Secondary Antibodies

Goat Anti-Mouse IgG FITC conjugate (Product No. F0257). From C. Rieder, Wadsworth Center, Division of Molecular Medicine, Lab of Cell Regulation, Albany, NY.		Anti-Rabbit IgG-FITC (Product No. F0382). From Lynn Burgess, Natural Sciences Department, Dickinson State University, Dickinson, ND.

Secondary antibodies are polyclonal or monoclonal antibodies that bind to primary antibodies or antibody fragments, such as the Fc or Fab regions. They are typically labeled with probes that make them useful for detection, purification or sorting applications.

Sigma’s polyclonal secondary antibodies are produced from the serum of host animals such as mouse, rabbit, goat and sheep, whereas, monoclonal secondary antibodies are produced from mouse hybridoma clones. Secondary antibodies are used in many applications including:

• Immunopurification
• ELISA
• Western blotting
• Immunohistochemistry
• Cell based assays
• Flow cytometry

The specific utility of a secondary antibody depends upon its conjugated probe(s). Probes are molecules that support various detection technologies. The most common detection systems for conjugated secondary antibodies are colorimetric or fluorescent. Colorimetric assays are typically based on the use of alkaline phosphatase (AP) or horseradish peroxidase (HRP) or its derivatives. The biotin avidin (streptavidin) conjugate binding system is often used to amplify the colorimetric signal for AP or HRP. The most common fluorescent assays utilize Fluorescein (FITC), Rhodamine or its derivative, TRITC, Cyanine (Cy3), or Phycoerythrin (R-PE).

Sigma^® Life Science offers over 600 secondary antibodies from a variety of host species. Search here for the antibody you need:

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• See also: Protein A, G and L Resins
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