Phospho-Tau (Thr205) (E8Q5Z) Mouse mAb #25377

Tau is a heterogeneous microtubule-associated protein that promotes and stabilizes microtubule assembly, especially in axons. Six isoforms with different amino-terminal inserts and different numbers of tandem repeats near the carboxy terminus have been identified, and tau is hyperphosphorylated at approximately 25 sites by Erk, glycogen synthase kinase-3 (GSK-3), and CDK5 (1,2). Phosphorylation decreases the ability of tau to bind to microtubules. Neurofibrillary tangles are a major hallmark of Alzheimer's disease (AD); these tangles are bundles of paired helical filaments (PHFs) composed of hyperphosphorylated tau. In particular, phosphorylation at Ser396 by GSK-3 or CDK5 destabilizes microtubules. Furthermore, research studies have shown that inclusions of tau are found in a number of other neurodegenerative diseases, collectively known as tauopathies (1,3).

Phosphorylation of tau at Thr205 is found in Alzheimer's disease brain. This phosphorylation is the result of the activity of GSK-3, protein-kinase A (PKA), and other kinases (4,5). Protein phosphatases have been shown to decrease the levels of phospho-tau at Thr205, including protein phosphatase 5 (PP5) (6).