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. 1998 Aug 1;112(2):243–257. doi: 10.1085/jgp.112.2.243

Figure 2.

Figure 2

The S460G:A463C:T469V mutant conducts large sodium currents in the absence of potassium. (A) Sequence comparison between the pore and the S6 region of the Kv2.1 and the Shaker channel. The amino acid differences between the two channels are highlighted. In this study, the starred residues in the S6 of Shaker were mutated to their counterparts in Kv2.1. (B) Current sweeps are from outside-out patches and were elicited by 76-ms voltage ramps from −100 to +200 mV. The pipette solution contained 140 mM NaCl and 0 KCl. With external 140 mM KCl (#1), a large inward potassium current is observed. Replacement of external K with 140 mM NMGCl (#2) allows for large outward sodium currents. The outward current is entirely blocked by 80 nM Agitoxin (#3). (C) Current traces are from an outside-out patch in symmetrical 140 mM NaCl. The currents were elicited by a step from −100 to +100 mV and a repolarization back to −100 mV. Both outward and inward currents are readily blocked by 140 mM external TEA.