Figure 3.

Lipid substrate dependence of ATPase activity of disease mutants and additional E897 mutants. The ATPase activity of the wild type bATP8A2 (WT) and the indicated mutants was determined at the indicated concentrations of PS (a, b) or PE (c, d). The total lipid concentration was fixed at 2.5 mg/mL (the remainder constituted by PC). The activity is shown as % of V_max (the absolute value of V_max is given in Table 1). The lines represent best fits of the Hill equation V/V_max = [L]^H/(K_0.5 ^H + [L]^H), where the ligand L is either PS or PE. The Hill coefficient H resulting from the regression was ∼1 in all cases. The extracted K_0.5 values and statistics are shown in Table 1.