Figure 6. Ion dependence and I/V profile of DmNAT1.

A. Phenylalanine-induced currents associated with ion charge transport are shown. A DmNAT1 expressing oocyte was tested with solutions containing 100 mM LiCl, 98 mM KCl, 98 mM Na gluconate (NaGlc), or 98 mM NaCl, respectively. B. Amino acid-dependent current-voltage (I/V) relations as a function of co-transported ion and organic substrate (Phe). All recordings were made from a representative oocyte expressing DmNAT1. I/V plots show the currents evoked by 1 mM phenylalanine upon Na⁺ substitution in the bathing medium. Line colors represent different ion profiles of oocyte-bathing solution (see graph inset). Solid and dotted lines of the same color represent I/Vs with or without Phe, respectively. C. I/V profiles in which “background” currents (in the absence of organic substrates) were subtracted from currents obtained in the presence of 1 mM substrate concentrations. All presented characteristics were acquired at holding potential = -50 mV. Decremented square pluses were used for IV reconstruction; first pulse = +30 mV, last pulse = -90 mV; base = -10 mV.