GO:0160227 oligosaccharyltransferase complex B: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0160227 (oligosaccharyltransferase complex B, OST-B) is a cellular_component defined by the presence of STT3B as its catalytic subunit.
• OST-B transfers preassembled oligosaccharides onto acceptor asparagine residues of nascent polypeptides, a co-translational and post-translational N-glycosylation step.
• OST-B and OST-A have non-redundant roles; OST-B preferentially glycosylates sequon sites skipped by OST-A and contributes to HIV-1 envelope glycoprotein glycosylation.
• Loss of OST-B function alters chaperone function and receptor trafficking, and OST-B is required for inflammatory signaling to NF-kB.
• OST complex inhibition is a validated therapeutic strategy in aggressive lymphomas and prion disease models.
• CRISPR knockout, point-mutation, knock-in and overexpression models are essential to dissect OST-B subunit-specific functions in disease.
Description
Oligosaccharyltransferase complex B (OST-B) is a multiprotein cellular_component defined by the presence of STT3B as its catalytic subunit. It catalyzes the en bloc transfer of a preassembled oligosaccharide from a lipid-linked oligosaccharide donor onto the side-chain amide nitrogen of asparagine residues within Asn-X-Ser/Thr sequons of nascent polypeptides. This N-glycosylation reaction is essential for protein folding, stability, trafficking and cell-surface presentation of receptors and adhesion molecules. OST-B operates alongside the STT3A-containing OST-A complex, and the two complexes have distinct but overlapping substrate repertoires. Recent structural and functional studies have clarified how OST-B is recruited to the secretory translocon and how its activity is regulated during protein biogenesis. Beyond its core biosynthetic role, OST-B has emerged as a therapeutic node in cancer, inflammation and neurodegeneration, making it a high-value target for CRISPR-based functional genomics.
oligosaccharyltransferase complex B At A Glance
| GO ID | GO:0160227 |
|---|---|
| GO term | oligosaccharyltransferase complex B |
| Ontology | cellular_component |
| Synonym | OST-B |
| Major function | Catalyzes en bloc transfer of a lipid-linked oligosaccharide to asparagine residues of nascent polypeptides, using STT3B as the catalytic subunit |
| Catalytic subunit | STT3B |
| Subcellular location | Endoplasmic reticulum membrane, associated with the secretory translocon |
| Related complex | Oligosaccharyltransferase complex A (OST-A), which contains STT3A |
| Disease relevance | Aggressive lymphomas, inflammatory signaling, prion disease, viral infection and tumor metastasis |
What Is GO:0160227?
GO:0160227, oligosaccharyltransferase complex B, is a cellular_component ontology term describing an oligosaccharyltransferase complex that contains STT3B as the catalytic subunit. The complex is a membrane-embedded enzyme that transfers a lipid-linked oligosaccharide to asparagine residues of acceptor proteins, thereby initiating N-linked glycosylation.
Why Is oligosaccharyltransferase complex B Important in Cell Biology?
OST-B is important because it defines a distinct N-glycosylation route that cannot be fully compensated by OST-A, and its catalytic subunit STT3B determines which sequons are glycosylated on secretory and membrane proteins. This specificity influences chaperone function, receptor trafficking and inflammatory signaling, and OST-B has been linked to aggressive lymphomas, prion propagation, respiratory viral infection and tumor metastasis. Consequently, OST-B is both a mechanistic hub for glycobiology and a tractable target for therapeutic intervention and CRISPR functional genomics.
• OST-B provides a non-redundant N-glycosylation activity that glycosylates sequons skipped by OST-A.
• STT3B-containing OST-B controls chaperone function and receptor trafficking in the secretory pathway.
• OST-B is required for inflammatory signaling to NF-kB, and a druggable pocket in an OST subunit has been identified by CRISPR screens.
• Inhibition of the OST complex effectively treats rodent and human prions, highlighting OST-B as a neurodegeneration target.
• OST-B contributes to HIV-1 envelope glycoprotein glycosylation, affecting viral entry and immune evasion.
• Host genetic screens link OST components to respiratory viral infection susceptibility.
• Functional inactivation of an OST isoform suppresses tumor metastasis, supporting OST-B as a cancer progression node.
• Targeting N-linked glycosylation is a therapeutic strategy in aggressive lymphomas.
• OST-B is a model system for studying co-translational versus post-translational protein modification.
• CRISPR knockout and point-mutation models enable dissection of OST-B subunit-specific functions.
What Happens During oligosaccharyltransferase complex B?
Recognition of acceptor sequons on nascent polypeptides
In simple terms: OST-B scans new proteins as they emerge and finds the sugar-attachment tags.
