Figure 1.

BOI Proteins Interact with DELLA Proteins.

(A) Yeast two-hybrid data showing interactions between the four BOIs (BOI, BRG1, BRG2, and BRG3) and five DELLAs (GAI, RGA, RGL1, RGL2, and RGL3). SD-2, minimal medium lacking Trp and Leu; SD-4, minimal medium lacking Trp, Leu, His, and adenine.

(B) MBP pull-down assay showing the interaction between plant-expressed FLAG-tagged BOIs and recombinant MBP-DELLAs. Extracts of 7-d-old light-grown stable transgenic seedlings expressing FLAG-tagged BOI, BRG2, BRG3, or GFP (BOI-OX5, BRG2-OX1, BRG3-OX1, or GFP-OX) were mixed with MBP-tagged GAI, RGA, RGL2, or MBP alone and precipitated with MBP resin. Precipitated BOIs were detected with an anti-FLAG antibody. Ponceau S shows the amount of MBP-fused protein stained by Ponceau S dye.

(C) Coimmunoprecipitation assay showing the interaction between FLAG-BOI and endogenous RGA in the sly1-10 mutant. FLAG-tagged BOI or FLAG-tagged GFP was transiently expressed in 10-d-old light-grown sly1-10 mutant by Agrobacterium tumefaciens infiltration and precipitated with an anti-FLAG antibody. Precipitated RGA was detected with an anti-RGA antibody (see Supplemental Figure 2 online). Input shows the amount of RGA detected by anti-RGA antibody.

(D) Coimmunoprecipitation assay showing the interaction between stably expressed FLAG-tagged BOI and endogenous RGA. Stable transgenic seedlings expressing either FLAG-tagged BOI (BOI-OX5) or FLAG-tagged GFP (GFP-OX) were grown on the medium containing 1 µM PAC under the white light condition for 10 d. After precipitating with an anti-FLAG antibody, coimmunoprecipitated endogenous RGA was detected with an anti-RGA antibody. *Immunoprecipitated GFP-FLAG; **immunoprecipitated BOI-FLAG. GFP-FLAG signal is much stronger than BOI-FLAG due to much higher expression level of GFP-FLAG.

[See online article for color version of this figure.]