Sequences of the third complementarity determining region of antibody
heavy chains (CDRH3s) are listed according to their length. Human sequ
ences vary from 2 to 26 amino acids residues, but less extensively in
other species. When combined with the other five complementarity deter
mining regions, this enormous length variation of CDRH3, together with
amino acid substitutions in their sequences, can provide a very large
number of antibody specificities and can influence the shape of antib
ody combining sites.