L13 MHC Flashcards
what cells do not have MHC
red blood cells
where is MHC I expressed
all nucleated cells
where is MHC II expressed
antigen presenting cells; DC, B cells, monocytes and macrophages
structure of MHC I
single chain covalently bound to soluble molecule beta II mycoglobulin
what is mycoglobulin for ?
stabilise the single chain MHC I
how long is MHC I
9 amino acids
structure of MHC II
2 chains: alpha and beta
which is the variable chain in MHC II
beta chain
how long are the amino acid chains in MHC
> 15
Where do MHC I get their peptides
cytoplasmic antigen
where does MHC II get peptides
outside the cell brought in by phagocytosis etc
content is digested by phagolysome and peptides are realeased
MHC II and peptide is loaded onto cell surfaceq
what happens when an infected cell dies
DC take it up and destroys content
what is the process of cross priming
when antigen leaks out of a lysosome and into the cytoplasm
it is then loaded onto MHC I and activates the cytotoxic CD8 T cell
what prevents peptides longer than 9-10 amino acids from binding
conserved amino acids
what does MHC require ot be stable
peptide bound to the anitgen binding groove
what happens to MHC that is non-peptide bound
recycled from cell surface or doesnt reach surface
if we are not chronically infected why do we express MHCI and II
in absence of infection almost 100% of MHC will be loaded with self-peptides
what stabilises immature MHC II and prevents premature loading of self-peptide
Li chaperone/protein
when and how is Li cleaved
just prior to peptide loading by proteases
what do antigen presenting cells express
MHC I
MHC II
what type of MHC is only on antigen presenting cells
MHC II
what type of MHC is only on antigen presenting cells
MHC II
where do most polymorphism of MHC occur
Beta chain of MHC II
hoe are peptide bound to the MHC groove
anchor residues
what is the primary role of the invariant chain
stabilise MHC II
