Quiz 4 part 3 Flashcards
MHC genes are in a cluster of closely linked genes on chromosome ____
in humans, this is the….
6
HLA complex (human leukocyte antigen complex)
do HLA genes rearrange?
NO
instead, HLA genes exhibit high genetic polymorphism and gene families
which is more compact — the class 2 region or the class 1 region? what does this imply?
the class 2 region is more compact than the class 1 region.
this implies that there is a very small probability of crossover for the class 2 region (too close together)
how many MHC class 1 isotypes are there?
6
what are the 6 class 1 MHC isotypes?
HLA-A
HLA-B
HLA-C
HLA-E
HLA-G
HLA-F
Which MHC class 1 isotypes present to CD8+ T cells and are also ligands for NK cells?
HLA-A
HLA-B
HLA-C
Which MHC Class 1 isotypes are ONLY NK cell ligands (dont present to T cells)
HLA-E
HLA-G
what is the function of HLA-F
HLA-F is a chaperone that transports HLA molecules that have lost peptide
in MHC class 1, which locus’s have the greatest number of allotypes (most variation)
HLA-A
HLA-B
HLA-C
there are _____ MHC class 2 isotypes
name them
5
HLA-DP
HLA-DQ
HLA-DR
HLA-DM
HLA-DO
Which MHC class 2 isotypes present to CD4+ T cells?
HLA-DP
HLA-DQ
HLA-DR
Which MHC Class 2 isotypes regulate loading onto other MHC Class 2 molecules?
HLA-DM
HLA-DO
which can develop MORE combinations — MHC Class 1 or MHC class 2?
class 2 because it is a DIMER. there is variation in both the alpha chain and beta chain
In MHC class 2, which has more diversity – B chains or A chains?
B chains
of the MHC class 1 isotypes, which are HIGHLY polymorphic?
HLA-A
HLA-B
HLA-C
MHC class 1 diversifies where?
in the binding pocket
MHC Class 2 diversifies where?
in the beta chain
does MHC class 1 or MHC class 2 only diversify on 1 side of the protein?
class 2 bc it only diversifies in the beta chain
what is the optimum size of peptide for MHC class 1
9mer
what binds to HLA-A
HIV reverse transcriptase
what binds to HLA-B
influenza A nucleoprotein
which has a stricter consensus for binding peptides – MHC class 1 or MHC class 2
MHC class 1 is more strict – must be certain size
in order to bond to MHC, the T cell has to recognize….
TWO THINGS
The peptide bound to MHC AND
MHC molecule itself
why would a t cell receptor ever not be able to recognize an MHC molecule?
bc isotypes exist (ie: HLA-A, HLA-B)
“response to an antigen is restricted by the HLA isotype.” what is the term for this?
MHC class restriction
in organ transplantation, what does it mean when they’re “finding a match”
they’re trying to match HLA type
Why is it an advantage to have multiple MHC genes and genetic polymorphism?
a greater number of pathogen-derived peptides can be presented
how are MHC genes inherited?
as a haplotype — from a single parent
those with more divergent haplotypes have ____ advantage
similarly, _____zygous have an advantage over ____zygous
greater
heterozygous have an advantage over homozygous
Non self MHC molecules are recognized by….
alloreactive T cells
