MHC and Ag Presentation Flashcards
(153 cards)
1
Q
MHC stands for
A
Major Histocompatibility Complex
2
Q
what are the types of MHC
A
MHC class I and II
3
Q
what is another name of MHC
A
transplantation antigens
4
Q
describe MHC class I structure and binding
A
one polypeptide chaina nd b/w two regions of that same chain you bind the peptide
5
Q
describe MHC class II structure and binding
A
one polypeptide and a separate polypeptide and b/w those two polypeptides you bind the peptide
6
Q
human version of MHC is called
A
HLA
7
Q
class I has what HLA
A
HLA A
B
C
8
Q
Class II HLA ha
A
HLA - DR
HLA-DP
HLA-DQ
9
Q
what is the primary function MHC gene
A
to present antigenic peptides
10
Q
normally MHC genes are presenting
A
self
11
Q
CD4 (T-helper) see antigen on surface of
A
MHC class II
12
Q
CD8 see antigen on surface of
A
MHC I
13
Q
CD8 and you’re sick and you’re attacking chances are what is it attacking
A
it’s a virus
14
Q
draw out CD8 binding MHC class I
A
pg 8
15
Q
draw out CD4 binding MHC class II
A
pg 8
16
Q
CD4 is
A
helper T cell
17
Q
CD8 is
A
killer T cell
18
Q
the 3d structure of MHC class I requires presence of what to work correctly
A
beta2 microglobulin
19
Q
what three genes code for MHC class I polypeptides
A
HLA-A, HLA-B, and HLA-C
20
Q
HLA stands for
A
human leukcoyte antigen
21
Q
beta2 microglobulin
A
it is a part of MHC class I, needed for it to function it is encoded for gene at another location thatn the alpha chain
22
Q
MHC II composed of
A
two polypeptide chains: alpha & beta
23
Q
if you’re not sick what will MHC bind
A
self
24
Q
if you are sick what will MHC bind
A
whatever antigen
25
different MHC II that we have
HLA-DP, HLA-DQ and HLA-DR
26
where do we have MHC I
everywhere BUT RBC (no nucleus)
| basically all cells with nucleus
27
where will we not have MHC I
RBC
28
MHC protein is expressed ____ on cell surface
codominantly
29
what does codomoinantly mean in regards to MHC class I
mom: abc
dad: abc
we express from both parents equally
30
MHC class II expressed on what cells
B cells
Macrophages
Dendritic cells
(all APC)
31
MHC II are expressed _____
codominantely
32
human MHC class II isotypes
HLA-DP
HLA-DQ
HLA-DR
33
how polymorphic is insulin
not. it is very conserved b/w us and even b/w species
34
MHC is the most ______ thing we know of
polymorphic
35
what is the most polymorphic thing we know of
MHC (HLA for humans)
36
define allele
different forms of a gene; many genes have multiple alleles
37
define homozygote
alleles at a locus are the same
38
define heterozygote
alleles at a locus are different
39
define co-dominant gene expression
all alleles for a particular gene locus are expressed in an individual
40
define haplotype
a set of alleles of a group of closely linked genes which are usually inherited as a unit.
41
HLA genes are expressed
co-dominently
42
what can often happen regarding haplotypes of paternal and maternal alleles
they can recombine their alleles and child would get a mixture of the genes and create a brand new haplotype
43
compare and contrast homozygote for MHC vs. heterozygote for MHC
pg 18
44
in terms of MHC II you can create
trans molecule
45
trans molecule
ex: HLA-DP
alpha chain maternal, beta chain paternal. can potentailly mix apha maternal with beta paternal and create completely new set
46
the more variable for MHC the more
different pieces it can present or put in the space to present
47
you want to fit what into MHC
a lot of different proteins, a HUGE amount, so you need MHC to be incredibly diverse
48
HLA class 1, the α3 region is
identical in all of them
49
HLA class I α1 α2 are
very variable b/w the MHC
50
what is holding on to the epitope in HLA
beta sheets
51
what is surrounding the beta sheets in HLA
alpha helixes
52
HLA needs to interact w/
interacting with peptide or interacting with TCR
53
in position 2 of HLA-A binding motif always
leucine or methionine
54
in position 6 of HLA-A binding motif always have
valine
55
positino 9 of HLA-A binding motif always have
leucine or valine
56
peptide binding motif
speicif aa that is anochor
| it needs certain aa at certain locations in order for peptide to bind
57
what is example of HLA-A peptide that binds class I
HIV reverse transcriptase
58
T cells recognize
short peptidees
59
the bound peptide belongs to the binding motif for HLA-A*02:01, could you bind a different peptide outside of HIV reverse transcriptase?
yes, it is a pretty general recognition. it just needs certain things in certain binding motifs.
