Figure 2.

Separation of Golgi apparatus membranes and active Ca²⁺ uptake from tonoplast. A, ATP-dependent Ca²⁺ uptake in subcellular fractions measured in the presence of 1 μm free Ca²⁺. B, Suc concentration across the gradient determined by refractometry. C, XG-FucTase activity. D, Total protein across the gradient. E, UDPase activity measured in native gels. F, Detection of γ-TIP using western blots. The measurements were done in triplicate. The average relative activity and its deviation were plotted. The relative activity was standardized by setting the highest value obtained from the measurements at 100% relative activity. All subsequent values were then adjusted accordingly and the deviation was calculated. The highest value on each case correspond to: A, 0.314 pmol min⁻¹ μL⁻¹; and C, 0.13 pmol min⁻¹ μL⁻¹.