Related Experiment Video
Updated: May 5, 2026

Measuring Peptide Translocation into Large Unilamellar Vesicles
Published on: January 27, 2012
TAP1-dependent peptide translocation in vitro is ATP dependent and peptide selective
J C Shepherd1, T N Schumacher, P G Ashton-Rickardt
1Division of Immunobiology FMB402, Howard Hughes Medical Institute, Yale Medical School, New Haven, Connecticut 06510.
Transporters associated with antigen processing (TAP) 1 and 2 are crucial for T cell recognition of infected cells. This study shows TAP1 functions as an ATP-dependent peptide translocator in a cell-free system.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- T cells identify infected cells by recognizing foreign peptide fragments presented by MHC class I molecules.
- MHC class I peptide binding occurs in the endoplasmic reticulum.
- Mutant cell analyses revealed the necessity of Transporters Associated with Antigen Processing (TAP) 1 and 2 for adequate peptide supply.
Purpose of the Study:
- To investigate the function of TAP1 in peptide transport.
- To characterize TAP1 as a molecular translocator.
Main Methods:
- Utilized a cell-free system to study TAP1 function.
- Investigated ATP dependence and peptide specificity.
Main Results:
- Demonstrated that TAP1 is an ATP-dependent molecular translocator.
- Showed that TAP1 exhibits sequence-specific peptide binding.
- Confirmed TAP1's role in the peptide processing pathway.
Conclusions:
- TAP1 is a key component of the peptide loading complex.
- Understanding TAP1 function is critical for T cell-mediated immunity.
- This research provides insights into antigen processing mechanisms.
Related Concept Videos
Translocation of Proteins into the Mitochondria
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Energy to Drive Translocation
Generally, polypeptides are unfolded by two distinct...
Protein Transport into the Inner Mitochondrial Membrane
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Cotranslational Protein Translocation
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Post-translational Translocation of Proteins to the RER
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Protein Transport to the Thylakoids

