The transporter associated with antigen processing (TAP) is active in a post-ER compartment

Esther Ghanem, Susanne Fritzsche, Mohammed Al-Balushi, Jood Hashem, Lana Ghuneim, Lena Thomer, Hubert Kalbacher, Peter Van Endert, Emmanuel Wiertz, Robert Tampé, Sebastian Springer*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


The translocation of cytosolic peptides into the lumen of the endoplasmic reticulum (ER) is a crucial step in the presentation of intracellular antigen to T cells by major histocompatibility complex (MHC) class I molecules. It is mediated by the transporter associated with antigen processing (TAP) protein, which binds to peptide-receptive MHC class I molecules to form the MHC class I peptide-loading complex (PLC). We investigated whether TAP is present and active in compartments downstream of the ER. By fluorescence microscopy, we found that TAP is localized to the ERGIC (ER-Golgi intermediate compartment) and the Golgi of both fibroblasts and lymphocytes. Using an in vitro vesicle formation assay, we show that COPII vesicles, which carry secretory cargo out of the ER, contain functional TAP that is associated with MHC class I molecules. Together with our previous work on post-ER localization of peptide-receptive class I molecules, our results suggest that loading of peptides onto class I molecules in the context of the peptide-loading complex can occur outside the ER.

Original languageEnglish
Pages (from-to)4271-4279
Number of pages9
JournalJournal of Cell Science
Issue number24
Publication statusPublished - Dec 15 2010


  • ABC transporter
  • Antigen presentation
  • Endoplasmic reticulum to Golgi transport

ASJC Scopus subject areas

  • Cell Biology


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