title: Effect of metallic cations and pH on reassembly of glial fibrillary acidic protein.
abstract: Glial fibrillary acidic protein (GFAP), which was purified from acetone powder of the bovine spinal cord, was reassembled in 0.1 M imidazole HCl buffer containing metallic cations, Ca(2+), Mg(2+), Na(+) or K(+) at physiological or more acidic pH. An electron microscopy revealed reassembled glial filaments at pH 6.8 without any cations but amorphous aggregates at pH 6.3 which were readily observed as a white precipitate by the naked eye. Under more alkaline pH (pH 7.4) only rod-shaped short filaments were formed. In the presence of mM concentrations of Ca(2+) or Mg(2+), thick bundles of glial filaments, detectable by light microscopy, were formed at acidic pH. At pH 7.4 long reassembled filaments could be formed in the buffer containing divalent cations. Na(+) (0.1 M) made filament-like structures of GFAP but they are rather random compared to the filaments promoted by the divalent cations. K(+) made only amorphous aggregation of the short filaments. These findings indicate that the reassembly of GFAP at physiological pH requires essentially divalent cations but not ionic strength.
authors.affiliation: Department of Neuropsychiatry, Osaka University Medical School, 1-1-50, Fukushima, Fukushima-ku, Osaka 553, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Tanaka
authors.forename: K
authors.initials: K
authors.lastname: Tada
authors.forename: M
authors.initials: M
authors.lastname: Takeda
authors.forename: S
authors.initials: S
authors.lastname: Hariguchi
authors.forename: T
authors.initials: T
authors.lastname: Nishimura