BIOL 2050U Lecture Notes - Themis, Immunoglobulin Class Switching, Exon
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GENETIC BASIS OF ANTIBODY DIVERSITY
Structural basis of antigen binding
- Antibody sequence variability is clustered
variability = # of different observed aa’s/ frequency of most common
range = 1(least) – 400(most)
observe clustering in 3 HYPERVARIABLE regions
interspersed by FRAMEWORK regions
true for light and heavy chains
**hypervariable regions involved in antigen binding**
also called CDR’s (complementarity determining regions)
- 3D structure of antibody domains:
all domains have IMMUNOGLOBULIN fold
all fold independently and there is interaction between HC and LC
(VH interacts w/ VL)
hypervariable regions cap the distal end
- 3D structures of antibody/ligand binding:
larger proteins more interaction (more CDR’s involved)
framework residues contact somewhat
large interacting surfaces w/ high STERIC complementarity
hydrophobics/h-bonds are V. important
LITTLE conf. change (saves energy)
EPITOPE = minimal amt of antigen needed to bind antibody