60
class I MHC is very limited on what
size that can fit - has to be 9 aa
61
MHC class II is different than MHC I regarding size b/c
they have oepn ends and can fit more aa
62
what are anchor residues for MHC I
3,5,8
63
what are anchor residues for MHC II
1,4,6
64
where will MHC domains participate in binding in MHC class I
alpha 1 and alpha 2
65
where will MHC domains partiicpate in binding in MHC II
alpha 1 and beta 1
66
CD1 is similar ot
class I MHC
67
CD1 is family of
MHC class I encoded outside the MHC
68
CD1 presents what
microbial lipids
69
CD1 present microbial lipids to
CD1-restricted T cells - NKT cells
| natural killer cells!
70
if APC present non-self or altered self, what happens
immune response initiated
71
ultimate goal of MHC I
present non-self or altered self to result as a target cell
72
APC
dendritic
activated macrophages
b cells
73
B7 is going to be on surface of
APC
74
B7-1 is what CD
CD80
75
B7-2 is what CD
CD86
76
CD28 is on surface of
T cell
77
B7 will bind to
CD28 on T cell
78
what is the first signal that happens for everything for immune response
binding antigen
79
TCR sees epitope and portion of
MHC presenting
80
antigen processing
proteolytic degradation
| make large proteins into small peptides (and some lipids)
81
antigen presentation
display
| display bound to MHCI or II on surface of APC
82
MHC-restriction recognition
processed and presented antigens in the context of MHC
molecules are recognized by specific T cell receptors (TCRs)
Antigens are presented by MHC I to CD8+ T cells
Antigens are presented by MHC II to CD4+ T cells
83
CD8 are
MHCI restricted
84
Class I is CD8 restricted b/c it requirs
CD8 receptor binding to class I
85
MCH II restrictd to CD4+ b/c
it requires CD4 receptor binding to MHCII
86
MHC class I
cytosol
87
MHC Class II
endocytic vesicles
88
when macrophage is presented what does it do when presented from class II
it becomes a better macrophage and activates more macrophages
89
give summary of class II infection
Big picture: infection, exracellular. Probalby bac. Take it in via endocytic vesicle, chop into pieces, miss with lysosome, bring MHC II and combine the two vesicles (one with pieces with MHC II) and express it on the outside. The origin of peptide was extracellular infection
90
give summary of class I infection
Class I
Got virus, virus makes copies of itself inside cell. In cell have mechanism for degrading proteins: proteasome, it becomes little pieces, now have mechanism to take the little pieces into ER, in ER have MHC I and it combines with protein pieces (epitope) and then go to cell and express
91
which MHC calss is intracellular origin
class I
92
which MHC class is extracellular origin
class II
93
lysosomes
special organelle containing proteases and other hydrolytic enzymes
very acidic
94
Endosomes/Phagosomes:
acidic vesicles containing foreign proteins and proteolytic enzymes
they bring in the foreign proteins
95
when the vesicle take in the bac. what will happen as it goes through the cell
there are pumps that make the vesicle containig the bac. (or whatever else) acidic which helps it to degrade the protein
96
vesicle containing class II molecule called
MIIC
97
what is MIIC
the actual vesicle that joins with the epitopes
98
when making MHC II there is alpha and beta chain, is the space open while it is being made?
no - invariant chain is blocking the peptide binding site
99
what blocks MHC II epitope binding site in ER
invariant chain
100
what is second role of invariant chain
guides to wherever the acidic vesicles are to fuse with phagolysosome.
