Figure 4. Structure of a Representative MHCI Molecule showing the conserved N-glycan Site.
The Asn78 in MHCII (Figure 5) and N86 in MHCI (HLA-A2; 3D25 in the PDB) sites of N-glycosylation (red) are localized in structurally analogous locations. This universally conserved N-glycosylation site is at one end of the peptide (green) binding groove. The function of the N-glycan at N86 promotes folding and chaperone interactions, but has not been shown to be directly involved with antigen binding or presentation.