Immunology Lecture 5. Flashcards Preview

immunology > Immunology Lecture 5. > Flashcards

Flashcards in Immunology Lecture 5. Deck (15):

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

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


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


What is formed by the RAG complex?

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


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


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

only heavy chains - NOT light chains


What is the importance of N and P nucleotides?

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


When is H-chain gene rearrangement checked?

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


When is L-chain gene rearrangement checked?

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


How does switching from IgM to IgD happen?

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


How does switching between transmembrane and secreted immunoglobulin happen?

selective splicing of primary RNA transcript


How does class switching occur?

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


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)


When does AID function?

during immune response with T cell help


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

somatic hypermutation


Can the IgM to IgG class switching be reversed?

NO - those genes are spliced out