L05: Organization and Expression of Ig Genes

Question 1

Which chain does this code for?

Answer 1

lambda light chain

Question 2

Which chain does this code for?

Answer 2

Kappa light chain

Question 3

Which chain does this code for?

Answer 3

Heavy chain

Question 4

How are the light chains rearranged?

Answer 4

• A single V is joined to a single J
• This activates the promoter of at the leader region of the V attached to the J
• transcription goes until it reaches stop codon at the end of the constant domain following the J

Question 5

After gene rearrangement, how are primary transcripts proccessed?

Answer 5

• introns spliced out
• poly-A tail added when leaving ribosome
• leader region joine with RER, poly-A tail removed
• Leader region removed in RER
• Is now a mature ligth chain (peptide)

Question 6

How does message processing for the Kappa LC differ from that of the Lambda LC?

Answer 6

-extra Js are also removed along with introns

Question 7

Which gene(s) has/have more than one constant region?

Answer 7

Lambda and heavy chain genes

Question 8

D regions are only found in the…

Answer 8

Heavy chain gene

Question 9

How is the heavy chain gene rearranged?

Answer 9

• first a D is joined to a J
• Then a V is joined to that D that joined to a J

Question 10

There are transcriptional stop signals at the end of every constant region except for:

Answer 10

the mu (µ)

Question 11

The end of constant regions on the heavy chain gene have:

Answer 11

membrane spanning regions

*Light chains will not have this*

Question 12

The order of gene rearrangement

Answer 12

1. heavy chain
2. light chain

Question 13

only ____ b-cells will splice out the membrane spanning regions of its constant domain

Answer 13

mature, antigen-activated

Question 14

you will almost never see a soluble ____ -class antibody

Answer 14

D-class

Question 15

one-turn sequences have ____ bases

Answer 15

12

Question 16

two-turn sequences have___ turns

Answer 16

23

Question 17

Which parts of the RSS are cut out when the loops are formed?

Answer 17

• one/two turn sequences
• AT rich region
• parts of the heptamer

Question 18

After hair-pin loops are cut in the light chains, ___ occurs

Answer 18

P-nucleotide addition

Question 19

After hair-pin loops are cut in the light chains, ___ occurs

Answer 19

N-nucleotide addition

Question 20

The first two loops of the CDR are determined by the ___

Answer 20

V region

Question 21

somatic hypermutation occurs in the ___

Answer 21

lymph nodes

Question 22

Class switching involves the ____ region of the antibody

Answer 22

the F_c stem region, CDR will remain the same

Question 23

What motivates class switching?

Answer 23

• T_H cells give cytokine signals to the B-cells that say we need a specific (non mu) class of stem