The Immunogen: Glial Fibrillary Acidic Protein (GFAP) was discovered by Amico Bignami and coworkers as a major fibrous protein of multiple sclerosis plaques (1). It was subsequently found to be a member of the 10nm or intermediate filament protein family, specifically the intermediate filament protein family Class III, which also includes peripherin, desmin and vimentin. The GFAP protein runs on gels at ~55kDa protein, usually associated with lower molecule weight bands which are thought to be proteolytic fragments and alternate transcripts from the single gene. GFAP is strongly and specifically expressed in astrocytes and certain other astroglia in the central nervous system, in satellite cells in peripheral ganglia, and in non-myelinating Schwann cells in peripheral nerves. In many damage and disease states GFAP expression is heavily upregulated in astrocytes. In addition neural stem cells frequently strongly express GFAP. Antibodies to GFAP are therefore very useful as markers of astrocytic cells and neural stem cells. In addition many types of brain tumor, presumably derived from astrocytic cells, heavily express GFAP. Finally, Alexander's disease was recently shown to be caused by point mutations in protein coding region of the GFAP gene (2). All forms of Alexander disease are characterized by the presence of Rosenthal fibers, which are GFAP containing cytoplasmic inclusions found in astrocytes.

Left: Western blot of whole rat cerebellum homogenate stained with RPCA-GFAP, at dilution of 1:100,000. A prominent band running with an apparent SDS-PAGE molecular weight of ~50kDa corresponds to rodent GFAP. A lower band at ~45kDa is a proteolytic fragment derived from the GFAP molecule. Right: Mixed neuron-glial cultures stained with rabbit GFAP (red channel) and chicken vimentin CPCA-Vim (green channel). The fibroblastic cells contain only vimentin and so are green, while astrocytes contain either vimentin and GFAP, so appearing golden, or predominantly GFAP, in which case they appear red. Blue is nuclear DNA stain.

Antibody Characteristics: he initial challenge was performed with a preparation of recombinant GFAP expressed in bacteria and highly purified. Subsequent boosts were performed with GFAP purified from a Triton X-100 extract of myelin associated material from bovine spinal cord, following an "axonal flotation" procedure (3). The GFAP was further purified by centrifugation and ion exchange chromatography in 6m urea on DEAE cellulose.This antibody is provided as crude serum and has an extremely high titre (see below). Store at 4°C or -20°C. Avoid repeat freezing and thawing.

Suggestions for use: For immunocytochemistry on cells in tissue culture or in tissue sections, try this antibody at about between about 1:1,000 using fluorescent secondary antibodies or 1:5,000 using peroxidase or other enzyme linked methods. For immunoblotting 1:50,000 is recommended. Expect to see a band at 55kDa and another at about 48kDa, apparently a breakdown product of the 55kDa band.

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References:

1. Bignami A, Eng LF, Dahl D, Uyeda CT. Localization of the glial fibrillary acidic protein in astrocytes by immunofluorescence. Brain Res. 43:429-35 1972.

2. Brenner M, Johnson AB, Boespflug-Tanguy O, Rodriguez D, Goldman JE and Messing A. Mutations in GFAP, encoding glial fibrillary acidic protein, are associated with Alexander disease. Nat Genet 27:117-20 2001

3. Liem RKH, Yen SH, Salomon GD and Shelanski ML. Intermediate filaments in nervous tissues. J Cell Biol 79:637-745 (1978).

Price and Availability: - We currently supply 100 microliter aliquots for $200. Material is in stock and ready for immediate shipping.

Limitations: This product is for research use only and is not approved for use in humans or in clinical diagnosis.

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