中文摘要：

油菜素内酯（brassinosteroids,BRs）是一类重要的类固醇激素,参与调控植物生长发育的许多过程。结合应用遗传学、生物化学以及蛋白质组学等研究手段现已基本阐明了BR信号转导的主要过程。BRI1作为受体在细胞表面感知BR,BRI1抑制子BKI1从质膜上解离下来,使BRI1与其共受体BAK1结合。BRI1和BAK1通过顺序磷酸化将BR信号完全激活。活化的BRI1将BSK磷酸化激活,BSK活化BSU1,BSU1将BIN2去磷酸化使其失活,解除BIN2对BES1/BZR1的抑制功能。PP2A可以将BES1/BZR1去磷酸化激活,又可以将受体BRI1去磷酸化促使其降解。BR信号的传递最终使去磷酸化状态的BES1/BZR1在细胞内累积,激活BR信号通路下游的转录调控。

英文摘要：

Brassinosteroids（BRs） are a class of steroidal hormones,playing essential roles in a wide range of processes during plant growth and development.The combined genetics,biochemistry and proteomics approaches have been employed to elucidate the major events in BR signaling pathway,mainly via a series of reversible phosphorylation and dephosphorylation processes.Perception of BR by the BR receptor BRI1 at cell surface leads to the dissociation of BRI1 kinase inhibitor BKI1 from the plasma membrane and association of BRI1 with its co-receptor BAK1.Sequential transphosphorylation of the paired BRI1/BAK1 receptor kinases completely activates the BR signaling cascade.BRI1 phosphorylation of the BSK kinases leads to the activation of the BSU1 phosphatases,which can function to dephosphorylate and inactivate the BIN2 kinase.PP2A phosphatases play dual roles in mediating BR signaling pathway including dephosphorylating BES1/BZR1 transcription factors to promote their functions and dephosphorylating BRI1 to make it less stable.These events result in the accumulation of unphosphorylated BES1/BZR1 transcription factors in the nucleus and subsequent activation of the downstream transcriptional network.