GO:0097602 cullin family protein binding: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0097602 (cullin family protein binding) is a molecular function describing binding to a member of the cullin family, hydrophobic scaffold proteins of E3 ubiquitin ligases.
• Cullins assemble with RING-box proteins, adaptors and substrate receptors to form CRL (cullin-RING ligase) complexes that polyubiquitinate target proteins for proteasomal degradation.
• The best-characterized cullin-binding module is the SCF complex, in which SKP1 bridges cullin-1 (CUL1) to F-box substrate receptors such as COI1 and FBXO32.
• Cullin-binding proteins control diverse physiology, including jasmonate signaling through SCF(COI1)-JAZ recognition, skeletal muscle atrophy through atrogin-1/MAFbx and MuRF1, and RAS GTPase degradation through LZTR1-CUL3.
• Phosphorylation of substrates and of cullin complex components is a major regulatory input that determines cullin-based ubiquitination in tumorigenesis.
• CRISPR knockout, point-mutation, knock-in and overexpression models, combined with CRISPR library screening and bioinformatics, are core tools for dissecting cullin family protein binding in disease.
Description
GO:0097602, cullin family protein binding, is a molecular function term that captures the physical interaction between a protein and a member of the cullin family. Cullins are hydrophobic scaffold proteins that serve as the structural backbone of cullin-RING ubiquitin ligases (CRLs), the largest class of E3 enzymes in eukaryotes. Because CRLs mark specific substrates with ubiquitin chains that direct them to the proteasome, proteins that bind cullins are central regulators of protein stability, signal transduction and cell fate. The term is therefore relevant to any researcher mapping ubiquitin-dependent degradation pathways, from plant hormone signaling to human cancer. Mechanistically, cullin family protein binding is not a single interaction but a modular recognition event. A typical CRL contains a cullin, a RING-box protein, and substrate adaptors or receptors that bind the cullin directly or through bridging proteins. For example, in the SCF (SKP1-CUL1-F-box) complex, the F-box protein is the substrate receptor, while SKP1 binds CUL1 and the F-box domain, linking substrate recognition to cullin-based catalysis. This architecture explains why cullin-binding proteins are so diverse and why the same GO term applies to plant JAZ repressors, muscle atrophy ligases and RAS GTPase degradation factors. For biomedical researchers, GO:0097602 provides a functional annotation that connects a candidate protein to ubiquitin ligase biology. Annotating a protein with cullin family protein binding predicts that it may act as an adaptor, receptor or regulator of a CRL, and therefore that its loss or mutation could stabilize or destabilize specific substrates. This makes the term a practical entry point for CRISPR screens, proteomic interaction studies and disease modeling, especially in cancer and metabolic or degenerative conditions where CRL substrates are dysregulated.
cullin family protein binding At A Glance
| GO ID | GO:0097602 |
|---|---|
| GO term | cullin family protein binding |
| Ontology | molecular_function |
| Synonym | cullin binding |
| Definition | Binding to a member of the cullin family, hydrophobic proteins that act as scaffolds for ubiquitin ligases (E3). |
| Major function | Mediates assembly and substrate recruitment of cullin-RING ubiquitin ligases (CRLs). |
| Representative complexes | SCF (SKP1-CUL1-F-box) and related CRL complexes. |
| Representative binders | F-box proteins, SKP1, BTB/POZ adaptors, DDB1, RING-box proteins and LZTR1. |
| Disease relevance | Cancer, muscle atrophy, RAS-driven disorders and inflammatory signaling. |
What Is GO:0097602?
In simple terms, GO:0097602 means a protein can physically stick to a cullin. The official QuickGO definition states that it is binding to a member of the cullin family, hydrophobic proteins that act as scaffolds for ubiquitin ligases (E3). The synonym cullin binding is used interchangeably. This function is molecular rather than process-level: it describes the binding event itself, not the downstream ubiquitination or degradation that follows.
Why Is cullin family protein binding Important in Cell Biology?
Cullin family protein binding is important because it defines the assembly interface of the largest family of E3 ubiquitin ligases, which control the half-life of many regulatory proteins. Without cullin-binding adaptors and receptors, CRLs cannot recognize substrates, so this function sits at the decision point between protein synthesis and degradation. Dysregulation of cullin-binding proteins has been linked to tumorigenesis, muscle wasting and RAS GTPase turnover, making the term a high-value annotation for disease gene discovery and drug target validation.
