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Gene Review

NHX1  -  sodium/hydrogen exchanger 1

Arabidopsis thaliana

Synonyms: AT-NHX1, ATNHX, ATNHX1, NA(+)/H(+) ANTIPORTER, Na+/H+ exchanger 1, ...
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High impact information on NHX1

  • This salinity tolerance was correlated with higher-than-normal levels of AtNHX1 transcripts, protein, and vacuolar Na+/H+ (sodium/proton) antiport activity [1].
  • Taken together, the presence of a vacuolar calmodulin-like protein acting on the vacuolar-localized AtNHX1 C terminus in a Ca(2+)- pH-dependent manner suggests the presence of signaling entities acting within the vacuole [2].
  • Arabidopsis thaliana Na(+)/H(+) exchanger 1 (AtNHX1), the most abundant vacuolar Na(+)/H(+) antiporter in A. thaliana, has important roles affecting the maintenance of cellular pH, ion homeostasis, and the regulation of protein trafficking [2].
  • The binding of AtCaM15 to AtNHX1 was Ca(2+)- and pH-dependent and decreased with increasing pH values [2].
  • Our results also indicate that, whereas the N terminus of AtNHX1 is facing the cytosol, almost the entire C-terminal hydrophilic region resides in the vacuolar lumen [3].

Biological context of NHX1

  • Fusion of the SP to At-NHX1 resulted in an increase in the magnitude of Na(+)/H(+) exchange, indicating a role for the SP in protein targeting or regulation [4].
  • Hyper-osmotic up-regulation of AtNHX1, 2 or 5 expression is not dependent on the SOS pathway that controls ion homeostasis [5].
  • AtNHX1, 2 or 5 suppress, with differential efficacy, the Na+/Li+-sensitive phenotype of a yeast mutant that is deficient in the endosomal/vacuolar Na+/H+ antiporter ScNHX1 [5].
  • Predicted amino acid sequence similarity, protein topology and the presence of functional domains conserved in AtNHX1 and prototypical mammalian NHE Na+/H+ exchangers led to the identification of five additional AtNHX genes (AtNHX2-6) [5].
  • The majority of exons for Arabidopsis, rice and wheat orthologues of NHX1, NHX5 and SOS1 were conserved except for those at the amino and carboxy terminal ends [6].

Anatomical context of NHX1

  • Experiments on vacuolar vesicles isolated from yeast expressing At-NHX1 or NHX1 provided direct evidence for pH-gradient-energized Na(+) accumulation into the vacuole [4].
  • To study the ion selectivity of the AtNHX1 protein, we have purified a histidine-tagged version of the protein from yeast microsomes by Ni(2+) affinity chromatography, reconstituted the protein into lipid vesicles, and measured cation-dependent H(+) exchange with the fluorescent pH indicator pyranine [7].
  • Strong induction of GUS activity in root hair cells was observed, which suggests a role of AtNHX1 in storing Na+ in the enlarged vacuoles in root hair cells [8].
  • The membrane topology of the Arabidopsis thaliana Na(+)/H(+) exchanger isoform 1 (AtNHX1) was investigated by examining the topogenic function of transmembrane (TM) segments using a cell-free system [9].

Associations of NHX1 with chemical compounds

  • AtNHX1 and AtNHX2 transcripts accumulate in response to ABA but not to NaCl in the aba2-1, mutant indicating that the osmotic responsiveness of these genes is ABA-dependent [5].
  • The vacuolar localization of the C terminus of the AtNHX1, taken together with the regulation of the antiporter selectivity by its C terminus, demonstrates the existence of luminal vacuolar regulatory mechanisms of the antiporter activity [3].
  • Transgenic Brassica napus plants overexpressing AtNHX1, a vacuolar Na(+)/H(+) antiport from Arabidopsis thaliana, were able to grow, flower, and produce seeds in the presence of 200 mM sodium chloride [10].
  • Regulation of expression of the vacuolar Na+/H+ antiporter gene AtNHX1 by salt stress and abscisic acid [8].
  • When yeast cells were challenged with lithium, a tracer for sodium, the main effect of the mutations in AtNHX1 was a reduction in the amount of compartmentalized lithium [11].

