FIGURE 5.

AtCLCa C terminus is involved in the interaction with ATP. Anion currents (left panels) and I/V characteristics (right panels) measured in clca-2 knock-out mutant vacuoles extracted from protoplasts transiently transfected with wild type AtCLCa (a), D753A (b), and H620A mutants (c). a, currents recorded in vacuoles transfected with wild type AtCLCa showed an inhibition by 5 mm ATP comparable with that observed in Fig. 2. b, vacuoles transfected with the D753A mutants displayed an inhibition of the current by 5 mm ATP that is greatly diminished. c, vacuoles transfected with the H620A mutants instead are inhibited by 5 mm ATP in a way comparable with wild type (see panel a). Vacuolar and cytosolic standard solutions added with ATP as indicated (see “Experimental Procedures”). For I-V curves, mean I values ± S.E. are shown (n = 3–4). Ctrl, control.