Fig. 7: SSM-based electrophysiology measurements of bison NHA2ΔN proteoliposomes.
From: Structure, mechanism and lipid-mediated remodeling of the mammalian Na+/H+ exchanger NHA2
a, Transient currents recorded on NHA2ΔN proteoliposomes under symmetrical pH 7.5 and increasing Na+ concentration jumps as shown. Inset: zoomed-in responses to NHA2ΔN in which the ion-binding aspartates were substituted to cysteine (D277C–D278C). b, Transient currents recorded after addition of 150 mM NaCl at symmetrical pH 6.5, 7.5 and 8.5 for bison NHA2ΔN. c, As in b for the bison NHA2ΔN construct in which Asp278 and Asp279 were substituted with cysteine. d, Peak current averages in response to different concentration jumps. The first bars show peak currents obtained by pH jumps from pH 7.0 to pH 6.0 titrated with HCl. The following bars show peak currents upon exchange of 150 mM choline chloride with 150 mM of the given salt at pH 7.5. Error bars show the mean values ± s.d. of n = 6 independent experiments (sensors). e, The pH was varied independently inside (pHi) and outside (pHo) the proteoliposomes, followed by 150 mM NaCl jumps to activate NHA2 in the presence of a pH gradient. Only a pH reduction on the outside dramatically affects current amplitudes, which is consistent with an electroneutral transport cycle43,44. Representative results of recordings performed on two individual sensors are shown.
