Figure 1.

Condensate-templated actinosome formation. (a) Schematic demonstrating stepwise addition of reagents to produce actinosomes. (b) Epifluorescence microscopy images at different stages of actinosome formation. Top: homogeneous mixture of ATTO-532-labeled actin monomers and FITC-labeled polylysine (labeled fraction 10% w/w). Middle: addition of the NTP mixture (GTP + ATP) triggers coacervation, resulting in polylysine/NTP coacervates with actin localized on the surface. Bottom: Mg²⁺ triggers actin polymerization at the expense of ATP hydrolysis, ultimately resulting in coacervate dissolution and formation of a shell made up of actin filaments and polylysine. (c) Line graphs corresponding to the dotted lines in panel (b) showing surface localization of actin on the condensates with polylysine concentrated in the interior (top) and colocalization of the actin and polylysine in actinosomes (bottom). (d) Confocal microscopy images of actinosomes stained with ATTO-594-labeled phalloidin (blue), which selectively binds to actin filaments; FITC-labeled polylysine (labeled fraction 10% w/w) is visualized in green. (e) Line graphs corresponding to the dotted lines in panel (d) showing surface localization of phalloidin-stained actin filaments (blue) along with polylysine (green).