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First published online July 20, 2007; 10.1104/pp.107.104299 Plant Physiology 145:75-86 (2007) © 2007 American Society of Plant Biologists RTE1 Is a Golgi-Associated and ETR1-Dependent Negative Regulator of Ethylene Responses1,[C],[W]National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
Arabidopsis (Arabidopsis thaliana) RTE1 encodes a membrane protein and negatively regulates ethylene responses. Genetic and transformation studies suggest that the function of the wild-type RTE1 is primarily dependent on ETR1 and can be independent on the other receptors. Ethylene insensitivity caused by the overexpression of RTE1 is largely masked by the etr1-7 mutation, but not by any other receptor mutations. The wild-type ETR1 N terminus is sufficient to the activation of the RTE1 function and the ectopic expression of etr1(1–349) restored ethylene insensitivity conferred by 35S::gRTE1 in etr1-7. The RTE1 N terminus is not essential to the etr1-2 function and the expression of rte1(N  49), which has an N-terminal deletion of 49 amino acid residues, restored ethylene insensitivity in etr1-2 rte1-2. The ectopic expression of GREEN FLUORESCENT PROTEIN (GFP)-RTE1 conferred ethylene insensitivity in wild type and the GFP fusion displayed fast movement within the cytoplasm. The GFP-RTE1 and EYFP-NAG proteins colocalized and the Brefeldin A treatment caused aggregation of GFP-RTE1, suggesting RTE1 is a Golgi-associated protein. Our results suggest specificity of the RTE1 function to ETR1 and that endomembranes may play a role in the ethylene signal transduction.
Ethylene is a gaseous hormone important to plant growth and development. In Arabidopsis (Arabidopsis thaliana), the dark-grown seedling exhibits an elongated and thin hypocotyl and a long radical root. Ethylene treatment causes the so-called triple response in etiolated seedlings; that is, growth inhibition in the seedling hypocotyl and radical root, the swelling of the hypocotyl, and exaggerated tightening in the apical hook (Guzman and Ecker, 1990  ). For light-grown seedlings exhibiting ethylene responses, the primary root becomes short and cotyledons are small, erected, and epinastic (Xie et al., 2006). In the adult stage, ethylene responses lead to reduction in rosette size (Hua and Meyerowitz, 1998; Xie et al., 2006). The seedling triple response can be used to isolate ethylene response mutants in Arabidopsis (Guzman and Ecker, 1990) and to score for degrees of ethylene responses (Hua and Meyerowitz, 1998; Qu and Schaller, 2004; Xie et al., 2006).
There are five ethylene receptors (ETR1, ERS1, ETR2, EIN4, and ERS2) in Arabidopsis and they are structurally similar to prokaryotic two-component modules. Suc gradient fractionation suggests that ETR1 is an endoplasmic reticulum (ER)-associated protein (Chen et al., 2002
A chemical screen for a mutant responsive to the ethylene antagonist trans-cyclooctene identifies RESISTANT TO ANTAGONIST1 (RAN1), which encodes a copper-transporting P-type ATPase protein (Hirayama et al., 1999
RTE1 encodes a putative membrane protein, conserved among higher eukaryotes, and is isolated from a suppressor screen against the dominant etr1-2 receptor mutant (Resnick et al., 2006
The etr1-2 mutation (102Ala In this study, we comprehensively analyzed genetic interactions of RTE1 and ethylene receptor genes in loss-of-function mutants and RTE1 overexpression lineages. Domains that could be important to the function of ETR1 and RTE1 were studied through the expression of truncated etr1 and rte1 variants. Subcellular localization of the RTE1 and rte1-2 proteins was shown by expressing functional GFP fusions in Arabidopsis and onion (Allium cepa) epidermal cells. Possible mechanisms by which ethylene responses are regulated by ETR1 and RTE1 are discussed.
