Microtubule-associated protein, tau is abnormally hyperphosphorylated in the brain of patients with Alzheimer's disease, and is the major protein subunit of paired helical filaments. There is also a significant pool of non-paired helical filament abnormally phosphorylated tau in Alzheimer's disease brain. Tau is a family of six isoforms, derived from a single gene by mRNA splicing. Tau protein is produced by a single gene expressed predominantly in neurons. They vary in size from 352-441 amino acides. In Alzheimer disease Tau is hyperphosphorylated, containing 3-4 fold more phosphoate/mole of the protein than the normal tau. Recent investigations show that MARK and PKA phosphorylate several sites within the repeats (notably the KXGS motifs including Ser262, Ser324, and Ser356, plus Ser320); in addition PKA phosphorylates some sites in the flanking domains, notably Ser214. This type of phosphorylation strongly reduces tau's affinity for microtubules, and at the same time inhibits tau's assembly into PHFs (Paired helical filament).

The antibody is stable for at least 1 year from the date of receipt when stored at -20°C to -70°C. Reconstituted antibody can also be aliquotted and stored at 4°C for 1 month or at -20°C to -70°C in a manual defrost freezer for many months without detectable loss activity. Please avoid freeze-thaw cycles.

The antibody specifically detects phosphorylated protein derived from human brain tissue. It recognizes PHF-tau phosphorylated at Ser199 in both ELISA and WB. This antibody shows no cross-reactivity with other unrelated protein.