Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.
Tyrosine phosphorylation controls brassinosteroid receptor activation by triggering membrane release of its kinase inhibitor
Zachary L. Nimchuk3,
Elliot M. Meyerowitz3,, and
1 Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA; 2 Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, California 92037, USA; 3 Division of Biology 156-29, California Institute of Technology, Pasadena, California 91125, USA
Receptor tyrosine kinases control many critical processes inmetazoans, but these enzymes appear to be absent in plants.Recently, two Arabidopsis receptor kinases—BRASSINOSTEROIDINSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED KINASE1 (BAK1), thereceptor and coreceptor for brassinosteroids—were shownto autophosphorylate on tyrosines. However, the cellular rolesfor tyrosine phosphorylation in plants remain poorly understood.Here, we report that the BRI1 KINASE INHIBITOR 1 (BKI1) is tyrosinephosphorylated in response to brassinosteroid perception. Phosphorylationoccurs within a reiterated [KR][KR] membrane targeting motif,releasing BKI1 into the cytosol and enabling formation of anactive signaling complex. Our work reveals that tyrosine phosphorylationis a conserved mechanism controlling protein localization inall higher organisms.