Major Histocompatibility Complex (MHC) (Week 5)

Question 1

MHC proteins are…

Answer 1

polygenic = many genes for MHC Class I and II proteins
polymorphic = multiple variants, or alleles, of each gene within the population

Question 2

MHC diverse binding

Answer 2

• Every individual has a set of MHC molecules with different ranges of peptide-binding specificities
• Diversity generated through gene conversion (NO gene rearrangement)

Question 3

MHC Class I protein structure

Answer 3

• formed with two polypeptides
• 𝛼 chain (𝛼1, 𝛼2, and 𝛼3) and β chain (β2 macroglobulin)
• form peptide binding groove

Question 4

MHC Class II protein structure

Answer 4

• formed with two similar polypeptides
• 𝛼 chain (𝛼1 and 𝛼2) and β chain (β1 and β2)
• form peptide binding groove

Question 5

Anchor residues

Answer 5

• key residues that bind to MHC peptide groove
• Allows for many peptides to bind in
  different configurations

Question 6

MHC haplotype

Answer 6

combination of MHC alleles found
on a single chromosome

Question 7

Most individuals are for MHC genes

Answer 7

heterozygous

Question 8

Advantages of MHC heterozygosity

Answer 8

1. Different peptide-binding specificities = = presentation of more pathogen derived peptides during infection
2. Increases the number of activated
   pathogen-specific T cells = greater
   immune response