Predominant actions of cytosolic BSU1 and nuclear BIN2 regulate subcellular localization of BES1 in brassinosteroid signaling

Mol Cells. 2010 Mar;29(3):291-6. doi: 10.1007/s10059-010-0034-y. Epub 2010 Jan 14.


During brassinosteroid (BR) signaling in Arabidopsis, BSU1 (bri1 SUPPRESSOR1) phosphatase and BIN2 (BRASSINOSTEROID INSENSITIVE2) kinase regulate the signal intensity by determining the phosphorylation status of the transcription factors BZR1 (BRASSINAZOLE RESISTANT1) and BES1 (bri1 EMS SUPPRESSOR1). Here, we report hat BIN2 and BSU1 are nucleocytoplasmic regulators that modulate the subcellular localization of BES1, with differential activities between the nucleus and the cytosol. In our experiments, the nuclear BIN2 induced phosphorylation and nuclear export of BES1 more efficiently than cytosolic BIN2.The cytoplasmic BSU1 mediated the dephosphorylation and nuclear translocation of BES1 more efficiently than the nuclear one. BSU1 compromised the dwarf phenotype of bri1-5, a weak allele of BRI1 (BR-INSENSITIVE 1) receptor kinase, more effectively when localized in the cytosol than in the nucleus in transgenic plants. In conclusion, the predominance of cytosolic BSU1 and nuclear BIN2 might be required for the efficient subcellular localization of BES1 in BR signaling.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / metabolism*
  • Arabidopsis Proteins / physiology*
  • Cell Nucleus / metabolism*
  • Cytosol / metabolism*
  • DNA-Binding Proteins
  • Hydroxysteroids / metabolism*
  • Nuclear Proteins / metabolism*
  • Phosphoprotein Phosphatases / physiology*
  • Plant Growth Regulators / metabolism*
  • Protein Kinases / physiology*
  • Signal Transduction / physiology*


  • Arabidopsis Proteins
  • BES1 protein, Arabidopsis
  • DNA-Binding Proteins
  • Hydroxysteroids
  • Nuclear Proteins
  • Plant Growth Regulators
  • Protein Kinases
  • BIN2 protein, Arabidopsis
  • BSU1 protein, Arabidopsis
  • Phosphoprotein Phosphatases