Fig. 1.

Light-activated F-actin–MTs composites. (A) GMPCPP-stabilized MTs are bundled by a specific MT cross-linker, PRC1-NSΔC, and driven by streptavidin-based kinesin motor clusters. AMP-PNP–bound G-actin is added to the MT bundle network and polymerizes in the high-salt buffer. After 2 h, filamentous actin formed a uniform interpenetrating actin network. At that point, DMNPE-caged ATP (cATP) was cleaved with UV light, and the kinesin motors generated large-scale reorganization. (B) Confocal microscopy shows the isotropic uniform interpenetrating network of actin and MTs. (C) UV illumination releases caged ATP, generating flows measured by particle image velocimetry. (D) Kinesin-driven flow drives the reorganization of the actin and MT networks (Movie S1). Yellow arrows indicate the velocity field.