Figure 4.

The APB Motif Is Necessary for Binding phyB (Pfr).

GAD fusions with full-length PIFs (containing wild-type APB, closed rectangles, or mutated APB, open rectangles) were used as baits in in vitro coimmunoprecipitation assays. PhyB (Pfr) or phyB (Pfr) reconverted to Pr by a far-red light pulse (marked as Pr) were used as prey. Schematic diagrams on the left show the design of the experiments, and the SDS-PAGE separations of the pellet fractions are shown on the right of each panel.

(A) GAD:PIF5 binds phyB (Pfr) but the point mutations (E31A, L32A, G37A, and Q38A) abrogate binding to phyB.

(B) APB mutations in PIF4:GAD (G35A) and GAD:PIF3 (E31A/G37A) eliminate their interactions with phyB (Pfr).