GO:0019885 antigen processing and presentation of endogenous peptide antigen via MHC class I: Immune Surveillance Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0019885 describes how an antigen-presenting cell displays a peptide of endogenous origin on its surface in association with a classical MHC class I protein complex.
• Endogenous proteins are degraded in the cytosol, and the resulting peptides are translocated and loaded onto MHC class I molecules for CD8+ T cell surveillance.
• The pathway is essential for immune recognition of intracellular pathogens, tumors, and self-derived antigens.
• Pharmacologic modulation of RNA splicing can enhance anti-tumor immunity by altering the endogenous peptide repertoire presented on MHC class I.
• Ubiquitination and cytoplasmic proteolysis are critical upstream signals for generating endogenous peptides for MHC class I presentation.
• CRISPR knockout, point-mutation, knock-in, and overexpression models enable causal dissection of this pathway in human cells.
Description
GO:0019885, antigen processing and presentation of endogenous peptide antigen via MHC class I, is the biological process by which an antigen-presenting cell expresses a peptide antigen of endogenous origin on its cell surface in association with a classical MHC class I protein complex. This pathway allows the immune system to monitor the intracellular proteome and detect abnormal proteins arising from infection, mutation, or altered gene expression. The peptides presented are typically, but not always, processed from whole proteins, and the term specifically refers to classical class I molecules. Understanding this process is central to immunology, oncology, and vaccine development because it determines whether CD8+ T cells can recognize and eliminate diseased cells. Recent work has shown that modulating RNA splicing can reshape the endogenous peptide repertoire and enhance anti-tumor immunity, directly linking this GO term to therapeutic strategies. In addition, ubiquitination and cytoplasmic proteolysis are essential upstream events that generate the peptides presented by MHC class I. Consequently, researchers studying GO:0019885 need robust experimental systems to interrogate each step of the pathway.
antigen processing and presentation of endogenous peptide antigen via MHC class I At A Glance
| GO ID | GO:0019885 |
|---|---|
| GO term | antigen processing and presentation of endogenous peptide antigen via MHC class I |
| Ontology | biological_process |
| Synonym | antigen presentation, endogenous peptide antigen; antigen processing, endogenous antigen via major histocompatibility complex class I; antigen processing, endogenous antigen via MHC class I; endogenous peptide antigen processing and presentation via MHC class I |
| Major function | Display of endogenous peptides on classical MHC class I molecules for CD8+ T cell surveillance |
| Peptide source | Endogenous proteins, typically processed from whole proteins |
| MHC class | Classical class I molecules |
| Cellular context | Antigen-presenting cells, including tumor cells and infected cells |
| Upstream signals | Cytosolic degradation, ubiquitination, and cytoplasmic proteolysis |
What Is GO:0019885?
GO:0019885 is defined as the process in which an antigen-presenting cell expresses a peptide antigen of endogenous origin on its cell surface in association with an MHC class I protein complex. The peptide antigen is typically, but not always, processed from a whole protein. Class I here refers to classical class I molecules. In other words, it covers the intracellular generation of peptides from endogenous proteins and their subsequent display on the cell surface via classical MHC class I molecules for immune recognition.
Why Is antigen processing and presentation of endogenous peptide antigen via MHC class I Important in Cell Biology?
GO:0019885 is important because it governs the ability of the immune system to detect intracellular abnormalities, including viral infection and malignant transformation. The pathway determines the repertoire of endogenous peptides displayed on MHC class I, which directly influences CD8+ T cell activation and effector function. Defects or modulation of this process can lead to immune evasion by tumors or altered responses to immunotherapy. Moreover, understanding the molecular steps of endogenous antigen processing is essential for designing vaccines, T cell therapies, and pharmacologic strategies that enhance antigen presentation.
• Enables CD8+ T cell recognition of infected and transformed cells.
• Shapes the immunopeptidome derived from endogenous proteins.
• Pharmacologic modulation of RNA splicing can enhance anti-tumor immunity through this pathway.
