Formation of peptide loading complex (PLC)

Stable Identifier
R-HSA-983142
Type
Reaction
Species
Homo sapiens
Compartment
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Upon interaction of Beta-2-microglobin (B2M) with MHC class I Heavy Chain (HC), calnexin is fully replaced by its soluble ortholog calreticulin (CRT) and this complex is incorporated into the peptide loading complex (PLC). PLC is a multiprotein complex that includes CRT, ERp57 and the additional components tapasin, transporter associated with antigen processing (TAP) and Bap31. The stoichometry of components in PLC remains unclear. The PLC loads antigenic peptides onto MHC class I molecules; components of the PLC cooperate to stabilize the MHC class I complex and optimally load peptides. Tapasin is a type I transmembrane protein that interacts directly with TAP and tethers the MHC complex to it. TAP facilitates the transport of peptides from the cytosol to the ER lumen. B cell receptor–associated protein (Bap31), a putative cargo receptor, associates with HC and acts as a retrograde transporter, carrying peptide-loaded class I MHC molecules.

Literature References
PubMed ID Title Journal Year
16465444 The macromolecular peptide-loading complex in MHC class I-dependent antigen presentation

Koch, J, Tampé, R

Cell Mol Life Sci 2006
19119025 Insights into MHC class I peptide loading from the structure of the tapasin-ERp57 thiol oxidoreductase heterodimer

Dong, G, Wearsch, PA, Peaper, DR, Cresswell, P, Reinisch, KM

Immunity 2009
15286279 Tapasin enhances MHC class I peptide presentation according to peptide half-life

Howarth, M, Williams, A, Tolstrup, AB, Elliott, T

Proc Natl Acad Sci U S A 2004
19426129 The peptide-loading complex--antigen translocation and MHC class I loading

Schölz, C, Tampé, R

Biol Chem 2009
19361863 A transmembrane tail: interaction of tapasin with TAP and the MHC class I molecule

Simone, LC, Wang, X, Solheim, JC

Mol Immunol 2009
14718384 Quality control of MHC class I maturation

Paulsson, KM, Wang, P

FASEB J 2004
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