The reversible fibril formation is proposed to be responsible for the dynamic association properties of lowcomplexity (LC) domains in natural droplet-forming proteins . As a representative example, the selfassembling motifs within the FUS LC domain adopt reversible fibers that dissolve in response to heating and phosphorylation . This characteristic is fundamentally distinct from the thermostable fibrils observed in pathologic amyloid. We expect that, similar to these natural reversible amyloid cores, the YK13 peptide forms a reversible fibril. To explore this, we sequentially introduced ATP and ATPase into a solution of YK13 peptide. Thioflavin-T fluorescence was enhanced upon the addition of ATP and returned to background levels upon subsequent ATPase addition (Fig. ). Upon further ATP addition, the fluorescence was temporally enhanced, followed by a decline. This transient response to ATP was repeatedly observed. Notably, the disassembly rate correlated with ATPase concentration, with rapid dissociation on the order of seconds (t1/2 < 30 s) at the highest concentrations of ATPase (Supplementary Fig. ).