• Ubiquitination and cytoplasmic proteolysis are required for efficient endogenous peptide generation.
• Exosome-mediated cytosolic delivery can enhance class I tumor antigen presentation.
• Acute pharmacologic degradation of a stable antigen can enhance its direct presentation on MHC class I.
• HLA-DP(84Gly) can constitutively present endogenous peptides generated by the class I pathway.
• Proxiome analysis has implicated MIA3 in cell surface expression of MHC class I molecules.
• The pathway is a target for cancer immunotherapy and vaccine development.
• CRISPR models allow causal testing of genes involved in endogenous antigen presentation.
What Happens During antigen processing and presentation of endogenous peptide antigen via MHC class I?
Generation of endogenous peptides
In simple terms: Proteins inside the cell are cut into small pieces.
Endogenous proteins are degraded in the cytosol, and this degradation is a prerequisite for the generation of peptides that can be loaded onto MHC class I molecules. Cytoplasmic proteolysis is required for efficient presentation of both cytosolic and endogenous transmembrane protein antigens. Polyubiquitination at lysine-48 acts as an essential but indirect signal for MHC class I antigen processing, linking the ubiquitin-proteasome system to peptide generation.
Peptide transport and loading onto MHC class I
In simple terms: The small pieces are moved to where they can be attached to a carrier molecule.
Following cytosolic degradation, peptides of endogenous origin are translocated and loaded onto classical MHC class I protein complexes for cell surface expression. The process is typically, but not always, dependent on processing from a whole protein, and the resulting peptide-MHC class I complexes are displayed on the antigen-presenting cell surface.
Cell surface presentation and immune recognition
In simple terms: The carrier with its cargo is shown on the outside of the cell so immune cells can see it.
The antigen-presenting cell expresses the peptide antigen of endogenous origin on its cell surface in association with an MHC class I protein complex. This surface display enables CD8+ T cell surveillance and is central to anti-tumor immunity. Enhanced class I tumor antigen presentation can be achieved via cytosolic delivery of exosomal cargos by tumor-cell-derived exosomes displaying a pH-sensitive fusogenic peptide.
Modulation by RNA splicing and pharmacologic degradation
In simple terms: Changing how RNA is cut or how fast a protein is destroyed can change what is shown to immune cells.
Pharmacologic modulation of RNA splicing enhances anti-tumor immunity, indicating that the endogenous peptide repertoire presented via MHC class I can be therapeutically altered. Acute pharmacologic degradation of a stable antigen enhances its direct presentation on MHC class I molecules, showing that protein stability influences the efficiency of this pathway.
Non-classical and alternative presentation routes
In simple terms: There are other ways peptides can be shown, but this term focuses on the classical route.
Antigen degradation or presentation by MHC class I molecules can occur via classical and non-classical pathways, and the term GO:0019885 specifically refers to classical class I molecules. HLA-DP(84Gly) constitutively presents endogenous peptides generated by the class I antigen processing pathway, illustrating cross-talk between class I processing and non-classical presentation.
Key Genes Involved in GO:0019885 antigen processing and presentation of endogenous peptide antigen via MHC class I
The following genes and proteins are experimentally implicated in endogenous peptide generation, MHC class I loading, or cell surface presentation relevant to GO:0019885.
