Plant biology

Surface Steroid Sensors

Science's STKE  20 Mar 2001:
Vol. 2001, Issue 74, pp. tw11
DOI: 10.1126/stke.2001.74.tw11

The brassinosteroid insensitive gene (BRI1) encodes a plasma membrane-localized, transmembrane serine/threonine kinase of the leucine-rich repeat (LRR) family. Genetic studies suggest that BRI1 participates in the response to the plant steroid hormone brassinosteroid. Wang et al. provide evidence from binding assays with BRI1-overexpressing plants and immunoprecipitation of BRI1 that BRI1 is in fact the brassinosteroid receptor. Furthermore, treatment of seedlings with brassinosteroid induced phosphorylation of BRI1, which was dependent on the cytoplasmic kinase domain of BRI1, suggesting that BRI1 autophosphorylates in response to brassinosteroid binding. Genomic analysis indicates that plants lack conventional nuclear steroid hormone receptors. These studies confirm that steroid signaling is initiated at the plasma membrane in plants and suggest that steroid signaling initiates a phosphorylation cascade beginning with the steroid receptor itself.

Z.-Y. Wang, H. Seto, S. Fujioka, S. Yoshida, J. Chory, BRI1 is a critical component of a plasma-membrane receptor for plant steroids. Nature 410, 380-383 (2001). [Online Journal]