Protein A and G are immunoglobulin-binding proteins of microbial origin that bind to mammalian immunoglobulins. Our Protein A is isolated from the bacteria Staphylococcus aureus while our Protein G is produced recombinantly. The high-affinity of protein A and protein G for the Fc region of polyclonal and monoclonal IgG-type antibodies forms the basis for purification of IgG, IgG fragments containing the Fc region, and IgG subclasses.
Protein A binds the Fc portion of human IgG1, IgG2, and IgG4, mouse IgG2a and IgG2b, and rabbit, porcine, guinea pig, and canine IgG. Protein G binds IgG including all human and mouse subclasses but does not bind IgM, IgA, IgE, or bovine serum albumin.