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K~(+)-ATPase and its transport characterization of plasma membrane vesicles from sorghum roots after osmotic stress

Yi Yin, Tang Zhangcheng

Shanghai Institute of Plant Physiology,The Chinese Academy of Sciences.Shanghai 200032

Abstract

Sealed inside-out plasma membrane vesicles prepared by step sucrose gradient from sorghu (Sorghum vulgare L. Jinza No. 5) roots were used to study ATPase activity and K~(+) transport across the membrane. In the absence of Mg~(2+), PM ATPase shoed a pH optimum of 7.5 under PEG-1000 stress. It was unlike plant PM H~(+)-ATPase which need Mg~(2+) and had an optimum pH value of 6.5. Further research proved that the ATPase had a highaffinity for ATP and a low K~(+) transport rate which was not related to H&&~(+)&& transport. The inhibition of its activity by cycloheximide and vanadate showed that it was a P-type ATPase synthesized de novo under osmotic stress. Basing on these observations we conclude that the ATPase is a primary ion-motive K~(+)-ATPase induced by osmotic stress.

Key words: Sorghum root;Plasma membrane vesicles;K~(+)-ATPase;Osmotic stress

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Citing This Article：

Yi Yin, Tang Zhangcheng. K~(+)-ATPase and its transport characterization of plasma membrane vesicles from sorghum roots after osmotic stress. Acta Physiol Sin 1996; 48 (3): (in Chinese with English abstract).