PathScan^® RP Tau 4R Sandwich ELISA Kit

The rapid protocol (RP) PathScan^® RP Tau 4R Sandwich ELISA Kit is a solid phase sandwich enzyme-linked immunosorbent assay (ELISA) that detects endogenous levels of Tau 4R protein (Tau 4R iso6/iso7/iso8) in a reduced assay time of 1.5 hours. Incubation of cell lysates and detection antibody on the coated microwell plate forms a sandwich with Tau 4R protein in a single step. The plate is then extensively washed and TMB reagent is added for signal development. The magnitude of absorbance for the developed color is proportional to the quantity of Tau 4R protein. Learn more about all of your ELISA kit options here.

*Antibodies in this kit are custom formulations specific to kit.

The PathScan^® RP Tau 4R Sandwich ELISA Kit detects endogenous levels of Tau 4R isoforms 6, 7, and 8, and does not cross-react with Tau 3R isoforms 2, 4, or 5, as shown in Figure 1. The kit sensitivity is shown in Figure 2. This kit detects proteins from the indicated species, as determined through in-house testing, but may also detect homologous proteins from other species.

Tau is a heterogeneous microtubule-associated protein that promotes and stabilizes microtubule assembly, especially in axons. Six isoforms with different amino-terminal inserts and different numbers of tandem repeats near the carboxy terminus have been identified, and tau is hyperphosphorylated at approximately 25 sites by Erk, glycogen synthase kinase-3 (GSK-3), and CDK5 (1,2). Phosphorylation decreases the ability of tau to bind to microtubules. Neurofibrillary tangles are a major hallmark of Alzheimer's disease (AD); these tangles are bundles of paired helical filaments (PHFs) composed of hyperphosphorylated tau. In particular, phosphorylation at Ser396 by GSK-3 or CDK5 destabilizes microtubules. Furthermore, research studies have shown that inclusions of tau are found in a number of other neurodegenerative diseases, collectively known as tauopathies (1,3).

Alternative splicing of exon 10 results in the expression of two groups of tau; three-repeat and four-repeat tau. Isoforms 2, 4, and 5 express three microtubule binding repeat domains (tau 3R) while isoforms 6, 7, and 8 express four microtubule binding repeat domains (tau 4R) (4). The localization of tau 3R and tau 4R in cells can be expressed differently in mild or pathological conditions, including tau 3R in Pick's disease (PiD) and corticobasal degeneration (CBD), while in Alzheimer's disease equally expresses both tau 3R and tau 4R (5,6). The repeat-dependent tau has a different pattern of phosphorylation in different diseases, and also has the ability and patterns of aggregation (7-9).