chapter 3 Flashcards
(95 cards)
1
Q
any event that instructs a cell to change its metabolic or proliferative state
A
cellular signal
2
Q
How are cell signals usually generated?
A
binding of a ligand to a complementary cell-bound receptor
3
Q
How can a cell become more or less susceptible to actions of a ligand?
A
by increasing or decreasing expression of the receptor for that ligand
4
Q
What type of bonding occurs between receptor-ligand and why?
A
multiple non-covalent bonds bc covalent are too strong
5
Q
Describe the strength of the bond between ligand-receptor?
A
each individual bond is weak but deliver a total strong binding affinity
6
Q
a measure of strength of ligand binding
A
dissociation constant (kd)
7
Q
Receptor-ligand interactions may be _______valent
A
multivalent
8
Q
Multivalency increases ____________of the interactions
A
avidity
9
Q
the strength of an individual bond
A
affinity
10
Q
What is avidity?
A
the combined strength of binding of multiple interactions
11
Q
An interaction may have _______affinity but ___________ overall avidity
A
weak, high
12
Q
Ligand-receptor binding induces molecular change in the receptor:
A
- Conformational
- Dimerization/clustering
- Location in the membrane
- Covalent modification
13
Q
Receptor alterations induce cascades of intracellular events:
A
- Activation of enzymes
- Changes in intracellular locations of
molecules
14
Q
Immune Receptors bear immunoglobulin:
A
domains
15
Q
Immune receptors can be:
A
transmembrane, cytosolic, or
secreted
16
Q
What is a fancy word for antibody?
A
immunoglobulin
17
Q
What is the state of the immunoglobulin that is secreted?
A
it is lacking the carboxyl terminus transmembrane segment
18
Q
contains an antibody of defined specificity
A
B-cell receptor (BCR)
19
Q
specificity is for peptides derived from APC degraded antigen presented on MHC molecules
A
T-cell receptor (TCR)
20
Q
T-cell coreceptors that define different subsets of T-cell function
A
CD4 & CD8
21
Q
A quaternary protein with two identical heavy chains and
two identical light chains
A
antibody
22
Q
Why is it called heavy/light chain?
A
the molecular weight is higher in the heavy chain
23
Q
Antigen specificity is by the interaction between:
A
light/heavy chain variable regions
24
Q
What are some functions of the interaction of the constant regions of the heavy chain?
A
antibody effector activity, phagocytosis, and complement fixation
25
what type of bonds holds the antibody together?
intra/interchain disulfide covalent bonds
26
The segment of an immunoglobulin heavy chain between the Fc and Fab regions. It gives flexibility to the molecule and allows the two antigen-binding sites to function independently.
hinge region
27
What does Fab stand for?
fragment antigen binding
28
What does Fc stand for?
Fragment crystallizable
29
What is found at the antibody combing site?
Three hypervariable regions of amino acids found in variable heavy (VH) and variable light (VL) regions
30
What is CDR1, CDR2, and CDR3?
complementarity-determining regions/antibody combining site
31
Interspersed near each CDR is an ___________________ that forms the framework region and is responsible for the folding of the CDRs to form the antibody combining site
invariant amino acid
32
What does the constant region consist of?
distinct classes of antibody called isotopes
33
What are the isotypes of the constant region of the heavy chain?
IgA, IgD, IgE, IgG, IgM
34
What are the isotopes of the constant region of the light chain?
Kappa and Lambda
35
transduce signals via ITAMs
Igα & Igβ
36
transmit and relay signals to cell interior
CD19, CD81, CD21
37
What complex does IgA consist of?
dimer
38
What complex does IgM consist of?
pentamer
39
What does ITAM stand for?
immunoreceptor tyrosine-based activation motif
40
Antibody molecules form a B-cell
receptor (BCR) complex with
molecules involved in:
signal transduction
41
Two TCR types _________________have diverse antigen binding characteristics
αβ (majority) and γδ
42
TCR recognizes and binds both ______________________ to which peptide is bound
antigen-derived peptide and MHC
43
Peptide sources can be from:
endogenously or exogenously processed antigens
44
The T-cell receptor (TCR) complexes
with coreceptor involved in:
antigen recognition
45
contains ITAMs that
transmit signal to cell
CD3 complex
46
function in increasing avidity of peptide binding by TCR
CD4, CD8
47
engages CD80 or CD86 on APC to fully activate a naive T cell
CD28
48
secreted, low-molecular-weight proteins that regulate the intensity and duration of the immune response by exerting a
variety of effects on lymphocytes and other immune cells that
express the appropriate receptor.
cytokine
49
cytokines are also referred to as_____________
interleukins
50
a group of low-molecular-weight cytokine that affect
chemotaxis of leukocytes
chemokine
51
describe properties of most cytokines
-soluble proteins
-released by one cell
-bind to receptors on another cell
-induce biological effects
52
TNF are what type of cytokine
membrane-bound
53
how are cytokine signals usually generated?