The Function of RTE1 Overexpression Is Primarily Dependent on ETR1
Ethylene insensitivity conferred by the RTE1 overexpression is almost masked by the etr1-7 null mutation (Resnick et al., 2006 The 35S promoter-driven genomic RTE1 clone (35S::gRTE1) was transformed to ers1-2 etr2-3 ein4-4 ers2-3, in which ETR1 is the only wild-type receptor gene. For three individual transformation lines examined, 35S::gRTE1 conferred ethylene insensitivity in wild type and ers1-2 etr2-3 ein4-4 ers2-3 in the seedling triple-response assay (Fig. 1, A and B ). As a control, the untransformed wild-type and quadruple mutants were ethylene responsive and displayed growth inhibition in the seeding hypocotyl and primary root.
Ethylene insensitivity conferred by 35S::gRTE1 was next examined in light-grown seedling. The ers1-2 etr2-3 ein4-4 ers2-3 mutant exhibited small cotyledons and short primary root when germinated under light (data not shown). As shown in Figure 1C, light-grown 35S::gRTE1 ers1-2 etr2-3 ein4-4 ers2-3 transformation lines exhibited normal growth and expanded cotyledons compared with wild type. Because ethylene insensitivity conferred by the overexpression of RTE1 is substantially inactivated by etr1-7, and our results show that the inactivation of the other four receptor genes does not perturb the function of the 35S::gRTE1 transgene, ethylene insensitivity conferred by the RTE1 overexpression is primarily dependent on ETR1. On the other hand, those lines represent individual transformation events; degrees of the 35S::RTE1 function affected by the etr1-7 mutation cannot be quantified. To score effects of the inactivation of ETR1 on the function of RTE1 overexpression, the 35S::gRTE1 transgene was genetically introgressed from individual wild-type transformation lines to etr1-7. As a result, the 35S::gRTE1 transgene was expressed on the same locus in wild type and etr1-7; effects of the etr1-7 mutation on the function of RTE1 overexpression can be quantitatively evaluated.
In one cross, the resulting F1 seedlings exhibited mild ethylene responses (data not shown). In the F2 generation, 39 individual seedlings were classified into three groups according to degrees of ethylene responses (Fig. 1D). According to this classification, we further scored 174 individual F2 seedlings, of which 61 individuals fell into the longest group, 46 into the second, and 67 into the shortest. Because the F1 parent had a reduced hypocotyl length when germinated in ethylene, we suspected that the second group would be 35S::gRTE1/–;ETR1/etr1-7. Analyzed by To further study how the copy number of 35S::gRTE1 and ETR1 would determine degrees of ethylene responses, three individual introgression lineages carrying different copy numbers of 35S::gRTE1 and ETR1 were scored for the seedling hypocotyl length (Fig. 1F). Lineages homozygous in 35S::gRTE1 and ETR1 (+/+; +/+) exhibited the longest seedling hypocotyl. The loss of one copy of 35S::gRTE1 (+/–; +/+) caused a mild reduction in the hypocotyl length. The loss of one copy of ETR1 (+/+; +/–) caused a greater reduction. Seedling hypocotyl of heterozygous lineages (+/–; +/–) was about 40% shorter than that of homozygous lineages (Fig. 1, G and H). When ETR1 was replaced by etr1-7, the hypocotyl was slightly longer than etr1-7 (P < 0.05). These results further indicate that not only is ETR1 gene but also the ETR1 dosage essential to the function of RTE1 overexpression.
