GO:0062062 oligosaccharyltransferase complex binding: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0062062 (oligosaccharyltransferase complex binding) is a molecular function defined as binding to an oligosaccharyltransferase (OST) complex.
• The OST complex catalyzes N-linked glycosylation of nascent polypeptides at the endoplasmic reticulum (ER) membrane.
• Proteins that bind the OST complex include viral restriction factors such as guanylate-binding protein 5 (GBP5), which inhibits glycoprotein maturation of multiple viruses.
• The OST subunit STT3A is a key component; its interaction with β-catenin and PD-L1 regulates antitumor immunity in cervical cancer.
• Pharmacological suppression of HHLA2 glycosylation, which depends on OST activity, restores anti-tumor immunity in colorectal cancer.
• CRISPR screens have identified a druggable pocket in an OST subunit required for inflammatory signaling to NF-κB.
Description
Oligosaccharyltransferase (OST) complex binding (GO:0062062) is a molecular function that describes the physical interaction between a protein and the OST complex, a multimeric enzyme responsible for N-linked glycosylation in the endoplasmic reticulum (ER). This binding event is critical for diverse cellular processes, including protein folding, viral restriction, and immune signaling. Understanding the proteins that bind the OST complex provides insights into glycosylation-dependent pathways and potential therapeutic targets. Recent studies have identified several OST-binding proteins, such as GBP5, which inhibits viral replication by binding to the OST complex and blocking glycoprotein maturation. Additionally, the OST subunit STT3A interacts with β-catenin and PD-L1, influencing antitumor immunity in cervical cancer. These findings underscore the importance of GO:0062062 in both host defense and cancer biology.
oligosaccharyltransferase complex binding At A Glance
| GO ID | GO:0062062 |
|---|---|
| GO term | oligosaccharyltransferase complex binding |
| Ontology | molecular_function |
| Synonym | None |
| Major function | Binding to the oligosaccharyltransferase complex, which catalyzes N-linked glycosylation |
| Related complex | Oligosaccharyltransferase (OST) complex, composed of subunits including STT3A, STT3B, and others |
| Key interacting proteins | GBP5, β-catenin, PD-L1, HHLA2 |
| Disease relevance | Viral infections, cancer, inflammatory signaling |
| Research methods | CRISPR screens, co-immunoprecipitation, proteomics, imaging |
What Is GO:0062062?
GO:0062062 is defined as the molecular function of binding to an oligosaccharyltransferase complex. The OST complex is a multi-subunit enzyme that transfers oligosaccharides to asparagine residues in nascent polypeptides, a process known as N-linked glycosylation. Proteins that bind the OST complex may regulate its activity, localize to the ER membrane, or compete with substrates, thereby modulating glycosylation and downstream signaling.
Why Is oligosaccharyltransferase complex binding Important in Cell Biology?
GO:0062062 is important because the OST complex is central to N-linked glycosylation, a co-translational modification that affects protein stability, trafficking, and function. Proteins that bind the OST complex can modulate glycosylation of viral envelope proteins, immune receptors, and tumor-associated antigens, thereby influencing viral pathogenesis and cancer immune evasion. For example, GBP5 binding to the OST complex inhibits replication of multiple viruses by preventing glycoprotein maturation. In cancer, OST subunit STT3A interacts with β-catenin and PD-L1, promoting immune escape in cervical cancer. Thus, understanding OST complex binding offers opportunities for antiviral and anticancer therapies.
• Regulates N-linked glycosylation of viral glycoproteins, affecting viral entry and immune evasion.
• Modulates inflammatory signaling to NF-κB through OST subunit interactions.
• Influences antitumor immunity by controlling PD-L1 glycosylation and stability.
• Affects glycosylation of HHLA2, a B7-family immune checkpoint, in colorectal cancer.
• Provides a target for pharmacological intervention in cancer and viral infections.
• Essential for protein quality control in the ER and secretion.
• Involved in host-pathogen interactions through interferon-inducible proteins like GBP5.
• Potential biomarker for cancers with dysregulated glycosylation.
• Enables CRISPR screening to identify druggable pockets in OST subunits.
• Contributes to the development of single-subunit OSTs for biotechnological applications.
Molecular Mechanism of oligosaccharyltransferase complex binding
Recognition and Binding to the OST Complex
In simple terms: Proteins that bind the OST complex recognize specific subunits or regions, often at the ER membrane.
The OST complex is a multi-subunit enzyme embedded in the ER membrane, with subunits such as STT3A and STT3B forming the catalytic core. Binding proteins, such as GBP5, interact with the OST complex through specific domains, as shown by co-immunoprecipitation and functional assays. This binding can occur co-translationally or post-translationally, depending on the protein and cellular context.
