Antibody Structure (complete) Flashcards
Define H Chain
AKA: Heavy chain
MW: 50,000
5 types: gamma, alpha, mu, epsilon, delta (corresponds with each Ab)
- Each Ab has at least 2 H chains
- Each H chain has 1 variable domain [V(H)]
- Also 3-4 constant domains [C(H1-4)]
Define L Chain
AKA: Light chain
MW: 25,000
- Each Ab has at least 2 L chains
- Each L chain has 1 variable domain [V(L)]
- Also 1 constant domain [C(L)]
Define kappa and lambda chains
2 kinds of L chain
Each cell that makes Ab has a choice between the two, but only uses one kind
Define hinge region
Allows for flexibility
When bound to antigen, constant part of Ab can change conformation
Define Fab, F(ab2), Fc
Fab: S–S bonds between H chains fully reduced
F(ab2): 2 Fabs still joined by S–S bond
Fc: non-antigen binding region of Ab — makes Ab participate in the complement system
Define complementarity-determining regions (hypervariable regions)
3 regions with most of the variability — AA variability
This is the area unique to the Ab! It binds the Ag!
Define variable (V) and constant (C) domains
V: at N-terminal end of Ab, differences in AA sequences between Abs of different specificities
C: region (almost) identical on Abs, made of 1 (L chain) to 4 (epsilon and mu) compact, structurally similar domains called C domains
Define V(L) and C(L)
V: variable domain of L chain
C: constant domain of L chain
Define V(H) and C(H)
V: variable domain of H chain
C: constant domain of H chain
Draw an electrophoretic separation of human serum. Identify the albumin, alpha(1), alpha(2), beta and gamma peaks.
GO DRAW IT ! or at least look it uppppp :D
Serum put into electrophoresis and makes this graph — Ab activity seen in the gamma region
Name the 5 antibody classes
1) IgG
2) IgE
3) IgD
4) IgA
5) IgM
What is in the structure of IgG?
- 2 L chains
- 2 gamma (H) chains
What is in the structure of IgE?
- 2 L chains
- 2 epsilon (H) chains
What is in the structure of IgD?
- 2 L chains
- 2 delta (H) chains
What is in the structure of IgA?
- 4 L chains
- 4 alpha (H) chains
- 1 joining (J) chain
- 1 secretory (S) component
What is in the structure of IgM?
- 10 L chains
- 10 mu (H) chains
- 1 joining (J) chain
Draw a diagram of the structure of IgG. —- Label heavy and light chains, Fc and Fab parts, J chains if any, Ab combining sties, main interchain disulfide bonds, secretory components
GO DRAW IT
Draw a diagram of the structure of IgE. —- Label heavy and light chains, Fc and Fab parts, J chains if any, Ab combining sties, main interchain disulfide bonds, secretory components
GO DRAW IT
Draw a diagram of the structure of IgD. —- Label heavy and light chains, Fc and Fab parts, J chains if any, Ab combining sties, main interchain disulfide bonds, secretory components
GO DRAW IT
Draw a diagram of the structure of IgA. —- Label heavy and light chains, Fc and Fab parts, J chains if any, Ab combining sties, main interchain disulfide bonds, secretory components
GO DRAW IT
Draw a diagram of the structure of IgM. —- Label heavy and light chains, Fc and Fab parts, J chains if any, Ab combining sties, main interchain disulfide bonds, secretory components
GO DRAW IT
Arrange IgG, IgM, and IgA in terms of molecular size..
IgM > IgA > IgG
900K > 400K > 150K
What are the approximate normal concentrations in serum of IgG, IgM, and IgA.
IgG: 1000 mg/dL
IgM: 100mg/dL
IgA: 200mg/dL
dL = 100mL
Describe the structure of Ab combining sites.
Where the Ab binds to the antigen
Made up of V domains of both H and L chains [aka V(H) and V(L)]
Explain why complementarity-determining regions are also called hypervariable regions.
- 3 hypervariable regions on the variable domain of L and H chains
- these have more AA variability
- AAs in hypervariable regions comprise the actual antigen-binding site
Give an example of a subclass
Immunoglobulins are divided into subclasses b/c of slight differences in AA sequence on C(H)
IgG1, IgG2, IgG3, IgG4 …
IgA1, IgA2… etc
Give an example of an allotype
Minor allelic differences in immunoglobulin sequences between individuals
Determined by allotypes of parents
Give an example of an idiotype
Unique combining region
Made up of CDR AAs of its L and H chain that each Ab has
What is an anti-idiotype?
Abs made that recognize the unique sequence of that combining site
