunit, such as neddylation, are known to regulate cullin-RING ligase activity in general. In disease contexts, additional factors such as VHL can paradoxically affect CUL2-mediated clearance of misfolded TDP-43. Tissue-specific expression of complex components, as seen in the testis-specific E3 complex, further tunes CRL2 activity.
Cul2-RING ubiquitin ligase complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CUL2 | ALS, TDP-43 proteinopathy | CUL2 knockout or knockdown in oligodendrocyte cell lines |
| FEM1C | Colorectal cancer metastasis | FEM1C overexpression or knockout in colorectal cancer cells |
| ZSWIM4 | Embryonic patterning defects | Zswim4 knockout mouse or zebrafish models |
| RIPK1 | Necroptosis-related inflammatory diseases | RIPK1-targeting degrader in cell-based necroptosis assays |
| Cul2 testis-specific complex | Male infertility | Testis-specific knockout mouse models |
Cul2-RING ubiquitin ligase complex in neurodegeneration
CUL2-mediated clearance of misfolded TDP-43 is paradoxically affected by VHL in oligodendrocytes in ALS, suggesting that CRL2 dysfunction may contribute to TDP-43 proteinopathy. AMBRA1, a protein linked to mitophagy regulation, has emerging evidence in aging-related diseases and may intersect with CRL2 pathways. These findings position GO:0031462 as a potential therapeutic target in neurodegenerative conditions.
Cul2-RING ubiquitin ligase complex in cancer
Downregulation of FEM1C, a SOCS-box substrate receptor likely acting through CRL2, enhances metastasis and proliferation in colorectal cancer. The E7 oncoprotein from human papillomaviruses interacts with host cell proteins, including potential CRL2 components, highlighting a role in viral oncogenesis. These observations suggest that CRL2 components can act as tumor suppressors or oncogenic modulators depending on context.
Cul2-RING ubiquitin ligase complex in fertility and development
A testis-specific E3 ubiquitin ligase complex containing Cul2 governs spermiogenesis and male fertility, demonstrating a specialized role for CRL2 in reproduction. ZSWIM4 regulates embryonic patterning and BMP signaling by promoting nuclear Smad1 degradation through CRL2, linking the complex to developmental signaling. These findings underscore the importance of GO:0031462 in developmental and reproductive biology.
Cul2-RING ubiquitin ligase complex in cell death and inflammation
Targeted degradation of RIPK1 through CRL2 modulates the necroptosis pathway, indicating a role for GO:0031462 in programmed cell death and inflammation. This has implications for diseases where necroptosis contributes to pathology, such as inflammatory and neurodegenerative disorders.
From Cul2-RING ubiquitin ligase complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does CUL2 loss affect TDP-43 clearance? | CUL2 knockout in oligodendrocyte cell lines |
| Does FEM1C downregulation promote metastasis? | FEM1C knockout or overexpression in colorectal cancer cells |
| How does ZSWIM4 regulate Smad1 degradation? | ZSWIM4 knockout or point-mutation models in embryonic stem cells |
| Can RIPK1 degradation be targeted to modulate necroptosis? | RIPK1-targeting degrader in cell-based assays |
| What is the role of testis-specific Cul2 complex in fertility? | Testis-specific Cul2 knockout mouse |
| How do CRL2 components interact with viral oncoproteins? | E7-expressing cell lines with tagged CRL2 subunits |
How to Study the Cul2-RING ubiquitin ligase complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Immunoprecipitation-mass spectrometry | Protein interactions and complex composition | Identifying CRL2 subunits and substrates |
| Ubiquitin remnant profiling | Ubiquitination sites on substrate proteins | Mapping TDP-43, SLBP, Smad1 ubiquitination |
| CRISPR knockout screens | Gene requirements for CRL2 function | Discovering regulators of substrate degradation |
| Fluorescence microscopy | Subcellular localization of CRL2 components | Visualizing nuclear Smad1 degradation |
| In vitro ubiquitination assay | Catalytic activity of the E3 ligase | Testing subunit requirements |
| Western blot | Steady-state levels of substrate proteins | Assessing degradation of TDP-43, SLBP, RIPK1 |
| Co-immunoprecipitation | Physical interactions between CRL2 subunits | Validating adaptor-substrate receptor binding |
| RNA-seq | Transcriptional changes upon CRL2 perturbation | Identifying downstream pathways |
Proteomics and ubiquitin profiling
Mass spectrometry-based proteomics can identify substrates and interactors of the Cul2-RING ubiquitin ligase complex by immunoprecipitating tagged components such as CUL2 or SOCS-box receptors. Ubiquitin remnant profiling can map ubiquitination sites on substrates like TDP-43, SLBP, Smad1 and RIPK1. These methods are essential for defining the substrate repertoire of GO:0031462.
CRISPR-based functional genomics
CRISPR knockout screens can identify genes required for CRL2 function or for the degradation of specific substrates. For example, knocking out CUL2 or FEM1C can reveal effects on TDP-43 clearance or cancer cell proliferation. These screens are powerful for discovering novel regulators and substrates of GO:0031462.
