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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
What may occur upon extended receptor-ligand binding?
cytoskeletal organization
26
What is the relative Kd of low-affinity ligand binding?
low affinity = higher Kd (inverse)
27
What is the relative Kd of high-affinity ligand binding?
high affinity = lower Kd (inverse)
28
What do immune receptors have?
Immunoglobulin domains
29
What are the 3 types of immune receptors?
Transmembrane Cytosolic Secreted
30
What is a secreted immune receptor?
Antibody
31
What kind of immune receptor has an anchoring point for the ligand?
Transmembrane
32
What happens to an immunoglobulin lacking the carboxyl terminus transmembrane segment?
secreted (lacks anchor point)
33
What is a feature of secreted immunoglobulins? (antibodies)
Hydrophilic segment - likes to be soluble
34
What is the overall strength of the binding recognition between the ligand and the receptor?
Binding affinity
35
Why are antibodies secreted?
lack an anchor point within membrane - lack carboxyl terminus transmembrane segment
36
Where is the transmembrane domain located?
carboxyl terminus
37
What is associated with the transmembrane domain in a BCR?
- cytosolic segment - hydrophobic segment - spacer
38
What happens when a B cell becomes activated?
secretes antibodies
39
How does a B cell become activated/ secrete antibodies?
goes from membrane-bound/ transmembrane receptor to secreted = antibody
40
What are the antibodies of BCR's defined by?
Specificity
41
What do BCRs contain?
antibody of defined specificity
42
What is the specificity of TCRs?
peptides derived from APC degraded antigen - presented on MHC molecules
43
What receptor recognizes degraded antigen from APC on MHC molecules?
TCR
44
What are the T-cell co-receptors that define different subsets of T-cell function?
CD4/ CD8
45
What defines the different subsets of T cell function?
T cell co-receptors = CD4/ CD8
46
What kind of protein is an antibody?
quaternary
47
How many chains does an antibody have?
= quaternary protein 2 identical heavy chains 2 identical light chains
48
How is antigen specificity created?
interaction between light/heavy chains variable regions
49
What chains are the interior V in an antibody?
heavy chains
50
What chains are the exterior V in an antibody?
light chains
51
Interaction between what is responsible for antigen specificity?
variable regions of light/ heavy chains
52
Interaction between what is responsible for antibody effector activity?
constant regions of heavy chain
53
How many parts do the heavy chains have?
4
54
How many parts do the light chains have?
2
55
What are some examples of antibody effector activity?
phagocytosis/ complement fixation
56
What part of the antibody allows the receptor to move?
Hinge
57
What 3 regions of amino acids are found in variable heavy/ light chains? (VH/VL)
Hypervariable
58
What forms the antibody binding site?
3 hypervariable regions coming together
59
What are the hypervariable regions of VH/ VL called?
Complementarity-determining regions
60
What are the 3 complementarity-determining (hypervariable) regions?
CDR1/ CDR2/ CDR3 - each in VH/ VL
61
Why is high variability important?
recognize many ligands/ antigens
62
What is interspersed near each CDR? What does it do?
invariant amino acid - forms framework region
63
What is the framework region responsible for?
folding of CDRs to form antibody-combining site
64
What determines the antibody isotype?
constant region
65
What are the distinct classes of antibodies called?
Isotypes
66
What are the 5 heavy chain isotypes of antibodies?
IgA/ IgD/ IgE/ IgG/ IgM - alpha/ delta/ epsilon/ gamma/ mu
67
What are the 2 light chain isotypes of antibodies?
kappa lambda
68
What identifies the 5 distinct classes of antibodies?
antiserum to constant region of heavy chain
69
What antibody is a pentamer?
IgM
70
What antibody has disulphide bonds to connect the 5 antibodies?
IgM
71
What antibody is a dimer?
IgA
72
How is the IgA dimer connected?
J chain
73
What antibodies look similar but different hinge regions?
IgG/ IgD
74
How can you differentiate IgG/ IgD hinge regions?
IgG- 2 bonds IgD- 1 bond
75
What does it mean if you see a transmembrane domain?
not secreted
76
What do antibody molecules form a BCR complex with?
molecules involved in signal transduction
77
What molecules transduce signals via immunoreceptor tyrosine-based motifs? = ITAMs
Iga/ IgB (alpha/ beta)
78
What are ITAMs?
immunoreceptor tyrosine-based activation motifs
79
What molecules transmit/ relay signals to cell interior?
CD19/ CD81/ CD21
80
What is any event that instructs a cell to change its metabolic/ proliferative state?
Cellular signal
81
How are signals usually generated?
binding of ligand to complimentary cell-bound receptor
82
What does increasing/ decreasing expression of a receptor for a ligand do?
cell becomes more/ less susceptible to actions of ligand
83
How can a cell become more/ less susceptible to the actions of a ligand?
increasing/ decreasing receptor expression for ligand
84
What often induces a change in transcriptional program of target cell?
cell signaling
85
Where does integration of all signals received by a cell occur?
molecular level inside cell
86
What initiates signalling in B/ T cells?
antigen-mediated receptor clustering
87
What is often a result of receptor clustering?
dimerization/ multimerization
88
Where are clustered receptors localized?
in lipid rafts
89
What allows movement of clustered receptors/ strengthened bond/ stronger interaction?
localization in lipid rafts
90
What part of the antibody binds the ligand?
variable chain
91
What immunoglobulin has a similar hinge region to IgA (dimer version)?
IgD
92
What is CR2 also known as?
CD21
93
What are the 5 major steps cell signalling?
1. ligand binds receptor 2. adaptor recruitment 3. phosphorylation 4. activation 5. transcription

x- Immunology MICR 3230 (11 decks)

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