Related Experiment Video
Updated: Jun 20, 2026

Reverse Yeast Two-hybrid System to Identify Mammalian Nuclear Receptor Residues that Interact with Ligands and/or Antagonists
Published on: November 15, 2013
Brassinosteroid signal transduction from cell-surface receptor kinases to nuclear transcription factors
Tae-Wuk Kim1, Shenheng Guan, Yu Sun
1Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA.
Abstract:
Brassinosteroid (BR) regulates gene expression and plant development through a receptor kinase-mediated signal transduction pathway. Despite the identification of many components of this pathway, it remains unclear how the BR signal is transduced from the cell surface to the nucleus. Here we describe a complete BR signalling pathway by elucidating key missing steps. We show that phosphorylation of BSK1 (BR-signalling kinase 1) by the BR receptor kinase BRI1 (BR-insensitive 1) promotes BSK1 binding to the BSU1 (BRI1 suppressor 1) phosphatase, and BSU1 inactivates the GSK3-like kinase BIN2 (BR-insensitive 2) by dephosphorylating a conserved phospho-tyrosine residue (pTyr 200). Mutations that affect phosphorylation/dephosphorylation of BIN2 pTyr200 (bin2-1, bin2-Y200F and quadruple loss-of-function of BSU1-related phosphatases) support an essential role for BSU1-mediated BIN2 dephosphorylation in BR-dependent plant growth. These results demonstrate direct sequential BR activation of BRI1, BSK1 and BSU1, and inactivation of BIN2, leading to accumulation of unphosphorylated BZR (brassinazole resistant) transcription factors in the nucleus. This study establishes a fully connected BR signalling pathway and provides new insights into the mechanism of GSK3 regulation.
Related Concept Videos
Cell Signaling in Plants
Signal Transduction: Overview
Typically, signal transduction involves three...
Types of Receptors: Internal Receptors
Similar to membrane-bound receptors, the binding of a ligand to the intracellular receptor of causes a conformational change in the...
Internal Receptors
Amplifying Signals via Enzymatic Cascade
Transducer Mechanism: Nuclear Receptors
About 48 different soluble family members of nuclear receptors are identified that can be divided into two main classes:

