Localization of the Raf-like kinase CTR1 to the endoplasmic reticulum of Arabidopsis through participation in ethylene receptor signaling complexes.

The plant hormone ethylene is perceived by a five-member family of receptors related to the bacterial histidine kinases. The Raf-like kinase CTR1 functions downstream of the ethylene receptors as a negative regulator of ethylene signal transduction. CTR1 is shown here to be associated with membranes of the endoplasmic reticulum in ...
Arabidopsis as a result of its interactions with ethylene receptors. Membrane association of CTR1 is reduced by mutations that eliminate ethylene receptors and by a mutation in CTR1 that reduces its ability to bind to the ethylene receptor ETR1. Direct evidence that CTR1 is part of an ethylene receptor signaling complex was obtained by co-purification of the ethylene receptor ETR1 with a tagged version of CTR1 from an Arabidopsis membrane extract. The histidine kinase activity of ETR1 is not required for its association with CTR1, based on co-purification of tagged ETR1 mutants and CTR1 after expression in a transgenic yeast system. These data demonstrate that CTR1 is part of an ethylene receptor signaling complex in Arabidopsis and support a model in which localization of CTR1 to the endoplasmic reticulum is necessary for its function. Additional data that demonstrate a post-transcriptional effect of ethylene upon the expression of CTR1 suggest that production of ethylene receptor signaling complexes may be coordinately regulated.
Mesh Terms:
Arabidopsis, Blotting, Northern, Cell Membrane, Centrifugation, Density Gradient, Endoplasmic Reticulum, Glutathione Transferase, Immunoblotting, Microsomes, Models, Biological, Mutation, Plant Proteins, Protein Binding, Protein Kinases, Proto-Oncogene Proteins c-raf, RNA, Receptors, Cell Surface, Recombinant Fusion Proteins, Signal Transduction, Sucrose, Time Factors
J. Biol. Chem.
Date: Sep. 05, 2003
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