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Characterization of Ca~(2+)-ATPase which drives active transport of Ca~(2+) in plasma membrane vesicles isolated from pulp cell of Malus pumila fruits

Zhou Wei, He Ping

Soil and Fertilizer Institute,Chinese Academy of Agricultural Sciences.Beijing 100081

Abstract

The relationship between Ca~(2+)-dependent ATPase(Ca~(2+)-ATPase) and ATP-dependent Ca~(2+) transport in plasma membrane vesicles isolated from pulp cell of Malus pumila fruits and the influence of hormones on this enzyme were investigated by using ~(45)Ca~(2+) tracing. Results showed that the Ca~(2+) ionophore A_(23187) and is localized at the plasma membrane. Ca~(2+)-ATPase activity and ATP-dependent Ca~(2+) uptake show very similar saturation kinetics with erythrosin B (50% inhibition at about 0.1 #mu#mol/L), free Ca~(2+) (half-maximal rate at about 0.1 #mu#mol/L), and ATP (K_(m) 50 #mu#mol/L), demonstrating that it is this enzyme that drives ATP-dependent Ca~(2+) transport in plasma membrane vesicles. Both Ca~(2+)-ATPase and Ca~(2+) uptake could be promoted also by IAA or NAA, but none by GA.

Key words: Plasma membrane vesicles;Ca~(2+)-ATPase;Ca~(2+) transport;Hormone;Pulp cell of Malus pumila fruits

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Citing This Article：

Zhou Wei, He Ping. Characterization of Ca~(2+)-ATPase which drives active transport of Ca~(2+) in plasma membrane vesicles isolated from pulp cell of Malus pumila fruits. Acta Physiol Sin 1999; 51 (2): (in Chinese with English abstract).