ASTROGLIAL AND AXONAL PROTEINS IN ISOLATED BRAIN FILAMENTS .1. ISOLATION OF THE GLIAL FIBRILLARY ACIDIC PROTEIN AND OF AN IMMUNOLOGICALLY ACTIVE CYANOGEN-BROMIDE PEPTIDE FROM BRAIN FILAMENT PREPARATIONS OF BOVINE WHITE MATTER

The glial fibrillary acidic protein and an immunologically active cyanogen bromide peptide were purified by immunoaffinity chromatography from 8 M urea extracts of brain filament preparations isolated from bovine white matter according to Norton's procedure. The protein accounted for approximately 30% of the total protein in this preparation and for the largest fraction in the 50 000 molecular weight range. The fraction not absorbed to the immuno-Sepharose column reacted with neurofilament antisera by double immunodiffusion. On sodium dodecyl sulfate gel electrophoresis the main bands in the non-adsorbed fraction were at 74 000 daltons and above 100 000. Several bands were seen in the 50 000 molecular weight range. It is concluded that glio- and neurofilaments co-purify together in Norton's procedure and that neurofilaments are probably heterogeneous in polypeptide composition. © 1979.