Other interactions of NHX1


Analytical, diagnostic and therapeutic context of NHX1


  1. Salt tolerance conferred by overexpression of a vacuolar Na+/H+ antiport in Arabidopsis. Apse, M.P., Aharon, G.S., Snedden, W.A., Blumwald, E. Science (1999) [Pubmed]
  2. Vacuolar Na+/H+ antiporter cation selectivity is regulated by calmodulin from within the vacuole in a Ca2+- and pH-dependent manner. Yamaguchi, T., Aharon, G.S., Sottosanto, J.B., Blumwald, E. Proc. Natl. Acad. Sci. U.S.A. (2005) [Pubmed]
  3. Topological analysis of a plant vacuolar Na+/H+ antiporter reveals a luminal C terminus that regulates antiporter cation selectivity. Yamaguchi, T., Apse, M.P., Shi, H., Blumwald, E. Proc. Natl. Acad. Sci. U.S.A. (2003) [Pubmed]
  4. Arabidopsis thaliana and Saccharomyces cerevisiae NHX1 genes encode amiloride sensitive electroneutral Na+/H+ exchangers. Darley, C.P., van Wuytswinkel , O.C., van der Woude , K., Mager, W.H., de Boer , A.H. Biochem. J. (2000) [Pubmed]
  5. Differential expression and function of Arabidopsis thaliana NHX Na+/H+ antiporters in the salt stress response. Yokoi, S., Quintero, F.J., Cubero, B., Ruiz, M.T., Bressan, R.A., Hasegawa, P.M., Pardo, J.M. Plant J. (2002) [Pubmed]
  6. Arabidopsis-rice-wheat gene orthologues for Na(+) transport and transcript analysis in wheat-L. elongatum aneuploids under salt stress. Mullan, D.J., Colmer, T.D., Francki, M.G. Mol. Genet. Genomics (2007) [Pubmed]
  7. The arabidopsis Na+/H+ exchanger AtNHX1 catalyzes low affinity Na+ and K+ transport in reconstituted liposomes. Venema, K., Quintero, F.J., Pardo, J.M., Donaire, J.P. J. Biol. Chem. (2002) [Pubmed]
  8. Regulation of expression of the vacuolar Na+/H+ antiporter gene AtNHX1 by salt stress and abscisic acid. Shi, H., Zhu, J.K. Plant Mol. Biol. (2002) [Pubmed]
  9. Topogenic properties of transmembrane segments of Arabidopsis thaliana NHX1 reveal a common topology model of the Na+/H+ exchanger family. Sato, Y., Sakaguchi, M. J. Biochem. (2005) [Pubmed]
  10. Engineering salt-tolerant Brassica plants: characterization of yield and seed oil quality in transgenic plants with increased vacuolar sodium accumulation. Zhang, H.X., Hodson, J.N., Williams, J.P., Blumwald, E. Proc. Natl. Acad. Sci. U.S.A. (2001) [Pubmed]
  11. Mutants of the Arabidopsis thaliana cation/H+ antiporter AtNHX1 conferring increased salt tolerance in yeast: the endosome/prevacuolar compartment is a target for salt toxicity. Hernández, A., Jiang, X., Cubero, B., Nieto, P.M., Bressan, R.A., Hasegawa, P.M., Pardo, J.M. J. Biol. Chem. (2009) [Pubmed]
  12. DNA array analyses of Arabidopsis thaliana lacking a vacuolar Na+/H+ antiporter: impact of AtNHX1 on gene expression. Sottosanto, J.B., Gelli, A., Blumwald, E. Plant J. (2004) [Pubmed]
  13. Cloning and characterization of a wheat vacuolar cation/proton antiporter and pyrophosphatase proton pump. Brini, F., Gaxiola, R.A., Berkowitz, G.A., Masmoudi, K. Plant Physiol. Biochem. (2005) [Pubmed]
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