Such 'misfolding hotspots' are also predicted by HP-models . Our findings explain the strong inhibitory effect of charge-modifications in this region, as found in earlier work The computed TSE is supported experimentally by the pioneering use of Tanford β value to a misfolding reaction, β T (Supplementary Material). Additionally, FoldX-calculations of the expected ∆∆G ‡-A from the simulated TSE agree with the experimental data (Figure ). Collectively these findings provide compelling evidence that elongation of PI3K-SH3 fibrils proceeds through a single well-defined TSE.