Alteration by EGTA of the human red cell Ca2+-ATPase

AbstractThe effect of EGTA on Ca2+-ATPase activity was studied in fragmented membranes and solubilized preparations from human red cells. A dual action was found. At low concentrations (0.1–1 mM), EGTA increased Ca2+ affinity without affecting Vmax. By contrast, high concentrations (5–10 mM), EGTA was inhibitory. Both effects were partially reversible