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Fig. 3 | BMC Biology

Fig. 3

From: Q&A: what are brassinosteroids and how do they act in plants?

Fig. 3

The brassinosteroid signal transduction pathway in the absence (a) and presence (b) of brassinosteroid (BR) in Arabidopsis. Brassinosteroid binding induces BRI1 heterodimerization with its co-receptor BAK1, resulting in activation of BRI1, phosphorylation of BKI1 by BRI1 and dissociation of BKI1 from BRI1. These events lead to full activation of BRI1, which phosphorylates BSK1 and CDG1. Once activated, BSK1 and CDG1 promote the activation of the phosphatase BSU1, thus dephosphorylating and inactivating BIN2. The inactivated BIN2 allows the presence of the dephosphorylated form of BZR1/2, which can move into the nucleus and regulate transcription of many target genes. The phosphorylated BZR1/2 are retained in the cytoplasm by 14-3-3. Arrows and short lines represent promotion and inhibition, respectively. The small circles containing the letter ‘P’ indicate phosphorylation

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