Relationship between anion binding and anion permeability revealed by mutagenesis within the cystic fibrosis transmembrane conductance regulator chloride channel pore
Relationship between anion binding and anion permeability revealed by mutagenesis within the cystic fibrosis transmembrane conductance regulator chloride channel pore
复制标题
囊性纤维化跨膜电导调节器氯离子通道孔内诱变揭示阴离子结合与阴离子通透性之间的关系
DOI：
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
P. Linsdell
中科院分区：
文献类型：
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作者：
P. Linsdell
1使用膜片钳记录分析了在两种不同哺乳动物细胞系中表达的野生型和突变型囊性纤维化跨膜传导调节因子（CFTR）Cl−通道孔内的阴离子结合。具体来说，实验测量了不同阴离子的电导率和其他渗透阴离子阻止Cl−渗透通过孔隙的能力。2在对称离子条件下，野生型CFTR通道的电导顺序为Cl− >NO3− >Br−≥甲酸根>F− >SCN− → ClO 4 −。3没有观察到高的SCN−电导，在所用条件下也没有SCN−对电导的异常摩尔分数效应。在对称离子条件下无法测量碘离子电流，但在双离子条件下，I-电导似乎较低。4通过CFTR通道的氯离子电流被低浓度（10 mM）的SCN−、I−和ClO 4 −阻断，这意味着这些阴离子在孔内的结合相对紧密。5 CFTR中改变阴离子通透性序列的两个突变F337 S和T338 A也改变了阴离子电导序列。此外，SCN-、I-和ClO 4-的阻断作用在两种突变体中均减弱。这两种效应都与孔内阴离子结合的改变一致。6突变对阴离子渗透性和相对阴离子电导的影响表明，对于大多数阴离子，渗透性的增加与电导的增加有关。这表明CFTR通道孔不能通过突变区域内的选择性阴离子结合来实现其阴离子选择性。相反，它表明，进入F337和T338周围的区域的阴离子促进其通过孔。在野生型CFTR通道中，阴离子进入该关键孔区域可能由阴离子水合能主导。
1 Anion binding within the pores of wild‐type and mutant cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channels, expressed in two different mammalian cell lines, was assayed using patch clamp recording. Specifically, experiments measured both the conductance of different anions and the ability of other permeant anions to block Cl− permeation through the pore. 2 Under symmetrical ionic conditions, wild‐type CFTR channels showed the conductance sequence Cl− >NO3− >Br−≥formate >F− >SCN−∼ ClO4−. 3 High SCN− conductance was not observed, nor was there an anomalous mole fraction effect of SCN− on conductance under the conditions used. Iodide currents could not be measured under symmetrical ionic conditions, but under bi‐ionic conditions I− conductance appeared low. 4 Chloride currents through CFTR channels were blocked by low concentrations (10 mM) of SCN−, I− and ClO4−, implying relatively tight binding of these anions within the pore. 5 Two mutations in CFTR which alter the anion permeability sequence, F337S and T338A, also altered the anion conductance sequence. Furthermore, block by SCN−, I− and ClO4− were weakened in both mutants. Both these effects are consistent with altered anion binding within the pore. 6 The effects of mutations on anion permeability and relative anion conductance suggested that, for most anions, increased permeability was associated with increased conductance. This indicates that the CFTR channel pore does not achieve its anion selectivity by selective anion binding within the mutated region. Instead, it is suggested that entry of anions into the region around F337 and T338 facilitates their passage through the pore. In wild‐type CFTR channels, anion entry into this crucial pore region is probably dominated by anion hydration energies.
影响因子：
3.4
作者：
Nonner, W;Eisenberg, B
通讯作者：
Eisenberg, B
类短杆菌肽通道中渗透能量学的半显微蒙特卡罗研究：阳离子选择性的起源。
影响因子：
3.4
作者：
Dorman,V;Partenskii,MB;Jordan,PC
通讯作者：
Jordan,PC