Fig. 5.

Electrophoretic and ion-dependent characteristics of SNF-5. A collection of current–voltage (I–V) plots recorded from SNF-5-expressing oocytes. The plots were built from reciprocal current and voltage amplitudes recorded during 2 s voltage ramp stimulus, e.g. initial holding potential −50 mV, drop to −110 mV, 2 s ramp increase up to +10 mV, and final drop to −50 mV. The three different panels represent IV collections for selected amino acids: 1 mmol l⁻¹ l-Glu, l-Pro and l-Met in four different solutions: normal medium (98 mmol l⁻¹ NaCl); Cl⁻-free medium with Cl⁻ substituted by gluconate⁻ (98 mmol l⁻¹ NaGlc); Na⁺-free medium with Na⁺ substituted by K⁺ (98 mmol l⁻¹ KCl); and Na⁺/K⁺-free medium with major alkali cations substituted by Li⁺ (98 mmol l⁻¹ LiCl). The ion-specific I–V plots are indicated by distinct line patterns as shown in the inset. Each I–V plot represents the amino acid-specific component acquired as a current response during application of amino acid (~90% saturation point), with point by point subtraction of leak current recorded immediately before the amino acid application. Values were acquired from different oocytes and were subsequently filtered (0.1 Hz) and normalized under the assumption that amplitudes of leak and amino acid-induced currents are linear functions of SNF-5 expression.