Specificity of the function of RTE1 overexpression to ETR1 was reciprocally demonstrated in the quadruple and etr1-7 mutants. However, the function of RTE1 overexpression could be hypermorphic or neomorphic; roles of receptor genes in the wild-type RTE1 function will need to be examined in loss-of-function mutants. In this study, the rte1-2 mutation was introgressed to receptor mutants to examine if the inactivation of any receptor genes would result in the inactivation of the wild-type RTE1 gene. Because rte1 mutants phenocopy etr1-7 (Resnick et al., 2006
Mutants defective in RTE1 and multiple receptor genes were scored for seedling and adult phenotypes and degrees of ethylene responses were scored by the seedling triple-response assay (Fig. 2, A and C
). To eliminate endogenous ethylene production, the ethylene biosynthesis inhibitor L-
Although the inactivation of RTE1 leads to derepression in ethylene responses, the introgression of the rte1-2 mutation to etr1-7 ers2-3 did not alter degrees of ethylene responses in the seedling triple-response assay as well as in other developmental stages (Fig. 2). This result is consistent with the previous study that rte1 phenotypically resembles etr1 rte1 mutants (Resnick et al., 2006 ). These data suggest that the wild-type RTE1 cannot repress ethylene responses in the absence of ETR1.
Northern analysis shows that the RTE1 transcript accumulates 2.5 h after ethylene treatment (Resnick et al., 2006 In dark-grown seedlings, fluorescence was the highest in cotyledons and weaker in hypocotyl and root (Fig. 3A ). Figure 3B shows 3-week-old plants that displayed the strongest fluorescence in growing young leaves (Fig. 3C). Figure 3D shows that developing leaves, leaf veins, rachis, and flowers exhibited strong fluorescence in an adult plant. Tissues between veins in expanded leaves exhibited weaker fluorescence. For light-grown seedlings, cotyledons and developing leaves exhibited the highest fluorescence than hypocotyls and roots (Fig. 3E).
In northern analysis, the RTE1 hybridization signal appears as a doublet (Resnick et al., 2006 ), implying the existence of transcripts with two lengths. To further characterize the two transcripts, sequence of the 3' end of the RTE1 transcript was examined by the 3' RACE, and we did not identify any alternative polyadenylation site (data not shown). Examined by the 5' RACE, the RTE1 transcript gave two major amplification signals (Fig. 3F) and the resulting cDNA fragments were sequenced. For three independent 5' RACE and sequencing, we identified that sequence of the short fragment starts in the second intron and that the long fragment represents the full-length RTE1 transcript (Fig. 3G). Our data show that RTE1 is globally expressed throughout developmental stages and has two transcripts.
Although RTE genes are prevalent in higher eukaryotes, domains or motifs of known function are not found in RTE1. RTE1 shares poor similarity with other plant RTE-like proteins in the N terminus (Barry and Giovannoni, 2006
In this study, two rte1 variants with N-terminal deletions were each expressed in etr1-2 rte1-2 and the resulting transformation lines were scored for the seedling triple response. We found that each of the overexpression of rte1(N
These results imply that the RTE1 N terminus may not exhibit functional specificity; rather, nearly 20% of the RTE1 N terminus is not essential to the etr1-2 function. Because the loss of the second transmembrane domain inactivates RTE1 (Resnick et al., 2006 ), the C terminus cannot be dispensable.
Our data show that ETR1 is essential to the RTE1 function; domains on ETR1 that could be essential to the functioning of RTE1 were next examined.
The etr1(1–609) transgene encodes a receiver domain-lacking etr1 variant and etr1(1–349) encodes an etr1 variant that has the three transmembrane domains (TMDs) and the GAF domain (Xie et al., 2006
These results show that the ETR1 N terminus, including the three transmembrane domains and the GAF domain, is sufficient to the functioning of RTE1 while ETR1 His-kinase and receiver domains can be dispensable.
In an attempt to identify the subcellular localization of the RTE1 protein, each of the RTE1 N and C termini was fused with the GFP and ectopically expressed under the control of the native RTE1 or 35S promoter. The RTE1-GFP fusion, of which the RTE1 C terminus was fused with GFP, failed to cause ethylene insensitivity in wild type and to rescue the rte1-2 mutation in rte1-2 etr1-2 (data not shown). The GFP-RTE1 fusion, of which GFP was fused to the N terminus of RTE1, was able to cause some degrees of ethylene insensitivity in wild type and partially rescue the rte1-2 mutation in rte1-2 etr1-2 (Fig. 6, A and B ). The expression of 35S::GFP-rte1-2 failed to, respectively, restore and confer ethylene insensitivity in etr1-2 rte1-2 and wild type (data not shown).