OST-B recognizes Asn-X-Ser/Thr sequons in nascent polypeptides and transfers a preassembled oligosaccharide to the asparagine amide nitrogen. This step is tightly coupled to protein translocation at the secretory translocon, and OST-B preferentially acts on sequons that are not efficiently glycosylated by OST-A.
En bloc transfer of lipid-linked oligosaccharide
In simple terms: The enzyme moves a whole sugar tree from a lipid carrier onto the protein in one go.
The catalytic STT3B subunit of OST-B catalyzes en bloc transfer of a lipid-linked oligosaccharide donor to the acceptor asparagine, forming an N-glycosidic bond. This reaction is the committed step of N-linked glycosylation and determines the initial glycan structure of the protein.
Co-translational and post-translational glycosylation
In simple terms: Some sugars are added while the protein is still being made, and some are added afterward.
OST-B can act both co-translationally and post-translationally, and structural studies show regulated N-glycosylation at the secretory translocon. This dual timing allows OST-B to glycosylate sites that become accessible only after partial folding or after OST-A has acted.
Quality control and trafficking of glycoproteins
In simple terms: The sugars added by OST-B act like shipping labels that guide protein folding and delivery.
N-glycans introduced by OST-B are read by lectin chaperones and quality-control machinery, influencing protein folding and receptor trafficking. Loss of OST-B function alters chaperone function and receptor trafficking, demonstrating its role in secretory pathway homeostasis.
Signaling and disease-relevant outputs
In simple terms: OST-B activity feeds into signals that control inflammation and disease.
OST-B activity is required for inflammatory signaling to NF-kB, and CRISPR screens have identified a druggable pocket in an OST subunit. OST complex inhibition also affects prion propagation and HIV-1 envelope glycosylation, linking OST-B to neurodegeneration and viral infection.
Key Genes Involved in GO:0160227 oligosaccharyltransferase complex B
The following genes and proteins are the principal components and regulators of oligosaccharyltransferase complex B (GO:0160227) and its associated biology.
| Gene | Major Role | Research Relevance |
|---|---|---|
| STT3B | Catalytic subunit of OST-B; transfers oligosaccharide to asparagine residues | Defines OST-B identity; knockout and point-mutation models reveal substrate specificity |
| STT3A | Catalytic subunit of OST-A, the paralogous complex | Comparative studies distinguish OST-A and OST-B functions |
| MAGT1 | Accessory subunit of OST-B; supports STT3B stability and activity | Mutations affect glycosylation and immune function; CRISPR models test subunit dependence |
| TUSC3 | Accessory subunit of OST-B; modulates OST-B assembly | Candidate for knock-in and knockout studies of OST-B composition |
| DDOST | Core OST subunit shared with OST-A | Essential for complex integrity; knockout is lethal or severe |
| RPN1 | Core OST subunit; ribosome and translocon interaction | Target for tagged knock-in to map OST-B interactome |
| RPN2 | Core OST subunit; structural scaffold | Used in proteomic studies of OST-B assembly |
| OST4 | Small subunit required for OST complex stability | Point mutations can disrupt complex assembly |
| SEC61A1 | Translocon subunit that coordinates OST-B recruitment | Knock-in models test translocon-OST coupling |
| NFKB1 | Downstream transcription factor in OST-B-dependent inflammatory signaling | Reporter assays and knockout models test OST-B to NF-kB signaling |
| NFKB2 | Downstream transcription factor in OST-B-dependent inflammatory signaling | CRISPR screens identify OST-B dependency |
| PRNP | Prion protein whose glycosylation depends on OST activity | OST inhibition models in prion disease |
| HIV-1 env | Viral envelope glycoprotein glycosylated by OST-B | Viral glycosylation studies in OST-B knockout cells |
| CD19 | B-cell receptor component relevant to lymphoma glycosylation | Lymphoma models testing OST inhibition |
| MYC | Oncogene linked to aggressive lymphoma biology | Combination studies with OST inhibitors |
| STT3B paralogs | Sequence-related proteins informing OST evolution | Comparative genomics and structural modeling |
How Is oligosaccharyltransferase complex B Regulated?