• Defines the scaffold-binding step that assembles cullin-RING ligases, the largest class of E3 ubiquitin ligases.
• Enables substrate recognition in SCF complexes through F-box proteins such as COI1 and FBXO32.
• Controls jasmonate signaling in plants via SCF(COI1)-mediated JAZ repressor degradation.
• Regulates skeletal muscle atrophy through cullin-dependent ligases such as atrogin-1/MAFbx and MuRF1.
• Participates in RAS GTPase degradation through LZTR1 recognition and cullin-based complexes.
• Is modulated by phosphorylation, linking kinase signaling to cullin-based ubiquitination in tumorigenesis.
• Provides a functional annotation for interpreting CRISPR screens and proteomic interaction maps.
• Connects to viral-host interaction networks, as shown by SARS-CoV-2 protein interaction maps that include cullin-associated factors.
• Supports autophagy regulation through linear ubiquitination and stabilization of ATG13 by LUBAC and OTULIN.
• Offers a mechanistic entry point for targeted protein degradation strategies in cancer and other diseases.
Molecular Mechanism of cullin family protein binding
Cullin scaffolds and CRL assembly
In simple terms: Cullins act like a molecular rack on which the ubiquitin machinery is built.
Cullins are hydrophobic scaffold proteins that form the backbone of cullin-RING ubiquitin ligases. A cullin binds a RING-box protein at its C-terminus and a substrate adaptor or receptor at its N-terminus, creating a modular E3 complex. This scaffold function is the reason GO:0097602 is defined as binding to a cullin family member rather than to a specific domain: the term captures the interaction that positions adaptors on the cullin scaffold.
SCF complexes and F-box substrate receptors
In simple terms: In SCF complexes, an F-box protein is the interchangeable part that grabs the target protein.
The SCF complex is the archetypal cullin-based ligase, composed of SKP1, CUL1 and an F-box protein. The F-box protein binds SKP1 through its F-box motif and simultaneously recognizes the substrate, while SKP1 bridges to CUL1. In jasmonate signaling, the F-box protein COI1 binds JAZ repressors as substrates, and this interaction depends on the SCF(COI1) complex. FBXO32 is another F-box protein whose cullin-dependent activity targets PTEN for degradation in lung adenocarcinoma.
Adaptor diversity beyond F-box proteins
In simple terms: Different cullins use different adaptor systems, so cullin binding is a shared function across many protein families.
Cullin family protein binding is not limited to F-box proteins. BTB/POZ domain proteins, DDB1-containing adaptors and other substrate receptors can bind cullins directly or through bridging proteins. LZTR1 is a cullin-associated factor that recognizes RAS GTPases for degradation, illustrating how a non-F-box protein can use cullin binding to control small GTPase abundance. This diversity explains why GO:0097602 is annotated to many proteins with otherwise unrelated domain architectures.
Phosphorylation-dependent regulation of cullin binding
In simple terms: Phosphate tags on substrates or adaptors can switch cullin-based degradation on or off.
Phosphorylation regulates cullin-based ubiquitination at multiple levels, including substrate recognition and complex assembly. Because many CRL substrates require prior phosphorylation to be recognized, kinases and phosphatases act as upstream regulators of cullin family protein binding. This regulatory layer is particularly important in tumorigenesis, where altered kinase signaling can change which substrates are degraded.
Cullin binding in ubiquitin-like and autophagy pathways
In simple terms: Cullin-associated ubiquitin machinery also influences processes beyond simple protein degradation, such as autophagy.
LUBAC and OTULIN regulate autophagy initiation and maturation by mediating linear ubiquitination and stabilization of ATG13. Although this pathway involves linear ubiquitin chains rather than canonical cullin-RING ligases, it illustrates how ubiquitin-modifying complexes intersect with cullin-associated biology and how cullin-binding proteins can influence autophagic flux. SARS-CoV-2 protein interaction maps have also identified cullin-associated factors as viral targets, suggesting that cullin binding is relevant to host-pathogen interactions.
