Tau is a member of the microtubule-associated protein (MAP) family that facilitates microtubule formation in axons.{55125,55126} It is primarily expressed in neurons and localized to axons, but trace amounts have been observed in glial cells and several peripheral tissues including kidney, lung, and testis. Tau is composed of an N-terminal projection domain that interacts with neurofilaments, cytoplasmic organelles, and neuronal cell membranes and a C-terminal microtubule binding domain that facilitates microtubule polymerization and stabilization. It is encoded by MAPT in humans, a 16-exon gene that produces 6 isoforms via alternative mRNA splicing. Mutations in MAPT lead to changes in expression of tau isoforms and the formation of insoluble protein aggregates that cause familial frontotemporal dementia (FTD) and parkinsonism linked to chromosome 17 (FTDP-17).{55127} Tau is subject to post-translational modifications, including phosphorylation, and hyperphosphorylation of tau is associated with the formation of neurofibrillary tangles and neuronal cell death in postmortem brains from patients with Alzheimer's disease. Cayman's Tau Polyclonal Antibody can be used for immunohistochemistry (IHC), immunocytochemistry (ICC), and Western blot (WB) applications. The antibody recognizes three isoforms of tau at approximately 48, 65, and 75 kDa from human, bovine, mouse, porcine, and rat samples.