Week 17: (A) Immunoglobulins

Question 1

What are the 2 main components of adaptive immunity?

Answer 1

cellular immunity and antibodies

Question 2

How do antibodies (immunoglobulins) work?

Answer 2

recognise antigens

Question 3

What is an antigen?

Answer 3

any substance that elects an immune response

Question 4

What is the portion that an antibody can recognise?

Answer 4

epitope/ antigenic determinant

Question 5

How many macromolecules make up a micro-organism?

Answer 5

many

Question 6

How many antigenic points are there on each macromolecules of a microorganism?

Answer 6

many different antigenic sites on each macromolecule

Question 7

Where are immunoglobulins present?

Answer 7

plasma, tissues, secretions, lymphatic system

Question 8

What are immunoglobulins the products of?

Answer 8

humoral immune system (a part of the adaptive immune system)

Question 9

What are immunoglobulins secreted by?

Answer 9

activated B cells= plasma cells

Question 10

What are the 5 classes of immunoglobulins?

Answer 10

IgG
IgM
IgA
IgD
IgE

Question 11

What are the 2 functions that all immunoglobulin classes provide?

Answer 11

recognition

effector (get rid of foreign material recognised)

Question 12

What is the N terminal of the light and heavy chains called?

Answer 12

variable region

Question 13

What is the C terminal of the light and heat chains?

Answer 13

constant region

Question 14

What holds the heavy and light chains together?

Answer 14

disulphide bridges

Question 15

What holds the heavy chains together?

Answer 15

interchain disulphide bridges

Question 16

What was the enzyme papain used for?

Answer 16

found to cleave the upper and lower parts of the structure

Question 17

What are the upper parts of an antibody called?

Answer 17

Fab = fragment antigen binding - response for binding antigen

Question 18

What are the lower parts of the antibody called?

Answer 18

fragment crystallisable - responsible for effector function

Question 19

Why is the hinge region called the hinge region?

Answer 19

it affords lot of flexibility within the molecule, Fab move distinctly from the Fc region

Question 20

What are the 2 types of light chains?

Answer 20

lambda and kappa

Question 21

In an individual antibody are both light chains the same type?

Answer 21

YES

Question 22

What does the heavy chain determine?

Answer 22

the class of antibody

Question 23

What do the antibody chains fold up to form?

Answer 23

globular domains

Question 24

How many chains does the light chain fold up to form?

Answer 24

2 globular domains

Question 25

How many domains does the heavy chain fold up to form?

Answer 25

4 or 5 globular domains

Question 26

What is the structure/features of each domain?

Answer 26

2 beta sheets. linked by a disulphide bridge to form a beta barrel

Question 27

What is the folded structure of an antibody known as?

Answer 27

immunoglobulin fold

Question 28

What are the names of the heavy chain globular domains?

Answer 28

VH, CH1, CH2, CH3 (and CH4)

Question 29

What are the names of the light chain globular domains?

Answer 29

VL, CL

Question 30

What are the close pairing of domains?

Answer 30

VH+ VL
CH1+ CL
CH3 +CH3

Question 31

Why do the CH2 domains not pair?

Answer 31

immunoglobulins are glycosylated
The region lying between the 2 CH2 domains in IgG, N-linked oligosaccharides (sugar moiety’s) lie of inner surface of domain and stabilise the pairing

Question 32

Why are they n-linked oligosaccharides?

Answer 32

attached to the Asn residues in the sequence Asn-X-Ser/Thr where X is any amino acid except Pro

Question 33

What is the N-linked consensus attachment sequence for an N-linked oligosaccharide in any protein?

Answer 33

Asn-X-Ser/Thr

Question 34

What position is Asparagine on a IgG?

Answer 34

297 in the heavy chain, where n-linked oligosaccharides are attached.

Question 35

What is the immunoglobulin fold?

Answer 35

aka immunoglobulin domains

2 layer sandwich of 2-7 antiparallel beta strand, layered into 2 beta sheets