Description General description Native protein A from Staphylococcus aureus. Provides a versatile and economical means for isolating, detecting, and purifying antibodies. It is especially useful in immunohistochemical studies because, unlike secondary antibodies, it does not bind to cell Fc receptors and, therefore, will not give high background reactions. Strongly reactive with guinea pig; human IgG1, IgG2, and IgG4; mouse IgG2b, and rabbit. Weakly reactive with bovine; human IgA, IgE, and IgM; and mouse IgG3. Nonreactive with goat; horse; human IgD and IgG3; rat; mouse IgG1; and sheep. Protein A, a component of the cell wall of Staphylococcus aureus, is sometimes called the universal second step reagent because it binds to the Fc portion of most immunoglobulin classes. It provides a versatile and economical means for isolating, detecting, and purifying antibodies. It is especially useful in immunohistochemical studies because, unlike secondary antibodies, it does not bind to cell Fc receptors and, therefore, will not give high background reactions. Strongly reactive with guinea pig; human IgG1, IgG2 and IgG4; and rabbit. Weakly reactive with bovine; human IgA, IgE and IgM; and mouse.Nonreactive with goat; horse; human IgD and IgG3; rat; and sheep. Packaging 5 mg in Plastic ampoule Warning Toxicity: Standard Handling (A) Reconstitution Following initial thaw, aliquot and freeze (-20°C). Stock solutions are stable for up to 3 months at -20°C. Other Notes Sjødahl, J. 1976. FEBS Lett.67, 1976.