Tau protein is a highly soluble microtubule-associated protein (MAP). In humans, these proteins are found mostly in neurons compared to non-neuronal cells. Tau is a phosphoprotein with 79 potential Serine (Ser) and Threonine (Thr) phosphorylation sites on the longest tau isoform. The abnormally hyperphosphorylated microtubule-associated protein Tau (p-Tau) inhibits microbule assembly and disrupts microtubules by competing with tubulin/microtubules in associating with normal Tau, MAP1 and MAP2. p-Tau can be dephosphorylated by protein phosphatase PP-2B, PP-2A and PP-1, which are all present in neurons. p-Tau is predominately present in neuronal somata and dendrites and, to a lesser extent in axons.
