Recognition of antigens by single-domain antibody fragments: the superfluous luxury of paired domains.
The antigen-binding site of antibodies from vertebrates is formed by combining the variable domains of a heavy chain (VH) and a light chain (VL). However, antibodies from camels and llamas are an important exception to this in that their sera contain, in addition, a unique kind of antibody that is formed by heavy chains only. The antigen-binding site of these antibodies consists of one single domain, referred to as VHH. This article reviews the mutations and structural adaptations that have taken place to reshape a VH of a VH-VL pair into a single-domain VHH with retention of a sufficient variability. The VHH has a potent antigen-binding capacity and provides the advantage of interacting with novel epitopes that are inaccessible to conventional VH-VL pairs.
Muyldermans
S
S
Vrije Universiteit Brussel, Vlaams Interuniversitair Instituut Biotechnologie, 65, B-1640 Sint Genesius Rode, Paardenstraat, Belgium. svmuylde@vub.ac.be
Cambillau
C
C
Wyns
L
L
D000595:Amino Acid Sequence; D000937:Antigen-Antibody Reactions; D001666:Binding Sites, Antibody; D022801:Complementarity Determining Regions; D006801:Humans; D007128:Immunoglobulin Fragments / Q000737:chemistry / Q000276:immunology*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
D022801:Complementarity Determining Regions; D007128:Immunoglobulin Fragments