To determine whether alterations in the tau Fyn interaction might correlate with disease related factors in AD and FTDP 17 , we have performed real time surface plasmon resonance studies on a panel of 21 tau constructs with Fyn SH 3 . ^^^ In addition , the affinity between 4R tau and Fyn SH 3 was increased 25 45 fold by phosphorylation mimicking mutations or by FTDP 17 mutations . ^^^