在非洲爪蟾卵母细胞中表达的犬甜菜碱 - γ-氨基丁酸转运体BGT - 1中的三种电流。

Three kinds of currents in the canine betaine-GABA transporter BGT-1 expressed in Xenopus laevis oocytes.

作者信息

Forlani G, Bossi E, Perego C, Giovannardi S, Peres A

机构信息

Laboratory of Cellular and Molecular Physiology, Department of Structural and Functional Biology, University of Insubria, Varese, Italy.

出版信息

Biochim Biophys Acta. 2001 Apr 23;1538(2-3):172-80. doi: 10.1016/s0167-4889(00)00144-0.

DOI:10.1016/s0167-4889(00)00144-0

PMID:11336788

Abstract

The cloned canine betaine-GABA cotransporter BGT-1 has been heterologously expressed in Xenopus laevis oocytes in order to characterize its electrophysiological properties. Voltage-clamp experiments on transfected oocytes reveal the presence of three types of membrane current which are absent in non-injected oocytes: (i) an organic substrate-independent current (uncoupled current); (ii) a transport-associated current, seen upon addition of betaine or GABA; (iii) presteady-state currents induced by voltage changes. The three kinds of current are analogous to those reported in structurally similar cotransporters. The transport-associated current is strictly dependent on the presence of Na(+). The good correlation between the amount of charge underlying the presteady-state currents and the transport-associated current indicates that both processes are due to the activity of the transporter.

摘要

为了表征其电生理特性，已将克隆的犬甜菜碱 -γ-氨基丁酸共转运体BGT -1在非洲爪蟾卵母细胞中进行了异源表达。对转染卵母细胞进行的电压钳实验揭示了三种膜电流的存在，而未注射的卵母细胞中不存在这些电流：(i) 一种不依赖有机底物的电流（解偶联电流）；(ii) 添加甜菜碱或γ-氨基丁酸后出现的与转运相关的电流；(iii) 由电压变化诱导的预稳态电流。这三种电流类似于在结构相似的共转运体中报道的电流。与转运相关的电流严格依赖于Na(+) 的存在。预稳态电流所涉及的电荷量与转运相关电流之间的良好相关性表明，这两个过程均归因于转运体的活性。