immunoglobins

Question 1

What are charaterisitcs of Immunoglobins?

Answer 1

stable durable structure

high affinity and specificity for non self molecules

cross linking ability (agglutination)

can signal NSM presence to the immune system/complement

Question 2

What joins the heavy and light chains?

Answer 2

Disuphide bridges

Question 3

What are the different classes of heavy chains?

Answer 3

alpha, delta, epsilon, gamma, mew

Question 4

What types do light chains come in?

Answer 4

kappa and lambda

Question 5

What is charasterisitc of IgA

Answer 5

in secreteoru fluids. breast milk for example to offer new borns defence against gastrointestial infection

binds to pathogens and blcoks their attachment to epithelial surfaces

ususally as a dimer with a J chain

they are coating antibodies

move across the epitheial lininging for secretion outside the body via transcytosis

Question 6

What is IgD

Answer 6

absent in many mamals and it func in the serum is not clear.

acts as a cell surface receptor on B lympocytes

Question 7

What is IgE

Answer 7

found in minute quanitites in the serum and is involved in the response to parasites and allergic responses (binds mast cells)

has 5Ig domains

Question 8

What is IgG

Answer 8

has teh gamma goblulin
is the major class of Ig in the serum of 75%
also found in the intestinal fluid
can cross the placenta via receptor mediated endocytosis
is found at 6-18mg/ml
has subtypes G1-G4 but all have the same function

Question 9

what is IgM

Answer 9

Is the first antibody produced when an infection is detected
found in the serum and is a pentamer

5Ig joined by disulphide bridges and a J chain.

Question 10

What is Papain digestion

Answer 10

used to get fragments of antibodies.
produces 3 fragements.
2x Fab and 1x Fc

Question 11

What is pepsin digestion?

Answer 11

makes 1x (Fab)2 and then many small fragments of the Fc

Question 12

What did the digestions of the Antibody teach us?

Answer 12

1. Fab can bind to the antigen
2. (Fab)2 can bind antigen and cross link non self molecules
3. Fc fragments cannot bind to antigen but can bind and activate immune cells and complement (class dependent)

Question 13

What does the flexible hinge allow?

Answer 13

improved cross linking

Question 14

What is opsinisation?

Answer 14

labelling for phagocytosis

Question 15

What is the genentic basis for Hypervariability loops?

Answer 15

not enough genes in the genome for one gene per antibody.

Question 16

How does gene recombination occur on the kappa light chain

Answer 16

3 sub genes. V J and C
chr 2
40V, 5J, 1C

any of the copies of the subgenes can be joined together to create the final version

Question 17

how does gene recombinaton occur on the Lambda Light chain?

Answer 17

3 sub genes V J and C
chr 22
30V, 4J, 4C

Question 18

how does gene recombination on the heavy chain?

Answer 18

4 genes V, D, J, and C
chr 14
51V, 27D, 6J

additional nucleotides are added between V and D

Question 19

Why are antibodies useful in labs?

Answer 19

1) resistant to denaturing as they are stable molecules
2) highly specific to what they bind to ( dont bind to self molecules)
3) very strong binding
4) easily generated and collected in polyclonal form.
5) they are easily purified
6) they are easily labelled. can add things to the Fc region

Question 20

How are antibodies collected and purified?

Answer 20

1) coat chromatogrpahy bead with antigen
2) make an affinity collumn by putting in many beads
3) add serum sample to the top of it and run though the collumn.
4) antibodies bind to the antigen and stay in the column
5) pass strong acid down column to denature the antibdoies and antibdoies will fall off.
6) collect fallen off antibodies and when pH returned they will refold

Question 21

How are antibodies crystalised?

Answer 21

add KcsA tetramer.

Question 22

What is useful about shark and camelid antibodies in labs?

Answer 22

they are heavy chain only.
dimer
only one variable domain

they can enter living cells and bind to cytoplasmic proteins

more stable (can be boiled)

however still very expensive to produce

Question 23

How many Ig domains do the heavy and light chains have in immunoglobins

Answer 23

Heavy chain has 4 ig domains around 450aa

light have 2 Ig domains around 220aa.

Question 24

What is the structure of an Ig domain?

Answer 24

consists of a small beta barrel of 7-8 antiparallel beta strands with a disulphide bridge connecting a 4 sheet to a 3 sheet.

Question 25

What are the different classes of Ig domains?

Answer 25

IgA, IgD, IgE, IgG, IgM

Question 26

which Ig is found in sweat tears and breast milk?

Answer 26

IgA

Question 27

By which process can IgA move to areas its needed?

Answer 27

Transcystosis. moves the IgA acorss the epithelial lining for secretions outside the body.

Question 28

what Ig acts as a cell surface receptor for B lymphocytes?

Answer 28

IgD

Question 29

has 5 Ig domains and is involved in response to allergic reactions by binding to mast cells. Which Ig is this?

Answer 29

IgE

Question 30

When someone is infected what is the first Ig produced to fight the infection?

Answer 30

IgM

Question 31

what are features of the Fc region of an immunoglobin?

Answer 31

The Fc region is for receptor binding, complement activation and to act as a placental receptor.

Question 32

The part of an Ig which makes contact with an antigen is known as what?

Answer 32

the Epitope.

Question 33

The aa that make up the epitopes are not near to each-other in aa sequence tells us what about the structure?

Answer 33

brings up the concept that proteins are folded. an epitope may not exist until it is folded into its 3D form.

Question 34

Where are the hypervariability loops found in Ig domains.

Answer 34

DEBAGFC

found between D and E(HV2), B and C(HV1) and G and F(HV3)

died extravagantly because cars go fast.

Question 35

What is the genetic basis for the variability in antibodies?

Answer 35

not enough genes in genome for one gene per antibody.
combining of genes during maturation of B cells.
mutation of genes during activation of B cells.

Question 36

What type of B cells express IgM and IgD?

Answer 36

naive B cells

Question 37

Activated B cells express what antibodies?

Answer 37

igG, IgE or IgA

Question 38

What genes switch the function of the antibodies (class switching)

Answer 38

the C gene. antigen recognition remains the same.

Question 39

Why are immunoglobins very useful in labs?

Answer 39

1) highly resistant to denaturing. stable molecules
2) they are highly specific in what they bind to.
3) Very strong binding
4) easily generated and collected in polyclonal form.
5) they are easily purified.
6) easily labelled. can add things to the Fc region.

Question 40

Describe the process in collecting and purifying antibodies.

Answer 40

1) coat a chromatography bead and coat it with an antigen.
2) make an affinity column by stacking many beads.
3) add serum sample to top that will run through the beads.
4) antibodies will bind to the antigen and stay behind in the column.
5) pass strong acid solution down column causing the antibodies to denature and fall off.
6) collect these and they will refold when their pH is returned to normal.

Question 41

What are some of the drawbacks of conventional antibodies for immunofloresence?

Answer 41

1) hard/expensive to produce in large quantities as monoclonals
2) they are large and cannot enter cells
3) can only inestigate the interior of isolated, fixed cells/tissue slices.
4) cannot be made in bacteria.
5) may not have an antibody for the thing ur intrested in.

Question 42

What is specific to camelid and shark antibodies?

Answer 42

Heavy chain only.
dimer
1 variable domain.

Question 43

what can camelid and shark antibodies be used for that conventional antibodies cannot

Answer 43

can be expressed in E.coli.
they are much smaller and thus can enter living cells and bind to cytoplasmic proteins.
they are so stable they can actually be boiled.