Protein G, similar to Protein A, is an immunoglobulin-binding protein expressed in group C and G Streptococcal bacteria but with different specificities. It binds to the constant region of many species of immunoglobulin G and can be used to detect, quantify and purify IgG antibodies and antibody/antigen complexes. Recombinant protein A/G is an excellent tool for purification and detection of mouse monclonal antibodies from IgG subclasses without interference from other serum proteins. Individual subclasses of mouse monoclonals are most likely to have stronger affinity to this chimeric protein than to either Protein A or Protein G. Binding is less pH-dependent than either Protein A or Protein G alone. Optimal pH 5- 8.
