On the mechanism of activation of CaATPase by a single univalent cation

It has been demonstrated with ox-brain microsome membranes that the mechanism of CaATPase activation by a single univalent cation is different in case of Na+-ont he one hand-and K+ and its congeners-on the other. Whereas Na+ increases the amount of 32-P protein (phosphorylated intermediate), K+ causes only an insignificant increase or decrease compared to the Ca-2+-containing sample. Our findings support the assumption that the altered activity of the Na-K-ATPase (modified by the presence of Ca-2+) is responsible for the univalent cation activation of the CaATPase.