OST-B activity is regulated at multiple levels, including its recruitment to the secretory translocon and the availability of lipid-linked oligosaccharide donors. Structural studies show regulated N-glycosylation at the translocon, indicating that OST-B engagement with substrates is spatially and temporally controlled. OST-B and OST-A have differential contributions to substrate glycosylation, so their relative expression and subunit composition influence which sequons are modified. In disease contexts, OST-B-dependent inflammatory signaling to NF-kB can be modulated pharmacologically, and a druggable pocket in an OST subunit has been identified. OST complex inhibition affects prion propagation, suggesting that OST-B activity is rate-limiting for some pathogenic glycosylation events.
oligosaccharyltransferase complex B and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| STT3B | Aggressive lymphoma and inflammatory signaling | STT3B knockout lymphoma cell lines and xenografts |
| MAGT1 | Glycosylation-related immune dysfunction | MAGT1 knockout and knock-in cell models |
| PRNP | Prion disease | OST inhibitor treatment in prion-infected rodent models |
| HIV-1 env | Viral glycosylation and entry | OST-B knockout cells infected with HIV-1 |
| OST isoform | Tumor metastasis | Overexpression and knockout metastasis models |
Cancer and aggressive lymphomas
Targeting N-linked glycosylation is a therapeutic strategy in aggressive lymphomas, and OST-B-dependent glycosylation supports oncogenic signaling and survival. Functional inactivation of an oligosaccharyltransferase isoform suppresses tumor metastasis, indicating that OST-B contributes to cancer progression. CRISPR screens have revealed a druggable pocket in an OST subunit required for inflammatory signaling to NF-kB, linking OST-B to tumor-promoting inflammation.
Neurodegeneration and prion disease
Oligosaccharyltransferase complex inhibition effectively treats rodent and human prions, demonstrating that OST-B-dependent glycosylation of the prion protein is required for propagation. This positions OST-B as a target in neurodegenerative proteinopathies.
Infectious disease and viral glycosylation
OST-B differentially contributes to HIV-1 envelope glycoprotein glycosylation, affecting viral entry and immune recognition. Shared host genetic landscapes of respiratory viral infection implicate OST components in susceptibility to viral pathogens.
Protein trafficking and chaperone-related disorders
Regulated N-glycosylation controls chaperone function and receptor trafficking, so OST-B dysfunction can alter secretory protein homeostasis and cell-surface receptor presentation. These defects underlie a range of congenital and acquired disorders of glycosylation.
From oligosaccharyltransferase complex B-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is STT3B required for N-glycosylation of a specific substrate? | STT3B knockout cell line |
| Does a point mutation in the catalytic site abolish OST-B activity? | STT3B point-mutation knock-in |
| How does OST-B assemble with accessory subunits? | Tagged knock-in of MAGT1 or TUSC3 |
| Does OST-B overexpression alter receptor trafficking? | STT3B overexpression cell model |
| Which genes mediate OST-B-dependent NF-kB signaling? | CRISPR library screening in OST-B-competent cells |
| Can OST-B inhibition suppress metastasis? | OST isoform knockout and overexpression in metastasis models |
How to Study the oligosaccharyltransferase complex B Process
| Method | What It Measures | Typical Application |
|---|---|---|
| CRISPR knockout | Loss of OST-B subunit function | Testing substrate glycosylation dependency |
| Point-mutation knock-in | Catalytic versus structural roles | Dissecting STT3B active site |
| Glycoproteomics | Site-specific N-glycosylation occupancy | Comparing OST-A and OST-B substrates |
| CRISPR library screening | Genes required for OST-B-dependent signaling | Identifying druggable OST pockets |
| NF-kB reporter assay | Inflammatory signaling output | Testing OST-B inhibitors |
| Viral infection assay | Host susceptibility and viral glycosylation | Respiratory virus and HIV-1 studies |
| Prion propagation assay | Infectivity and glycosylation dependence | Evaluating OST inhibitors in prion disease |
| Structural biology | Complex architecture and translocon coupling | Mechanistic studies of OST-B |
CRISPR knockout and point-mutation models
CRISPR knockout of STT3B and accessory subunits is used to test OST-B dependency, while point mutations in the catalytic domain distinguish catalytic activity from scaffolding functions. Positive selection CRISPR screens have identified druggable pockets in OST subunits required for inflammatory signaling.
Glycoproteomics and mass spectrometry
Mass spectrometry-based glycoproteomics maps which sequons are glycosylated by OST-B versus OST-A, revealing substrate specificity and site occupancy. This approach is essential for comparing OST-B knockout and wild-type cells.
Structural biology and imaging
Structural studies of regulated N-glycosylation at the secretory translocon reveal how OST-B engages substrates and the translocon. Fluorescence imaging of tagged OST-B subunits tracks assembly and localization in live cells.
Functional assays for signaling and disease
NF-kB reporter assays and viral infection assays measure OST-B-dependent signaling and host-pathogen interactions. Prion propagation assays in rodent and human models test OST inhibition efficacy.