Fluorescence patterns of 35S::GFP-RTE1- and RTE1p::GFP-RTE1-transformed wild type were similar to that of the 35S::GFP-rte1-2 transformed, except that RTE1p::GFP-RTE1 gave a weaker fluorescence signal (see Supplemental Fig. S1). These results indicate that the GFP-RTE1 fusion protein is functional and dominant, and that its subcellular localization could be sites where RTE1 exerts its function. Besides, the rte1-2 mutation may cause dysfunction of RTE1, rather than mislocalization as previously proposed (Resnick et al., 2006 ).
Laser scanning confocal microscopy (LSCM) shows that the green fluorescence signal of GFP-RTE1 was fast moving, suggesting that its movement is associated with cellular structures in the cytoplasm (Fig. 6C). Because RTE1 encodes a membrane protein, we next examined if RTE1 may associate with any endomembranes, including the ER and Golgi. GFP-ER, an ER-localized marker, displayed a unique reticular fluorescence pattern that is distinct to GFP-RTE1 and EYFP-NAG (see Supplemental Fig. S2), of which EYFP-NAG was a marker for the Golgi localization (Xu and Scheres, 2005 Because the RTE1 function is ETR1 dependent and ETR1 is localized to the ER, we next examined if trace amounts of RTE1 would localize to the ER. By the LSCM, a three-dimensional (3-D) fluorescence pattern was constructed. GFP-RTE1 displayed a similar 3-D pattern as EYFP-NAG and the fluorescence largely located to the Golgi. In addition, weak reticular fluorescence was also visible in small regions (Fig. 6E). This result suggests that GFP-RTE1 is mainly localized to the Golgi; very small amounts of GFP-RTE1 and EYFP-NAG may reside in the ER.
According to its size (in micrometers), fast-moving feature, and colocalization with EYFP-NAG, RTE1 appears to predominantly associate with the Golgi. Brefeldin A (BFA) is a fungal toxin and can cause the accumulation of the Golgi, the so-called BFA compartments, and the redistribution of Golgi membranes into the ER in plant cells (Nebenfuhr et al., 2002 Effects of ethylene treatment on the RTE1 protein were next examined. 1-Aminocyclopropane-1-carboxylic acid (ACC) is the immediate precursor of ethylene biosynthesis and has been used to replace the ethylene treatment. For a period of 60 min ACC treatment, the movement, subcellular localization, and fluorescence intensity of the green fluorescence were not noticeably altered in seedlings expressing the 35S::GFP-RTE1 transgene (Fig. 6C). For prolonged (3 h) ACC treatments, the GFP fluorescence intensity gradually dropped; as a comparison, the water treatment gave a similar drop in the GFP fluorescence in Arabidopsis (Fig. 6F). Our data suggest that the ethylene (ACC) treatment dose not regulate RTE1 at protein levels.
etr1-7 and rte1 mutants are phenotypically identical and it is hypothesized that RTE1 is largely required for the wild-type ETR1 function (Resnick et al., 2006 ). Our data, however, show that the function of RTE1 is ETR1 dependent and that ETR1 has a greater effect than RTE1 on the repression of ethylene responses. This discrepancy is not mutually exclusive but could be caused by ways that the rte1 and etr1 mutant phenotypes were scored. For example, subtle effects caused by the rte1 and etr1 mutations on ethylene responses become prominent in multiple mutants but not in single mutants. Because the inactivation of ETR1 masks the RTE1 function, it is likely that RTE1 has a regulatory role in the wild-type ETR1 activity and that the loss of RTE1 weakens, but does not nullify, the ETR1 receptor signal output. As a result, the introgression of rte1-2 to receptor mutants, except for etr1-7, leads to enhanced ethylene responses. Without ETR1, RTE1 becomes an orphan component and cannot exert repression in ethylene responses; thus, the introgression of rte1 to etr1-7 mutants had little effect on ethylene responses. In other words, the etr1-7 mutation indeed results in the inactivation of both ETR1 and RTE1 while rte1 mutations cause the inactivation of RTE1 as well as the weakening of the ETR1 activity. This hypothesis further explains why the rte1-3 ers1-3 mutant would not exhibit the extremely severe etr1 ers1 mutant phenotype.
