Additionally, leveraging the homotopic assembly of YK peptides enabled us to design and fabricate multicomponent droplets in the cells. In vitro investigations showed that the cationic YK peptides respond to adenosine triphosphate (ATP), forming reversible amyloid-like fibrils--an essential structure observed in natural droplet-forming proteins. In the presence of poly-anion species, the YK-fused sfGFP assembled into colloids of approximately 20 nm in diameter, which subsequently coalesced into micron-scale droplets upon introducing a crowding reagent.