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MHC and its role in Ag presentation - Coggle Diagram
MHC and its role in Ag presentation
Expression of MHC I and II
Professional APC: DCs, macrophages, activated B cells
Non-Professional APC: all nucleated cells in the body (only under normal conditions)
The TCR-pMHC interaction = low affinity
(needs co-receptors = bind MHC molecule + enhance the affinity of TCR-pMHC interaction + Initiation of signaling from TCR)
expressed co-receptor correlates with the recognized MHC
molecule that presents Ag
CD8 T cells recognize pMHC class I molecules
'cytotoxic' function
CD4 T cells recognize pMHC class II molecules
‘helper’ function
co-receptor signaling = part of signal 1
MHC Class II
assemble into a similar quaternary structure
allele-specific Ag peptide-binding cleft or groove facing out
more conserved area facing the cell membrane
peptide binding groove have alpha helices and beta sheets
length of the peptides bound by it is not constrained
bind and present peptides of extracellular origin,
i.e. exogenous peptides
MHC Class I
Transmembrane glycoproteins
each MHC chain has several Ig-like domains
present antigenic peptides to T cells
modular secondary structure
peptide binding groove have alpha helices and beta sheets
bind short peptides
of 8–10 amino acids by both ends
bind and present peptides generated within the
cell, i.e. endogenous peptides (includes self proteins)