Generation of Adaptive Immune Response 10/21

RAG (Recombination Activation Genes)

Transposase

RSS

Recombination Signal Sequence

What do transposases do?

Cleave the host DNA to insert the episome.

Does every segment have a RSS around it?

Yes

What is the order of recombination of D, V, and J?

DJ, Then VDJ

In a light chain, V joins to J.

True

Does recombination occur in the CH2 and CH3 part of the heavy chain?

No

What cells are RAG genes expressed in?

Developing B and T lymphocytes

If you didn’t have RAG, would you still have mature B or T lymphocytes?

No tf you would not

What does TdT do?

Add/subtract additional bases to generate imprecise ends on the DNA hairpin

What is the 12/23 rule?

Only RSS with 12bp spacers can join RSS with 23bp spacers. It is why D-J joins and not V-H in heavy chain genes

Is RAG needed during antibody Ig isotype switching? (like IgA to IgG)

No. Because recombination occurs in introns

What initiates the switch to another antibody type?

External signals on the B-cell in the periphery and not the bone marrow

What antibody is always produced first, because no switch is required?

IgM

Does switching the isotype of the antibody result in losing some of the C-region (constant region) genes?

yesss

What does isotype switching allow the antibody to do?

Allow the same variable region to act as different antibody forms

Which classes of immunoglobulin activate the complement system?

IgG and IgM

Which class of immunoglobulin has a high affinity binding for mast cells and basophils?

IgE

What determines the shift between producing antibodies that are secreted into the environment vs those that are on the cell surface?

Alternative RNA processing. You’d get a different C-terminus that would allow the change

Do B or T cells have more ways to generate diversity?

B cells

Just helpful images

Switching of constant region occurs after B-cell has 2 things

Antigen bound and signals from T-cells or cytokines