Details

Autor(en) / Beteiligte

• Ksiezak-Reding, Hanna
• Liu, Wan-Kyng
• Yen, Shu-Hui

Titel

Phosphate analysis and dephosphorylation of modified tau associated with paired helical filaments

Ist Teil von

• Brain research, 1992-12, Vol.597 (2), p.209-219

Ort / Verlag

London: Elsevier B.V

Erscheinungsjahr

1992

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• We performed phosphate of tau proteins isolated fromal human brain, tau associated with paired helical filaments (PHF-tau), Alzheimerr tau not associated with PHF. These tau fractions were of high purity. Normal and Alzheimer tau were purified by heat treatment, acid extraction and calmodulin-affinity chromatography with or without HPLC. Fractions containing primarily PHF-tau polypeptides of 60, 64, and 68 kDa and their degraded fragments were purified either on a sucrose density gradieent as filaments (PHF) or by heat treatment and acid extraction as amorphous proteins (PHF-tau). PHF and PHF-tau were found to contain 6–8 mol phosphate/mol protein while normal and Alzheimer tau proteins contained 1.9 and 2.6 mol phosphate/mol protein, respectively. Upon 2-h incubation with alkaline phosphatase, PHF lost two of the phosphate groups without apparent changes in the stability and morphology of PHF. The released phosphate originated from the N-terminal half of PHF-tau as determined by immunoblotting with antibodies to epitopes blocked by phosphorylation, Tau-1 and E-2, and by a prominent shift in the electrophoretic mobility of some fragmetss of PHF-tau. The shift in mobility was not observed with the C-terminal fragments of 25–26 kDa, whth retained the epitope to Tau 46. The results suggest that the phosphorylation sites not affected by phosphatase may be located in the 25–26 kDa C-terminal region of PHF-tau and may play a role in structural stability of PHF.