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7 Cards in this Set
- Front
- Back
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Immunoglobulins are encoded in gene segments
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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 |
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What are V, J, D, C?
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V= variable segment
J= joining segment D=diversity C= constant |
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Enzymes involved in gene segment recombination
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- 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 |
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How do we diversify Ig genes by V(D)J?
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1. somatic hypermutation
2. gene conversion 3. class switching >> all relying on DNA repair and recombination process initiated by enzyme AID (in B cells) |
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How does somatic hypermutation diversify V region?
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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) |
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HOw does class switching diversify V region?
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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.
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De Novo Pathway
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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 |
