Schematic representation of the three regimes observed with the different RNA concentrations. In the absence of RNA, formation of amyloid fibrils proceeds via condensation, and aggregation is promoted at the interface of the condensates. In the second regime, at low RNA concentration, heterotypic proteinRNA interactions promote condensation and fibril formation, which also in this case are observed at the interface of the condensates. In the third regime, at high RNA concentration, condensation is suppressed, and the formation of amyloid fibrils occurs without condensation. Bright-field and fluorescence microscopy images of the time evolution of amyloid formation are shown in Supplementary Figs. 16 18 .