Regulation of Glycosylation Activity
In simple terms: Binding to the OST complex can turn its glycosylation activity up or down.
GBP5 binding to the OST complex inhibits glycoprotein maturation of multiple viruses, likely by interfering with the transfer of oligosaccharides to nascent viral proteins. In contrast, β-catenin binding to STT3A may enhance glycosylation of PD-L1, promoting its stability and immune checkpoint function. Thus, OST-binding proteins can act as positive or negative regulators of glycosylation.
Substrate Selection and Competition
In simple terms: Some binding proteins may compete with normal substrates for access to the OST complex.
The OST complex normally recognizes N-X-S/T sequons on nascent polypeptides. Binding proteins like GBP5 may sterically hinder access of viral glycoproteins to the catalytic site, thereby reducing glycosylation. This competition can selectively affect viral glycoproteins over host proteins, contributing to antiviral specificity.
Downstream Signaling and Immune Modulation
In simple terms: Binding to the OST complex can trigger signaling that affects immune responses.
In cancer, STT3A binding to β-catenin leads to increased PD-L1 glycosylation and immune evasion. Similarly, HHLA2 glycosylation, dependent on OST activity, suppresses antitumor immunity in colorectal cancer. Pharmacological suppression of glycosylation restores immune recognition, highlighting the therapeutic potential of targeting OST complex binding.
Structural Insights and Druggability
In simple terms: The structure of the OST complex reveals pockets that can be targeted by drugs.
CRISPR screens have identified a druggable pocket in an OST subunit required for inflammatory signaling to NF-κB. Structural studies of the OST complex, including cryo-EM, have revealed the architecture of subunit interactions and potential binding sites for regulatory proteins. These insights facilitate the design of small molecules that modulate OST complex binding.
Key Genes Involved in GO:0062062 oligosaccharyltransferase complex binding
The following genes and proteins are key players in oligosaccharyltransferase complex binding and its downstream effects.
| Gene | Major Role | Research Relevance |
|---|---|---|
| STT3A | Catalytic subunit of OST complex; binds β-catenin and PD-L1 | Target in cervical cancer; regulates immune evasion |
| STT3B | Catalytic subunit of OST complex; involved in post-translational glycosylation | Potential target for glycosylation inhibitors |
| GBP5 | Interferon-inducible GTPase; binds OST complex and inhibits viral glycoprotein maturation | Antiviral restriction factor; therapeutic target |
| β-catenin | Binds STT3A; regulates PD-L1 glycosylation | Oncogenic signaling; immune checkpoint regulation |
| PD-L1 | Immune checkpoint; glycosylation by OST affects stability | Cancer immunotherapy target |
| HHLA2 | B7-family immune checkpoint; glycosylation by OST | Colorectal cancer immunotherapy target |
| NF-κB | Inflammatory transcription factor; OST subunit required for signaling | Inflammation and cancer |
| OST1 (yeast) | Yeast OST subunit; model for complex assembly | Basic glycosylation research |
| WBP1 (yeast) | Yeast OST subunit; essential for viability | Model for OST function |
| OST2 (yeast) | Yeast OST subunit; stabilizes complex | Model for OST assembly |
| SWP1 (yeast) | Yeast OST subunit; involved in substrate recognition | Model for glycosylation |
| OST3/OST6 (yeast) | Yeast OST subunits; oxidoreductase activity | Redox regulation of glycosylation |
| STT3 (bacterial) | Single-subunit OST in bacteria; enables IgG glycosylation | Biotechnological applications |
| PglB (bacterial) | Campylobacter lari OST; used for glycoengineering | Antibody glycosylation |
| Ribosome | Interacts with OST complex during co-translational translocation | Translation-coupled glycosylation |
| Sec61 translocon | ER membrane channel; coordinates with OST | Protein biogenesis |
| TRAP complex | ER membrane protein complex; associates with OST | Glycosylation regulation |
How Is oligosaccharyltransferase complex binding Regulated?
