6.1 General remarks
Overview
6.1 General remarks
Antibodies exist in a number of different formats. The most frequently used format is an immunoglobulin G (IgG), which is a large, Y-shaped protein composed of two identical light chains and two identical heavy chains, both containing variable and constant domains. Antibodies bind specifically to antigen targets via the antigen-binding region, which contains complementarity-determining regions (CDRs). In the case of an IgG, the antigen-binding region consists of a heavy and a light chain variable domain, each variable domain having three CDRs.
Other immunoglobulin structures are also known, such as heavy-chain-only antibodies that consist of only two identical heavy chains (with variable and constant domains) and have an antigen-binding region consisting of a single variable domain with only three CDRs.
Thanks to knowledge of the structure-function relationships of antibody parts, it has been possible to create antibody derivatives for a multitude of applications. These include antibody fragments, bispecific or multispecific antibodies and antibody fusion products.
In general, antibodies can be defined by (but are not limited to):
(a)their own structure (amino acid sequences)
(b)nucleic acid sequences encoding the antibody
(c)reference to the target antigen
(d)target antigen and further functional features