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Fig. 1 | BMC Plant Biology

Fig. 1

From: An extracellular cation coordination site influences ion conduction of OsHKT2;2

Fig. 1

Electrophysiological characteristics of OsHKT2;2 in Xenopus laevis oocytes. a Representative currents elicited in control cells (not injected with cRNA). Only currents for Na30K1 solution are shown since highest currents are expected under these conditions. Control currents for all conditions are shown in Additional file 2: Figure S2. b-h Representative OsHKT2;2 mediated whole cell currents recorded two days after cRNA injection. Currents were recorded at indicated Na+ and K+ concentrations: Na0K1 - no NaCl and 1 mM KCl, Na0K30 - no NaCl and 30 mM KCl, Na03K0 - 0.3 mM NaCl without KCl, Na03K1 - 0.3 mM NaCl and 1 mM KCl, Na30K0 - 30 mM NaCl without KCl, Na30K1 - 30 mM NaCl and 1 mM KCl, Na30K30 - 30 mM NaCl and 30 mM KCl. The holding potential was set to the zero current level (approximately -45 mV with solution Na30K1) and 1 s voltage pulses were stepped from +20 to -160 mV in -15 mV decrements. A 1.5 s resting interval was allowed between successive voltage steps. The current (μA) and time (ms) scale for all traces shown in A through H is shown at the bottom of panel A. i Mean current-voltage (IV) curves. Standard deviation calculated from data obtained from five to eight measurements obtained on five different days and from four different oocyte batches. Currents were normalized to currents measured at -145 mV in Na30K1 solution. Inset: Reversal potentials (Vrev) were determined based on the data plotted in I and plotted against the extracellular Na+ concentration. Symbols for Vrev and IV-curve data are identical and correspond to the same solutions in both plots. The external Na+ dependency of the Vrev values obtained with 1 mM KCl (filled triangle and diamond) or without KCl (empty triangle and circle) in extracellular solutions was fitted with a semi-logarithmic function (line K1 and K0). The dashed line represents the curve for an ideally Na+ permeable channel. j Currents elicited by a -145 mV voltage pulse, measured at the beginning (dark grey) or end (white) of the voltage pulse, and as average currents over the whole voltage pulse (light grey). Currents were normalized to currents measured in Na30K1 solution. Numbers in the plot indicate the degree of current reduction over time (from beginning to end of the voltage pulse). The magnitude of deactivation is stated in percentage. Means and standard deviation were obtained from data of five to eight measurements

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