lecture 3 - TCR and MHC Flashcards

1
Q

T celld come out the bone marrow and go to the

A

thymus where the gene segments are rearranged

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2
Q

generation of diversity of TCR

A

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

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3
Q

does somatic hypermutation happen in TCR

A

no

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4
Q

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

A

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

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5
Q

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

A

constant region

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6
Q

what chromosome are TCRalpha genes on

A

14

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7
Q

what chromosome are the TCRbeta genes on

A

7

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8
Q

what chromosome is the Ig heavy chain on `

A

14

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9
Q

what chromosome if the Ig light chain on

A

2 for kappa
22 for lamda

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10
Q

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

A

TCR gamma and delta

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11
Q

what chromosome is TCR gamma on

A

7

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12
Q

what chromosome is TCR delta on

A

14

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13
Q

differences between MHC and TCR/BRC

A

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

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14
Q

APC examples

A

B cells, macrophages, dendritic cells

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15
Q

MHC is located on what chromosome

A

6

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16
Q

class I MHC molecules are

A

HLA-A, B and C

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17
Q

class II MHC molecules are

A

HLA-DP, DQ and DR

18
Q

HLA-DR has 2

A

beta chains

19
Q

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

20
Q

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

A

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

21
Q

where is most of the polymorphism

A

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

22
Q

high levels of polymorphism allows

A

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

23
Q

downside with high polymorphism

A

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

24
Q

how do peptides end up bound to MHC molecules

A

antigen processing and presentation

25
peptides from antigens inside the cell (e.g virus) are usually presented by which MHC
class I
26
peptides from exogenous antigens (e.g bacteria) are presented by which MHC
class II
27
presentation by MHC class I: intracellular antigen is broken down into peptides by
proteasome
28
peptides transport into endoplasmic reticulum and peptide binds to
MHC class I
29
MHC is then presented at cell surface with the
peptide
30
what are the peptides transported to ER by
TAP transporter
31
what complex holds the MHC in the ER until peptide is bound
PLC (peptide loading complex)
32
presentation by class II: takes up antigen into a
endocytic vesicle
33
peptides are produced and what fuses with the endocytic vesicle
vesicle containing MHC class II
34
peptides bind to MHC class II and MHC is
presented at the surface
35
what does the invariant chain do
forms a complex with MHC class II
36
what does this complex do
blocks the binding of peptides when class II is being made
37
when is the invariant chain is the cleaved
when it fuses to the endosome as its acidic
38
what does this cleavage leave bound to the MHC class II
CLIP (a short peptide fragment)
39
what binds to the MHC class II releasing CLIP
HLA-DM allowing peptides to bind and the MHC goes to the cell surface
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
41
HLA-DM and TAP are coded for within the
MHC