Immunology Lecture 4

Genes=
genetic info for 1 protein flanked by promoter, terminator, etc (introns, and extrons)

Gene Segments are pieces of an exon (V) segments must be rearranged (DNA) some flanked by promoter

V= variable segment
J= joining segment
D=diversity
C= constant

- RAG1
- RAG2
(both are missing in SCID mice)
- DNA Ligase IV: for sticking DNA together
- DNA-PK: defect in SCID mice
- Ku70:Ku80 = protein
- Artemis
- TdT= affect result in recombinant DNA

1. somatic hypermutation
2. gene conversion
3. class switching
>> all relying on DNA repair and recombination process initiated by enzyme AID (in B cells)

by introduction of point mutation, resulting:
- greater affinity for the antigen
(activated Bcells producing mutated Ig are selected for survival, which increase the affinities of the Ab for the antigen as immune response proceeds)

class-switching does not affect V-region, but increase functional diversity of Ig's by replacing C(miu) with another H-chain C region to produce IgG, IgA, or IgE antibodies.

De novo origins come from Aspartate, Glycine, Folate, Glutamine and carbon dioxide.
De novo pathways
-- do not use free bases: adenine (abbreviated as A), guanine (G), cytosine (C), thymine (T) (or uracil (U)
-- refers to the synthesis of complex molecules (DNA replication) from simple molecules such as sugars or amino acids