Mutations of I94 gating by voltage and changes in extracellular pH.
A. Records of currents recorded from oocytes expressing I94V (above) and I94S (below) TASK-1. External solutions contain 70mM K+ and currents were recorded under voltage steps in increments of 10mV from a holding potential of −20mV to between +100mV and −50mV. B. Relationship between the membrane current, normalised to that at pHo = 8.5, (ordinate) and pHo (abscissa) for I94V (○) and I94L (●), measured at −40mV. The solid line gives the fit of Eqn (2) to the values at −40mV, with pKa = 6.13 for I94V and 7.04 for I94L. For all parts of this figure, the dashed line gives the best fit to wild type at −40mV (as in Fig. 6B). C. Similar relationships for I94S at −40mV (○). For I94S at −40mV, the solid line gives pKa = 6.54 (from wild type) and a = 0.08, b = 0.92. D. Similar relationships for A100T −40mV (○). The solid line gives pKa = 6.64 (from wild type), a = 0.20, b = 0.78 for the fit to −40mV.