The binding of proteins to the OST complex is regulated at multiple levels. Interferon signaling induces GBP5 expression, which then binds the OST complex to inhibit viral glycoprotein maturation. In cancer, β-catenin signaling upregulates STT3A, enhancing PD-L1 glycosylation and immune evasion. Additionally, the OST complex itself is regulated by ER stress and the unfolded protein response, which can alter subunit expression and activity. Pharmacological inhibition of glycosylation can modulate OST complex binding and downstream signaling.
oligosaccharyltransferase complex binding and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| GBP5 | Viral infections (influenza, etc.) | KO or overexpression in cell lines; viral infection assays |
| STT3A | Cervical cancer, immune evasion | KO or point mutation in cancer cell lines; PD-L1 glycosylation assays |
| HHLA2 | Colorectal cancer | KO or overexpression; glycosylation inhibitors |
| NF-κB pathway | Inflammatory signaling | CRISPR screens; OST subunit KO |
| STT3B | Congenital disorders of glycosylation | Patient-derived cells; knock-in of mutations |
Viral Infections
GBP5 binds the OST complex and inhibits replication of multiple viruses by preventing glycoprotein maturation. This mechanism is part of the interferon-induced antiviral response and highlights the OST complex as a host factor exploited by viruses. Targeting OST complex binding could lead to broad-spectrum antivirals.
Cancer Immune Evasion
In cervical cancer, FAT4 overexpression promotes antitumor immunity by regulating the β-catenin/STT3/PD-L1 axis. STT3A, a subunit of the OST complex, binds β-catenin and mediates PD-L1 glycosylation, enhancing immune checkpoint activity. In colorectal cancer, HHLA2 glycosylation by the OST complex suppresses antitumor immunity, and pharmacological suppression restores immune responses. These findings link OST complex binding to cancer immunotherapy.
Inflammatory Signaling
A CRISPR screen identified a druggable pocket in an OST subunit required for inflammatory signaling to NF-κB. This suggests that OST complex binding is critical for inflammatory pathways and could be targeted in inflammatory diseases and cancer.
From oligosaccharyltransferase complex binding-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does GBP5 binding to OST complex inhibit viral replication? | GBP5 KO and overexpression cell lines; viral infection |
| Does STT3A point mutation affect PD-L1 glycosylation? | STT3A point-mutation knock-in in cancer cells |
| Can a tagged OST subunit reveal binding partners? | Tagged knock-in of STT3A or STT3B; co-IP |
| Does overexpression of β-catenin alter OST complex binding? | β-catenin overexpression in cervical cancer cells |
| Is OST complex binding required for NF-κB signaling? | CRISPR KO of OST subunits; NF-κB reporter assays |
| Can bacterial OST glycosylate full-length IgG? | Single-subunit OST expression in bacteria |
How to Study the oligosaccharyltransferase complex binding Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Co-IP | Physical interaction between proteins | Identify OST complex binding partners |
| Mass spectrometry | Protein composition and modifications | Proteomic analysis of OST complex |
| CRISPR screen | Gene essentiality or drug targets | Discover regulators of NF-κB signaling |
| Western blot | Protein expression and glycosylation | Assess PD-L1 or HHLA2 glycosylation |
| Lectins | Glycan structures | Detect N-linked glycosylation |
| Cryo-EM | 3D structure of macromolecules | Visualize OST complex architecture |
| Fluorescence microscopy | Subcellular localization | Co-localization of binding proteins with OST |
| Ribo-seq | Translation efficiency | Study co-translational glycosylation |
Co-Immunoprecipitation and Proteomics
Co-immunoprecipitation (co-IP) followed by mass spectrometry can identify proteins that bind the OST complex. For example, GBP5 was shown to bind the OST complex by co-IP. Proteomic approaches can reveal dynamic changes in OST complex interactions under different conditions.
CRISPR Screens
Genome-wide CRISPR screens have been used to identify genes required for inflammatory signaling to NF-κB, leading to the discovery of a druggable pocket in an OST subunit. Positive selection CRISPR screens can uncover regulators of OST complex binding and glycosylation.
Glycosylation Assays
Glycosylation status of target proteins can be assessed by Western blot with lectins or by mass spectrometry. Pharmacological suppression of glycosylation restores antitumor immunity in colorectal cancer, as shown by HHLA2 glycosylation assays. These methods are essential to study the functional consequences of OST complex binding.
Structural Biology and Imaging
Cryo-electron microscopy and X-ray crystallography have provided structural insights into the OST complex and its interactions. Fluorescence microscopy can visualize co-localization of binding proteins with the OST complex at the ER.
How CRISPR Can Be Used to Study GO:0062062 oligosaccharyltransferase complex binding
Knockout
CRISPR knockout of OST subunits or binding proteins can reveal their roles in glycosylation and downstream signaling. For example, knockout of STT3A reduces PD-L1 glycosylation and enhances antitumor immunity. Knockout of GBP5 increases viral replication, confirming its antiviral function.
Point Mutation
Point mutations in OST subunits can dissect specific binding interfaces. For instance, mutations in the druggable pocket of an OST subunit identified by CRISPR screens can abolish NF-κB signaling. Point mutations in STT3A can affect its interaction with β-catenin.
