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

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

Stable Identifier

R-HSA-983170

Type

Pathway

Species

Homo sapiens

ReviewStatus

5/5

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

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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 Wearsch, PA, Cresswell, P	Curr Opin Cell Biol	2008
18641646	The known unknowns of antigen processing and presentation Vyas, JM, Van der Veen, AG, Ploegh, HL	Nat Rev Immunol	2008
19178136	Molecular mechanisms of MHC class I-antigen processing: redox considerations Kim, Y, Kang, K, Kim, I, Lee, YJ, Oh, C, Ryoo, J, Jeong, E, Ahn, K	Antioxid Redox Signal	2009
12495737	Assembly and export of MHC class I peptide ligands Antoniou, AN, Powis, SJ, Elliott, T	Curr Opin Immunol	2003
15224092	Post-proteasomal antigen processing for major histocompatibility complex class I presentation Rock, KL, York, IA, Goldberg, AL	Nat Immunol	2004