Purified by Protein G affinity chromatography. Conjugation: 40nm colloidal gold particle at 20ug/ml. Protein G lacking the albumin binding region (avoids undesirable reactions with albumin); Fc binding domain is still present. Each Protein G molecule can bind 2 molecules of IgG, allowing the formation of a precipitate. Protein G is a small globular cell surface protein produced by Streptococcus sp. It is composed of two or three nearly identical domains of 55 amino acids each. It binds to Fc fragment of IgG with high affinity. Protein G will bind IgGs from many species including all human and mouse subclasses. It does not recognize IgM, IgA, IgE or serum albumin. Protein G binds IgG from rat,, but substantially more weakly than IgG from other species. Recombinant Protein G is a highly stable surface receptor from Streptococcus sp. Lancefield Group G, produced in Escherichia coli, which is capable of binding the Fc portion of immunoglobulins, especially IgGs, from a large number of spec