Tau protein is a microtubule-associated protein expressed in neuroaxon and has molecular weight of 50 - 70 kDa. Some Alzheimer's patients have sites where tau protein is accumulated abnormally. This antibody reacts with phosphorylated part in amino acid sites, 386 - 406 (TDHGAEIVYKSPVVSGDTSPR) of Tau protein. It does not react with the most carboxyl-terminal peptide (396 - 441) of normal human Tau protein.