Astroglial and axonal proteins in isolated brain filaments. II. Isolation of a 70 000-dalton polypeptide from bovine brain filament preparations by immunoaffinity chromatography with antineurofilament antisera.

Antineurofilament antisera raised against chicken brain antigen were used to isolate neurofilament protein from bovine brain filament preparations by immunoaffinity chromatography. Glial fibrillary acidic protein, the subunit of glial filaments, passed unabsorbed through the column. The Mr 70 000 component of the neurofilament triplet was tightly absorbed to the column and essentially the only protein eluted at pH 2.5. The other two components of the triplet, of approximately 200 000 and 150 000 daltons, were less tightly attached to the column and eluted at pH 6.0 in 5 M urea.