Fig. 6.
D305 is uniquely required for the charge movements. (A) The relative position and nature of residues included in the neutralization scan is depicted on the topology model. These residues were individually mutated to isosteric, nonprotonatable amino acids and mutants were analyzed in voltage jumps experiments at pHout 7.5. (B) Representative traces of the aspartate mutants. Mutation of D305 to asparagine or glutamate abolished the transients. After recording, oocytes were disimpaled and observed by fluorescence microscopy to confirm surface expression of the D305 mutants. (C and D) Boltzmann distribution parameters were derived from ON-step Q-Vm curves. (E) Mean decay times of the transient currents caused by voltage steps to/from +130 mV. *P < 0.05 relative to the control construct.