Molecular Mechanism for Plant Steroid Receptor Activation by Somatic Embryogenesis Co-Receptor Kinases

Abstract

Steroid Receptor Signaling Plant brassinosteroids signal to diverse pathways in plant physiology. These steroid hormones are perceived at the cell surface, where they bind to the receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1). Santiago et al. (p. 889 , published online 8 August) now show that somatic embryogenesis receptor kinase 1 (SERK1) complexes with BRI1. Together, these receptor kinases form the steroid binding site, with the hormone acting as a “molecular glue” that stabilizes the interaction. Hormone-induced heteromerization of BRI1 with SERK1 leads to the activation of the cytoplasmic signaling cascade, triggering plant growth and differentiation.