title: Localization of the Raf-like kinase CTR1 to the endoplasmic reticulum of Arabidopsis through participation in ethylene receptor signaling complexes.
abstract: 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.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of New Hampshire, Durham, New Hampshire 03824, USA.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Gao
authors.forename: Yi-Feng
authors.initials: YF
authors.lastname: Chen
authors.forename: Melynda D
authors.initials: MD
authors.lastname: Randlett
authors.forename: Xue-Chu
authors.initials: XC
authors.lastname: Zhao
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Findell
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Kieber
authors.forename: G Eric
authors.initials: GE
authors.lastname: Schaller
mesh_terms: D017360:Arabidopsis / Q000201:enzymology*; D015152:Blotting, Northern; D002462:Cell Membrane / Q000201:enzymology; D002499:Centrifugation, Density Gradient; D004721:Endoplasmic Reticulum / Q000201:enzymology* / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D015151:Immunoblotting; D008861:Microsomes / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D010940:Plant Proteins / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases / Q000096:biosynthesis* / Q000737:chemistry*; D019908:Proto-Oncogene Proteins c-raf / Q000737:chemistry*; D012313:RNA / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D013395:Sucrose / Q000494:pharmacology; D013997:Time Factors
chemical_list: D010940:Plant Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; C083750:ethylene receptors, plant; D013395:Sucrose; D012313:RNA; D005982:Glutathione Transferase; D011494:Protein Kinases; C477753:CTR1 protein, Arabidopsis; D019908:Proto-Oncogene Proteins c-raf