Rabbit Anti-Human Tau (phospho Ser199) monoclonal antibody for FC, ICC, IHC-P, IF, WB. Tau protein plays a very important role in nucleation and stabilization of microtubules by associating with tubulin subunits. In humans, Tau is predominantly expressed in the brain, and is involved in neurodegeneration when the protein is misfolded, hyperphosphorylated, or self-assembles into tangles. Six isoforms of Tau with varying degree of affinity to tubulin exist. Numerous serine/threonine kinases, including GSK-3 beta, protein kinase A, and casein kinase II (CK2) phosphorylate Tau. Phosphorylation of the serine 396 residue is triggered through GSK-3beta and cdk5. The gene encoding the Tau protein consists of 16 exons, and is located at chromosomal locus 17q21.