Fig. 3

Rapid Kinetics of PHYB-PIF6 Binding and Unbinding

(A) Time sequence of a sagittal confocal slice through NE cells of a 15-somite embryo labeled with PHYB-MCherry-CAAX and PIF6-EGFP. Only the PIF6-EGFP signal is shown. At 0 s, 740 nm illumination was replaced with BF illumination and PIF6-EGFP was rapidly recruited to the membrane as illustrated by 8- and 36-s time points.

(B and C) Quantification of PIF6-EGFP intensity over time following BF (B) and 740 nm (C) illumination. EGFP intensity was normalized to mean levels at t = 0 s. One-phase exponentials (shown in blue) were fitted to EGFP levels, generating time constants (τ) for binding (B) and unbinding (C) of PIF6 to PHYB. τ = time taken for EGFP levels to either decrease by a factor of 1/e (approximately 36.8% of the original amount) or to increase by a factor of 1  1/e (approximately 63.2% of the asymptotic value). Error bars denote SEM. Black lines denote 95% confidence bands. (B) (i) Quantification was from the cells shown in (A). (ii) Illustration of PIF6-EGFP sampling areas. (C) Quantification of unbinding from NE cells in a 22-somite embryo.