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首页> 外文期刊>Biochemistry >Effects of deglycosylation of sodium channels on their structure and function.
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Effects of deglycosylation of sodium channels on their structure and function.

机译：钠通道的去糖基化对其结构和功能的影响。

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Voltage-gated sodium channels are important membrane proteins underlying electrical signaling in the nervous and muscular systems. They undergo rapid conformational changes between closed resting, activated, and inactivated states. Approximately 30% of the mass of the sodium channel is carbohydrate, present as glycoconjugate chains, mostly composed of N-acetylhexosamines and sialic acid. In this study, the effects of removing the carbohydrate on the functional and structural properties of highly purified sodium channels from Electrophorus electricus were investigated. After enzymatic deglycosylation, channels were reconstituted into planar lipid bilayers. In the presence of batrachotoxin, substates became evident and the single-channel conductance of the deglycosylated channels was slightly reduced relative to that of native channels, consistent with electrostatic effects due to the reduction in negative charge at the extracellular vestibule of the channel. The previously reported state-dependent changes in the circular dichroism spectra that are associated with the binding of the anticonvulsant drug Lamotrigine and batrachotoxin are also seen in the modified channels. Synchrotron radiation circular dichroism (SRCD) spectroscopy on the type of sugars found in the sodium channel showed that unlike most carbohydrates, these sugars produce a significant dichroic signal in the far-ultraviolet region. This can account for all of the measured SRCD-detected spectral differences between the native and deglycosylated channels, thereby indicating that no net change in protein secondary structure results from the deglycosylation procedure. Furthermore, thermal denaturation studies detected no significant differences in stability between native and deglycosylated channels. In summary, while the sugars of the voltage-gated sodium channels from electroplax are not essential for functional or structural integrity, they do appear to have a modulating effect on the conductance properties of these channels.
机译：电压门控钠通道是神经和肌肉系统中电信号基础的重要膜蛋白。它们在封闭的静止，激活和灭活状态之间经历快速的构象变化。钠通道质量的大约30％是碳水化合物，以糖缀合物链的形式存在，主要由N-乙酰基己糖胺和唾液酸组成。在这项研究中，研究了去除碳水化合物对电泳的高纯钠通道功能和结构特性的影响。酶促去糖基化后，通道被重建为平面脂质双层。在存在batrachotoxin的情况下，亚状态变得明显，去糖基化通道的单通道电导相对于天然通道略微降低，这与静电效应相一致，这是由于通道细胞外前庭负电荷的减少所致。在修饰的通道中还可以看到以前报道的圆形二色性光谱的状态依赖性变化，该变化与抗惊厥药拉莫三嗪和巴曲毒素的结合有关。对钠通道中发现的糖类型进行同步辐射圆二色性（SRCD）光谱分析表明，与大多数碳水化合物不同，这些糖在远紫外线区域产生明显的二色性信号。这可以解决天然和去糖基化通道之间所有测量到的SRCD检测到的光谱差异，从而表明去糖基化过程不会导致蛋白质二级结构发生净变化。此外，热变性研究未发现天然和去糖基化通道之间的稳定性没有显着差异。总而言之，尽管来自electroplax的电压门控钠通道的糖对于功能或结构完整性不是必需的，但它们似乎确实对这些通道的电导特性具有调节作用。

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