Figure 4.

(A) Standard curve generated using known amounts of Pi from sodium phosphate dissolved in ultrapure water combined with the ammonium molybdate/malachite green reagent as described in materials and methods. Color was allowed to develop for 10 minutes at room temperature before measuring A₆₆₀. (B) Simultaneous assay measurement of ⁴⁵Ca²⁺ accumulation (left y-axis) and Pi release (right y-axis) in the presence of 300 nM free Ca²⁺. Reactions were carried out with 3 mM Mg²⁺, 2 mM ATP for 10 minutes at 37°C with no additional treatments (control) or in the presence of 100 nM TG or 10 μM Ca2+ ionophore A23187.