How CRISPR Can Be Used to Study GO:0160227 oligosaccharyltransferase complex B
Knockout
CRISPR knockout of STT3B or accessory subunits such as MAGT1 and TUSC3 abolishes OST-B function and reveals which substrates depend on OST-B versus OST-A. Knockout models are used to test inflammatory signaling to NF-kB and tumor metastasis phenotypes.
Point Mutation
Point mutations in the STT3B catalytic domain distinguish enzymatic activity from complex assembly and scaffolding roles. Such models help map the druggable pocket identified in OST subunits by CRISPR screens.
Knock-in
Tagged knock-in of OST-B subunits enables interactome mapping and live-cell imaging of complex assembly at the translocon. Knock-in of disease-associated variants tests their impact on glycosylation and trafficking.
Overexpression
Overexpression of STT3B or accessory subunits tests gain-of-function effects on receptor trafficking, chaperone function and viral glycosylation. Overexpression models also assess whether increased OST-B activity promotes metastasis.
How EDITGENE Supports oligosaccharyltransferase complex B Research
Researchers studying oligosaccharyltransferase complex B-related genes often need to determine whether a candidate gene is causally involved in N-glycosylation, inflammatory signaling or disease progression, and CRISPR-based models provide the most direct route to that answer.
Contact EDITGENE today to design your custom CRISPR model for oligosaccharyltransferase complex B research.
Frequently Asked Questions About oligosaccharyltransferase complex B
What is oligosaccharyltransferase complex B?
It is a cellular_component defined by the presence of STT3B as its catalytic subunit, and it transfers a lipid-linked oligosaccharide to asparagine residues of nascent polypeptides.
What is the GO ID for oligosaccharyltransferase complex B?
The GO ID is GO:0160227, with synonym OST-B.
What genes are involved in oligosaccharyltransferase complex B?
Key genes include STT3B, MAGT1, TUSC3, DDOST, RPN1, RPN2 and OST4, with STT3B as the catalytic subunit.
How does OST-B differ from OST-A?
OST-B contains STT3B, whereas OST-A contains STT3A, and the two complexes have differential contributions to substrate glycosylation.
What diseases are linked to OST-B?
OST-B has been linked to aggressive lymphomas, inflammatory signaling, prion disease, HIV-1 glycosylation, respiratory viral infection and tumor metastasis.
Is OST-B a drug target?
Yes, a druggable pocket in an OST subunit has been identified by CRISPR screens, and OST inhibition treats prions and aggressive lymphomas in models.
What research methods are used to study OST-B?
CRISPR knockout, point-mutation knock-in, glycoproteomics, structural biology, NF-kB reporter assays and viral infection assays are commonly used.
Can OST-B be studied with CRISPR screens?
Yes, positive selection CRISPR screens have revealed OST subunits required for inflammatory signaling to NF-kB.
What is the role of STT3B in OST-B?
STT3B is the catalytic subunit that transfers the oligosaccharide to acceptor asparagine residues.
How does OST-B affect protein trafficking?
N-glycans added by OST-B are read by chaperones and quality-control machinery, and loss of OST-B alters chaperone function and receptor trafficking.
Conclusion
Oligosaccharyltransferase complex B (GO:0160227) is a STT3B-containing cellular_component that executes a critical N-glycosylation step in the secretory pathway. Its non-redundant functions in chaperone biology, receptor trafficking, inflammatory signaling and host-pathogen interactions make it a compelling target for cancer, neurodegeneration and infectious disease research. CRISPR-based knockout, point-mutation, knock-in and overexpression models are essential tools for dissecting OST-B subunit-specific mechanisms and for translating these findings into therapeutic strategies.
References
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- 2. Scheich S et al.. 2023. Targeting N-linked Glycosylation for the Therapy of Aggressive Lymphomas.. Cancer Discov 13(8):1862-1883 PMID: 37141112
- 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. Beauchemin KS et al.. 2026. Oligosaccharyltransferase (OST) complex inhibition effectively treats rodent and human prions.. PLoS Pathog 22(1):e1013867 PMID: 41525337
- 5. Soriaga LB et al.. 2025. Shared host genetic landscape of respiratory viral infection.. Proc Natl Acad Sci U S A 122(20):e2414202122 PMID: 40372436
- 6. Yamsek M et al.. 2026. Structural basis of regulated N-glycosylation at the secretory translocon.. Nature 649(8097):777-784 PMID: 41261126
- 7. Atabey T et al.. 2025. Differential contributions of human oligosaccharyltransferase complexes OST-A and OST-B to HIV-1 envelope glycoprotein glycosylation.. bioRxiv PMID: 40950086
- 8. Shi Y et al.. 2025. Functional inactivation of oligosaccharyltransferase a isoform suppresses tumor metastasis.. Glycobiology 36(2) PMID: 41499148
