钾离子对无机磷酸（Pi）或三磷酸腺苷（ATP）所致肌浆网ATP酶磷酸化的影响。
Effect of K+ on phosphorylation of the sarcoplasmic reticulum ATPase by either Pi or ATP.
作者信息
Chaloub R M, de Meis L
出版信息
J Biol Chem. 1980 Jul 10;255(13):6168-72.
The effect of K+ on phosphorylation of the Ca2+-dependent ATPase of the sarcoplasmic reticulum by either Pi or ATP was studied using a millisecond mixing and quenching device. Equilibrium levels of phosphoenzyme formed by Pi were progressively decreased in the presence of increasing K+ concentrations. This effect was more pronounced in empty vesicles than in vesicles previously loaded with calcium. Potassium did not modify the initial rate of enzyme phosphorylation by Pi but increased the rate of phosphoenzyme hydrolysis 4- to 6-fold. Using low ATP concentration (50 micro M), the steady state level of phosphoenzyme was decreased by the addition of K+. This effect disappeared when the ATP concentration was raised to 1 mM.
使用毫秒级混合和淬灭装置研究了钾离子（K⁺）对无机磷酸（Pi）或三磷酸腺苷（ATP）介导的肌浆网钙依赖性ATP酶磷酸化的影响。在Pi形成的磷酸酶平衡水平在K⁺浓度增加时逐渐降低。这种效应在空囊泡中比在先前加载钙的囊泡中更明显。钾离子不会改变Pi对酶磷酸化的初始速率，但会使磷酸酶水解速率增加4至6倍。使用低ATP浓度（50微摩尔）时，添加K⁺会降低磷酸酶的稳态水平。当ATP浓度提高到1毫摩尔时，这种效应消失。
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