MAPT and supranuclear palsy, progressive, 1: Here, we show that phospho-mimicking substitutions (Ser/Thr → Glu; referred to as ‘Phospho-Plus’ henceforth) on specific epitopes in the R1-R2 repeat domains (S262/T263/S289/S305) restrict the seeding ability of AD-tau, but not PSP-tau.