Reactome | Formation of peptide loading complex (PLC)

Formation of peptide loading complex (PLC)

Stable Identifier

R-HSA-983142

Type

Reaction [binding]

Species

Homo sapiens

Compartment

lumenal side of endoplasmic reticulum membrane, endoplasmic reticulum membrane, endoplasmic reticulum lumen

ReviewStatus

5/5

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Formation of peptide loading complex (PLC)

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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
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
16465444	The macromolecular peptide-loading complex in MHC class I-dependent antigen presentation Koch, J, Tampé, R	Cell Mol Life Sci	2006
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