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Gene Review

HKT1  -  sodium transporter HKT1

Arabidopsis thaliana

Synonyms: ATHKT1, HKT1;1, T9A4.5, high-affinity K+ transporter 1
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Disease relevance of HKT1


High impact information on HKT1

  • Functional expression in yeast and Xenopus oocytes revealed that wheat HKT1 mediates Na(+)-coupled K(+) transport [4].
  • The reverse mutation in HKT1, Gly-91 to serine, abrogated K(+) permeability [4].
  • A single-point mutation, Ser-68 to glycine, was sufficient to restore K(+) permeability to AtHKT1 [4].
  • Furthermore, the hkt1 mutations abrogate the growth inhibition of the sos3-1 mutant that is caused by K(+) deficiency on culture medium with low Ca(2+) (0.15 mM) and <200 microM K(+) [1].
  • However, computer analysis of the AtHKT1 sequence identified eleven potential transmembrane segments [2].

Biological context of HKT1

  • We report here the isolation of a cDNA homologous to HKT1 from Arabidopsis (AtHKT1) and the characterization of its mode of ion transport in heterologous systems [5].
  • The deduced amino acid sequence of AtHKT1 is 41% identical to that of HKT1, and the hydropathy profiles are very similar [5].
  • Analysis of the genome sequence in the region flanking the T-DNA left border indicated that sos3-1 hkt1-1 and sos3-1 hkt1-2 plants have allelic mutations in AtHKT1 [1].
  • AtHKT1 facilitates Na+ homeostasis and K+ nutrition in planta [6].
  • AtHKT1 transgene expression exacerbates K(+) deficiency of sos3-1 or wild-type seedlings [6].

Anatomical context of HKT1

  • Second, with a reticulocyte-lysate supplemented with dog-pancreas microsomes, we demonstrated that N-glycosylation occurs at position 429 of AtHKT1 [2].
  • Third, immunocytochemical experiments with FLAG-tagged AtHKT1 in HEK293 cells revealed that the N and C termini of AtHKT1, and the regions containing residues 135-142 and 377-384, face the cytosol, whereas the region of residues 55-62 is exposed to the outside [2].
  • Immunoelectron microscopy studies using anti-AtHKT1 antibodies demonstrate that AtHKT1 is targeted to the plasma membrane in xylem parenchyma cells in leaves [7].

Associations of HKT1 with chemical compounds

  • K(+) transporters of the HKT1 superfamily have been cloned from wheat (Triticum aestivum), Arabidopsis, and Eucalyptus camaldulensis [8].
  • Notable examples include novel alleles of SOS1 and mutations to genes encoding the STT3a subunit of the oligosaccharyltransferase, syntaxin, RNA polymerase II CTD phosphatases, transcription factors, ABA biosynthetic enzyme, Na(+) transporter HKT1, and SUMO E3 ligase [9].
  • The athkt1 mutant alleles had a smaller and inverse influence on the potassium (K+) content compared with the Na+ content of the xylem, suggesting that K+ transport may be indirectly affected [7].

Other interactions of HKT1

  • The effects of sos1 in suppressing spiral1 defects and in causing abnormal drug responses were nullified in the presence of the hkt1 Na(+) influx carrier mutation in roots but not in hypocotyls [10].


  1. AtHKT1 is a salt tolerance determinant that controls Na(+) entry into plant roots. Rus, A., Yokoi, S., Sharkhuu, A., Reddy, M., Lee, B.H., Matsumoto, T.K., Koiwa, H., Zhu, J.K., Bressan, R.A., Hasegawa, P.M. Proc. Natl. Acad. Sci. U.S.A. (2001) [Pubmed]
  2. Evidence in support of a four transmembrane-pore-transmembrane topology model for the Arabidopsis thaliana Na+/K+ translocating AtHKT1 protein, a member of the superfamily of K+ transporters. Kato, Y., Sakaguchi, M., Mori, Y., Saito, K., Nakamura, T., Bakker, E.P., Sato, Y., Goshima, S., Uozumi, N. Proc. Natl. Acad. Sci. U.S.A. (2001) [Pubmed]
  3. Calcium regulation of sodium hypersensitivities of sos3 and athkt1 mutants. Horie, T., Horie, R., Chan, W.Y., Leung, H.Y., Schroeder, J.I. Plant Cell Physiol. (2006) [Pubmed]
  4. Glycine residues in potassium channel-like selectivity filters determine potassium selectivity in four-loop-per-subunit HKT transporters from plants. Mäser, P., Hosoo, Y., Goshima, S., Horie, T., Eckelman, B., Yamada, K., Yoshida, K., Bakker, E.P., Shinmyo, A., Oiki, S., Schroeder, J.I., Uozumi, N. Proc. Natl. Acad. Sci. U.S.A. (2002) [Pubmed]
  5. The Arabidopsis HKT1 gene homolog mediates inward Na(+) currents in xenopus laevis oocytes and Na(+) uptake in Saccharomyces cerevisiae. Uozumi, N., Kim, E.J., Rubio, F., Yamaguchi, T., Muto, S., Tsuboi, A., Bakker, E.P., Nakamura, T., Schroeder, J.I. Plant Physiol. (2000) [Pubmed]
  6. AtHKT1 facilitates Na+ homeostasis and K+ nutrition in planta. Rus, A., Lee, B.H., Muñoz-Mayor, A., Sharkhuu, A., Miura, K., Zhu, J.K., Bressan, R.A., Hasegawa, P.M. Plant Physiol. (2004) [Pubmed]
  7. Enhanced salt tolerance mediated by AtHKT1 transporter-induced Na unloading from xylem vessels to xylem parenchyma cells. Sunarpi, n.u.l.l., Horie, T., Motoda, J., Kubo, M., Yang, H., Yoda, K., Horie, R., Chan, W.Y., Leung, H.Y., Hattori, K., Konomi, M., Osumi, M., Yamagami, M., Schroeder, J.I., Uozumi, N. Plant J. (2005) [Pubmed]
  8. Characterization of two HKT1 homologues from Eucalyptus camaldulensis that display intrinsic osmosensing capability. Liu, W., Fairbairn, D.J., Reid, R.J., Schachtman, D.P. Plant Physiol. (2001) [Pubmed]
  9. Identification of plant stress-responsive determinants in arabidopsis by large-scale forward genetic screens. Koiwa, H., Bressan, R.A., Hasegawa, P.M. J. Exp. Bot. (2006) [Pubmed]
  10. Salt stress affects cortical microtubule organization and helical growth in Arabidopsis. Shoji, T., Suzuki, K., Abe, T., Kaneko, Y., Shi, H., Zhu, J.K., Rus, A., Hasegawa, P.M., Hashimoto, T. Plant Cell Physiol. (2006) [Pubmed]
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