Organization/ Expression Lymphocyte Receptor Genes

Question 1

What do the letters in V (D) J stand for?
= gene segments

Answer 1

variable/ joining/ diversity

Question 2

Where does V (D) J recombination occur?

Answer 2

primary organs = bone marrow/ thymus

Question 3

Why is D in brackets V (D) J ?

Answer 3

not always present/ needed for recombination
- D only in heavy chain (not light)

Question 4

How does V (D) J recombination occur?

Answer 4

random rearrangements

Question 5

What is the result of V (D) J recombination?

Answer 5

novel amino acid sequences in antigen-binding regions of Igs/ TCRs

Question 6

Why is V (D) J recombination important?

Answer 6

recognition of nearly all pathogens
- including altered self-cells

Question 7

How do B cells create different possible antibodies in developing lymphocytes?

Answer 7

Recombination of gene segments

Question 8

Can a B cell create different possible antibodies in a mature lymphocyte?

Answer 8

no
- only in developing lymphocyte/ not once activated

Question 9

What segments are only used in heavy chains?

Answer 9

D

Question 10

What variable segments are present in light chain?

Answer 10

V/J

Question 11

What variable segments are present in heavy chain?

Answer 11

V/D/J

Question 12

Why are different gene segment combinations important?

Answer 12

recognize different antigens

Question 13

What is the constant region gene segment?

Answer 13

C

Question 14

What is an immunoglobulin protein?

Answer 14

Antibody

Question 15

What are the chains in an Ig protein?

Answer 15

2 identical heavy
2 identical light

Question 16

What are the 2 possibilities for the 2 identical light chains on an Ig protein?

Answer 16

kappa/ lambda

Question 17

Where is each set of gene families (kappa/ lambda/ heavy chain) encoded?

Answer 17

each on separate chromosomes

Question 18

How do you know if you are looking at a heavy/ light chain?

Answer 18

no D= light
D= heavy

Question 19

What do kappa light-chain genes pair?

Answer 19

V / J segments

Question 20

What do lambda light-chain genes pair?

Answer 20

J / C segment

Question 21

What segments does heavy-chain gene organization include?

Answer 21

VH/ DH/ JH/ CH

Question 22

What is required to encode the variable region of the heavy chain of the Ig molecule?

Answer 22

recombination between 3 gene segments
- VH/ D/ JH

Question 23

How is V (D) J recombination directed?

Answer 23

by a signal sequence (RSS)

Question 24

What flanks each antibody gene segment?

Answer 24

RSSs = Recombination Signal Sequences

Question 25

What happens to the spacer when 12 bp RSS and 23 bp RSS pair?

Answer 25

spacer removed

Question 26

What is needed for recombination to occur?

Answer 26

12/23 rule

Question 27

What is the 12/23 rule?

Answer 27

12 bp RSS must pair with a 23 bp RSS

Question 28

What is a one-turn spacer?

Answer 28

12 bp RSS

Question 29

What is a two-turn spacer?

Answer 29

23 bp RSS

Question 30

What is the spacer?

Answer 30

RSS

Question 31

What gene segment is the 12 bp RSS from?

Answer 31

V cluster

Question 32

What gene segment is the 23 bp RSS from?

Answer 32

J cluster

Question 33

What chain is a 2-step process for recombination?

Answer 33

Heavy

Question 34

What enzyme joins gene segments?

Answer 34

RAG 1/2 recombinase

Question 35

What does RAG stand for?

Answer 35

Recombination Activating Gene

Question 36

What enzyme (RAG 1/2 recombinase) is needed for recombination?

Answer 36

both proteins

Question 37

What RAG recombinase protein is more important?

Answer 37

RAG1

Question 38

Why is RAG1 more important?

Answer 38

forms complex with RSS stabilized by binding RAG2

Question 39

What is the role of RAG2?

Answer 39

binding stabilizes the RSS/ RAG1 complex

Question 40

What is responsible for recognizing/ cutting DNA at the immunoglobulin-encoding region/ RSS?

Answer 40

RAG1/2 complex

Question 41

What are the 10 well-defined steps of V(D)J recombination? first 7 = both 8-10 = only heavy chain (D)

Answer 41

1. RAG proteins recognize/ bind to RSS 2. Cleavage of DNA 3. Formation of hairpin at V / J region 4. Ligation/ removal of signal ends 5. Hairpin cleavage 6. Overhang extension 7. Ligation of light-chain V / J segments 8. Exonuclease trimming 9. N-nucleotide addition 10. Ligation/ repair of heavy chain

Question 42

What are the 5 mechanisms to generate antibody diversity in naive B cells?

Answer 42

Multiple gene segments Combinatory diversity (light/ heavy chain) Templated nucleotide addition Exonuclease trimming Non-templated nucleotide addition

Question 43

What ensures each B cell synthesizes only 1 heavy/ 1 light chain?

Answer 43

Allelic exclusion

Question 44

What happens to potentially autoreactive receptors in light-chains?

Answer 44

Receptor editing

Question 45

What is the result of asymmetrical cleaving of hairpin structures?

Answer 45

Templated nucleotide addition (uneven number bp)

Question 46

What involves losing nucleotides/ changing reading frames?

Answer 46

Exonuclease trimming (randomize to fill in)

Question 47

What involves adding random nucleotides between joints?

Answer 47

Non-templated nucleotide addition

Question 48

What is non-templated nucleotide addition mediated by?

Answer 48

TdT activity