Knock-in
Knock-in of tagged OST subunits (e.g., HA or GFP) enables co-IP and imaging studies to track binding dynamics. Knock-in of disease-associated mutations can model congenital disorders of glycosylation.
Overexpression
Overexpression of binding proteins like GBP5 or β-catenin can enhance or inhibit OST complex function. Overexpression of FAT4 regulates the β-catenin/STT3/PD-L1 axis in cervical cancer. Overexpression of bacterial OST in E. coli enables glycosylation of full-length IgG.
How EDITGENE Supports oligosaccharyltransferase complex binding Research
Researchers studying oligosaccharyltransferase complex binding-related genes often need to determine whether a candidate gene is causally involved in glycosylation, viral restriction, or immune signaling. EDITGENE provides comprehensive CRISPR services to create precise cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for oligosaccharyltransferase complex binding research.
Frequently Asked Questions About oligosaccharyltransferase complex binding
What is GO:0062062?
GO:0062062 is a Gene Ontology molecular function term defined as binding to an oligosaccharyltransferase complex, which is involved in N-linked glycosylation.
What genes are involved in oligosaccharyltransferase complex binding?
Key genes include STT3A, STT3B, GBP5, β-catenin, and PD-L1, among others.
How does GBP5 inhibit viral replication?
GBP5 binds to the OST complex and inhibits glycoprotein maturation of multiple viruses, thereby restricting replication.
What is the role of STT3A in cancer?
STT3A binds β-catenin and mediates PD-L1 glycosylation, promoting immune evasion in cervical cancer.
Can CRISPR screens identify OST complex binding regulators?
Yes, CRISPR screens have identified a druggable pocket in an OST subunit required for NF-κB signaling.
What diseases are associated with oligosaccharyltransferase complex binding?
Viral infections, cancer (cervical, colorectal), and inflammatory diseases.
How is oligosaccharyltransferase complex binding studied?
Methods include co-IP, mass spectrometry, CRISPR screens, glycosylation assays, and structural biology.
What is the oligosaccharyltransferase complex?
It is a multi-subunit enzyme in the ER membrane that catalyzes N-linked glycosylation of proteins.
Does HHLA2 glycosylation affect antitumor immunity?
Yes, pharmacological suppression of HHLA2 glycosylation restores anti-tumor immunity in colorectal cancer.
Can bacterial OST be used for antibody glycosylation?
Yes, a single-subunit OST from bacteria enables glycosylation of full-length IgG antibodies.
Conclusion
GO:0062062 (oligosaccharyltransferase complex binding) is a critical molecular function that regulates N-linked glycosylation, impacting viral infections, cancer immunity, and inflammatory signaling. Understanding the proteins that bind the OST complex and their mechanisms provides opportunities for therapeutic intervention. EDITGENE offers a suite of CRISPR services to model these interactions and accelerate discovery.
References
- 1. Gemmer M et al.. 2023. Visualization of translation and protein biogenesis at the ER membrane.. Nature 614(7946):160-167 PMID: 36697828
- 2. Wang S et al.. 2025. Interferon-inducible guanylate-binding protein 5 inhibits replication of multiple viruses by binding to the oligosaccharyltransferase complex and inhibiting glycoprotein maturation.. mBio 16(12):e0293025 PMID: 41247044
- 3. Lampson BL et al.. 2024. Positive selection CRISPR screens reveal a druggable pocket in an oligosaccharyltransferase required for inflammatory signaling to NF-κB.. Cell 187(9):2209-2223.e16 PMID: 38670073
- 4. Wang S et al.. 2024. Interferon-Inducible Guanylate-Binding Protein 5 Inhibits Replication of Multiple Viruses by Binding to the Oligosaccharyltransferase Complex and Inhibiting Glycoprotein Maturation.. bioRxiv PMID: 38746287
- 5. Wang D et al.. 2023. FAT4 overexpression promotes antitumor immunity by regulating the β-catenin/STT3/PD-L1 axis in cervical cancer.. J Exp Clin Cancer Res 42(1):222 PMID: 37658376
- 6. Zhang D et al.. 2024. Pharmacological suppression of HHLA2 glycosylation restores anti-tumor immunity in colorectal cancer.. Cancer Lett 589:216819 PMID: 38522775
- 7. Knauer R et al.. 1999. The oligosaccharyltransferase complex from yeast.. Biochim Biophys Acta 1426(2):259-73 PMID: 9878773
- 8. Sotomayor B et al.. 2025. Discovery of a single-subunit oligosaccharyltransferase that enables glycosylation of full-length IgG antibodies in bacteria.. Nat Commun 16(1):6152 PMID: 40610439
