Differences between tau isoforms. (A) The six tau isoforms differ by the presence or absence of N-terminal exons 2 and 3 and the presence or absence of the C-terminal exon 10, which encodes microtubule binding repeat 2. Labels on the left indicate the isoform name, while labels on the right indicate the number of amino acids present in each corresponding isoform. (B) Each lane is labeled with the name of the isoform analyzed. Each isoform migrates a distinct distance on a Coomassie stained 10% SDS-polyacrylamide gel.