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x- Immunology MICR 3230 > Recognition and Response > Flashcards

Recognition and Response Flashcards

1
Q

What bonds occur in receptor-ligand binding?

A

multiple noncovalent bonds

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2
Q

Is a non-covalent bond irreversible?

A

no- bond can be broken

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3
Q

What is the measure of ligand binding strength?

A

Kd = Dissociation constant

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4
Q

What are the 2 requirements for receptor-ligand binding/ cell to become activated?

A

-sufficient binding energy
- for sufficient time

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5
Q

What are the 3 types of receptor-ligand interactions?
(noncovalent)

A

Hydrogen bond
Ionic bond
Van der waals/ Hydrophobic interactions

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6
Q

How strong must each bond be for receptor-ligand binding?

A
  • each individual bond can be weak
  • total binding affinity strong
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7
Q

How can a strong binding affinity be achieved?

A

many weaker bonds occur between receptors/ ligands
= great cumulative bond strength

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8
Q

Is binding affinity the strength of one bond?

A

no- cumulative bond strength

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9
Q

What is a ligand called with only one binding site?
- 1 receptor/ 1 ligand = specific

A

Univalent

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10
Q

What is a ligand called with many binding sites?

A

Multivalent

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11
Q

What increases the avidity of receptor-ligand interactions?

A

Multivalency

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12
Q

What is the strength of an individual bond called?

A

Affinity

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13
Q

What is the combined strength of binding multiple interactions called?

A

Avidity

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14
Q

Does weak affinity mean weak avidity?

A

no- interactions can still have high overall avidity
- individually weak, strong together

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15
Q

What is it called when the receptor-ligand interaction can occur at 2 sites?

A

Bivalent interaction

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16
Q

What is induced by ligand-receptor binding?

A

molecular change in receptor
- receptor alterations

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17
Q

What is the result of receptor alterations?
(after ligand-receptor binding)

A

= intracellular cascades
- enzyme activation
- changes in intracellular locations of molecules

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18
Q

Why is cluster formation favoured?

A

conformational change
- harder to disrupt interaction

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19
Q

What are some receptor alterations induced by ligand-receptor binding?

A
  • conformational
  • dimerization/ clustering
  • membrane location
  • covalent modification
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20
Q

What is another term for clustering?

A

Aggregation

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21
Q

What impact does aggregation due to ligand binding have on Kd?

A

enhances it (stronger)

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22
Q

What do cell-cell interactions rely on to maintain contact over long periods of time?

A

binding affinity

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23
Q

How are Kd and binding affinity related?

A

inversely

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24
Q

What does extended receptor-ligand contact facilitate?

A
  • signal transduction
  • exchange of cytokine signals
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25
Q

What may occur upon extended receptor-ligand binding?

A

cytoskeletal organization

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26
Q

What is the relative Kd of low-affinity ligand binding?

A

low affinity = higher Kd (inverse)

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27
Q

What is the relative Kd of high-affinity ligand binding?

A

high affinity = lower Kd (inverse)

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28
Q

What do immune receptors have?

A

Immunoglobulin domains

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29
Q

What are the 3 types of immune receptors?

A

Transmembrane
Cytosolic
Secreted

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30
Q

What is a secreted immune receptor?

A

Antibody

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31
Q

What kind of immune receptor has an anchoring point for the ligand?

A

Transmembrane

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32
Q

What happens to an immunoglobulin lacking the carboxyl terminus transmembrane segment?

A

secreted (lacks anchor point)

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33
Q

What is a feature of secreted immunoglobulins? (antibodies)

A

Hydrophilic segment
- likes to be soluble

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34
Q

What is the overall strength of the binding recognition between the ligand and the receptor?

A

Binding affinity

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35
Q

Why are antibodies secreted?

A

lack an anchor point within membrane
- lack carboxyl terminus transmembrane segment

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36
Q

Where is the transmembrane domain located?

A

carboxyl terminus

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37
Q

What is associated with the transmembrane domain in a BCR?

A
  • cytosolic segment
  • hydrophobic segment
  • spacer
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38
Q

What happens when a B cell becomes activated?

A

secretes antibodies

39
Q

How does a B cell become activated/ secrete antibodies?

A

goes from membrane-bound/ transmembrane receptor to secreted = antibody

40
Q

What are the antibodies of BCR’s defined by?

A

Specificity

41
Q

What do BCRs contain?

A

antibody of defined specificity

42
Q

What is the specificity of TCRs?

A

peptides derived from APC degraded antigen
- presented on MHC molecules

43
Q

What receptor recognizes degraded antigen from APC on MHC molecules?

A

TCR

44
Q

What are the T-cell co-receptors that define different subsets of T-cell function?

