Molecular cloning and functional characterization of the Aplysia FMRFamide-gated Na+ channel
Molecular cloning and functional characterization of the Aplysia FMRFamide-gated Na+ channel
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DOI：
10.1007/s00424-005-1498-z
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发表时间：
2006-02-01
影响因子：
4.5
通讯作者：
Abe, G
中科院分区：
文献类型：
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作者：
Furukawa, Y;Miyawaki, Y;Abe, G
FMR家族门控钠离子通道(FaNaC)是目前已知的唯一一种多肽门控离子通道，属于上皮性Na+通道/退行性变蛋白(ENaC/DEG)家族。我们利用聚合酶链式反应从黑线海兔的CNS文库中克隆了一个可能的FaNaC，并对其在非洲爪哇卵母细胞中的特性进行了研究。黑曲霉FaNaC(AkFaNaC)由653个氨基酸组成，与ENaC/DEG家族的其他成员一样，该序列预测了两个推测的膜结构域和一个较大的胞外结构域。在表达AkFaNaC的卵母细胞中，FMRFamide可诱发阿米洛利敏感的Na+电流。与已知的FaNaCs(Helix和Helisoma FaNaCs)不同，AkFaNaC可被外部钙离子阻断，但不能被镁离子阻断。此外，该电流的脱敏作用可被镁离子增强，但不被钙离子所增强。在低pH和高pH条件下，FMRFamide门控电流均受到抑制。这些结果表明AkFaNaC是海兔的FaNaC，该通道具有海兔特有的功能结构域。
FMRFamide-gated Na+ channel (FaNaC) is the only known peptide-gated ion channel, which belongs to the epithelial Na+ channel/ degenerin (ENaC/ DEG) family. We have cloned a putative FaNaC from the Aplysia kurodai CNS library using PCR, and examined its characteristics in Xenopus oocytes. A. kurodai FaNaC (AkFaNaC) comprised with 653 amino acids, and the sequence predicts two putative membrane domains and a large extracellular domain as in other members of the ENaC/ DEG family. In oocytes expressing AkFaNaC, FMRFamide evoked amiloride-sensitive Na+ current. Different from the known FaNaCs ( Helix and Helisoma FaNaCs), AkFaNaC was blocked by external Ca2+ but not by Mg2+. Also, desensitization of the current was enhanced by Mg2+ but not by Ca2+. The FMRFamide-gated current was depressed in both low and high pH. These results indicate that AkFaNaC is an FaNaC of Aplysia, and that the channel has Aplysia specific functional domains.