Mutational analysis suggests that ETR1 exists in transmitter-on and transmitter-off states. The transmitter-on ETR1 can be either free of ethylene (state I) or bound with ethylene (state II). The transition of ETR1 from state II to state III (transmitter off) abolishes the ETR1 receptor activity. The etr1-2 mutation (102Ala Conceivably, in wild type, endogenous RTE1 protein is not sufficient to the stabilization of ethylene-bound ETR1 in the transmitter-on states; thus, ethylene binding converts the ETR1 protein to the transmitter-off state III. When overexpressed, the RTE1 protein may exceed a threshold that would be sufficient to, constitutively, maintain the ethylene-bound ETR1 protein in an active state, leading to ethylene insensitivity. This hypothesis is in agreement with our finding that the copy number of the 35S::gRTE1 transgene and ETR1 receptor gene determines degrees of ethylene insensitivity. In the 35S::gRTE1/– lineages (+/–; +/+) the RTE1 level could be lower but still exceeds a threshold to stabilize majority of the ETR1 protein in the transmitter-on states. For lineages in which one copy of ETR1 is lacking, levels of the active ETR1 in active states are reduced, leading to substantial weakening in ethylene insensitivity even if an excessive amount of the RTE1 protein is available. When single copy of each 35S::gRTE1 and ETR1 genes are both missing (+/–; +/–), levels of transmitter-on ETR1 become even lower and degrees of ethylene insensitivity are reduced. Possibly, excessive amount of the RTE1 protein nonspecifically maintains a minor fraction of the other receptors in an active state; as a result, the 35S::gRTE1 etr1-7 lineages exhibit weak ethylene insensitivity. The dominant etr1-1 protein does not bind ethylene and thus stays in a constitutive transmitter-on state that is completely independent on RTE1. Although the RTE1 transcript accumulates upon the ethylene treatment, the amount of elevation appears modest and insufficient to alter ethylene responses. However, the minor up-regulation in the RTE1 expression could fine tune ethylene responses.
Because the expression of etr1(1–349) restored ethylene insensitivity in 35S::gRTE1 etr1-7, the ETR1 N terminus could be a target of RTE1. Previously we demonstrated that the receptor signal output mediated by the truncated etr1(1–349) is dependent on subfamily I receptors (Xie et al., 2006
Our data suggest that RTE1 is ubiquitously expressed based on the LUC fluorescence pattern. Because the ETR1 promoter-driven LUC also shows a whole-plant expression pattern (C.-K. Wen, unpublished data), both RTE1 and ETR1 may express concurrently. These results are in agreement with the fact that the etr1-2 function is RTE1 dependent and that the etr1-2 mutation leads to whole-plant ethylene insensitivity (Resnick et al., 2006
The identification of the short RTE1 transcript implies that the RTE1 transcript could be spliced or that the RTE1 locus could have two genes. Although functional significance of the existence of two RTE1 transcripts is unknown, the formation of the short transcript does not appear to be a result of random degradation because it begins at specific site within the second intron. On the other hand, the overexpression of the RTE1 cDNA clone confers ethylene insensitivity in wild type (Resnick et al., 2006
The subcellular localization of GFP fusions shows that both RTE1 and rte1-2 are associated with the Golgi. Computational prediction (Yuan and Teasdale, 2002
