Antibodies

Question 1

Which class antibody is this?

Answer 1

E-class

Question 2

Which class antibody is this?

Answer 2

A-class

Question 3

Which class antibody is this?

Answer 3

G-class

Question 4

Which class antibody is this?

Answer 4

D-class

Question 5

Which class antibody is this?

Answer 5

M-class

Question 6

M-class

Answer 6

Hinge or bend? rigid

Forms complexes? yes

J chain? yes

Subclasses? no

Timing- first class produced in maturing B-cells

Membrane-spanning Ig receptor? yes, naive and memory

Role- general

Question 7

D-class

Answer 7

Hinge or bend? hinge

Forms complexes? no

J chain? no

Subclasses? no

Timing-produced as Ig receptor on mature but naive B-cells

Membrane-spanning Ig receptor? on naive cells, rarely memory or soluble

Role- aids naive B-cell activation

Question 8

G-class

Answer 8

Hinge or bend? hinge

Forms complexes? no

J chain? no

Subclasses? yes, 4

Timing- after class-switching in activated B-cells

Membrane-spanning Ig receptor? memory cells

Role- specific responses to acute infections

Question 9

A-class

Answer 9

Hinge or bend? hinge

Forms complexes? yes

J chain? yes

Subclasses? yes, 2

Timing- after class-switching in activated B-cells

Membrane-spanning Ig receptor? memory cells

Role- crosses epithelia, protects boundaries

Question 10

E-class

Answer 10

Hinge or bend? bend

Forms complexes? no

J chain? no

Subclasses? yes, 1

Timing- after class-switching in activated B-cells

Membrane-spanning Ig receptor? memory cells

Role- T_H2 response: allergies, pollutants, chronic infections

Question 11

How do you make monoclonal antibodies?

Answer 11

Fuse the normal B cell with a myeloma cell to create a hybridoma

Question 12

Plasma (B) cell

Answer 12

• makes desired antibody
• can synthesize nucleotides by de novo pathway
• can synthesize nucleotides by salvage pathway
• divides for only a couple of weeks

Question 13

Myeloma (B cancer) cell

Answer 13

• selected line makes no antibody
• can synthesize nucleotides by de novo pathway
• can NOT synthesize nucleotides by salvage pathway
• divides indefinitely

Question 14

B-cell receptor

Answer 14

1. If the antibody is stuck in the membrane, sticking out, it’s a receptor.
2. B-cells recognize foreign antigen when two neighboring receptors bind to it and cross-link.
3. The signal is transduced by the associated heterodimer of Igα/Igβ, both of which have long cytoplasmic tails.
4. Naïve B cells have M or D class receptors.
5. Memory B cells can have receptors of any class.

Question 15

Antigen binding

Answer 15

1. Antigen bound to the 6 loops at the tips of the Y arms by the same weak interactionsthat produce enzyme-substrate interactions.
2. As with enzyme-substrate interaction, the binding can involve induced fit, distortion inboth structure of anybody and antigen.

Question 16

Travelling Down the Heavy Chain

Answer 16

1. variable region
2. first constant domain
3. Hinge-bend region
4. Next constant domain
5. carboxy-terminal constant domain

Question 17

Basic unit of all antibodies

Answer 17

In all cases, the basic unit has two heavy and two light chains and the light can be either κ or λ.