Antibody Structure (complete)

Question 1

Define H Chain

Answer 1

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)]

Question 2

Define L Chain

Answer 2

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)]

Question 3

Define kappa and lambda chains

Answer 3

2 kinds of L chain

Each cell that makes Ab has a choice between the two, but only uses one kind

Question 4

Define hinge region

Answer 4

Allows for flexibility

When bound to antigen, constant part of Ab can change conformation

Question 5

Define Fab, F(ab2), Fc

Answer 5

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

Question 6

Define complementarity-determining regions (hypervariable regions)

Answer 6

3 regions with most of the variability — AA variability

This is the area unique to the Ab! It binds the Ag!

Question 7

Define variable (V) and constant (C) domains

Answer 7

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

Question 8

Define V(L) and C(L)

Answer 8

V: variable domain of L chain

C: constant domain of L chain

Question 9

Define V(H) and C(H)

Answer 9

V: variable domain of H chain

C: constant domain of H chain

Question 10

Draw an electrophoretic separation of human serum. Identify the albumin, alpha(1), alpha(2), beta and gamma peaks.

Answer 10

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

Question 11

Name the 5 antibody classes

Answer 11

1) IgG
2) IgE
3) IgD
4) IgA
5) IgM

Question 12

What is in the structure of IgG?

Answer 12

• 2 L chains

- 2 gamma (H) chains

Question 13

What is in the structure of IgE?

Answer 13

• 2 L chains

- 2 epsilon (H) chains

Question 14

What is in the structure of IgD?

Answer 14

• 2 L chains

- 2 delta (H) chains

Question 15

What is in the structure of IgA?

Answer 15

• 4 L chains
• 4 alpha (H) chains
• 1 joining (J) chain
• 1 secretory (S) component

Question 16

What is in the structure of IgM?

Answer 16

• 10 L chains
• 10 mu (H) chains
• 1 joining (J) chain

Question 17

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

Answer 17

GO DRAW IT

Question 18

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

Answer 18

GO DRAW IT

Question 19

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

Answer 19

GO DRAW IT

Question 20

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

Answer 20

GO DRAW IT

Question 21

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

Answer 21

GO DRAW IT

Question 22

Arrange IgG, IgM, and IgA in terms of molecular size..

Answer 22

IgM > IgA > IgG

900K > 400K > 150K

Question 23

What are the approximate normal concentrations in serum of IgG, IgM, and IgA.

Answer 23

IgG: 1000 mg/dL
IgM: 100mg/dL
IgA: 200mg/dL

dL = 100mL

Question 24

Describe the structure of Ab combining sites.

Answer 24

Where the Ab binds to the antigen

Made up of V domains of both H and L chains [aka V(H) and V(L)]

Question 25

Explain why complementarity-determining regions are also called hypervariable regions.

Answer 25

• 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

Question 26

Give an example of a subclass

Answer 26

Immunoglobulins are divided into subclasses b/c of slight differences in AA sequence on C(H)

IgG1, IgG2, IgG3, IgG4 …

IgA1, IgA2… etc

Question 27

Give an example of an allotype

Answer 27

Minor allelic differences in immunoglobulin sequences between individuals

Determined by allotypes of parents

Question 28

Give an example of an idiotype

Answer 28

Unique combining region

Made up of CDR AAs of its L and H chain that each Ab has

Question 29

What is an anti-idiotype?

Answer 29

Abs made that recognize the unique sequence of that combining site