首页> 外文期刊>Biochimica et Biophysica Acta. General Subjects >A novel vanadium transporter of the Nramp family expressed at the vacuole of vanadium-accumulating cells of the ascidian Ascidia sydneiensis samea.
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A novel vanadium transporter of the Nramp family expressed at the vacuole of vanadium-accumulating cells of the ascidian Ascidia sydneiensis samea.

机译:Nramp家族的一种新的钒转运蛋白在海鞘亚述亚铁孢子的钒积累细胞的液泡中表达。

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BACKGROUND: Vanadium is an essential transition metal in biological systems. Several key proteins related to vanadium accumulation and its physiological function have been isolated, but no vanadium ion transporter has yet been identified. METHODS: We identified and cloned a member of the Nramp/DCT family of membrane metal transporters (AsNramp) from the ascidian Ascidia sydneiensis samea, which can accumulate extremely high levels of vanadium in the vacuoles of a type of blood cell called signet ring cells (also called vanadocytes). We performed immunological and biochemical experiments to examine its expression and transport function. RESULTS: Western blotting analysis showed that AsNramp was localized at the vacuolar membrane of vanadocytes. Using the Xenopus oocyte expression system, we showed that AsNramp transported VO(2+) into the oocyte as pH-dependent manner above pH 6, while no significant activity was observed below pH 6. Kinetic parameters (K(m) and V(max)) of AsNramp-mediated VO(2+) transport at pH 8.5 were 90nM and 9.1pmol/oocyte/h, respectively. A rat homolog, DCT1, did not transport VO(2+) under the same conditions. Excess Fe(2+), Cu(2+), Mn(2+), or Zn(2+) inhibited the transport of VO(2+). AsNramp was revealed to be a novel VO(2+)/H(+) antiporter, and we propose that AsNramp mediates vanadium accumulation coupled with the electrochemical gradient generated by vacuolar H(+)-ATPase in vanadocytes. GENERAL SIGNIFICANCE: This is the first report of identification and functional analysis on a membrane transporter for vanadium ions.
机译:背景:钒是生物系统中必不可少的过渡金属。已经分离了几种与钒积累及其生理功能有关的关键蛋白,但尚未鉴定出钒离子转运蛋白。方法:我们鉴定并克隆了来自海生亚胞体Ascidia sydneiensis samea的Nramp / DCT膜金属转运蛋白家族(AsNramp)的一个成员,它可以在称为“印章环细胞”(Signet ring cells)的血细胞液泡中积聚极高的钒含量。也称为Vanadocytes)。我们进行了免疫和生化实验,以检查其表达和转运功能。结果:Western blotting分析显示AsNramp定位于血管细胞的液泡膜。使用非洲爪蟾卵母细胞表达系统,我们显示AsNramp在pH高于6时以pH依赖方式将VO(2+)运入卵母细胞,而在pH低于6时未观察到明显的活性。动力学参数(K(m)和V(max) ))在pH 8.5的AsNramp介导的VO(2+)转运分别为90nM和9.1pmol /卵母细胞/ h。大鼠同系物DCT1,在相同条件下未转运VO(2+)。过量的Fe(2 +),Cu(2 +),Mn(2+)或Zn(2+)抑制了VO(2+)的运输。 AsNramp被揭示是一种新型的VO(2 +)/ H(+)反转运蛋白,我们建议AsNramp介导钒积累与液泡中H(+)-ATPase液泡产生的电化学梯度耦合。一般意义:这是关于钒离子膜转运蛋白的鉴定和功能分析的第一份报告。

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