FIGURE 7.
Concentration dependence of the inhibition of charge movements and anion conductance by TBOA. Shown is the blockade of charge movements (A) and anion conductance (B) by TBOA in oocytes expressing EAAC1-WT (squares), M367C (circles), M367L (triangles), or M367S (inverted triangles) using the same voltage protocol described in the legend to Fig. 2. Charge movements obtained in ND96 were calculated by adding the current time integrals during the “off” charge movements elicited by stepping back from −100 to −25 mV to those where the voltage was stepped back from +40 to −25 mV. The fraction of charge movement blocked at each TBOA concentration was normalized to the charge movement blocked by 5 μm TBOA (Q/Qmax). The ranges of the charge movements were 2.0–7.5 nC (EAAC1-WT), 1.5–8.0 nC (M367C), and 2.4–9.4 nC (M367L). In the case of M367S, the moved charge ranged from 0.3 to 0.8 nC, too small to perform reliable titrations (A). The steady-state currents inhibited by the indicated TBOA concentrations at +40 mV were measured in the 20 mm SCN−-containing external medium as described in the legend to Fig. 6 (I) and were normalized to those inhibited by 5 μm of TBOA (Imax). The data are the means ± S.E. of at least four repeats.