binding of ligand to its receptor
54
What type of binding is cytokine-receptor binding?
noncovalent
55
Cytokine-signaling end results often induce a change in the _________________________ of the target cell
transcriptional program
56
any event that instructs a cell to change its metabolic or proliferative state
cytokine signal
57
cytokine endocrine action:
released into the bloodstream to effect distant cells
58
cytokine paracrine action:
released to effect nearby cells
59
cytokine autocrine function:
released, but then bind to receptors on the cell that produced them
60
induces different biological effect dependent
on target cell
Pleiotropic activity
61
mediates similar effects on target cell
Redundant activity
62
combines two cytokine activities to be greater
than additive effect
Synergy effect
63
inhibits one cytokine’s effect by another’s
action
Antagonistic effect
64
effect of one cytokine on one target cell to produce
additional cytokine(s)
Cascade
65
-the first noninterferon cytokine to be identified
-Members of this family include important inflammatory mediators
Interleukin-1 family
66
Members of this large family of small cytokine molecules exhibit striking sequence and functional diversity.
Class 1 (hematopoietin) cytokine family
67
While the IFNs have important roles in antiviral responses, all are important modulators of immune responses.
Class 2 (interferon) cytokine family
68
Members of this family may be either soluble or
membrane-bound; they are involved in immune
system development, effector functions, and
homeostasis.
Tumor necrosis factor family
69
This is the most recently discovered family; members function to promote neutrophil accumulation and activation, and are
proinflammatory.
Interleukin-17 family
70
All serve chemoattractant function.
Chemokines
71
-promote inflammation
-stimulated by viral, parasitic, or bacterial antigens
-Secreted very early in immune responses by macrophages and dendritic cells
-Acts locally on capillary permeability and to pull leukocytes to infected tissues
-Acts systemically to signal the liver to produce acute phase proteins
IL-1 family
72
describe class I cytokines:
-diverse in action and cell target
-single protein family
-made up of multiple subunits
73
-IFN-α and IFN-β are 18–20 kDa dimers with antiviral effects
-Secreted by activated macrophages and dendritic cells
-Induce synthesis of ribonucleases and inhibit protein synthesis
Type I interferons
74
-Dimer produced by activated T/NK cells
-Potent modulator of adaptive immunity
Type II interferon (IFN-γ)
75
-Secreted by plasmacytoid dendritic cells
-Upregulate genes controlling viral replication and host cell
proliferation
Type III interferon family (IFN-λ)
76
regulates development, effector function, and homeostasis of cells of the skeletal, neuronal, and immune system
Tumor Necrosis Factor (TNF)
77
N-terminal vs C-terminal regions of TNF cytokines:
-Short intracytoplasmic N
-Longer extracellular C
78
Generally Type 2 transmembrane proteins form as _______________when binding to TNF receptor-1
trimers
79
proinflammatory and produced by activated
macrophages and other cell types
TNF-α
80
produced by activated lymphocytes, delivering signals to leukocytes and endothelial cells
TNF-β (lymphotoxin-α)
81
-proinflammatory molecules expressed on a variety of cells
- Receptors found on neutrophils, keratinocytes, and other
nonlymphoid cells
-Tend to work at the interface of innate and adaptive immunity
IL-17 family cytokines
82
what is the function of chemokines?
they direct leukocyte migration
83
describe the structure of chemokines:
-Small (7.5–12.5 kDa) proteins
-Possess highly conserved disulfide bonds that dictate both structure and category (six categories)
-Share two, four, or six conserved cysteine residues
84
Chemokine receptors are an example of _______________
receptors
G-protein-coupled
85
Chemokine receptors transduce signals via interactions with a polymeric________________
GTP/GDP-binding G protein
86
T/F: Many receptors can bind to more than one chemokine; and several chemokines are able to bind to more than one receptor
true
87
how do chemokines direct leukocyte migration?
Signaling through chemokine receptors helps cells move to different body areas
88
Integration of all signals received by a cell occurs______________________
at the molecular level inside the recipient cell
89
Antigen-mediated _______________initiates signaling in B
and T cells
receptor clustering
90
Clustered receptors are localized in________________
lipid rafts
91
an early step in many signaling pathways
Tyrosine phosphorylation
92
CD3 (T cells) and Igα/β (B cells) are phosphorylated on____________
ITAMs
93
Phosphorylated tyrosines serve as docking points for _____________molecules
adapter
94
Which kinases phosphorylate tyrosines?
Src-family
95
Antigen signaling includes:
1. Bringing dendritic cells into the required locations
2. Macrophages and neutrophils upregulate phagolysosome
activity and cytokine production
3. Dendritic cells exhibit antigen peptides on MHC class I and
MHC class II
4. Cytoplasmic proteasomes process antigen to peptides
5. Dendritic cells induced to secrete cytokine
