Lecture 18 Flashcards
1
Q
Ig Superfamily Members
A
- Antibodies
- B-Cell Receptors
- T-Cell Receptors
2
Q
Antibodies
A
Soluble B-Cell Receptors
3
Q
B-Cell Receptors
A
Membrane-Anchored Antibodies
4
Q
T-Cell Receptors
A
Membrane-Anchored MHC-ligand Receptor
5
Q
b-Pleated Sheet
A
- Laterally packed
- Anti-parallel or parallel
- Peptide-backbone
- R groups above/ below
6
Q
Immunoglobulin Domains
A
- Hydrogen bonding along peptide backbones
- A.A. in b-strands alternate hydrophobic or hydrophilic
3.
7
Q
Hydrophobic
A
Residues ‘sandwiched’ between folds
8
Q
Disulfide Bonding
A
Between b-stands on opposite folds
9
Q
Antibody Molecules
A
- Two IDENTICAL Heavy Chains
- 4/5 Ig Domains per Heavy Ch.
- Two IDENTICAL Light Chains
- 2 Ig Domains per Light Ch.
10
Q
Structure of Antibody Molecules 1
A
- Disulfide bonds covalently link the LIGHT and HEAVY chains
- Forms HETERODIMERS
11
Q
Structure of Antibody Molecules 2
A
- Disulfide bonds covalently link the two HEAVY chains
- Forms HETEROTETRAMERS
12
Q
Hinge Region
A
- Center of the HEAVY chains
- provide ‘molecular flexibility’
- multivalent antigens
- IgA, IgD, and IgG
13
Q
Glycosylation
A
Spreads antibodies for better receptor access
– tails of antibodies
14
Q
Glycosylation 2
A
- CH2 domains of IgA, IgD, and IgG
- CH3 domains of IgE and IgM
- CH-CH spacing
15
Q
Variable Region
A
Present in the NH2-terminal Ig domain of LIGHT AND HEAVY chain
16
Q
Variable Regions
A
- Linking segments between b-strands are markedly more variable
- Linking segments: more accommodations
17
Q
Linking Segments
A
Site responsible for specifying antigen binding
18
Q
CDR
A
Complimentary-determining region
19
Q
IgM
A
- Primary immunoglobulin
– “on go” - NO hinge region
- Generally found in serum
- Pentamer has 10 potential antigen binding sites
20
Q
IgD
A
- Expressed on a subset of naïve B-Cells
- Alternative mRNA splicing
- Hinge Region
21
Q
IgG
A
- Class switching
- Hinge region
- Most abundant immunoglobulin
- Crosses placenta
- “Work Horse”
22
Q
IgG: Four isotopes
A
- IgG1
- IgG2
- IgG3
- IgG4
23
Q
IgA
A
- Class Switching
- Hinge Region
- Mucosal antibody
24
Q
IgA: Two isotopes
A
- IgA1
- IgA2
25
IgE
1. Class switch
2. NO hinge region
3. Least abundant immunoglobulin
4. Allergic reactions
26
B- Cell Receptors
1. Membrane-bound Ab isoform
2. 'Activates' B-Cells after antigen binding
27
B-Cell Signal Transduction
Iga and Igb
28
B-Cell Antigen Binding
CR2 (CD21) and CD19
29
B-Cell Receptor Complex
1. Transduces antigen binding into intracellular signals
2. B-Cell Proliferation
3. B-Cell Differentiation
30
B-Cell Receptor: What does it make
Germinal Center OR Antibodies
31
T-Cell Receptor-Signaling Complex
1. Immunoglobulin Superfamily
2. One constant Ig region
3. One variable Ig region
4. Single transmembrane spanning domain
5. Truncated cytoplasmic domain
32
gd-TCR
1. Often concentrated in mucosa
2. Break the binding rules
3. Can include lipid/glycolipid antigens
33
V Domains
Three HyperVar regions
CDR
34
C Domains
Single b sheet
Disulfide link
35
TCR-CD3 Complex
1. zz (zeta-zeta)
2. ge (gamma-epsilon)
3. ed (epsilon-delta)
36
TCR-CD3 Complex
Promotes complex clustering within the plane of the membrane
37
CD4
1. Binds antigen-bound MHC II
2. Phosphorylated tail
3. Expressed in TH cells
38
CD8
1. a-b heterodimer or a-a heterodimer
2. Binds antigen-bound MHC I
3. Expressed in TC cells
39
T-Cell Receptor Complex
1. T-Cell Receptor
2. Signal Transduction: CD3 Complex
40
T-Cell Receptors: MHC recognition
1. CD4 - MHC II
2. CD8- MHC I
41
CD28
Co-receptor
- required for full activation
42
T-Cell Activation Results
1. Transduction of binding into the cell
2. Initiation of signaling pathways
3. Immediate responses
4. Long-term responses
