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首页> 外文期刊>The European Journal of Neuroscience >The large conductance Ca2+-activated potassium channel (pSlo) of the cockroach Periplaneta americana: structure, localization in neurons and electrophysiology.
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The large conductance Ca2+-activated potassium channel (pSlo) of the cockroach Periplaneta americana: structure, localization in neurons and electrophysiology.

机译：美洲大Per的大电导Ca2 +激活的钾通道（pSlo）：结构，在神经元中的定位和电生理。

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摘要

Voltage-activated, Ca2+-sensitive K+ channels (BK or maxi K,Ca channels) play a major role in the control of neuronal excitability. We have cloned pSlo, the BK channel alpha subunit of the cockroach Periplaneta americana. The amino acid sequence of pSlo shows 88% identity to dSlo from Drosophila. There are five alternatively spliced positions in pSlo showing differential expression in various tissues. A pSlo-specific antibody prominently stained the octopaminergic dorsal unpaired median (DUM) neurons and peptidergic midline neurons in Periplaneta abdominal ganglia. HEK293 cells expressing pSlo exhibit K+ channels of 170 pS conductance. They have a tendency for brief closures, exhibit subconductance states and show slight inward rectification. Activation kinetics and voltage dependence are controlled by cytoplasmic [Ca2+]. In contrast to dSlo, pSlo channels are sensitive to charybdotoxin and iberiotoxin. Mutagenesis at two positions (E254 and Q285) changed blocking efficacy of charybdotoxin. In contrastto pSlo expressed in HEK293 cells, native IbTx-sensitive K,Ca currents in DUM and in peptidergic neurons, exhibited rapid, partial inactivation. The fast component of the K,Ca current partly accounts for the repolarization and the early after-hyperpolarization of the action potential. By means of Ca2+-induced repolarization, BK channels may reduce the risk of Ca2+ overload in cockroach neurons. Interestingly, the neurons expressing pSlo were also found to express taurine, a messenger that is likely to limit overexcitation by an autocrine mechanism in mammalian central neurons.
机译：电压激活的Ca2 +敏感K +通道（BK或maxi K，Ca通道）在控制神经元兴奋性中起主要作用。我们已经克隆了美洲S（Periplaneta americana）的BK通道alpha亚基pSlo。 pSlo的氨基酸序列与果蝇的dSlo显示88％的同一性。 pSlo中有五个选择性剪​​接的位置，显示在各种组织中的差异表达。 pSlo特异性抗体显着地染色了翼周腹部神经节中的章鱼胺能背对中位（DUM）神经元和肽能中线神经元。表达pSlo的HEK293细胞表现出170 pS电导的K +通道。它们具有短暂闭合的趋势，表现出亚导状态，并表现出轻微的向内整流。激活动力学和电压依赖性受细胞质[Ca2 +]控制。与dSlo相反，pSlo通道对Charybdotoxin和iberiotoxin敏感。在两个位置（E254和Q285）的诱变改变了charybdotoxin的阻断功效。与在HEK293细胞中表达的pSlo相反，DUM和肽能神经元中的天然IbTx敏感的K，Ca电流表现出快速的部分失活。 K，Ca电流的快速成分部分解释了动作电位的重新极化和超极化后的早期。通过Ca2 +诱导的复极化，BK通道可降低蟑螂神经元中Ca2 +超载的风险。有趣的是，还发现表达pSlo的神经元表达牛磺酸，牛磺酸是一种通过哺乳动物中枢神经元的自分泌机制来限制过度兴奋的信使。

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