Anti-phospho-Tau (Ser422) Antibody, clone AP422

Microtubule-associated protein tau (UniProt: P10636; also known as Neurofibrillary tangle protein, paired helical filament-tau, PHF-tau) is encoded by the MAPT (also known as MAPTL, MTBT1, TAU) gene (Gene ID: 4137) in human. Tau, a heat-stable microtubule-associated protein, is expressed mainly in the brain, where it regulates the stability and orientation of microtubules in neurons, astrocytes, and oligodendrocytes. Tau protein is reported to be the major component of the paired helical filaments (PHFs) and neurofibrillary tangles (NFTs) that are characteristic of pathological brain lesions in Alzheimer s disease. Tau is a substrate for a multitude of protein kinases, and is phosphorylated at many different sites in Alzheimer s disease brain. It is believed that the phosphorylation of specific sites, rather than the overall extent of phosphorylation, is important in modulating the ability of Tau to bind microtubules and promote microtubule assembly. The de-phosphorylation of Tau protein promotes rapid and extensive microtubule polymerization, while the phosphorylation of Tau decreases its ability to promote microtubule assembly. Six isoforms of Tau have been described that are generated by alternative splicing in the central nervous system. This monoclonal AP422 Ab is specific for phosphoserine 422 (P10636-8, Tau-F; Tau-4, 2N4R) and strongly labels paired helical filament (PHF) tau from Alzheimer′s disease brain in a phosphorylation-dependent manner. AP422 only labels a small fraction of fetal tau and a very small fraction of tau from adult brain. The amount of tau phosphorylated at Ser-422 in normal brain is minor relative to that phosphorylated at sites recognized by other phosphorylation-dependent anti-tau antibodies of known epitope. Studies shows that AP422 is the most specific anti-tau antibody available for detecting the neurofibrillary lesions of Alzheimer′s disease and that, Ser-422 in tau is a good in vitro substrate for mitogen-activated protein kinase, but not for glycogen synthase kinase-3 or neuronal cdc2-like kinase. (Ref.: Hasegawa, M., et al. (1996). FEBS Lett. 384(1):25-30; Mukadam, A.S., et al. (2023). Science. 379(6639):1336-1341).

A linear peptide corresponding to 15 amino acids surrounding phosphoserine 422 from the C-terminal half of human Tau.

Quality Control Testing

Evaluated by Western Blotting in tau extracted from fetal rat brain tissue.

Western Blotting Analysis (WB): A 1:1000 dilution of this antibody detected tau extracted from fetal rat brain tissue but not in PPase treated tau extracted from fetal rat brain tissue.

Tested Applications

Immunofluorescence Analysis: A representative lot detected Tau in Immunofluorescence application (Mukadam, A.S., et al. (2023). Science. 379(6639): 1336-1341).

Electron Microscopy: A representative lot detected Tau in Electron Microscopy application (Hasegawa, M., et al. (1996). FEBS Lett. 384(1): 25-30).

Western Blotting Analysis: A representative lot detected Tau in Western Blotting application (Hasegawa, M., et al. (1996). FEBS Lett. 384(1): 25-30; Mukadam, A.S., et al. (2023). Science. 379(6639): 1336-1341).

Immunohistochemistry Applications: A representative lot detected phospho-Tau (Ser422) in Immunohistochemistry applications (Hasegawa, M., et al. (1996). FEBS Lett. 384(1): 25-30).

Dot Blot: A representative lot detected phospho-Tau (Ser422) in Dot Blot applications (Mukadam, A.S., et al. (2023). Science. 379(6639): 1336-1341).

ELISA Analysis: A representative lot detected phospho-Tau (Ser422) in ElISA application (Mukadam, A.S., et al. (2023). Science. 379(6639): 1336-1341).

Note: Actual optimal working dilutions must be determined by end user as specimens, and experimental conditions may vary with the end user.

Clone AP422 is a mouse monoclonal antibody that specifically detects Tau phosphorylated on serine 422.

Purified mouse monoclonal antibody IgG1 in buffer containing 0.1 M Tris-Glycine (pH 7.4), 150 mM NaCl with 0.05% sodium azide.

1.0 mg/mL. Please refer to guidance on suggested starting dilutions and/or titers per application and sample type.

Recommended storage: +2°C to +8°C.

Concentration: Please refer to the Certificate of Analysis for the lot-specific concentration.

Unless otherwise stated in our catalog or other company documentation accompanying the product(s), our products are intended for research use only and are not to be used for any other purpose, which includes but is not limited to, unauthorized commercial uses, in vitro diagnostic uses, ex vivo or in vivo therapeutic uses or any type of consumption or application to humans or animals.