fig1

Figure 1. Schematic representation of the protein structures of tau. Six tau isoforms (2N4R, 2N3R, 1N4R, 1N3R, 0N4R, and 0N3R) of 352-441 aa are formed due to alternative splicing of exon 2 (E2), E3, and E10. Tau consists of four regions: N-terminus, proline-rich domain, microtubule-binding domain, and C-terminus. The expression of human tau is developmentally regulated: the 0N3R isoform is expressed only in the fetal brain, and all six isoforms are expressed in the adult brain. In the adult brain, the levels of the 3R and 4R forms are approximately equal, while the 0N, 1N, and 2N tau isoforms account for ~37%, ~54%, and ~9% of total tau, respectively.