The Golgi complex has three functionally distinct subcompartments, the cis-Golgi, the Golgi stacks or medial Golgi, and the trans-Golgi network. Our data show that the BFA treatment caused the formation of the BFA compartment and did not result in the redistribution of GFP-RTE1 to the ER, implying that majority of the RTE1 protein is retained to the Golgi stack. RAN1 is essential to the function of wild-type ethylene receptors and believed to localize to the post-Golgi (Hirayama et al., 1999
The ETR1 receptor protein is shown to localize to the ER (Chen et al., 2002
Ethylene plays important roles in growth and development in higher plants. Little is known about its effects on lower plants and when plants would have acquired the usage of ethylene as a plant hormone during evolution. It is shown that lower plants and some cyanobacteria can bind ethylene. Interestingly, plant species exhibit a similar ethylene-binding capacity (Wang et al., 2006
Plant Material and Growth
rte1-2 and etr1-2 rte1-2 were from C. Chang (Resnick et al., 2006
For seedling measurement, a photo of dark-grown seedlings was taken and hypocotyl lengths were measured by VideoTesT (Moscow). Statistics for data analyses were followed as described (Xie et al., 2006
The genomic RTE1 was obtained by PCR using the primer set gRTE1-F (5'-ATGGATCCGGTTCATTGTACCTTTCTCC-3') and gRTE1-R (5'-ATGGATCCTCAAGTAATTATGTTCTTAAAACAGTA-3') and the resulting DNA was cloned to the binary vector pCGN18. The truncated N
RNA was isolated as described (Wen et al., 1999
The fluorescence generated by LUC was captured by a cold CCD cooled by liquid nitrogen to –110°C (VersArray System, Roper Scientific). Plants to be imaged were pretreated with luciferin (1 mM in 0.01% Triton X-100) for 18 h and retreated before ethylene treatment and fluorescence imaging.
LSCM (Carl Zeiss LSM510 META) was performed at the Facility Center of the National Laboratory of Plant Molecular Genetics in the Shanghai Institute of Plant Physiology and Ecology and the Two-Photon Microscopy Facility (Carl Zeiss LSM510 META) in the Institute of Neuroscience of Shanghai Institutes for Biological Sciences. For the detection of the coexpression of YFP and GFP fusions, fluorescence was separated by linear unmixing to eliminate the fluorescence bleed through. Separation of the green and yellow fluorescence by the linear unmixing algorithm was confirmed; the GFP expression did not show fluorescence signal in the YFP channel and the EYFP-NAG expression did not give signal in the GFP channel (see Supplemental Fig. S3). Colocalization was visually evaluated by merging images of the GFP and YFP. Fluorescence microscopy was performed using Nikon Eclipse E400 (Nikon). Fluorescence filter sets (FITC-3540B-NQF-ZERO, TXRED-4040B-NQF-ZERO, CFP-2432A-NQF, and YFP-2427A-NQF-ZERO) were from Laser 2000 Ltd. Dark-grown seedlings were subjected to microscopy. For BFA treatment, seedlings were immersed in 10 µM of BFA (dissolved in 0.5% ethanol) and subjected to confocal microscopy; 0.5% ethanol was used as a blank control. For ACC treatment, dark-grown seedlings were immerged in 10 µM ACC (dissolved in water) and subjected to confocal microscopy. For the quantitation of the GFP fluorescence in ACC- and water-treated seedlings, images of fluorescent seedlings were taken every 60 min and the intensity was measured. For imaging of the movement of GFP fluorescence, photos were taken every 6 s. For imaging of BFA and ethanol treatments, frames were taken every 3 min.
The following materials are available in the online version of this article.
