Immunology Lecture 5. Flashcards Preview

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Flashcards in Immunology Lecture 5. Deck (15):
1

What is included in the light chain locus? Heavy chain locus?

Light chain: V, J, (kappa or gamma) Heavy chain: V, D, J

2

How are V, D, & J brought together?

unique enzymes induced by recombinase genes: RAG1 and RAG2 - pull ends of DNA together, while another enzyme ligates, followed by TdT addition of n-nucleotides

3

What is formed by the RAG complex?

A DNA hairpin and then opens hairpin to generate palindromic P-nuclotides

4

How are the V, D, and J joined after ligation by RAG?

TdT - an enzyme that adds random nucleotides with no template until there is overlap and then an edit-repair enzyme comes and fixes it up - an exonuclease removes unpaired nucleotides

5

Where are N-regions (N-nucleotides) found?

only heavy chains - NOT light chains

6

What is the importance of N and P nucleotides?

add a bit of randomness to the splice site -> junctional diversity

7

When is H-chain gene rearrangement checked?

after V-DJ rearrangement (no checking after D-J rearrangement) 2 chances

8

When is L-chain gene rearrangement checked?

after H-chain works - start with K twice and then try L twice

9

How does switching from IgM to IgD happen?

selective splicing of PRIMARY RNA TRANSCRIPT - no class switching involving gene rearrangements

10

How does switching between transmembrane and secreted immunoglobulin happen?

selective splicing of primary RNA transcript

11

How does class switching occur?

a variable region is joined to a new constant region *except to IgD*

12

What is the function of AID? (activation induced deaminase)

class switching (by splicing) and somatic hypermutation (which ends up improving binding to antigen) - single base changes in hypervariable region (CDRs)

13

When does AID function?

during immune response with T cell help

14

What is the one mechanism that works for generating B-cell diversity but not T-cell diversity?

somatic hypermutation

15

Can the IgM to IgG class switching be reversed?

NO - those genes are spliced out