Protein A is a 42 kD, highly stable cell surface receptor isolated from Staphylococcus aureus which binds selectively and with high affinity to the Fc portion of IgG from various species.Protein A-gold is an electron dense, non-fading marker and can be used as a probe in electron microscopy (TEM and SEM), light microscopy and blotting. Protein A - 20 nm colloidal gold reacts specifically with IgG of human.
