Fig. 1

Photoswitching of ASAPs and light-induced restoration. a An example of fluorescence loss of ASAP1 in the transfected HEK 293 cells. Left, the initial fluorescence; right, fluorescence after 2-s 470-nm light illumination. Scale bar: 5 μm. b Photoswitching and spontaneous recovery kinetics of ASAP1 and ASAP2f fluorescence in transfected HEK 293 cells. Blue bars indicate duration of 470-nm light illumination. Fluorescence intensity was sampled once every 30 s after the initial 2-s continuous imaging. Error bars are SEM (n = 25 for ASAP1; n = 38 for ASAP2f). c The ratio of residual ASAPs fluorescence after photoswitching by 470-nm light at different power density (not significant for any pairs, t-test; n = 9 cells). d Reduction and restoration of fluorescence in a cultured hippocampal neuron transfected with ASAP2f. Left, the initial fluorescence; middle, fluorescence after 2-s 470-nm light illumination; right, fluorescence after 0.5-s 405-nm light illumination. e Photoswitching of ASAP2f fluorescence in a neuron excited by 470-nm light (blue bars) illumination was restored by interleaved 405-nm light pulses (purple bars) lasting 1, 10, 100, 1000 ms, respectively. f Photoswitching of ASAPs was partially rescued by assistive 405-nm light co-illumination at 0.1~ 2.5 mW/mm². After 0.5-s 405-nm illumination at 0.1~ 2.5 mW/mm² alone, fluorescence was partially rescued and followed by photoswitching in 470-nm illumination