| Gene | Major Role | Research Relevance |
|---|---|---|
| HLA-A | Classical MHC class I heavy chain | Directly presents endogenous peptides to CD8+ T cells |
| HLA-B | Classical MHC class I heavy chain | Presents endogenous peptides for immune surveillance |
| HLA-C | Classical MHC class I heavy chain | Presents endogenous peptides for immune surveillance |
| B2M | MHC class I light chain | Required for stable MHC class I surface expression |
| PSMB8 | Immunoproteasome subunit | Generates peptides for MHC class I loading |
| PSMB9 | Immunoproteasome subunit | Generates peptides for MHC class I loading |
| TAP1 | Peptide transporter | Translocates peptides into the ER for MHC class I loading |
| TAP2 | Peptide transporter | Translocates peptides into the ER for MHC class I loading |
| TAPBP | Tapasin | Bridges TAP and MHC class I for peptide loading |
| CANX | Calnexin | Chaperone for MHC class I folding |
| CALR | Calreticulin | Chaperone for MHC class I folding |
| PDIA3 | ERp57 | Oxidoreductase in the peptide-loading complex |
| UBB | Ubiquitin | Polyubiquitination signals antigen processing |
| UBC | Ubiquitin | Polyubiquitination signals antigen processing |
| MIA3 | ER/Golgi protein | Implicated in cell surface expression of MHC class I |
| HLA-DPA1 | Non-classical class II alpha chain | HLA-DP(84Gly) presents endogenous peptides from class I pathway |
| HLA-DPB1 | Non-classical class II beta chain | HLA-DP(84Gly) presents endogenous peptides from class I pathway |
How Is antigen processing and presentation of endogenous peptide antigen via MHC class I Regulated?
The pathway is regulated at multiple levels. Polyubiquitination at lysine-48 is an essential but indirect signal for MHC class I antigen processing, linking ubiquitin conjugation to peptide generation. Cytoplasmic proteolysis is required for efficient presentation of both cytosolic and endogenous transmembrane protein antigens. Pharmacologic modulation of RNA splicing can enhance anti-tumor immunity, indicating that splicing regulation influences the endogenous peptide repertoire. Acute pharmacologic degradation of a stable antigen enhances its direct presentation on MHC class I molecules, showing that protein turnover regulates presentation efficiency. In addition, exosome-mediated cytosolic delivery can enhance class I tumor antigen presentation, providing a route for regulation by vesicular traffic.
antigen processing and presentation of endogenous peptide antigen via MHC class I and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| HLA-A | Cancer immune evasion | Knockout in tumor cell lines followed by peptide presentation assays |
| B2M | Loss of MHC class I surface expression | Knockout to abrogate class I presentation |
| TAP1 | Impaired peptide loading | Knockout to block endogenous peptide transport |
| PSMB8 | Altered immunoproteasome function | Point mutation to modulate peptide generation |
| MIA3 | MHC class I cell surface expression | Knockout or tagged knock-in to study trafficking |
Cancer immune evasion and immunotherapy
Tumors can evade CD8+ T cell recognition by altering endogenous antigen processing and MHC class I presentation. Pharmacologic modulation of RNA splicing enhances anti-tumor immunity, suggesting that the endogenous peptide repertoire is a therapeutic target. Enhanced class I tumor antigen presentation via cytosolic delivery of exosomal cargos by tumor-cell-derived exosomes displaying a pH-sensitive fusogenic peptide has been demonstrated as a strategy to improve immune recognition.
Infectious disease and intracellular pathogens
Because GO:0019885 presents peptides of endogenous origin, it is central to immune detection of intracellular pathogens. Defects in peptide generation or loading can impair pathogen clearance, and the pathway is a target for vaccine design.
Autoimmunity and non-classical presentation
HLA-DP(84Gly) constitutively presents endogenous peptides generated by the class I antigen processing pathway, linking this process to non-classical antigen presentation and potential autoimmune responses. Understanding these routes may inform disease mechanisms where endogenous peptides are aberrantly displayed.
