Fig. 5. Binding to Hsp90 induces a conformational opening of ‘paper-clip’ Tau.

A structural model of Tau in the absence (left) and presence of Hsp90 (right) can be derived from EPR data of the Tau conformational ensemble. In the absence of Hsp90, Tau adopts a paper-clip shape with both termini folded back onto Tau-RD. In the presence of Hsp90 the N terminus folds outward, thereby uncovering Tau-RD.