Anti-IgG antibodies are useful reagents for the immunodetection and measurement of IgG in various samples. The target antigen refers to Immunoglobulin G, which is the most predominant serum antibody type in humans. The four IgG subtypes are IgG1, IgG2, IgG3, aAnti-IgG antibodies are useful reagents for the immunodetection and measurement of IgG in various samples. nd IgG4. The IgG molecule has a mass of roughly 150 kDa and contains four peptide chains: two identical gamma heavy (H) chains and two identical light (L) chains. It can also be subdivided into the F(c) region and the F(ab) region, which contains the epitope-recognition site. Anti-IgG antibodies can be used as secondary antibodies for the immunodetection of the various IgG subtypes raised from species.