Provoked changes in cellular calcium controlled protein phosphorylation and activity of quinate:NAD+ oxidoreductase in carrot cells

[摘要]

Quinate:NAD⁺ oxidoreductase activity decreased when carrot cell-suspension cultures were supplemented with the Ca²⁺-ionophore, A-23187 and EGTA. The protein phosphorylation pattern changed as judged by autoradiography. The loss in enzyme activity was correlated with the Ca²⁺ efflux. Addition of Ca²⁺ to protein extracts in combination with calmodulin or not had no effect. Initial quinate:NAD⁺ oxidoreductase activity was partially recovered only after preincubation with ATP-Mg²⁺ and Ca²⁺. The reactivation was abolished by EGTA or fluphenazine. It is concluded that cellular Ca²⁺ controls the enzyme activity by affecting its degree of phosphorylation in vivo.

[学科分类] 生物化学/生物物理

[关键词] Calcium;A-23187 Ionophore;Calmodulin;Protein phosphorylation;Protein kinase;(Carrot)