title: Tyrosine phosphorylation controls brassinosteroid receptor activation by triggering membrane release of its kinase inhibitor.
abstract: 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.
authors.affiliation: Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
authors.forename: Yvon
authors.initials: Y
authors.lastname: Jaillais
authors.forename: Michael
authors.initials: M
authors.lastname: Hothorn
authors.forename: Youssef
authors.initials: Y
authors.lastname: Belkhadir
authors.forename: Tsegaye
authors.initials: T
authors.lastname: Dabi
authors.forename: Zachary L
authors.initials: ZL
authors.lastname: Nimchuk
authors.forename: Elliot M
authors.initials: EM
authors.lastname: Meyerowitz
authors.forename: Joanne
authors.initials: J
authors.lastname: Chory
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D017124:Conserved Sequence; D004789:Enzyme Activation; D008958:Models, Molecular; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D016415:Sequence Alignment; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C513107:BKI1 protein, Arabidopsis; D014443:Tyrosine; D011494:Protein Kinases; C463660:BAK1 protein, Arabidopsis; C108270:BRI1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases