Tyrosine phosphorylation controls brassinosteroid receptor activation by triggering membrane release of its kinase inhibitor

Genes Dev. 2011 Feb 1;25(3):232-7. doi: 10.1101/gad.2001911.


Receptor tyrosine kinases control many critical processes in metazoans, but these enzymes appear to be absent in plants. Recently, two Arabidopsis receptor kinases--BRASSINOSTEROID INSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED KINASE1 (BAK1), the receptor and coreceptor for brassinosteroids--were shown to autophosphorylate on tyrosines. However, the cellular roles for tyrosine phosphorylation in plants remain poorly understood. Here, we report that the BRI1 KINASE INHIBITOR 1 (BKI1) is tyrosine phosphorylated in response to brassinosteroid perception. Phosphorylation occurs within a reiterated [KR][KR] membrane targeting motif, releasing BKI1 into the cytosol and enabling formation of an active signaling complex. Our work reveals that tyrosine phosphorylation is a conserved mechanism controlling protein localization in all higher organisms.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Arabidopsis / enzymology
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cell Membrane / metabolism*
  • Conserved Sequence
  • Enzyme Activation*
  • Models, Molecular
  • Mutation
  • Phosphorylation
  • Protein Binding
  • Protein Kinases / chemistry
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Protein Serine-Threonine Kinases / metabolism
  • Protein Structure, Tertiary
  • Protein Transport
  • Sequence Alignment
  • Tyrosine / metabolism*


  • Arabidopsis Proteins
  • BKI1 protein, Arabidopsis
  • Tyrosine
  • Protein Kinases
  • BAK1 protein, Arabidopsis
  • BRI1 protein, Arabidopsis
  • Protein Serine-Threonine Kinases