Week 17: (B) Major Histocompatibility Complex Flashcards
What are 3 clinical complications to MHC?
1) transplantation
2) individuals with certain HLA types are predisposed to certain diseases
3) Forensic medicine
What is the survival rate of a cumulative kidney graft?
0 mismatched ~ 80% survival
2 mismatches= 65% survival
What is the structure of a class 1 MHC protein?
alpha chain+ beta 2 micro-globulin
What is the structure of the class 2 HMC
alpha chain + beta chain. (both transmembrane)
What are the 2 domains closest to the membrane resemble?
immunoglobulin domains
What do the 2 domains furthest away from the membrane form?
fold together to create a long groove- antigenic peptide binds in this groove
Looking at the -ray crystal structure, what is the structure if the upper 2 domains?
form a peptide binding cleft, lined with beta strands underneath. edges are formed by the alpha helices.
Looking at the x-ray crystal structure, what is the structure of the lower 2 MHC domains?
MHC is a sandwich of beta sheets locked together with a disulphide bridge between 2 Cys residues
What is the major difference between MHC polymorphic variants?
located in peptide-binding cleft
influences what the peptides will bin.
recognised by the TCR structure
What is the groove called created by the upper 2 domains on class 1 MHC proteins?
peptide-binding cleft
How many peptides is does the Class 1 MHC groove have?
8-10
ends buried
How long is the peptide for Class 2 MHC groove?
ends of peptide not buried & peptide extends beyond cleft
What type of T cell does the MHC class 1 present peptides to?
Cytotoxic T cells (CD8+)
What type of T cell does the MHC class 2 present peptides to?
helper T cells (CD4+)
What happens to viral and cellular proteins in an infected host cell?
broken down and fragments expressed on the antigenic peptide groove.
