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. 2014 Mar 24;111(14):E1334–E1343. doi: 10.1073/pnas.1321165111

Fig. 2.

Fig. 2.

Flippase activity and ATPase activity of WT ATP8A2 and I364 mutants. (A) Transport of NBD-labeled PS (NBD-PS) was measured by reducing the fluorophore in the outer leaflet of the reconstituted vesicles with dithionite following incubation with ATP. The ordinate indicates the percentage of NBD-PS that was transported during the 2.5-min incubation with ATP, normalized to a flippase protein level equal to the average of the WT levels. (B–F) ATPase activity in the presence of PS, PE, and PC, and apparent affinity for PS or PE of WT and mutants, measured in the presence of PC and CHAPS and various concentrations of PS or PE. Values for the maximal activities per mg ATP8A2 protein, Vmax (μmol ATP/min/mg), obtained for each lipid are shown in B. In C–F, activities at the various lipid concentrations indicated on the abscissa are shown relative to Vmax. Error bars show SEs when larger than symbols. Dotted lines reproduce the data for WT. Refer to Table 1 for statistical analysis. Symbols for mutants are the same in E and F as in C and D.