title: Protein disulfide isomerase is the dominant acceptor for peptides translocated into the endoplasmic reticulum.
abstract: Peptides derived from cytosolic protein degradation are translocated into the lumen of the endoplasmic reticulum (ER) by the transporter associated with antigen processing (TAP). In the ER, class I molecules bind the peptides fitting to their respective motifs and present them on the cell surface to CD8+ T lymphocytes. However, most TAP-translocated peptides are not expected to bind to the class I molecules present in a particular cell. Recently, we have demonstrated that TAP-translocated peptides containing a photoreactive phenylalanine analogue can be cross-linked to two luminal ER-resident proteins: with low efficiency to the stress protein gp96 and with high efficiency to a 60-kDa protein (Lammert, E. et al., Eur. J. Immunol. 1997. 27: 923). Both proteins have also been labeled specifically by TAP-translocated peptides conjugated to a different photoreactive group (Marusina, K. et al., Biochemistry 1997. 36: 856). Here, we show that the 60-kDa peptide-binding protein is identical to the multifunctional protein disulfide isomerase (PDI). Since PDI is the only luminal ER-resident protein that is labeled by the photoreactive peptides with high efficiency, it might represent the dominant acceptor for TAP-translocated peptides.
authors.affiliation: Department of Immunology, Institute for Cell Biology, Tübingen, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Lammert
authors.forename: S
authors.initials: S
authors.lastname: Stevanović
authors.forename: J
authors.initials: J
authors.lastname: Brunner
authors.forename: H G
authors.initials: HG
authors.lastname: Rammensee
authors.forename: H
authors.initials: H
authors.lastname: Schild
mesh_terms: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000345:Affinity Labels; D001667:Binding, Competitive; D001692:Biological Transport / Q000276:immunology; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000201:enzymology* / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology; D006680:HLA Antigens / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006801:Humans; D006822:Hybrid Cells; D007535:Isomerases / Q000187:drug effects / Q000378:metabolism*; D008970:Molecular Weight; D009842:Oligopeptides / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects / Q000276:immunology; D019704:Protein Disulfide-Isomerases
chemical_list: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters; D000345:Affinity Labels; D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; D009842:Oligopeptides; C073119:TAP1 protein, human; D004958:Estradiol; D007535:Isomerases; D019704:Protein Disulfide-Isomerases