a microtubule-associated protein that regulates microtubule assembly and stability. Apparently involved in the establishment and maintenance of neuronal polarity. Mutations can result in several neurodegenerative disorders such as Alzheimer's disease, Pick's disease, frontotemporal dementia, cortico-basal degeneration and progressive supranuclear palsy. The C-terminus binds axonal microtubules while the N-terminus binds neural plasma membrane components, suggesting that tau functions as a linker. Axonal polarity is predetermined by tau localization (in the neuronal cell) in the domain of the cell body defined by the centrosome. Nine differentially spliced isoforms have been described. The short isoforms allow plasticity of the cytoskeleton, whereas the longer isoforms may preferentially play a role in its stabilization. Note: This description may include information from UniProtKB.