Key Genes Involved in GO:0097602 cullin family protein binding
The following genes and proteins represent major cullin-binding factors, substrate receptors and regulatory components discussed in the verified literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CUL1 | Scaffold cullin of SCF complexes | Core cullin for F-box protein binding and substrate ubiquitination |
| CUL3 | Scaffold cullin for BTB-based CRLs | Cullin partner in LZTR1-mediated RAS GTPase degradation |
| SKP1 | Adaptor bridging CUL1 and F-box proteins | Essential for SCF assembly and cullin binding |
| COI1 | F-box substrate receptor in jasmonate signaling | Binds JAZ repressors within SCF(COI1) |
| FBXO32 | F-box protein targeting PTEN | Cullin-dependent degradation linked to lung adenocarcinoma |
| LZTR1 | Cullin-associated RAS GTPase recognition factor | Structural basis for RAS degradation via cullin complexes |
| RBX1 | RING-box protein of CRLs | Catalytic component recruited by cullin scaffolds |
| DDB1 | Adaptor for CUL4-based CRLs | Bridges substrate receptors to cullin scaffolds |
| ATG13 | Autophagy initiation factor | Stabilized by linear ubiquitination involving LUBAC and OTULIN |
| LUBAC | Linear ubiquitin chain assembly complex | Regulates autophagy and ATG13 stability |
| OTULIN | Deubiquitinase for linear ubiquitin | Opposes LUBAC and modulates autophagy |
| Atrogin-1/MAFbx | Muscle-specific E3 ligase component | Required for skeletal muscle atrophy |
| MuRF1 | Muscle RING finger E3 ligase | Identified as a ligase required for muscle atrophy |
| JAZ proteins | Repressors of jasmonate signaling | Targets of SCF(COI1) for degradation |
| PTEN | Tumor suppressor and CRL substrate | Degraded by FBXO32 in lung adenocarcinoma |
| RAS GTPases | Small GTPases controlling growth | Recognized by LZTR1 for cullin-based degradation |
| SARS-CoV-2 proteins | Viral factors interacting with host cullin machinery | Mapped in host-pathogen interaction networks |
How Is cullin family protein binding Regulated?
Cullin family protein binding is regulated by phosphorylation of substrates and complex components, which controls cullin-based ubiquitination in tumorigenesis. Additional regulation occurs through the availability of adaptor proteins, the assembly state of the CRL, and the activity of deubiquitinases such as OTULIN that oppose linear ubiquitination and modulate autophagy-related stability of ATG13. Viral proteins can also perturb cullin-associated host networks, as shown by SARS-CoV-2 interaction maps.
cullin family protein binding and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| FBXO32 | Lung adenocarcinoma progression via PTEN degradation | KO and overexpression in lung cancer cell lines |
| LZTR1 | RAS GTPase degradation and RAS-driven disorders | Point-mutation and knock-in models of LZTR1-RAS interface |
| CUL3 | Cullin scaffold in CRL assembly and RAS turnover | KO and tagged knock-in for interaction proteomics |
| Atrogin-1/MAFbx | Skeletal muscle atrophy | KO and overexpression in muscle cell models |
| ATG13 | Autophagy regulation via linear ubiquitination | Knock-in and KO models for autophagy flux studies |
Cancer and tumorigenesis
Phosphorylation-dependent regulation of cullin-based ubiquitination is directly implicated in tumorigenesis, where altered CRL activity changes the stability of oncoproteins and tumor suppressors. FBXO32-mediated degradation of PTEN promotes lung adenocarcinoma progression, showing that a cullin-binding F-box protein can drive cancer by removing a tumor suppressor. These findings make cullin family protein binding a candidate axis for therapeutic targeting in cancers with dysregulated CRL components.
RAS-driven disorders
LZTR1 recognizes RAS GTPases for degradation through cullin-associated complexes, providing a structural basis for how cullin binding controls RAS abundance. Because RAS proteins are central to many cancers and developmental disorders, perturbations in cullin-binding factors such as LZTR1 can contribute to RAS pathway dysregulation.
Muscle atrophy and metabolic stress
Ubiquitin ligases required for skeletal muscle atrophy include atrogin-1/MAFbx and MuRF1, which operate within cullin-dependent E3 machinery. This links cullin family protein binding to catabolic muscle wasting and suggests that modulating CRL assembly could influence atrophy programs.
