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Purification of the Membrane Compartment for Endoplasmic Reticulum-associated Degradation of Exogenous Antigens in Cross-presentation
Published on: August 21, 2017
The transporter associated with antigen processing (TAP) is active in a post-ER compartment.
Esther Ghanem1, Susanne Fritzsche, Mohammed Al-Balushi
1Biochemistry and Cell Biology, Molecular Life Science Center, Jacobs University Bremen, 28759 Bremen, Germany.
Journal of Cell Science
|November 25, 2010
Summary
The transporter associated with antigen processing (TAP) functions beyond the endoplasmic reticulum (ER). This study finds TAP in ER-Golgi intermediate compartment and Golgi, suggesting peptide loading occurs outside the ER.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Antigen presentation via MHC class I molecules is vital for T cell response.
- The transporter associated with antigen processing (TAP) facilitates peptide translocation into the ER lumen for MHC class I loading.
- The precise localization and function of TAP in post-ER compartments remain largely uncharacterized.
Purpose of the Study:
- To investigate the presence and activity of TAP in cellular compartments downstream of the endoplasmic reticulum (ER).
- To determine if the MHC class I peptide-loading complex (PLC) functions in post-ER locations.
Main Methods:
- Fluorescence microscopy was employed to visualize TAP localization in fibroblasts and lymphocytes.
- An in vitro vesicle formation assay using COPII vesicles was utilized to assess TAP functionality.
- MHC class I molecules were analyzed for association with TAP in these vesicles.
Main Results:
- TAP was found to be localized in the ER-Golgi intermediate compartment (ERGIC) and the Golgi apparatus.
- Functional TAP was detected within COPII vesicles, which mediate transport out of the ER.
- TAP was observed to be associated with MHC class I molecules in these post-ER vesicles.
Conclusions:
- The transporter associated with antigen processing (TAP) is present and active in the ERGIC and Golgi.
- Peptide loading onto MHC class I molecules within the peptide-loading complex can occur in cellular compartments outside the endoplasmic reticulum.
- These findings expand our understanding of antigen processing and presentation pathways.
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