Abstract
Presentation of antigen-derived peptides by major histocompatibility complex (MHC) class I molecules is dependent on an endoplasmic reticulum (ER) resident glycoprotein, tapasin, which mediates their interaction with the transporter associated with antigen processing (TAP). Independently of TAP, tapasin was required for the presentation of peptides targeted to the ER by signal sequences in MHC class I-transfected insect cells. Tapasin increased MHC class I peptide loading by retaining empty but not peptide-containing MHC class I molecules in the ER. Upon co-expression of TAP, this retention/release function of tapasin was sufficient to reconstitute MHC class I antigen presentation in insect cells, thus defining the minimal non-housekeeping functions required for MHC class I antigen presentation.
MeSH terms
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ATP Binding Cassette Transporter, Subfamily B, Member 2
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ATP-Binding Cassette Transporters / chemistry
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ATP-Binding Cassette Transporters / metabolism
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Amino Acid Sequence
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Animals
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Antigen Presentation*
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Antigens / genetics
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Antigens / metabolism
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Antiporters / metabolism*
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Cell Line
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Dimerization
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Drosophila melanogaster
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Endoplasmic Reticulum / immunology
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Endoplasmic Reticulum / metabolism
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Genes, MHC Class I
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Histocompatibility Antigens Class I / metabolism*
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Immunoglobulins / metabolism*
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Membrane Transport Proteins
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Molecular Chaperones / metabolism
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Molecular Sequence Data
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Ovalbumin / genetics
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Ovalbumin / immunology
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Protein Conformation
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Transfection
Substances
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ATP Binding Cassette Transporter, Subfamily B, Member 2
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ATP-Binding Cassette Transporters
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Antigens
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Antiporters
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Histocompatibility Antigens Class I
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Immunoglobulins
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Membrane Transport Proteins
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Molecular Chaperones
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TAP1 protein, human
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tapasin
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Ovalbumin