G3DSA:1.10.870.10

MHC class II-associated invariant chain, trimerisation domain

CATH-Gene3D entry
Member databaseCATH-Gene3D
CATH-Gene3D typehomologous superfamily

Description
Imported from IPR036613

Newly synthesized MHCII proteins associate with a chaperone protein called the invariant chain (Ii) and form a nonameric complex (alpha3beta3Ii3) in the endoplasmic reticulum
[4]
. Ii plays a critical role in the assembly of the MHC, as well as in MHC II antigen processing by stabilising peptide-free class II alpha/beta heterodimers in a complex soon after their synthesis and directing transport of the complex from the endoplasmic reticulum to compartments where peptide loading of class II takes place
[3]
. In antigen-presenting cells (APCs), loading of MHC II molecules with peptides is regulated by Ii, which blocks MHC II antigen-binding sites in pre-endosomal compartments
[1]
. Several molecules then act upon MHC II molecules in endosomes to facilitate peptide loading: Ii-degrading proteases, the peptide exchange factor, human leukocyte antigen-DM (HLA-DM), and its modulator, HLA-DO (DO).

Ii first assembles into a trimer and then associates with three class II alpha/beta MHC heterodimers. This entry represents the trimerisation domain of Ii. Its structure has been determined by NMR
[2]
.

References
Imported from IPR036613

1.Achieving stability through editing and chaperoning: regulation of MHC class II peptide binding and expression. Busch R, Rinderknecht CH, Roh S, Lee AW, Harding JJ, Burster T, Hornell TM, Mellins ED. Immunol. Rev. 207, 242-60, (2005). View articlePMID: 16181341

2.Structure of a trimeric domain of the MHC class II-associated chaperonin and targeting protein Ii. Jasanoff A, Wagner G, Wiley DC. EMBO J. 17, 6812-8, (1998). View articlePMID: 9843486

3.MHC class II compartment subtypes: structure and function. Stern LJ, Potolicchio I, Santambrogio L. Curr. Opin. Immunol. 18, 64-9, (2006). View articlePMID: 16337363

4.Formation of a nine-subunit complex by HLA class II glycoproteins and the invariant chain. Roche PA, Marks MS, Cresswell P. Nature 354, 392-4, (1991). View articlePMID: 1956401

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