PT - JOURNAL ARTICLE AU - Preuss, Christian P. AU - Huang, Chun Y. AU - Gilliham, Matthew AU - Tyerman, Stephen D. TI - Channel-Like Characteristics of the Low-Affinity Barley Phosphate Transporter PHT1;6 When Expressed in <em>Xenopus</em> Oocytes AID - 10.1104/pp.109.152009 DP - 2010 Mar 01 TA - Plant Physiology PG - 1431--1441 VI - 152 IP - 3 4099 - http://www.plantphysiol.org/content/152/3/1431.short 4100 - http://www.plantphysiol.org/content/152/3/1431.full SO - Plant Physiol.2010 Mar 01; 152 AB - Remobilization of inorganic phosphate (Pi) within a plant is critical for sustaining growth and seed production under external Pi fluctuation. The barley (Hordeum vulgare) transporter HvPHT1;6 has been implicated in Pi remobilization. In this report, we expressed HvPHT1;6 in Xenopus laevis oocytes, allowing detailed characterization of voltage-dependent fluxes and currents induced by HvPHT1;6. HvPHT1;6 increased efflux of Pi near oocyte resting membrane potentials, dependent on external Pi concentration. Time-dependent inward currents were observed when membrane potentials were more negative than −160 mV, which was consistent with nH+:HPO42− (n &gt; 2) cotransport, based on simultaneous radiotracer and oocyte voltage clamping, dependent upon Pi concentration gradient and pH. Time- and voltage-dependent inward currents through HvPHT1;6 were also observed for SO42−and to a lesser degree for NO3−Cl−but not for malate. Inward and outward currents showed linear dependence on the concentration of external HPO42−similar to low-affinity Pi transport in plant studies. The electrophysiological properties of HvPHT1;6, which locates to the plasma membrane when expressed in onion (Allium cepa) epidermal cells, are consistent with its suggested role in the remobilization of Pi in barley plants.