Protein G
Protein G has affinity for both Fab- and Fc-fragments of human IgG by independent and separate binding sites. Binding to the Fc region of immunoglobulins from several species by a non-immune mechanism exhibits greater affinity for almost all mammalian immunoglobulin G than Protein A.

Genetically engineered truncated protein G retains affinity for IgG but lacks albumin and Fab binding sites and membrane-binding regions. Protein G can bind all the human and mouse IgG subclasses. It can bind to both the fragment crystallizable (Fc) and antigen-binding fragment (Fab) components of the antibody.

Applications:
Protein G is a powerful reagent for the detection and purification of IgG and can be used in various immunochemical assays including WB, IHC, IP, and ELISA.