lecture 3 - TCR and MHC

Question 1

T celld come out the bone marrow and go to the

Answer 1

thymus where the gene segments are rearranged

Question 2

generation of diversity of TCR

Answer 2

multiple V, D and J gene segments
combinational diversity between V, D and J
junction diversity

Question 3

does somatic hypermutation happen in TCR

Answer 3

no

Question 4

TCR alpha chain formation (similar to Ig light chain):
DNA breaks between V and J

Answer 4

random V and J join, then they join to a constant region

Question 5

TCR beta chain formation (similar to Ig heavy chain):
VD and J regions join and then to a

Answer 5

constant region

Question 6

what chromosome are TCRalpha genes on

Answer 6

14

Question 7

what chromosome are the TCRbeta genes on

Answer 7

7

Question 8

what chromosome is the Ig heavy chain on `

Answer 8

14

Question 9

what chromosome if the Ig light chain on

Answer 9

2 for kappa
22 for lamda

Question 10

TCRgamma and YCRdelta form a slightly different receptor.
so a TCR will either be TCR alpha and beta or

Answer 10

TCR gamma and delta

Question 11

what chromosome is TCR gamma on

Answer 11

7

Question 12

what chromosome is TCR delta on

Answer 12

14

Question 13

differences between MHC and TCR/BRC

Answer 13

there no gene rearrangement in MHC molecules
MHC molecules are expressed co-dominantly (MHCs from both chromosomes are expressed)

Question 14

APC examples

Answer 14

B cells, macrophages, dendritic cells

Question 15

MHC is located on what chromosome

Answer 15

6

Question 16

class I MHC molecules are

Answer 16

HLA-A, B and C

Question 17

class II MHC molecules are

Answer 17

HLA-DP, DQ and DR

Question 18

HLA-DR has 2

Answer 18

beta chains

Question 19

MHC are the most polymorphic genes known meaning there’s lots of

Answer 19

alleles

Question 20

a single cell can have up to how many different MHC molecules

Answer 20

12 (if they are heterozygous for all 6 MHC loci)

Question 21

where is most of the polymorphism

Answer 21

in the part of the MHC molecule that forms peptide binding groove (alpha 1 and 2)

Question 22

high levels of polymorphism allows

Answer 22

binding of vast range of peptides that can be presented to T cells

Question 23

downside with high polymorphism

Answer 23

increase risk of many auto immune mediated disease (e.g. presenting self antigens)
also makes donor organs for transplantation very complex

Question 24

how do peptides end up bound to MHC molecules

Answer 24

antigen processing and presentation

Question 25

peptides from antigens inside the cell (e.g virus) are usually presented by which MHC

Answer 25

class I

Question 26

peptides from exogenous antigens (e.g bacteria) are presented by which MHC

Answer 26

class II

Question 27

presentation by MHC class I:
intracellular antigen is broken down into peptides by

Answer 27

proteasome

Question 28

peptides transport into endoplasmic reticulum and peptide binds to

Answer 28

MHC class I

Question 29

MHC is then presented at cell surface with the

Answer 29

peptide

Question 30

what are the peptides transported to ER by

Answer 30

TAP transporter

Question 31

what complex holds the MHC in the ER until peptide is bound

Answer 31

PLC (peptide loading complex)

Question 32

presentation by class II:
takes up antigen into a

Answer 32

endocytic vesicle

Question 33

peptides are produced and what fuses with the endocytic vesicle

Answer 33

vesicle containing MHC class II

Question 34

peptides bind to MHC class II and MHC is

Answer 34

presented at the surface

Question 35

what does the invariant chain do

Answer 35

forms a complex with MHC class II

Question 36

what does this complex do

Answer 36

blocks the binding of peptides when class II is being made

Question 37

when is the invariant chain is the cleaved

Answer 37

when it fuses to the endosome as its acidic

Question 38

what does this cleavage leave bound to the MHC class II

Answer 38

CLIP (a short peptide fragment)

Question 39

what binds to the MHC class II releasing CLIP

Answer 39

HLA-DM allowing peptides to bind and the MHC goes to the cell surface

Question 40

in normal healthy cells MHC I and II will present peptides from self proteins to show what it looks like when its healthy so can see changes if its infected

Question 41

HLA-DM and TAP are coded for within the

Answer 41

MHC