Binding of brassinosteroids to the extracellular domain of plant receptor kinase BRI1

摘要: Both animals and plants use steroids as signalling molecules during growth development. Animal are principally recognized by members of the nuclear receptor superfamily transcription factors. In plants, BRI1, a leucine-rich repeat (LRR) kinase localized to plasma membrane, is critical component complex for brassinosteroids. Here, we present first evidence direct binding active brassinosteroids BRI1 using biotin-tagged photoaffinity castasterone (BPCS), biosynthetic precursor brassinolide (the most brassinosteroids). Binding studies BPCS, (3)H-labelled recombinant fragments show that minimal domain consists 70-amino acid island (ID) located between LRR21 LRR22 in extracellular together with carboxy-terminal flanking LRR (ID-LRR22). Our results demonstrate bind directly 94 amino acids comprising ID-LRR22 define new steroid hormones.