Figure 4.

NCX_Mj activity is independent of K⁺. Ca²⁺/⁴⁵Ca²⁺ exchange in K⁺-free (orange) or 25 mM K⁺ (blue) buffers. Liposomes, preloaded with either choline chloride or KCl buffer with 50 µM ⁴⁵CaCl₂, were diluted into choline chloride or KCl reaction buffer containing 25 µM CaCl₂. Note that buffers for this experiment were valinomycin-free. A triplicate dataset is averaged (error bars represent SEM).