Redox-regulated export of the major histocompatibility complex class I-peptide complexes from the endoplasmic reticulum

Sungwook Lee, Boyoun Park, Kwonyoon Kang, Kwangseog Ahn

Research output: Contribution to journalArticle

10 Citations (Scopus)


In contrast to the fairly well-characterized mechanism of assembly of MHC class I-peptide complexes, the disassembly mechanism by which peptide-loaded MHC class I molecules are released from the peptide-loading complex and exit the endoplasmic reticulum (ER) is poorly understood. Optimal peptide binding by MHC class I molecules is assumed to be sufficient for triggering exit of peptide-filled MHC class I molecules from the ER. We now show that protein disulfide isomerase (PDI) controls MHC class I disassembly by regulating dissociation of the tapasin-ERp57 disulfide conjugate. PDI acts as a peptide-dependent molecular switch; in the peptide-bound state, it binds to tapasin and ERp57 and induces dissociation of the tapasin-ERp57 conjugate. In the peptide-free state, PDI is incompetent to bind to tapasin or ERp57 and fails to dissociate the tapasin-ERp57 conjugates, resulting in ER retention of MHC class I molecules. Thus, our results indicate that even after optimal peptide loading, MHC class I disassembly does not occur by default but, rather, is a regulated process involving PDI-mediated interactions within the peptide-loading complex.

Original languageEnglish
Pages (from-to)3285-3294
Number of pages10
JournalMolecular Biology of the Cell
Issue number14
Publication statusPublished - 2009 Jul 15


All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

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