Ca²⁺-translocating ATPase of the plant plasma membrane

For Ca²⁺ to function as a second messenger in signal transduction, it is essential that plant cells maintain low cytoplasmic Ca²⁺ levels relative to internal organelles and the apoplast. At the plasma membrane, Ca²⁺ is actively transported out of the cytoplasm and current evidence supports the involvement of a primary Ca²⁺-translocating ATPase in mediating this energy-dependent process. This review examines the preliminary biochemical characterization of this transport enzyme.