Blumenthal E M, Kaczmarek L K
Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, Connecticut 06510.
J Neurosci. 1992 Jan;12(1):290-6. doi: 10.1523/JNEUROSCI.12-01-00290.1992.
When expressed in the Xenopus oocyte, the minK protein induces a slowly activating voltage-dependent potassium current (Isk). We studied the modulation of this current by altering intracellular cAMP levels and found that the amplitude of Isk is dramatically increased by treatments that raise cAMP levels and decreased by agents that lower cAMP levels. Preinjection of a protein inhibitor of the cAMP-dependent protein kinase blocked the effects of increased cAMP levels. There were no changes in the voltage dependence or kinetics of Isk. Mutations that eliminate a potential phosphorylation site on the minK protein did not block the effects of activating the kinase. In addition, the membrane capacitance of the oocyte increased and decreased in parallel with Isk. Our results fit a mechanism in which channel proteins are selectively inserted into and removed from the plasma membrane in response to changes in kinase activity.
当在非洲爪蟾卵母细胞中表达时，minK蛋白可诱导出一种缓慢激活的电压依赖性钾电流（Isk）。我们通过改变细胞内cAMP水平来研究该电流的调节作用，发现提高cAMP水平的处理可显著增加Isk的幅度，而降低cAMP水平的试剂则使其降低。预先注射cAMP依赖性蛋白激酶的蛋白抑制剂可阻断cAMP水平升高的作用。Isk的电压依赖性或动力学没有变化。消除minK蛋白上一个潜在磷酸化位点的突变并未阻断激活激酶的作用。此外，卵母细胞的膜电容与Isk平行增加和减少。我们的结果符合一种机制，即通道蛋白会根据激酶活性的变化选择性地插入质膜和从质膜上移除。
