
%0 Journal Article
%A Qiu, Quan-Sheng 
%A Su, Xue-Feng 
%T The influence of extracellular-side Ca<emph type="7">2+</emph> on the activity of the plasma membrane H<emph type="7">+</emph>-ATPase from wheat roots
%J Functional Plant Biology
%D 1999/01/29
%V 25
%N 8
%P 923-928
%K 
%R https://doi.org/10.1071/PP98036
%U https://www.publish.csiro.au/paper/PP98036 
%X Plasma membrane vesicles were purified from wheat roots by discontinuous sucrose gradient centrifugation and two-phase partitioning methods. The influence of extracellular-side Ca2+ on the activity of the plasma membrane H+ -ATPase from wheat roots was studied. The results showed that the ATP hydrolytic activities of the plasma membrane H+ -ATPase were inhibited by the cytoplasmic-side Ca2+. Within 0~200 &#181;mol/L the ATPase activity decreased gradually with the increase in Ca2+ concentration; the ATPase activity was inhibited by 40% when Ca2+ concentration was 1000 &#181;mol/L. However, the ATP hydrolytic activities were recovered by the presence of extracellular-side Ca2+. Results showed that the ATPase activities were increased with the increase in extracellular-side Ca2+; when the extracellular-side Ca2+ was 1000 &#181;mol/L, the ATPase activity was recovered by 87.5%. Further studies found that the extracellular-side Ca2+ increased the DPH polarisation and decreased the MC540 fluorescence intensity, showing that membrane fluidity was decreased and membrane stacking was increased by the external Ca2+. The above results suggested that the plasma membrane H+ -ATPase could be regulated by the extracellular side Ca2+ through affecting the plasma membrane physical states. 
