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Peptide selection by MHC-encoded TAP transporters
F Momburg1, J J Neefjes, G J Hämmerling
1Tumor Immunology Program, German Cancer Research Center, Heidelberg.
Current Opinion in Immunology
|February 1, 1994
Summary
The newly discovered MHC-encoded peptide transporters (TAP) are crucial for the immune system. These transporters select peptides based on sequence and length, aiding their entry into the endoplasmic reticulum for MHC class I association.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- The immune system relies on the precise presentation of antigens to T cells.
- MHC class I molecules present peptides derived from cytosolic antigens.
- A critical step involves transporting these peptides into the endoplasmic reticulum.
Purpose of the Study:
- To elucidate the functional requirements of MHC-encoded peptide transporters (TAP).
- To understand the mechanism of peptide translocation mediated by TAP.
- To investigate how TAP interacts with peptides for MHC class I loading.
Main Methods:
- Development of a novel assay to study TAP-mediated peptide transport.
- Analysis of peptide characteristics influencing TAP binding and translocation.
- Characterization of TAP transporter family and substrate specificity.
Main Results:
- TAP transporters are ATP-binding, multimembrane-spanning proteins found across diverse species.
- TAP demonstrates specificity for various peptide substrates.
- TAP preselects peptides based on sequence and length, aligning with MHC class I peptide binding requirements.
Conclusions:
- TAP plays a vital role in the adaptive immune response by facilitating peptide transport.
- The discovered mechanism of TAP-mediated peptide selection is essential for effective antigen presentation.
- TAP's function represents a solution to the topological challenge of delivering cytosolic peptides to the ER lumen.