A

CD4/ CD8

45
Q

What defines the different subsets of T cell function?

A

T cell co-receptors = CD4/ CD8

46
Q

What kind of protein is an antibody?

A

quaternary

47
Q

How many chains does an antibody have?

A

= quaternary protein
2 identical heavy chains
2 identical light chains

48
Q

How is antigen specificity created?

A

interaction between light/heavy chains variable regions

49
Q

What chains are the interior V in an antibody?

A

heavy chains

50
Q

What chains are the exterior V in an antibody?

A

light chains

51
Q

Interaction between what is responsible for antigen specificity?

A

variable regions of light/ heavy chains

52
Q

Interaction between what is responsible for antibody effector activity?

A

constant regions of heavy chain

53
Q

How many parts do the heavy chains have?

A

4

54
Q

How many parts do the light chains have?

A

2

55
Q

What are some examples of antibody effector activity?

A

phagocytosis/ complement fixation

56
Q

What part of the antibody allows the receptor to move?

A

Hinge

57
Q

What 3 regions of amino acids are found in variable heavy/ light chains? (VH/VL)

A

Hypervariable

58
Q

What forms the antibody binding site?

A

3 hypervariable regions coming together

59
Q

What are the hypervariable regions of VH/ VL called?

A

Complementarity-determining regions

60
Q

What are the 3 complementarity-determining (hypervariable) regions?

A

CDR1/ CDR2/ CDR3
- each in VH/ VL

61
Q

Why is high variability important?

A

recognize many ligands/ antigens

62
Q

What is interspersed near each CDR?
What does it do?

A

invariant amino acid
- forms framework region

63
Q

What is the framework region responsible for?

A

folding of CDRs to form antibody-combining site

64
Q

What determines the antibody isotype?

A

constant region

65
Q

What are the distinct classes of antibodies called?

A

Isotypes

66
Q

What are the 5 heavy chain isotypes of antibodies?

A

IgA/ IgD/ IgE/ IgG/ IgM
- alpha/ delta/ epsilon/ gamma/ mu

67
Q

What are the 2 light chain isotypes of antibodies?

A

kappa
lambda

68
Q

What identifies the 5 distinct classes of antibodies?

A

antiserum to constant region of heavy chain

69
Q

What antibody is a pentamer?

A

IgM

70
Q

What antibody has disulphide bonds to connect the 5 antibodies?

A

IgM

71
Q

What antibody is a dimer?

A

IgA

72
Q

How is the IgA dimer connected?

A

J chain

73
Q

What antibodies look similar but different hinge regions?

A

IgG/ IgD

74
Q

How can you differentiate IgG/ IgD hinge regions?

A

IgG- 2 bonds
IgD- 1 bond

75
Q

What does it mean if you see a transmembrane domain?

A

not secreted

76
Q

What do antibody molecules form a BCR complex with?

A

molecules involved in signal transduction

77
Q

What molecules transduce signals via immunoreceptor tyrosine-based motifs? = ITAMs

A

Iga/ IgB (alpha/ beta)

78
Q

What are ITAMs?

A

immunoreceptor tyrosine-based activation motifs

79
Q

What molecules transmit/ relay signals to cell interior?

A

CD19/ CD81/ CD21

80
Q

What is any event that instructs a cell to change its metabolic/ proliferative state?

A

Cellular signal

81
Q

How are signals usually generated?

A

binding of ligand to complimentary cell-bound receptor

82
Q

What does increasing/ decreasing expression of a receptor for a ligand do?

A

cell becomes more/ less susceptible to actions of ligand

83
Q

How can a cell become more/ less susceptible to the actions of a ligand?

A

increasing/ decreasing receptor expression for ligand

84
Q

What often induces a change in transcriptional program of target cell?

A

cell signaling

85
Q

Where does integration of all signals received by a cell occur?

A

molecular level inside cell

86
Q

What initiates signalling in B/ T cells?

A

antigen-mediated receptor clustering

87
Q

What is often a result of receptor clustering?

A

dimerization/ multimerization

88
Q

Where are clustered receptors localized?

A

in lipid rafts

89
Q

What allows movement of clustered receptors/ strengthened bond/ stronger interaction?

A

localization in lipid rafts

90
Q

What part of the antibody binds the ligand?

A

variable chain

91
Q

What immunoglobulin has a similar hinge region to IgA (dimer version)?

A

IgD

92
Q

What is CR2 also known as?

A

CD21

93
Q

What are the 5 major steps cell signalling?

A
  1. ligand binds receptor
  2. adaptor recruitment
  3. phosphorylation
  4. activation
  5. transcription

x- Immunology MICR 3230 (11 decks)

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