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Updated: Aug 2, 2026

Measuring Peptide Translocation into Large Unilamellar Vesicles
Published on: January 27, 2012
Peptide translocation by variants of the transporter associated with antigen processing
M T Heemels1, T N Schumacher, K Wonigeit
1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Abstract:
Major histocompatibility complex (MHC) class I molecules associate with peptides that are delivered from the cytosol to the lumen of the endoplasmic reticulum by the transporter associated with antigen processing (TAP). Liver microsomes of SHR and Lewis rats, which express different alleles of TAP (cim(b) and cim(a), respectively), accumulate different sets of peptides. Use of MHC congenic rats assigned this difference to the MHC, independent of the class I products expressed. Both the cim(a) and cim(b) TAP complexes translocate peptides with a hydrophobic carboxyl terminus, but translocation of peptides with a carboxyl-terminal His, Lys, or Arg residue is unique to cim(a). Thus, the specificity of the TAP peptide translocator restricts the peptides available for antigen presentation.
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