Autophagy and inflammatory signaling
LUBAC and OTULIN regulate autophagy initiation and maturation by mediating linear ubiquitination and stabilization of ATG13. Although this pathway is distinct from canonical cullin-RING ligation, it demonstrates how ubiquitin-modifying complexes that intersect with cullin biology can influence autophagy and inflammatory signaling. SARS-CoV-2 interaction maps further suggest that host cullin-associated networks are targeted during viral infection.
From cullin family protein binding-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a cullin-binding protein alter substrate stability? | CRISPR knockout cell line followed by proteomics |
| Does a specific cullin interface mutation disrupt binding? | Point-mutation knock-in of the cullin-binding domain |
| Can a disease-associated variant change cullin binding? | Knock-in of the patient variant and interaction assays |
| Where does the cullin-binding protein localize and with what partners? | Tagged knock-in for imaging and affinity purification |
| Does overexpression of a cullin-binding factor drive transformation? | Overexpression cell model with proliferation and degradation readouts |
| Which genes modify cullin-dependent phenotypes genome-wide? | CRISPR library screening with bioinformatics analysis |
How to Study the cullin family protein binding Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Affinity purification-mass spectrometry | Protein-protein interactions with cullins | Mapping CRL components and adaptors |
| CRISPR knockout screening | Gene requirement for cullin-dependent phenotypes | Identifying modifiers of degradation pathways |
| Cycloheximide chase | Substrate half-life | Testing whether cullin binding controls stability |
| Ubiquitination assay | Ubiquitin chain formation on substrates | Confirming E3 ligase activity of CRL complexes |
| Phosphorylation analysis | Phospho-status of substrates or adaptors | Linking kinase signaling to cullin-based ubiquitination |
| Structural biology | Atomic interface of cullin-substrate recognition | Understanding LZTR1-RAS and related interactions |
| Fluorescence imaging | Subcellular localization of cullin complexes | Validating tagged knock-in models |
| Bioinformatics pathway analysis | Enrichment of CRL and ubiquitin pathways | Interpreting CRISPR screen and proteomic data |
Interaction proteomics and affinity purification
Affinity purification of tagged cullin-binding proteins followed by mass spectrometry identifies CRL components and substrate receptors. This approach is particularly useful for defining which adaptors associate with a given cullin and how disease mutations alter those interactions.
CRISPR screening and functional genomics
CRISPR library screening can systematically test which genes are required for cullin-dependent degradation or for viability in cells with altered cullin-binding activity. Bioinformatics analysis of screen hits then maps candidate genes onto CRL pathways and predicts adaptor-substrate relationships.
Protein stability and ubiquitination assays
Cycloheximide chase, ubiquitination assays and proteasome inhibition are standard methods to measure whether cullin family protein binding controls substrate half-life. These assays are often paired with phosphorylation modulators because phosphorylation regulates cullin-based ubiquitination.
Structural and imaging approaches
Structural studies such as the analysis of LZTR1 recognition of RAS GTPases reveal how cullin-associated factors engage substrates at the atomic level. Fluorescence imaging of tagged knock-in proteins complements these structures by showing where cullin-binding complexes assemble in cells.
How CRISPR Can Be Used to Study GO:0097602 cullin family protein binding
Knockout
CRISPR knockout of a cullin-binding gene removes the protein and reveals which substrates depend on it for degradation. For example, knocking out FBXO32 would be expected to stabilize PTEN and suppress lung adenocarcinoma phenotypes, providing a direct test of cullin-dependent oncogenesis. Knockout models are also useful for validating hits from CRISPR library screens.
Point Mutation
Point-mutation models can disrupt the cullin-binding interface without deleting the entire protein, separating binding-dependent functions from scaffolding or other activities. Such models are valuable for testing disease-associated variants in cullin-binding proteins and for mapping the residues required for CRL assembly.
Knock-in
Knock-in of tags, reporters or patient variants allows precise tracking of cullin-binding proteins in their endogenous context. Tagged knock-in lines support imaging and affinity purification, while variant knock-in lines test whether specific mutations alter cullin binding and substrate turnover.
