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Regulatory action of a calmodulin binding protein on activity of the plasma membrane H~(+)-ATPase in wheat

Abstract

CaM BP-10 (BP-10) is a novel endogenous calmodulin (CaM)-binding protein that was observed in and isolated from plant. In our preliminary studies it has been shown that BP-10 specifically inhibits auxin (IAA)-induced coleoptile elongation and proton secretion. In order to investigate whether BP-10 inhibites proton secretion and cell elongation through inhibiting the activity of plasma membrane (PM) H~(+)-ATPase, the effect of BP-10 on the activity of wheat coleoptile PM H~(+)-ATPase has been studied. It was observed that neither IAA nor BP-10 had any effect on the activity of PM H~(+)-ATPase in vitro. In vivo, however, the activity of IAA-treated PM H~(+)-ATPase was higher than that of the control, and BP-10 specifically inhibited IAA-induced activity by 87.8%. In addition, the inhibitory effect could be reversed by IAA after BP-10 was removed from the medium, and it could also be overcome by the addition of CaM.

Key words: Calmodulin;CaM binding protein;Auxin;Plasma membrane H ~(+)-ATPase

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Citing This Article：

. Regulatory action of a calmodulin binding protein on activity of the plasma membrane H~(+)-ATPase in wheat. Acta Physiol Sin 1998; 50 (1): (in Chinese with English abstract).