TY - JOUR
T1 - The transporter associated with antigen processing (TAP) is active in a post-ER compartment
AU - Ghanem, Esther
AU - Fritzsche, Susanne
AU - Al-Balushi, Mohammed
AU - Hashem, Jood
AU - Ghuneim, Lana
AU - Thomer, Lena
AU - Kalbacher, Hubert
AU - Van Endert, Peter
AU - Wiertz, Emmanuel
AU - Tampé, Robert
AU - Springer, Sebastian
PY - 2010/12/15
Y1 - 2010/12/15
N2 - 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.
AB - 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.
KW - ABC transporter
KW - Antigen presentation
KW - Endoplasmic reticulum to Golgi transport
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U2 - 10.1242/jcs.060632
DO - 10.1242/jcs.060632
M3 - Article
C2 - 21098634
AN - SCOPUS:78649737453
SN - 0021-9533
VL - 123
SP - 4271
EP - 4279
JO - Journal of Cell Science
JF - Journal of Cell Science
IS - 24
ER -