Fig. 2: Exo70 optogenetics rescues the fusion mode defect of Exo70-KK.

a Schematic of Exo70 optogenetics using the CRY2-CIB system. PM, plasma membrane. b Exo70-KK–CRY2 optogenetics with or without CIB. Cells were activated at 2 Hz with 100-ms pulses of 488-nm light (1.5 W/cm²). Maximum-intensity projection of movies (top). Scale bars, 6 μm. Kymographs of Exo70 channel (bottom). Red arrowheads, stuck vesicles. Vertical scale bar, 6 μm. c Average image sequence of fusing vesicles from one cell (left). Scale bar, 2 μm. Exo70-KK–CRY2 traces (red), time aligned to fusion (right). Averages (bold line) of cell averages (light lines) are shown. n = 5 and 4 cells for + CIB and – CIB, respectively. d Three fusion modes (FF, KR and KS) observed with Exo70-KK–CRY2 activation (+CIB) using 100 mM HEPES. Average image sequence of FF, KR and KS events from one cell (left). Scale bar, 2 μm. TfRc-pH (green) and Exo70-KK–CRY2 (red) traces (average of cell averages) for fusion modes (right). Mean ± SEM. Black dashed lines, zero baseline. e Tethering half-times for different fusion modes (n = 6 cells). Mean ± SEM (*P = 0.013, **P = 0.0035, two-tailed Student’s t-test). f Rescue of FF by Exo70 optogenetics with (+) CIB, but not without (–) CIB. n = 6 cells for Exo70 WT, n = 7 cells for Exo70 KK, n = 5 cells for Exo70 optogenetics + CIB and n = 4 cells for Exo70 optogenetics – CIB. Mean ± SEM (***P = 5.9 × 10⁻⁴, two-tailed Student’s t-test).