We thank Drs. C. Chang for the etr1-2 rte1-2 and rte1-2 mutants and the rte1-2 cDNA clone, B. Scheres for the EYFP-NAG clone, J. Xu for advice on the separation of EYFP and GFP fluorescence, our colleagues H.X. Lin for  2 analysis and H.Q. Yang for the LUC clone, and Q. Wang for BFA treatment and confocal microscopy of the GFP-RTE1 lines. The linear unmixing algorithm was performed at the Two-Photon Microscopy Facility in the Institute of Neuroscience of Shanghai Institutes for Biological Sciences. Received June 18, 2007; accepted July 16, 2007; published July 20, 2007.
1 This work was supported by the Chinese Academy of Sciences, the National Natural Sciences Foundation of China (grant nos. 90408008 to C.-K. Wen and 30421001 to X.Y. Chen), and the Ministry of Science and Technology (grant no. 2002AA224021/2005AA227020 to C.-K. Wen).  The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Chi-Kuang Wen (qgwen{at}sibs.ac.cn).
[C] Some figures in this article are displayed in color online but in black and white in the print edition.
[W] The online version of this article contains Web-only data. www.plantphysiol.org/cgi/doi/10.1104/pp.107.104299 * Corresponding author; e-mail qgwen{at}sibs.ac.cn.
Barry CS, Giovannoni JJ (2006) From the cover: ripening in the tomato green-ripe mutant is inhibited by ectopic expression of a protein that disrupts ethylene signaling. Proc Natl Acad Sci USA 103: 7923–7928 Chen YF, Randlett MD, Findell JL, Schaller GE (2002) Localization of the ethylene receptor ETR1 to the endoplasmic reticulum of Arabidopsis. J Biol Chem 277: 19861–19866 Chilley PM, Casson SA, Tarkowski P, Hawkins N, Wang KLC, Hussey PJ, Beale M, Ecker JR, Sandberg GK, Lindsey K (2006) The POLARIS peptide of Arabidopsis regulates auxin transport and root growth via effects on ethylene signaling. Plant Cell 18: 3058–3072 Clough SJ, Bent AF (1998) Floral dip: a simplified method for Agrobacterium-mediated transformation of Arabidopsis thaliana. Plant J 16: 735–743[CrossRef][ISI][Medline] Francis MJ, Jones EE, Levy ER, Ponnambalam S, Chelly J, Monaco AP (1998) A Golgi localization signal identified in the Menkes recombinant protein. Hum Mol Genet 7: 1245–1252 Friml J, Yang X, Michniewicz M, Weijers D, Quint A, Tietz O, Benjamins R, Ouwerkerk PBF, Ljung K, Sandberg G, et al (2004) A PINOID-dependent binary switch in apical-basal PIN polar targeting directs auxin efflux. Science 306: 862–865 Guzman P, Ecker JR (1990) Exploiting the triple response of Arabidopsis to identify ethylene-related mutants. Plant Cell 2: 513–523 Hall AE, Bleecker AB (2003) Analysis of combinatorial loss-of-function mutants in the Arabidopsis ethylene receptors reveals that the ers1 etr1 double mutant has severe developmental defects that are EIN2 dependent. Plant Cell 15: 2032–2041 Hawes C, Satiat-Jeunemaitre B (2005) The plant Golgi apparatus—going with the flow. Biochim Biophys Acta 1744: 93–107[Medline] Hirayama T, Kieber JJ, Hirayama N, Kogan M, Guzman P, Nourizadeh S, Alonso JM, Dailey WP, Dancis A, Ecker JR (1999) RESPONSIVE-TO-ANTAGONIST1, a Menkes/Wilson disease-related copper transporter, is required for ethylene signaling in Arabidopsis. Cell 97: 383–393[CrossRef][ISI][Medline] Hua J, Meyerowitz EM (1998) Ethylene responses are negatively regulated by a receptor gene family in Arabidopsis thaliana. Cell 94: 261–271[CrossRef][ISI][Medline] Jurgens G (2004) Membrane trafficking in plants. Annu