Antigen Presentation: Folding, assembly and peptide loading of class I MHC

Stable Identifier
Homo sapiens
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Unlike other glycoproteins, correct folding of MHC class I molecules is not sufficient to trigger their exit from the ER, they exit only after peptide loading. Described here is the process of antigen presentation which consists of the folding, assembly, and peptide loading of MHC class I molecules. The newly synthesized MHC class I Heavy Chain (HC) is initially folded with the help of several chaperones (calnexin, BiP, ERp57) and then binds with Beta-2-microglobulin (B2M). This MHC:B2M heterodimer enters the peptide loading complex (PLC), a multiprotein complex that includes calreticulin, endoplasmic reticulum resident protein 57 (ERp57), transporter associated with antigen processing (TAP) and tapasin. Peptides generated from Ub-proteolysis are transported into the ER through TAP. These peptides are further trimmed by ER-associated aminopeptidase (ERAP) and loaded on to MHC class I molecules. Stable MHC class I trimers with high-affinity peptide are transported from the ER to the cell surface by the Golgi apparatus.
Literature References
PubMed ID Title Journal Year
18926908 The quality control of MHC class I peptide loading

Cresswell, P, Wearsch, PA

Curr Opin Cell Biol 2008
18641646 The known unknowns of antigen processing and presentation

Ploegh, HL, Van der Veen, AG, Vyas, JM

Nat Rev Immunol 2008
19178136 Molecular mechanisms of MHC class I-antigen processing: redox considerations

Jeong, E, Kim, Y, Ahn, K, Lee, YJ, Kim, I, Kang, K, Ryoo, J, Oh, C

Antioxid Redox Signal 2009
12495737 Assembly and export of MHC class I peptide ligands

Powis, SJ, Elliott, T, Antoniou, AN

Curr Opin Immunol 2003
15224092 Post-proteasomal antigen processing for major histocompatibility complex class I presentation

Rock, KL, Goldberg, AL, York, IA

Nat Immunol 2004
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