Modulation of a calcium-sensitive nonspecific cation channel by closely associated protein kinase and phosphatase activities.
Modulation of a calcium-sensitive nonspecific cation channel by closely associated protein kinase and phosphatase activities.
复制标题
通过密切相关的蛋白激酶和磷酸酶活性调节钙敏感的非特异性阳离子通道。
DOI：
10.1073/pnas.95.18.10938
复制
发表时间：
1998
影响因子：
11.1
通讯作者：
Kaczmarek,LK
中科院分区：
文献类型：
--
作者：
Wilson,GF;Magoski,NS;Kaczmarek,LK
非特异性阳离子通道的调节通常是神经元爆发和神经元活动的其他长期变化的基础。在袋细胞神经元ofAflasia，它最近已经提出，细胞内信使诱导的增加的活性的非特异性阳离子通道可能是基础的发病的30分钟期间的自发动作电位称为“后放电”。在膜片钳研究的通道，我们表明，开放的通道的概率可以增加平均10.7倍，通过应用ATP的细胞质侧的补丁。持续时间直方图表明，这种增加主要是由最慢时间常数描述的通道关闭的持续时间和百分比减少的结果。使用5′-腺苷酰亚氨二磷酸（一种不可水解的ATP类似物）时未观察到开放概率的增加，并且在存在H7或更特异性的钙/磷脂依赖性蛋白激酶C（PKC）抑制肽时被阻断（19-36）。由于在没有应用蛋白激酶的情况下观察到的ATP反应活性增加，我们的研究结果表明，内源性的激酶切除补丁介导的效果。ATP的影响可以逆转外源性应用蛋白磷酸酶1或微囊藻毒素敏感的磷酸酶也内源性切除补丁。这些结果，连同工作证明存在的蛋白酪氨酸磷酸酶在这些补丁，表明阳离子通道的一部分，包括至少三种酶的调节复合物。这种复合物可以作为分子开关激活阳离子通道，从而触发后放电。
Regulation of nonspecific cation channels often underlies neuronal bursting and other prolonged changes in neuronal activity. In bag cell neurons ofAplysia, it recently has been suggested that an intracellular messenger-induced increase in the activity of a nonspecific cation channel may underlie the onset of a 30-min period of spontaneous action potentials referred to as the “afterdischarge.” In patch clamp studies of the channel, we show that the open probability of the channel can be increased by an average of 10.7-fold by application of ATP to the cytoplasmic side of patches. Duration histograms indicate that the increase is primarily a result of a reduction in the duration and percentage of channel closures described by the slowest time constant. The increase in open probability was not observed using 5′-adenylylimidodiphosphate, a nonhydrolyzable ATP analog, and was blocked in the presence of H7 or the more specific calcium/phospholipid-dependent protein kinase C (PKC) inhibitor peptide(19–36). Because the increase in activity observed in response to ATP occurred without application of protein kinase, our results indicate that a kinase endogenous to excised patches mediates the effect. The effect of ATP could be reversed by exogenously applied protein phosphatase 1 or by a microcystin-sensitive phosphatase also endogenous to excised patches. These results, together with work demonstrating the presence of a protein tyrosine phosphatase in these patches, suggest that the cation channel is part of a regulatory complex including at least three enzymes. This complex may act as a molecular switch to activate the cation channel and, thereby, trigger the afterdischarge.