101
after invariant chain blocks things from entering MHC II what happens to it
chop it into pieces except for the CLIP
102
what is CLIP
a little part of the original invariant chain that is still blocking the epitope binding site of MHC II
103
what are two roles of invariant chain
blocks MHC II binding site
| brings (traffics) it to endosomes
104
once MHCII is bound to endosome and is surrounded by epitopes, what happens
HLA-DM comes in and helps exchange CLIP for peptide
105
role of HLA-DM is to facilitaet
removal of clip
| finding of the perfect epitope that will fit into peptide-motif
106
what is key HLA involving in peptide exchange
HLD-DM
107
HLA-DM works with what
HLA-DO
108
MHC class II compartment is
MIIC
109
li stands for
invariant chain
110
where do MHC I peptides originate
cytosol
111
MHC class I is
tissue specific
112
why is MHC I tissue specific
b/c the viruses will target specific cells - there is specificity int erms of tissue by virus
113
explain MHC Class I pathway
Virus enter cell, replicates, get proteins that are made in cytosol, so the protein is made in our own cells cytosol, proteasome, chops the protein made by viral mRNA into pieces, peptide piece brought into ER, LHA class I with peptides will be expressed on surface
114
endogenous means?
having an internal cause or origin
115
infectious virus can be presented in which class
I or II
116
MHC I has what kind of foreign Ag
exogenous
117
in MHC I what kind of proteasome takes in the virus protein
immunoproteasome
118
what is function of proteasome
normally our cells are disposed uneeded or damaged proteins its degraded by proteolysis
119
IFN gamma induces expression of
immunoproteasome
120
what is cap of immunoproteasome
PA28 cap
121
describe immunoproteasome
it is more efficient and works faster than the regular proteasome, activated by IFN gamma
122
TAP stands for
transporter associated with antigen processing
123
TAP 1 and TAP 2 requires
ATP
124
TAP facilitates
peptides that are virus to be taken to immunoproteasome
125
what upregulates expression of TAP
IFN gamma
126
when you look at MHC I it's single chain α and second molecule that for 3 D expression is needed, what is it
ß2m
| beta 2 microglobulin
127
what is essential for expression of MHC I
ß2m
| it won't be expressed without it
128
peptide binding in MHC I
peptide binding in MHCI α1 & 2
129
calnexin does what function
holds MHC I until ß2M arrives
130
what is purpose of life for MHC I
to hold a pathogen epitope for T cell
131
TAP facilitates transport of peptides from cytosol to
ER
132
tapasin facilitates
putting peptides into MHC b/w α1 and α2
133
tapasin, what is analgous protein in MHC II
HLA-DM
b/c peptide loading faciliated by HLA-DM in MHC II
**test question!!**
134
if peptides loaded into MHC I and they are too long
ERAP comes and trims the peptide from amino end
135
MHC I needs what length peptide in it
b/w 8 and 10
136
what does ERAP stand for
ER aminopeptidase
137
what does ERAP do
chop up peptide that is too long on MHC I from amino end
138
presenting self is great unless
you are doing transplant - that would be what is recognized in organ rejection
139
chances are if it is an intracellular antigen it is a
virus
140
certain drugs will neutralize the pH of endosomes, what does this do
block processing and presentation of MHC II
141
non-structural proteins of virus are not recognized by
| are recognized by
not recognized by CD4
| are recognized by CD8
142
cross-presentation
```
great example is hepetitis - b/c it only infects liver
answer to question is that you would take dying liver cell and take entire liver cell adn in the phagolysosome you continue class II pathway but some can escape and enter ER - so it does both class I and class II pathways
```
143
cross presentation is specific to which cells
dendritic cells
144
some viruses learn how our body works and have found ways to
interfere with antigen presentation by MHC class I molecules
145
what are immunoevasins
produced by viruses to interfere with presentation of MHC I to interfere with our immune system
146
some bacteria evade MHC II - how
escape endoosmes
neutralize endoosme acidification
block fusion with lysosome
sequester MHC II after vesicle fusion
147
CD1 think
lipid antigen
148
CD1 is similar to
MHC I
149
instead of presenting protein CD1 function is
to turn on T cell that will see lipid antigen instead of protein epitope
150
NKT cell
natural killer t cell
151
CD1 present to what
NKT & gamma delta T cell
152
normally CD1 binds self
glycolipid in ER
153
ultimately CD1 will express what on surface
lipid
