Expression of human pI(Cln) and ClC-6 in Xenopus oocytes induces an identical endogenous chloride conductance
Expression of human pI(Cln) and ClC-6 in Xenopus oocytes induces an identical endogenous chloride conductance
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DOI：
10.1074/jbc.272.6.3615
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发表时间：
1997-02-07
影响因子：
4.8
通讯作者：
Eggermont, J
中科院分区：
文献类型：
--
作者：
Buyse, G;Voets, T;Eggermont, J
PI(CLN)是一种在非洲爪哇卵母细胞中表达时能诱导外向整流性核苷酸敏感氯电流(I-CLN)的蛋白质，但其确切功能(质膜阴离子通道与通道的胞浆调节因子)仍存在争议。我们现在报道，当非洲爪哇卵母细胞注射人ClC-6RNA时，诱导出与I-CLN相同的氯电流。事实上，PI(ClN)和ClC-6诱导的电流都是向外整流的，它们在正电位下缓慢失活，并具有负离子渗透性顺序N3->；i->；br->；Cl->；葡萄糖酸盐。甜蜜素、NPPB和胞外cAMP阻断诱导电流，在分析前将注入的非洲爪哇卵母细胞在更高的温度(24或37℃)下孵育，电流表达的成功率显著提高。此外，在未注射的非洲爪哇卵母细胞中，有6.2%的卵母细胞可检测到I-CLN电流。因此，我们得出结论，非洲爪哇卵母细胞的I-CLN电流对应于一种内源性电导，这种电导可以被结构上无关的蛋白的表达所激活。此外，功能、生化和形态观察并不支持PI(CLN)在细胞膨胀后永久或短暂地驻留在质膜上的观点。因此，在非洲爪哇卵母细胞中，PI(CLN)不太可能形成负责I-CLN电流的通道。
pI(Cln) is a protein that induces an outwardly rectifying, nucleotide-sensitive chloride current (I-Cln) when expressed in Xenopus oocytes, but its precise function (plasma membrane anion channel versus cytosolic regulator of a channel) remains controversial. We now report that a chloride current identical to I-Cln is induced when Xenopus oocytes are injected with human ClC-6 RNA. Indeed, both the pI(Cln) and the ClC-6 induced current are outwardly rectifying, they inactivate slowly at positive potentials and have an anion permeability sequence NO3- > I- > Br- > Cl- > gluconate. Cyclamate, NPPB, and extracellular cAMP block the induced currents, The success rate of current expression is significantly increased when the injected Xenopus oocytes are incubated at a higher temperature (24 or 37 degrees C) prior to the analysis. In addition, the I-Cln current was detected in 6.2% of noninjected control Xenopus oocytes. We therefore conclude that the I-Cln current in Xenopus oocytes corresponds to an endogenous conductance that can be activated by expression of structurally unrelated proteins. Furthermore, functional, biochemical, and morphological observations did not support the notion that pI(Cln) resides in the plasma membrane either permanently or transiently after cell swelling. Thus, it is unlikely that pI(Cln) forms the channel that is responsible for the I-Cln current in Xenopus oocytes.