Xenopus laevis oocytes contain endogenous large conductance Ca2(+)-activated K+ channels.
Xenopus laevis oocytes contain endogenous large conductance Ca2(+)-activated K+ channels.
复制标题
非洲爪蟾卵母细胞含有内源性大电导Ca2(+)激活的K通道。
DOI：
10.1016/0028-3908(96)00134-7
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发表时间：
1996
影响因子：
4.7
通讯作者：
Reinhart,PH
中科院分区：
文献类型：
--
作者：
Krause,JD;Foster,CD;Reinhart,PH
非洲爪蟾卵母细胞已经成为研究克隆离子通道的杰出工具，主要是因为它们本质上表达大多数类型的离子通道的低水平。然而，当这些细胞用于单通道研究时，必须确定卵母细胞是否含有甚至低水平的内源性离子通道，其特性与正在研究的通道相似。我们在这里表明，X。绵羊卵母细胞表达内源性大电导Ca 2+激活的K+通道，其性质与哺乳动物的该通道亚型相似。内源性通道的开放概率（po）每e倍变化表现出12-14 mV的电压依赖性，可被微摩尔Ca 2+浓度激活，在对称的110 mM K+溶液中具有约200 pS的单通道电导。膜片钳实验表明，这种内源性通道以低密度存在（1001通道/3000 μm2）。如果内源性钾通道亚基能与其他外源性钾通道亚基形成功能性四聚体，那么它们将引起异质性通道群体的表达。因此，研究涉及异源表达的大电导Ca 2+激活的K+通道非洲爪蟾卵母细胞需要仔细的分析和解释。版权所有© 1996 Elsevier Science Ltd
Xenopus laevis oocytes have become a pre-eminent tool for studying cloned ion channels, primarily because they intrinsically express low levels of most types of ion channels. However, when these cells are used for single channel studies, it is essential to determine whether or not oocytes contain even low levels of endogenous ion channels with properties similar to the channel being investigated. We show here that X. laevis oocytes express endogenous large-conductance Ca2+-activated K+channels with properties similar to mammalian isoforms of this channel. The endogenous channels exhibit a voltage-dependence of 12–14 mV per e-fold change in open probability (po), can be activated by micromolar Ca2+concentrations, and have a single channel conductance of approximately 200 pS in symmetrical 110 mM K+solutions. Patch clamp experiments indicate that this endogenous channel is present at low densities (∼1 channel/3000 μm2). If endogenous channel subunits can form functional tetramers with other exogenous potassium channel subunits, then they will give rise to the expression of a heterogeneous channel population. Therefore, studies involving the heterologous expression of large-conductance Ca2+-activated K+channels in Xenopus laevis oocytes require careful analysis and interpretation. Copyright © 1996 Elsevier Science Ltd