FIGURE 6.
Temperature dependence of the transport activity of parental OpuA (panels A and B), OpuA[K3R2] (panel A), and OpuAΔ119 (panel B) at low and high internal ionic strength. Proteoliposomes with parental OpuA (○, •), OpuA (K3R2) (▵, ▴), and OpuAΔ119 (□, ▪) were composed of 50 mol % DOPE, 12 mol % DOPC, and 38 mol % DOPG and were loaded with 9 mm MgSO4, 9 mm Na2ATP plus 10 mm potassium Pi. Uptake of [14C]glycine betaine was assayed in 30 mm potassium Pi, pH 7.0, with (closed symbols) or without (open symbols) 250 mm KCl. Error bars show standard deviations of average rates from 3 independent experiments. Panel C is the Arrhenius transformation of the data from panels A and B.