Park Kang-Sik, Mohapatra Durga P, Misonou Hiroaki, Trimmer James S
Department of Pharmacology, School of Medicine, University of California, Davis, CA 95616, USA.
Science. 2006 Aug 18;313(5789):976-9. doi: 10.1126/science.1124254.
Dynamic modulation of ion channels by phosphorylation underlies neuronal plasticity. The Kv2.1 potassium channel is highly phosphorylated in resting mammalian neurons. Activity-dependent Kv2.1 dephosphorylation by calcineurin induces graded hyperpolarizing shifts in voltage-dependent activation, causing suppression of neuronal excitability. Mass spectrometry-SILAC (stable isotope labeling with amino acids in cell culture) identified 16 Kv2.1 phosphorylation sites, of which 7 were dephosphorylated by calcineurin. Mutation of individual calcineurin-regulated sites to alanine produced incremental shifts mimicking dephosphorylation, whereas mutation to aspartate yielded equivalent resistance to calcineurin. Mutations at multiple sites were additive, showing that variable phosphorylation of Kv2.1 at a large number of sites allows graded activity-dependent regulation of channel gating and neuronal firing properties.
离子通道磷酸化的动态调节是神经元可塑性的基础。Kv2.1钾通道在静息的哺乳动物神经元中高度磷酸化。钙调神经磷酸酶介导的依赖于活性的Kv2.1去磷酸化诱导电压依赖性激活的分级超极化偏移，从而抑制神经元兴奋性。质谱-SILAC（细胞培养中氨基酸的稳定同位素标记）鉴定出16个Kv2.1磷酸化位点，其中7个被钙调神经磷酸酶去磷酸化。将单个钙调神经磷酸酶调节位点突变为丙氨酸会产生类似于去磷酸化的增量偏移，而突变为天冬氨酸则产生对钙调神经磷酸酶的等效抗性。多个位点的突变具有累加性，表明Kv2.1在大量位点的可变磷酸化允许对通道门控和神经元放电特性进行分级的活性依赖性调节。
