The state of phosphorylation of normal adult brain tau, fetal tau, and tau from Alzheimer paired helical filaments at amino acid residue Ser262.
Antibody Ab262 was raised against a synthetic tau peptide (SKIGSTENLK, amino acids 258-267 of tau, termed Ser262 peptide). The antibody was more reactive with Ser262 peptide and unphosphorylated tau than a related phosphopeptide [SKIGS(P)TENLK, termed PSer262 peptide] and tau phosphorylated by a partially purified kinase, glycogen synthase kinase (GSK) 3 beta. AB262 reacted poorly with a peptide having the sequence DRV-QSKIGSLD (amino acids 348-358). Treatment of PSer262 peptide or GSK 3 beta phosphorylated tau with alkaline phosphatase increased Ab262 immunoreactivity, indicating that Ab262 is a reagent useful for studying tau phosphorylation at the Ser262 residue. The Ab262 immunoreactivity was detected in tau from normal brains and Alzheimer paired helical filament (PHF-tau) and in PHFs. Alkaline phosphatase treatment had no effect on the Ab262 immunoreactivity of normal tau and PHF-tau but altered the tau-1 and PHF-1 immunoreactivities, tau proteins from rat brains at 3 and 8 h postmortem exhibited 5 and 19%, respectively, more Ab262 immunoreactivity than tau from fresh tissues. In comparison, rat tau at 8 h postmortem was 40% more immunoreactive with Tau-1. The results suggest that Ser262 is not a major phosphorylation site in vivo. Moreover, there is little or no difference between PHF-tau and normal tau in the extent of phosphorylation at Ser262.
Liu
W K
WK
Department of Pathology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Yen
S H
SH
D000544:Alzheimer Disease / Q000378:metabolism*; D000595:Amino Acid Sequence; D001921:Brain / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005333:Fetus / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics; D010766:Phosphorylation; D011180:Postmortem Changes; D011994:Recombinant Proteins; D012016:Reference Values; D013997:Time Factors; D016875:tau Proteins / Q000235:genetics / Q000378:metabolism*
D010446:Peptide Fragments; D011994:Recombinant Proteins; D016875:tau Proteins