MHC Molecules and Antigen Presentation Flashcards
pMHC
MHC with peptide bound
The TCR is made up of. . .
One α chain, one β chain
Each contains its own distinct V domain with 3 hypervariable loops (6 total).
CD4+ T cells are ___ restricted. CD8+ T cells are ___ restricted.
CD4+ T cells are class II MHC restricted. CD8+ T cells are class I MHC restricted.
Antigen capture and DC migration
Naive T cell activation
Antigen processing takes place in. . .
the antigen-presenting cell (be it a professional APC or some random nucleated cell bearing a class I MHC)
Class I and Class II MHC Structure
Three types of Class I MHC
HLA-A
HLA-B
HLA-C
Three types of Class II MHC
HLA-DP
HLA-DQ
HLA-DR
Human HLA locus (in the genome)
MHC genes, as a whole, are more ___ than any other genes in the genome.
MHC genes, as a whole, are more polymorphic than any other genes in the genome.
If there are so many alleles, why are family members likely to be histocompatible?
Because all of the genes are at the same locus, they are usually inherited as a single HLA haplotype with Mendelian inheritance.
Properties of MHC molecules
How MHCs bind peptides
Why have multiple types of a single class of MHC?
Because they bind peptides at different sites, thus enabeling binding of a greater number of peptides.
How do class I and class II MHC not accidentally trigger a TCR meant for the other complex?
- This is in part the role of the CD4 or CD8 coreceptor
- The antigens are not in the same part of the binding cleft! Even ignoring CD4/CD8, this makes it practically impossible.
MHC genes are expressed. . .
codominantly
One individual has ___ types of MHC.
12!
3 class I and 3 class II from mom,
another 3 class I and 3 class II from dad.
MHCs are often upregulated by. . .
RTKs or other growth or activity-related receptors
Class II MHC loading pathway
______ contains N‐terminal sorting signals that deliver the class II MHC to the specialized endosomal compartment where HLA‐DM and the antigen peptides are located.
The invariant chain contains N‐terminal sorting signals that deliver the class II MHC to the specialized endosomal compartment where HLA‐DM and the antigen peptides are located.
Class I MHC loading pathway
Immunoproteasome
Type of proteasome found in APCs. Chops up peptides to be the perfect length for Class I MHC binding.
Transporter associated with antigen (TAP) pump
Pumps the peptides generated by the immunoproteasome into the lumen of the rough ER to be loaded onto maturing class I MHC molecules, which are conveniently held in place around the TAP pump by specialized chaperones.
