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pcb was extracted by methanolysis at 70c from protein precipitates of spirulina cell lysate ( seltzer chemical ) that were pre - washed to remove other tetrapyrroles species .
nih3t3 cells transiently transfected with the phytochrome and pif constructs were pre - incubated in the dark with 5m pcb for 30min and then washed before experiments .
noncoherent control - light frequencies were obtained by filtering white - light sources with 650 nm and 750 nm 20 nm bandpass filters ( edmund optics ) or a near - infrared rg9 glass filter ( newport ) . for morphology experiments ,
cells were serum - depleted ( 1% bovine calf serum ) for at least twelve hours before imaging .
pcb was extracted by methanolysis at 70c from protein precipitates of spirulina cell lysate ( seltzer chemical ) that were pre - washed to remove other tetrapyrroles species .
nih3t3 cells transiently transfected with the phytochrome and pif constructs were pre - incubated in the dark with 5m pcb for 30min and then washed before experiments .
noncoherent control - light frequencies were obtained by filtering white - light sources with 650 nm and 750 nm 20 nm bandpass filters ( edmund optics ) or a near - infrared rg9 glass filter ( newport ) . for morphology experiments ,
cells were serum - depleted ( 1% bovine calf serum ) for at least twelve hours before imaging .
genetically - encodable optical reporters , such as green fluorescent protein , have revolutionized the observation and measurement of cellular states . 
 however , the inverse challenge of using light to precisely control cellular behavior has only recently begun to be addressed ; semi - synthetic chromophore - tethered receptors1 and naturally - occurring channel rhodopsins have been used to directly perturb neuronal networks2,3 . 
 the difficulty of engineering light sensitive proteins remains a significant impediment to the optical control to most cell - biological processes . 
 here we demonstrate the use of a new genetically - encoded light - control system based on an optimized reversible protein - protein interaction from the phytochrome signaling network of arabidopsis thaliana . because protein - protein interactions are one of the most general currencies of cellular information , this system can in principal 
 be generically used to control diverse functions . here 
 we show that this system can be used to precisely and reversibly translocate target proteins to the membrane with micrometer spatial resolution and second time resolution . 
 we show that light - gated translocation of the upstream activators of rho - family gtpases , which control the actin cytoskeleton , can be used to precisely reshape and direct the cell morphology of mammalian cells . 
 the light - gated protein - protein interaction that has been optimized in this work should be useful for the design of diverse light - programmable reagents , potentially enabling a new generation of perturbative , quantitative experiments in cell biology .