Overexpression
Overexpression of a cullin-binding protein can drive substrate degradation or sequester adaptors, producing gain-of-function phenotypes relevant to cancer and other diseases. Overexpression models are often combined with degradation assays to confirm that the observed phenotype depends on cullin-based ubiquitination.
How EDITGENE Supports cullin family protein binding Research
Researchers studying cullin family protein binding-related genes often need to determine whether a candidate gene is causally involved in CRL assembly, substrate recognition or disease progression. EDITGENE provides the full spectrum of CRISPR cell models and screening services required to move from annotation to mechanism.
Contact EDITGENE today to design your custom CRISPR model for cullin family protein binding research.
Frequently Asked Questions About cullin family protein binding
What is GO:0097602 cullin family protein binding?
GO:0097602 is a molecular function term describing binding to a member of the cullin family, hydrophobic proteins that act as scaffolds for E3 ubiquitin ligases.
What genes are involved in cullin family protein binding?
Key genes include CUL1, CUL3, SKP1, COI1, FBXO32, LZTR1, RBX1, DDB1, ATG13, LUBAC, OTULIN, atrogin-1/MAFbx and MuRF1.
What is the function of cullin family protein binding?
It mediates assembly and substrate recruitment of cullin-RING ubiquitin ligases, which polyubiquitinate target proteins for proteasomal degradation.
How is cullin family protein binding regulated?
Phosphorylation of substrates and complex components regulates cullin-based ubiquitination, and deubiquitinases such as OTULIN modulate related ubiquitin pathways.
Which diseases are linked to cullin family protein binding?
Cancer, RAS-driven disorders, muscle atrophy and autophagy-related conditions have been linked to cullin-binding proteins and CRL components.
What is the SCF complex and how does it relate to cullin binding?
The SCF complex contains SKP1, CUL1 and an F-box protein; the F-box protein binds SKP1 and recognizes substrates, while CUL1 provides the cullin scaffold.
How does FBXO32 relate to cullin family protein binding?
FBXO32 is an F-box protein that mediates PTEN degradation and promotes lung adenocarcinoma progression through cullin-dependent ubiquitination.
What is the role of LZTR1 in cullin family protein binding?
LZTR1 recognizes RAS GTPases for degradation, and structural studies reveal the basis for this cullin-associated recognition.
How can CRISPR be used to study cullin family protein binding?
CRISPR knockout, point-mutation, knock-in and overexpression models, together with CRISPR library screening, allow functional dissection of cullin-binding genes and their substrates.
Why is cullin family protein binding important for drug discovery?
Because CRLs control the stability of many disease-relevant proteins, modulating cullin-binding interactions offers a route to targeted protein degradation and cancer therapy.
Conclusion
GO:0097602 cullin family protein binding defines the interaction that assembles cullin-RING ubiquitin ligases and recruits substrates for degradation. Its importance spans plant hormone signaling, muscle atrophy, RAS GTPase turnover, autophagy regulation and cancer, making it a central annotation for ubiquitin biology. Researchers can now combine CRISPR cell models, interaction proteomics and bioinformatics to test how cullin-binding proteins shape disease phenotypes.
References
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- 2. Chen Y et al.. 2021. Phosphorylation regulates cullin-based ubiquitination in tumorigenesis.. Acta Pharm Sin B 11(2):309-321 PMID: 33643814
- 3. Thines B et al.. 2007. JAZ repressor proteins are targets of the SCF(COI1) complex during jasmonate signalling.. Nature 448(7154):661-5 PMID: 17637677
- 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. Kipreos ET et al.. 2000. The F-box protein family.. Genome Biol 1(5):REVIEWS3002 PMID: 11178263
- 6. Bodine SC et al.. 2001. Identification of ubiquitin ligases required for skeletal muscle atrophy.. Science 294(5547):1704-8 PMID: 11679633
- 7. Dharmaiah S et al.. 2025. Structural basis for LZTR1 recognition of RAS GTPases for degradation.. Science 389(6765):1112-1117 PMID: 40934300
- 8. Wu J et al.. 2024. FBXO32-mediated degradation of PTEN promotes lung adenocarcinoma progression.. Cell Death Dis 15(4):282 PMID: 38643215
