Abstract
Plant steroid hormones, known as brassinosteroids (BRs), signal through a plasma membrane localized receptor kinase BRI1. We identified bes1, a semidominant suppressor of bri1, which exhibits constitutive BR response phenotypes including long and bending petioles, curly leaves, accelerated senescence, and constitutive expression of BR-response genes. BES1 accumulates in the nucleus in response to BRs. BES1 is phosphorylated and appears to be destabilized by the glycogen synthase kinase-3 (GSK-3) BIN2, a negative regulator of the BR pathway. These results establish a signaling cascade for BRs with similarities to the Wnt pathway, in which signaling through cell surface receptors leads to inactivation of a GSK-3 allowing accumulation of a nuclear protein that regulates target gene expression.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Amino Acid Sequence / genetics
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Arabidopsis / genetics
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Arabidopsis / growth & development*
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Arabidopsis / metabolism
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / isolation & purification*
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Arabidopsis Proteins / metabolism
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Cell Differentiation / genetics*
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Cell Nucleus / genetics
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Cell Nucleus / metabolism*
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DNA-Binding Proteins
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Down-Regulation / genetics
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Gene Expression Regulation, Plant / genetics*
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Molecular Sequence Data
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Mutation / genetics
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Nuclear Proteins / genetics
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Nuclear Proteins / isolation & purification*
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Nuclear Proteins / metabolism
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Phytosterols / metabolism*
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Plant Stems / genetics
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Plant Stems / growth & development*
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Plant Stems / metabolism
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Protein Kinases / genetics
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Protein Kinases / metabolism
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Up-Regulation / genetics
Substances
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Arabidopsis Proteins
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BES1 protein, Arabidopsis
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BZR1 protein, Arabidopsis
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DNA-Binding Proteins
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Nuclear Proteins
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Phytosterols
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Protein Kinases
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BIN2 protein, Arabidopsis