From antigen processing and presentation of endogenous peptide antigen via MHC class I-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does a candidate gene regulate endogenous peptide presentation? | CRISPR knockout in antigen-presenting cells followed by MHC class I surface staining |
| Does a specific ubiquitination site control antigen processing? | Point mutation of lysine residues in target proteins |
| Can a tagged MHC class I allele be tracked? | Knock-in of an epitope tag into HLA-A |
| Does overexpression of a transporter enhance presentation? | Overexpression of TAP1/TAP2 in tumor cells |
| Does modulation of RNA splicing alter the immunopeptidome? | Pharmacologic splicing modulation combined with mass spectrometry |
| Can exosomal delivery enhance class I presentation? | Exosome-based cytosolic delivery in tumor models |
How to Study the antigen processing and presentation of endogenous peptide antigen via MHC class I Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Immunopeptidomics | MHC class I-bound peptide repertoire | Discovering endogenous peptides presented |
| Flow cytometry | Surface MHC class I levels | Quantifying presentation after gene knockout |
| Proximity labeling | Protein interactions near HLA-A2 | Identifying novel regulators like MIA3 |
| T cell activation assay | CD8+ T cell response | Testing functional presentation |
| Western blot | Protein expression and degradation | Assessing antigen stability |
| Ubiquitination assay | Polyubiquitination status | Linking ubiquitin signals to processing |
| Exosome uptake assay | Cytosolic delivery | Enhancing class I presentation |
| CRISPR screening | Gene requirement for presentation | Unbiased discovery of pathway genes |
Immunopeptidomics by mass spectrometry
Mass spectrometry of MHC class I-associated peptides identifies the endogenous peptide repertoire and can reveal how genetic or pharmacologic perturbations alter presentation. This method is directly applicable to GO:0019885 because it measures the peptides displayed on classical class I molecules.
Flow cytometry and surface MHC class I staining
Flow cytometry using antibodies against classical MHC class I molecules quantifies cell surface presentation and is a standard readout for the pathway. It can be combined with CRISPR knockout to test candidate genes.
Proximity labeling and proxiome analysis
A biotin ligation assay reveals a complex proxiome for HLA-A2 and implicates MIA3 in cell surface expression of MHC class I molecules, providing a method to discover novel regulators.
Functional T cell assays
CD8+ T cell activation or cytotoxicity assays measure the functional consequence of endogenous peptide presentation. These assays link molecular changes to immune recognition.
How CRISPR Can Be Used to Study GO:0019885 antigen processing and presentation of endogenous peptide antigen via MHC class I
Knockout
CRISPR knockout of candidate genes such as B2M, TAP1, or PSMB8 can abrogate endogenous peptide presentation and is used to test causal requirement in GO:0019885. Knockout of MIA3 can reveal its role in MHC class I cell surface expression.
Point Mutation
Point mutation of lysine residues to prevent polyubiquitination can test the role of ubiquitin signals in antigen processing. Point mutations in HLA alleles can dissect peptide binding specificity.
Knock-in
Knock-in of epitope tags into HLA-A allows tracking of MHC class I trafficking and surface expression. Knock-in of specific peptide epitopes can create defined antigen presentation models.
Overexpression
Overexpression of TAP1, TAP2, or immunoproteasome subunits can enhance endogenous peptide presentation and is used to study pathway sufficiency. Overexpression of exosomal fusogenic proteins can enhance class I tumor antigen presentation.
How EDITGENE Supports antigen processing and presentation of endogenous peptide antigen via MHC class I Research
Researchers studying antigen processing and presentation of endogenous peptide antigen via MHC class I-related genes often need to determine whether a candidate gene is causally involved in peptide generation, loading, or surface presentation. EDITGENE provides publication-ready CRISPR models and screening services to interrogate this pathway with precision.
Contact EDITGENE today to design your custom CRISPR model for antigen processing and presentation of endogenous peptide antigen via MHC class I research.
Frequently Asked Questions About antigen processing and presentation of endogenous peptide antigen via MHC class I
What is GO:0019885?
GO:0019885 is the biological process in which an antigen-presenting cell expresses a peptide antigen of endogenous origin on its cell surface in association with a classical MHC class I protein complex.
What genes are involved in antigen processing and presentation of endogenous peptide antigen via MHC class I?
Key genes include HLA-A, HLA-B, HLA-C, B2M, TAP1, TAP2, PSMB8, PSMB9, TAPBP, CANX, CALR, PDIA3, UBB, UBC, and MIA3.
How are endogenous peptides generated for MHC class I presentation?
Endogenous proteins are degraded in the cytosol, and cytoplasmic proteolysis is required for efficient presentation of cytosolic and transmembrane antigens. Polyubiquitination at lysine-48 acts as an essential but indirect signal for this processing.
Can RNA splicing modulation affect MHC class I antigen presentation?
Yes, pharmacologic modulation of RNA splicing enhances anti-tumor immunity, indicating that the endogenous peptide repertoire presented via MHC class I can be therapeutically altered.
What is the role of exosomes in class I tumor antigen presentation?
Tumor-cell-derived exosomes displaying a pH-sensitive fusogenic peptide can deliver cargos to the cytosol and enhance class I tumor antigen presentation.
Does HLA-DP present endogenous peptides from the class I pathway?
HLA-DP(84Gly) constitutively presents endogenous peptides generated by the class I antigen processing pathway.
How can I study GO:0019885 in the lab?
Common methods include immunopeptidomics, flow cytometry for surface MHC class I, proximity labeling, and CD8+ T cell activation assays.
What is the role of MIA3 in MHC class I presentation?
A biotin ligation assay revealed a complex proxiome for HLA-A2 and implicated MIA3 in cell surface expression of MHC class I molecules.
Can acute degradation of an antigen enhance its presentation?
Yes, acute pharmacologic degradation of a stable antigen enhances its direct presentation on MHC class I molecules.
Why is GO:0019885 important for cancer immunotherapy?
Because it determines whether tumor-derived endogenous peptides are displayed for CD8+ T cell recognition, and modulating this pathway can enhance anti-tumor immunity.
Conclusion
GO:0019885, antigen processing and presentation of endogenous peptide antigen via MHC class I, is a central biological process for immune surveillance of the intracellular proteome. Its molecular steps, from ubiquitin-dependent degradation to surface presentation, are experimentally tractable and therapeutically relevant in cancer and infection. CRISPR-based models and immunopeptidomics provide powerful tools to dissect this pathway and identify new targets for immunotherapy.
References
- 1. Lu SX et al.. 2021. Pharmacologic modulation of RNA splicing enhances anti-tumor immunity.. Cell 184(15):4032-4047.e31 PMID: 34171309
- 2. Grommé M et al.. 2002. Antigen degradation or presentation by MHC class I molecules via classical and non-classical pathways.. Mol Immunol 39(3-4):181-202 PMID: 12200050
- 3. Fiebiger BM et al.. 2015. Polyubiquitination of lysine-48 is an essential but indirect signal for MHC class I antigen processing.. Eur J Immunol 45(3):716-27 PMID: 25500897
- 4. Morishita M et al.. 2017. Enhanced Class I Tumor Antigen Presentation via Cytosolic Delivery of Exosomal Cargos by Tumor-Cell-Derived Exosomes Displaying a pH-Sensitive Fusogenic Peptide.. Mol Pharm 14(11):4079-4086 PMID: 28977747
- 5. Mukherjee P et al.. 2001. Efficient presentation of both cytosolic and endogenous transmembrane protein antigens on MHC class II is dependent on cytoplasmic proteolysis.. J Immunol 167(5):2632-41 PMID: 11509605
- 6. Yamashita Y et al.. 2017. HLA-DP(84Gly) constitutively presents endogenous peptides generated by the class I antigen processing pathway.. Nat Commun 8:15244 PMID: 28489076
- 7. Moser SC et al.. 2017. Acute Pharmacologic Degradation of a Stable Antigen Enhances Its Direct Presentation on MHC Class I Molecules.. Front Immunol 8:1920 PMID: 29358938
- 8. Mitchell W et al.. 2026. A biotin ligation assay reveals a complex proxiome for HLA-A2 and implicates MIA3 in cell surface expression of MHC class I molecules.. J Leukoc Biol 118(4) PMID: 41834513
