Degree of variability in v regions of the H chains. gree of var chain.Note three areas of hypervariability CDR1,CDR2,and CDR3. DR. 150 CDR1 CDR2 100 .....1.......mm 0 40 60 80 100 Residue Position number Complementarity-determining Regions (CDR) CDR1(4) _CDR2 (15 DR3 (8) Hinge region HChain 440 amino acids L Chain 220 amino acid H chain 4 or 5 domains L Chain 2 domains 5achaeenge6 5 amino acids. There are 5 classes of H chai (IgG,IgM,IgA,IgD,and IgE) (Limchains