ER-60, a chaperone with thiol-dependent reductase activity involved in MHC class I assembly.
The assembly of newly synthesized MHC class I molecules within the endoplasmic reticulum and their association with the transporter associated with antigen processing (TAP) is a process involving the chaperones calnexin and calreticulin. Using peptide mapping by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to identify a new component, we now ... introduce a third molecular chaperone, the thiol-dependent reductase ER-60 (ERp57/GRP58/ERp61/HIP-70/Q2), into this process. ER-60 is found in MHC class I heavy chain complexes with calnexin that are generated early during the MHC class I assembly pathway. The thiol reductase activity of ER-60 raises the possibility that ER-60 is involved in the disulfide bond formation within heavy chains. In addition, ER-60 is part of the late assembly complexes consisting of MHC class I, tapasin, TAP, calreticulin and calnexin. In a beta2-microglobulin (beta2m)-negative mouse cell line, S3, ER-60-calnexin-heavy chain complexes are shown to bind to TAP, suggesting that beta2m is not required for the association of MHC class I heavy chains with TAP.
Mesh Terms:
ATP-Binding Cassette Transporters, Amino Acid Sequence, Animals, Antiporters, Calcium-Binding Proteins, Calnexin, Calreticulin, Cell Line, Enzyme Inhibitors, Heat-Shock Proteins, Histocompatibility Antigens Class I, Humans, Immunoglobulins, Indolizines, Isomerases, Membrane Transport Proteins, Mice, Molecular Chaperones, Molecular Sequence Data, Precipitin Tests, Protein Disulfide Reductase (Glutathione), Protein Disulfide-Isomerases, Rabbits, Ribonucleoproteins, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Tumor Cells, Cultured, alpha-Glucosidases, beta 2-Microglobulin
ATP-Binding Cassette Transporters, Amino Acid Sequence, Animals, Antiporters, Calcium-Binding Proteins, Calnexin, Calreticulin, Cell Line, Enzyme Inhibitors, Heat-Shock Proteins, Histocompatibility Antigens Class I, Humans, Immunoglobulins, Indolizines, Isomerases, Membrane Transport Proteins, Mice, Molecular Chaperones, Molecular Sequence Data, Precipitin Tests, Protein Disulfide Reductase (Glutathione), Protein Disulfide-Isomerases, Rabbits, Ribonucleoproteins, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Tumor Cells, Cultured, alpha-Glucosidases, beta 2-Microglobulin
EMBO J.
Date: Apr. 15, 1998
PubMed ID: 9545232
View in: Pubmed Google Scholar
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