Lecture 9 - MHC

Question 1

What does the TCR recognise?

Answer 1

The combined shape of the MHC and antigen

Question 2

Number of extracellular domains possessed by MHC

Answer 2

Four

Question 3

Length of peptides recognised by TCR

Answer 3

8-12aa

Question 4

Regions making up MHCI peptide-binding region

Answer 4

Alpha1, alpha2

Question 5

Regions of an MHC molecule
1)
2)
3)
4)

Answer 5

1) Antigen-binding region
2) Ig-like region
3) Transmembrane region
4) Cytoplasmic region

Question 6

Shape of peptide-binding cleft

Answer 6

Base of beta sheets

Surrounded by two alpha helices

Question 7

Chains of MHCI

Answer 7

Heavy chain - alpha1, alpha2, alpha3

Light chain - b2-microglobulin

Question 8

Differences between MHCI and MHCII
1)
2)
3)
4)

Answer 8

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

Question 9

At what orientation does TCR bind to MHC?

Answer 9

At a diagonal angle

Ensures maximum contact

Question 10

Does TCR contact mostly MHC or antigen?

Answer 10

TCR makes most contact with MHC surface

Question 11

TCR specificity

Answer 11

Specific to both antigen and MHC

Question 12

Does MHC expression change in cells?

Answer 12

Yes.

Upregulation during immune response

Question 13

How are MHC alleles expressed?

Answer 13

Codominantly
Both alleles (one from each parent) are expressed

Question 14

Location of HLA locus

Answer 14

Chromosome 6

Question 15

Location of b2-microglobulin gene

Answer 15

Chromosome 15