Measurement:$area$selected$in$figure$3B$calcula6on$ Supp$ $fig Cell$1$ Cell$2$ Cell$3$ Cell$4$ Cell$5$ Supplementary Figure 1 Cells used in the kinetic analysis shown in Fig. 1f. The green fluorescence in Fig. 1f was calculated based on the average green fluorescence intensity of box “1” subtracted by the background of box “2”. 1 1 1.0 Normalized fluo. Normalized fluorescence Normalized fluorescence 1 Cell 1 S6#1% S6#1% S6#2% Cell 2 S6#2% S6#3% Cell 3 S6#3% S5#1% Cell 4 S5#1% S5#2% Cell 5 S5#2% 0.5 0.5 0.5 0 0 -5 -5 00 10 10 55 Time (min) Time (min) 0 Supplementary Figure 2. -5 0 5 10 Time (min) The green fluorescence normalized by the co-expressed mCherry fluorescence against time after addition of 100nM rapamycin (at 0 min.). 2 Supplementary Figure 3. Cells used in the kinetic analysis shown in Fig. 1h. The green fluorescence in Fig. 1h was calculated based on the average green fluorescence intensity of box “2” subtracted by the background of box “1”. 3 Supplementary Movie 1. Structure model of UnaG shown in cartoon. The N-terminal fragment covering residues 1 and 72 is shown in cyan; the loop region between residues 73 and 84 is shown in orange; the C-terminal fragment covering residues 85 and 139 is shown in green. The chromophore bilirubin is shown in yellow. Supplementary Movie 2. Structure model of UnaG shown in cartoon and surface. The N-terminal fragment covering residues 1 and 72 is shown in cyan; the loop region between residues 73 and 84 is shown in orange; the C-terminal fragment covering residues 85 and 139 is shown in green surface. The chromophore bilirubin is shown in yellow. Supplementary Movie 3. Structure model of UnaG shown in cartoon and surface. The N-terminal fragment covering residues 1 and 72 is shown by the cyan surface; the loop region between residues 73 and 84 is shown in orange; the C-terminal fragment covering residues 85 and 139 is shown by the green surface. The chromophore bilirubin is shown in yellow. Supplementary Movie 4. Green and red fluorescence kinetics of the HEK293 “cell 1” upon addition of rapamycin. The HEK293 cell expressed N and C-terminal fragments (residues 1-84 and 85-139) fused to FKBP and Frb, with co-expressed mCherry. The Movie was recorded at 1min./frame. The entire Movie lasted 16 min. 4 Supplementary Movie 5. Green and red fluorescence kinetics of the HEK293 “cell 2” upon addition of rapamycin. The HEK293 cell expressed N and C-terminal fragments (residues 1-84 and 85-139) fused to FKBP and Frb, with co-expressed mCherry. The Movie was recorded at 1min./frame. The entire Movie lasted 16 min. Supplementary Movie 6. Green and red fluorescence kinetics of the HEK293 “cell 3” upon addition of rapamycin. The HEK293 cell expressed N and C-terminal fragments (residues 1-84 and 85-139) fused to FKBP and Frb, with co-expressed mCherry. The Movie was recorded at 1min./frame. The entire Movie lasted 16 min. Supplementary Movie 7. Green and red fluorescence kinetics of the HEK293 “cell 4” upon addition of rapamycin. The HEK293 cell expressed N and C-terminal fragments (residues 1-84 and 85-139) fused to FKBP and Frb, with co-expressed mCherry. The Movie was recorded at 1min./frame. The entire Movie lasted 16 min. Supplementary Movie 8. Green and red fluorescence kinetics of the HEK293 “cell 5” upon addition of rapamycin. The HEK293 cell expressed N and C-terminal fragments (residues 1-84 and 85-139) fused to FKBP and Frb, with co-expressed mCherry. The Movie was recorded at 1min./frame. The entire Movie lasted 16 min. Supplementary Movie 9. Green and red fluorescence kinetics of HEK293 cells upon addition of the FKBP and Frb inhibitor FK506. The HEK293 cells expressed N and C-terminal fragments of UnaG (residues 1-84 and 85-139) fused to FKBP and Frb, with 5 co-expressed mCherry. The cells were incubated with 100nM rapamycin, which was washed away before addition of FK506. The Movie was recorded at 1min./frame. The entire Movie lasted 52 min. Supplementary Movie 10. Green and red fluorescence kinetics of HEK293 cells expressing split Venus upon addition of the FKBP and Frb inhibitor FK506. The HEK293 cells expressed N and C-terminal fragments of split Venus fused to FKBP and Frb, with co-expressed mCherry. The cells were incubated with 100nM rapamycin, which was washed away before addition of FK506. The Movie was recorded at 1min./frame. The entire Movie lasted 150 min. Supplementary Movie 11. Green and red fluorescence kinetics of HEK293 cells upon addition of HBSS without FK506. The HEK293 cells expressed N and C-terminal fragments of UnaG (residues 1-84 and 85-139) fused to FKBP and Frb, with coexpressed mCherry. The cells were incubated with 100nM rapamycin, which was washed away before addition of buffer solution without FK506. The Movie was recorded at 1min./frame. The entire Movie lasted 31 min. 6