Imaging and subcellular localization
Fluorescence microscopy of tagged CRL2 components can reveal their subcellular localization and assembly dynamics. For instance, ZSWIM4 promotes nuclear Smad1 degradation, which can be visualized using nuclear markers. Imaging approaches help link GO:0031462 to specific cellular compartments and processes.
Biochemical reconstitution and ubiquitination assays
In vitro ubiquitination assays using purified Cul2-RING complex components, E1, E2 and substrate can reconstitute the ubiquitin transfer reaction. Such assays are used to test the requirement for specific subunits and to measure catalytic activity. They complement cellular studies and provide mechanistic insight into GO:0031462.
How CRISPR Can Be Used to Study GO:0031462 Cul2-RING ubiquitin ligase complex
Knockout
CRISPR knockout of CUL2 or substrate receptor genes such as FEM1C can abolish CRL2 function and stabilize substrates, leading to measurable phenotypes such as altered TDP-43 clearance or increased cancer cell proliferation. Knockout models are essential for testing causality of GO:0031462 components in disease.
Point Mutation
Point mutations in the RING domain or cullin subunit can disrupt catalytic activity or substrate recognition without affecting complex assembly. Such models help dissect the specific contribution of enzymatic activity versus scaffolding functions of GO:0031462.
Knock-in
Knock-in of tagged versions of CUL2 or SOCS-box receptors (e.g., HA, FLAG, GFP) enables affinity purification and imaging of the endogenous complex. This approach preserves physiological expression levels and is valuable for studying CRL2 dynamics.
Overexpression
Overexpression of substrate receptors such as FEM1C or ZSWIM4 can enhance degradation of their targets, providing gain-of-function models to study CRL2 biology. Overexpression of dominant-negative cullin mutants can also be used to inhibit CRL2 activity.
How EDITGENE Supports Cul2-RING ubiquitin ligase complex Research
Researchers studying Cul2-RING ubiquitin ligase complex-related genes often need to determine whether a candidate gene is causally involved in complex assembly, substrate recognition or downstream degradation. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models for such functional studies.
Contact EDITGENE today to design your custom CRISPR model for Cul2-RING ubiquitin ligase complex research.
Frequently Asked Questions About Cul2-RING ubiquitin ligase complex
What is the Cul2-RING ubiquitin ligase complex?
It is a multi-subunit E3 ubiquitin ligase (GO:0031462) in which a Cul2 subfamily cullin and a RING domain protein form the catalytic core, while an elongin-BC adaptor and a SOCS/BC-box protein confer substrate specificity.
What genes are involved in the Cul2-RING ubiquitin ligase complex?
Core genes include CUL2, ELOB, ELOC and RBX1, while substrate receptors include VHL, FEM1A, FEM1B, FEM1C and ZSWIM4.
What does GO:0031462 mean?
GO:0031462 is the Gene Ontology identifier for the Cul2-RING ubiquitin ligase complex, a cellular component term describing a specific class of cullin-RING E3 ligases.
What substrates are degraded by the Cul2-RING ubiquitin ligase complex?
Known substrates include misfolded TDP-43, SLBP, Smad1 and RIPK1.
How is the Cul2-RING ubiquitin ligase complex linked to ALS?
CUL2-mediated clearance of misfolded TDP-43 is paradoxically affected by VHL in oligodendrocytes in ALS, suggesting a role in TDP-43 proteinopathy.
What is the role of FEM1C in cancer?
Downregulation of FEM1C enhances metastasis and proliferation in colorectal cancer, indicating a tumor-suppressive role.
How does ZSWIM4 regulate BMP signaling?
ZSWIM4 promotes nuclear Smad1 degradation through the Cul2-RING complex, thereby regulating embryonic patterning and BMP signaling.
Can the Cul2-RING complex be targeted for drug discovery?
Yes, targeted degradation of RIPK1 through CRL2 modulates necroptosis, suggesting therapeutic potential for CRL2-based degraders.
What research methods are used to study GO:0031462?
Common methods include immunoprecipitation-mass spectrometry, ubiquitin remnant profiling, CRISPR knockout screens, fluorescence microscopy and in vitro ubiquitination assays.
What is the testis-specific Cul2 complex?
A testis-specific E3 ubiquitin ligase complex containing Cul2 governs spermiogenesis and male fertility, demonstrating tissue-specific functions of CRL2.
Conclusion
The Cul2-RING ubiquitin ligase complex (GO:0031462) is a modular E3 ligase that controls the stability of diverse regulatory proteins through a Cul2-RING catalytic core, an elongin-BC adaptor and SOCS/BC-box substrate receptors. Its substrates and components are implicated in neurodegeneration, cancer, fertility and developmental signaling, making it a high-value target for functional genomics and therapeutic development. Continued research using CRISPR models, proteomics and ubiquitin profiling will further illuminate how this complex achieves substrate specificity and how its dysfunction contributes to human disease.
References
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