The role of phosphorylation in the interaction of rabbit muscle phosphofructokinase with F-actin.
The role of phosphorylation in the interaction of rabbit muscle phosphofructokinase with F-actin.
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发表时间：
1986-02
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通讯作者：
M. Luther;J. Lee
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作者：
M. Luther;J. Lee
通过监测这种共价修饰对稳态动力学以及 F-肌动蛋白和酶之间复合物形成的影响，研究了磷酸化在兔肌肉磷酸果糖激酶调节中的作用。通过沉降监测在 pH 7.0 和 23 摄氏度下磷酸果糖激酶与 F-肌动蛋白的结合。这些实验表明磷酸化的磷酸果糖激酶比去磷酸化的形式对F-肌动蛋白具有更高的表观亲和力。对照实验表明复合物的形成是特定的。在 pH 7.0、23 摄氏度下进行的稳态动力学测量表明，F-肌动蛋白的存在不会显着影响去磷酸化形式的基本动力学特性。在相同条件下，F-肌动蛋白作为磷酸化形式的正效应子，且F-肌动蛋白的作用具有特异性。这些体外研究的结果与体内观察结果一致，体内观察结果表明，在刺激肌肉收缩时，酶被更大程度地磷酸化，并且与肌肉基质的结合增加。因此，磷酸果糖激酶的磷酸化不仅改变酶的动力学行为，而且还充当调节酶区室化的手段，以便为需要能量的细胞成分提供能量。
The role of phosphorylation in the regulation of rabbit muscle phosphofructokinase was investigated by monitoring the effect of this covalent modification on the steady-state kinetics and complex formation between F-actin and the enzyme. Binding of phosphofructokinase to F-actin at pH 7.0 and 23 degrees C was monitored by sedimentation. These experiments show that phosphorylated phosphofructokinase has a higher apparent affinity for F-actin than does the dephosphorylated form. Control experiments showed that the complex formation is specific. Steady-state kinetic measurements at pH 7.0, 23 degrees C, showed that the presence of F-actin did not significantly affect the basic kinetic properties of the dephosphorylated form. Under identical conditions, F-actin acted as a positive effector of the phosphorylated form, and the effect of F-actin is specific. Results from these in vitro studies are consistent with in vivo observations which show that upon stimulation of muscle contraction, the enzyme is phosphorylated to a greater extent and the binding to the muscle matrix is increased. Hence, phosphorylation of phosphofructokinase does not only alter the kinetic behavior of the enzyme, but also serves as a means to regulate the compartmentalization of the enzyme in order to provide energy to the cellular component where it is needed.