Lecture 9 - MHC Flashcards
What does the TCR recognise?
The combined shape of the MHC and antigen
Number of extracellular domains possessed by MHC
Four
Is the b2-microglobulin gene in the HLA locus?
No
On a different chromosome
Is the b2-globulin chain covalently linked to MHCI?
No
Length of peptides recognised by TCR
8-12aa
Regions making up MHCI peptide-binding region
Alpha1, alpha2
Regions making up MHCI Ig-like domain
Alpha3, B2-mocroglobulin
Size of alpha1, alpha2 and alpha3 domains
Each is 90aa
Regions of an MHC molecule 1) 2) 3) 4)
1) Antigen-binding region
2) Ig-like region
3) Transmembrane region
4) Cytoplasmic region
Shape of peptide-binding cleft
Base of beta sheets
Surrounded by two alpha helices
Chains of MHCI
Heavy chain - alpha1, alpha2, alpha3
Light chain - b2-microglobulin
MHCII structure
No heavy or light chains
Two equal chains, one made of alpha1, alpha2, the other made from beta1, beta2
Antigen-binding site of MHCII
Alpha1, beta1
Are the alpha1 and beta1 regions of the MHCII antigen-binding cleft covalently linked?
No
Differences between MHCI and MHCII 1) 2) 3) 4)
1) MHCI has b2-microglobulin
2) MHCI has a heavy and light chain. MHCII has two equal-length transmembrane proteins.
3) MHCI interacts with CD8. MHCII interacts with CD4
4) MHCII can bind slightly larger proteins than MHCI