Rev Cell Dev Biol 20: 481–504[CrossRef][ISI][Medline] Ma B, Cui ML, Sun HJ, Takada K, Mori H, Kamada H, Ezura H (2006) Subcellular localization and membrane topology of the melon ethylene receptor CmERS1. Plant Physiol 141: 587–597 Nebenfuhr A, Ritzenthaler C, Robinson DG (2002) Brefeldin A: deciphering an enigmatic inhibitor of secretion. Plant Physiol 130: 1102–1108 Qu X, Schaller GE (2004) Requirement of the histidine kinase domain for signal transduction by the ethylene receptor ETR1. Plant Physiol 136: 2961–2970 Resnick JS, Wen CK, Shockey JA, Chang C (2006) From the cover: REVERSION-TO-ETHYLENE SENSITIVITY1, a conserved gene that regulates ethylene receptor function in Arabidopsis. Proc Natl Acad Sci USA 103: 7917–7922 Ritzenthaler C, Nebenfuhr A, Movafeghi A, Stussi-Garaud C, Behnia L, Pimpl P, Staehelin LA, Robinson DG (2002) Reevaluation of the effects of Brefeldin A on plant cells using tobacco bright yellow 2 cells expressing golgi-targeted green fluorescent protein and COPI antisera. Plant Cell 14: 237–261 Saint-Jore-Dupas C, Gomord V, Paris N (2004) Protein localization in the plant Golgi apparatus and the trans-Golgi network. Cell Mol Life Sci 61: 159–171[CrossRef][ISI][Medline] Schaller GE, Bleecker AB (1995) Ethylene-binding sites generated in yeast expressing the Arabidopsis ETR1 gene. Science 270: 1809–1811 Scheres B, Xu J (2006) Polar auxin transport and patterning: grow with the flow. Genes Dev 20: 922–926 Surpin M, Raikhel N (2004) Traffic jams affect plant development and signal transduction. Nat Rev Mol Cell Biol 5: 100–109[CrossRef][ISI][Medline] Wang W, Esch JJ, Shiu SH, Agula H, Binder BM, Chang C, Patterson SE, Bleecker AB (2006) Identification of important regions for ethylene binding and signaling in the transmembrane domain of the ETR1 ethylene receptor of Arabidopsis. Plant Cell 18: 3429–3442 Wang W, Hall AE, O'Malley R, Bleecker AB (2003) Canonical histidine kinase activity of the transmitter domain of the ETR1 ethylene receptor from Arabidopsis is not required for signal transmission. Proc Natl Acad Sci USA 100: 352–357 Wen CK, Smith R, Banks JA (1999) ANI1: a sex pheromone-induced gene in ceratopteris gametophytes and its possible role in sex determination. Plant Cell 11: 1307–1318 Woeste KE, Kieber JJ (2000) A strong loss-of-function mutation in RAN1 results in constitutive activation of the ethylene response pathway as well as a rosette-lethal phenotype. Plant Cell 12: 443–455 Xie F, Liu Q, Wen CK (2006) Receptor signal output mediated by the ETR1 N terminus is primarily subfamily I receptor dependent. Plant Physiol 142: 492–508 Xiong L, David L, Stevenson B, Zhu JK (1999) High throughput screening of signal transduction mutants with luciferase imaging. Plant Mol Biol Rep 17: 159–170[CrossRef][ISI] Xu J, Scheres B (2005) Dissection of Arabidopsis ADP-RIBOSYLATION FACTOR 1 function in epidermal cell polarity. Plant Cell 17: 525–536 Yuan Z, Teasdale RD (2002) Prediction of Golgi type II membrane proteins based on their transmembrane domains. Bioinformatics 18: 1109–1115 This article has been cited by other articles:
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ABSTRACT
RESULTS
Thr) stabilizes the transmitter-on state II conformation, which allows ethylene binding to the etr1-2 protein but does not abolish receptor activity (Wang et al., 2006
-(2-aminoethoxyvinyl) Gly (AVG) was included in the seedling triple-response assay (
