Fig. 1.

Interacting partners in brassinosteroid (BR) signaling. Upon binding of brassinolide (BL) to BRI1, SERK3 dissociates from the receptor and transphosphorylation take place with SERK1/SERK3. Subsequently phosphorylation of BZR1 by BIN2 is inhibited. This leads to accumulation of dephosphorylated BZR1 and BES1 in the nucleus, which induces gene transcription. Furthermore, phosphorylated BZR1 translocated to the cytoplasm is retained there by 14-3-3 proteins, and only dephosphorylated BZR1 translocates back to the nucleus