Epitopes Flashcards

1
Q

What is the actual binding site of an antigen?

A

Epitopes

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2
Q

Do lymphocytes recognize entire antigens?

A

No, they recognize small, discrete sites

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3
Q

What is an epitope?

A

Small, discrete site on macromolecules

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4
Q

Antigenic determinants

A

Epitopes

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5
Q

How do B-cell epitopes bind AG

A

B-cells bind Ag directly via cell surface immunoglobulin

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6
Q

What can Ag be for B-cells?

A

Almost anything

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7
Q

For Ag in solution for B-cells what three things must the epitopes be?

A
  1. Topographically accessible (outside surface)
  2. Flexible and mobile
  3. Sequential or conformational (nonsequential)
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8
Q

What is a conformational epitope?

A

Nonsequential

Distinct entities that fold together

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9
Q

How is the epitope size defined?

A

Defined by the binding site of the antibody

Lock and key fit

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10
Q

What limits epitope size?

A

Complimentary binding between Ag-Ab

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11
Q

What can hold more aa? Conformational or linear

A

Conformational epitopes cover much greater space on flatter surface binding sites of Ab
Can hold 15-22 aa

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12
Q

Do all epitopes induce a response?

A

No, there is immunodominance

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13
Q

How many aa can typically fit in a linear epitope binding site?

A

6-7 aa or sugars

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14
Q

What are the four shapes of epitopes for B cells?

A
  1. Pocket
  2. Hot dog in bun
  3. Semi-circle
  4. Sphere
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15
Q

If I stretch out a conformational epitope will it work?

A

No, it needs to be in a 3D shape

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16
Q

Linear

A

sequential

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17
Q

Conformational

A

Non-sequential

18
Q

Can we denature and digest a linear epitope?

19
Q

Can we denature and digest a conformational epitope?

20
Q

What do T-cell epitopes see?

A

Only peptides

21
Q

Can a T-cell recognize soluble native Ag

22
Q

Can a T-cell bump into something and recognize it?

A

No, it needs to be instructed

23
Q

How does a T-cell recognize Ag?

A

The Ag has to be processed and whole peptide fragments are presented in association with MHC molecules

24
Q

MHC

A

Major Histocompatibility Complex

25
Oligomer
"few parts"
26
T-cell epitopes are oligomeric peptides of how many aa?
7-20 aa
27
MHC class 1 is how many aa?
9-11 aa
28
What does MHC 1 do?
Shows peptides to killer T-cells
29
How many aa is MHC class 2?
11-17 aa
30
What does MHC 2 do?
Shows peptides to helper T-cells
31
What is required to generate peptides?
Ag processing
32
Ag is seen as part of a trimolecular complex. What are the 3 parts?
TCR (tcell receptor) Ag MHC
33
Peptides must be amphipathic. What two regions do they need?
Hydrophilic - TCR | Hydrophobic - MHC
34
Hydrophobic
MHC
35
Hydrophilic
TCR
36
What does the TCR recognize?
MHC and peptide
37
Agretope
MHC binding site of the Ag
38
How do agretope sites bind?
Via hydrophobic aa
39
Epitope
TCR binding site
40
How do epitope sites bind?
Hydrophilic aa
41
How are immunodominant T-cell epitopes determined?
By what set of MHC molecules are expressed and what TCR are expressed