High molecular weight tau from Alzheimer’s disease brain is C-terminally truncated.

<p><b>A</b>. Western blot probed with Tau46 (C-terminal Tau antibody) and Tau13 (N-terminal antibody) showing the HMW fraction isolated from human AD brain tissue does not contain the full-length Tau (441 aa). <b>B</b>. Quantification of Tau13 and Tau46 from AD HMW fractions (n = 4 AD cases), showing that the amount of HMW tau that contains the C-terminal Tau46 epitope is significantly lower than the Tau13 N-terminal epitope. Dashed red lines indicate the same human case. Absolute amounts are calculated by normalization against a recombinant human full length tau standard. <b>C</b>. SDD-AGE analysis of a Control and AD case for total tau and TauC3 show that only the AD case has TauC3 signal in the High Molecular Weight (HMW) fraction. Error bars represent Mean +/- SEM. Two-tailed student t-test. *p<0.05.