MHC structure and function Flashcards
MHC located on chrmosome
6
what is most polymorphic gene in hman genome
MCH class I and II genes
What are the classical prodcuts of Class I genes?
HLA-A, B and C heavy chains
What the the classical products of MHC II genes?
heterodimer of HLA- DR, DQ, and DP
alpha and beta chains
Three key characteristics of MHC gene
polymorphic
polygeneic
codominant
How do T cell regocnize antiG
recognize foreign antigen in context of self MHC
Gene products for class II
6 gene products
What molecules are responsible for transplant rejection?
MHC I and II thus need to do tissue typing bfore transplant.
How many gene products do we match for
10
what gene producted is not accounted for during transplant match
HLA-DP
Chance of sibling being a match
1:4
Class I/II expressed on all nuclearted cells
Class I
What makes up Class I structure?
Class I heavy chain will form heterodimer with the light chain Beta2 microgoblulin
What type of association is there btwn the beta2micro and heavy chain of MHC 1
non-covalent and alpha chain goes through membrane
which domain spans membrane in Class I
alpha 3
is the beta 2microgob MCH endoced?
nope
Is beta2 micorglobulin polymorphic?
nope
what is the B2m structulally related to
immunoglobulin
Where are MHC II molecules expressed
only at specialized APCs
What does Class II MHC present antiG to
CD4T cells
What composes a class II MHC
alpha and beta chain each encoded by different gene
which chain of MHC II is more polymorphic
beta chain.. thus only one considrered for tissue typing
which domains of MHC II form peptide binding domain?
alpha 1 and beta 1
what’s significant about the alpha 2 and beta 2 domains of mch II
these domains fold and form the immunoglobulin fold
A TCR recognizes:
combination of peptide and self MHC
Where do polymorphisms occur in MHC I
in alpha helices adn beta sheet of the heavy chain
Where do polymorphisms occur in MHC II
alpha helices and beta sheets of the beta chain
size limit for peptides binding in MHC I groove
8-10 peptides
Determined that _________ distinct peps can bind to each class I MHC
> 1000
T/F: Each type of class I MHC binds to unique set of peptides
true
T/F a single nucleated cell expresses 10 to the 5th copies of each class I molecule thus each of the 1000 distinct peptides are presented at least once
False, each expressed 100-4000 copies per cell
Class ____ peptides are anchored at the end while Class ____ are not
Class I anchored
Class II not anchored
Class II peptides size:
10-16
Within a population there are _____ allelic variants thus while individual may be susceptible, population as a whole has protection d/t polymorphic characteristic of MHC
1000
High percentage of people that don’t respond to Hep B vaccine have:
HLA-DR7
This in an inflammatory, possibly autoimmune disease of vertebral joints
Anklyosing spondoytis
That HLA marker is responsible for predisposing ppl to AS
B27
HLA B27 found in :
but ___% with this will have AS
6% population
93% get AS
