Vanadium-binding proteins (vanabins) from a vanadium-rich ascidian Ascidia sydneiensis samea
Vanadium-binding proteins (vanabins) from a vanadium-rich ascidian Ascidia sydneiensis samea
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DOI：
10.1016/s0167-4781(03)00036-8
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发表时间：
2003-04-15
期刊：
影响因子：
--
通讯作者：
Michibata, H
中科院分区：
文献类型：
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作者：
Ueki, T;Adachi, T;Michibata, H
自上世纪初以来，人们就知道海鞘在其血细胞中积累了高水平的过渡金属钒，尽管这种奇怪的生物功能的机制仍不清楚。最近，我们鉴定了三种钒结合蛋白（vanabins），以前称为钒相关蛋白（VAP）[Zool.科学。 14 (1997) 37]，来自富含钒的海鞘Ascidia sydneiensis Samea的含钒血细胞（钒细胞）的细胞质部分。在这里，我们描述了 vanabins 金属结合能力的克隆、表达和分析。两个独立但相关的 vanabins（vanabin1 和 vanabin2）的重组蛋白分别与 10 和 20 个钒 (W) 离子结合，解离常数分别为 2.1 X 10(-5) 和 2.3 x 10(-5) M。钒 (IV) 与这些 vanabin 的结合可通过添加铜 (H) 离子来抑制，但不会通过镁 (H) 或钼酸 (VI) 离子来抑制。 Vanabins 是第一个被报道可与钒离子特异性结合的蛋白质；这将为解决海鞘选择性积累钒的问题提供线索。 (C) 2003 Elsevier Science B.V. 保留所有权利。
Since the beginning of the last century, it has been known that ascidians accumulate high levels of a transition metal, vanadium, in their blood cells, although the mechanism for this curious biological function remains unknown. Recently, we identified three vanadium-binding proteins (vanabins), previously denoted as vanadium-associated proteins (VAPs) [Zool. Sci. 14 (1997) 37], from the cytoplasm fraction of vanadium-containing blood cells (vanadocytes) of the vanadium-rich ascidian Ascidia sydneiensis samea. Here, we describe the cloning, expression, and analysis of the metal-binding ability of vanabins. Recombinant proteins of two independent but related vanabins, vanabin1 and vanabin2, bound to 10 and 20 vanadium(W) ions with dissociation constants of 2.1 X 10(-5) and 2.3 x 10(-5) M, respectively. The binding of vanadium(IV) to these vanabins was inhibited by the addition of copper(H) ions, but not by magnesium(H) or molybdate(VI) ions. Vanabins are the first proteins reported to show specific binding to vanadium ions; this should provide a clue to resolving the problem regarding the selective accumulation of vanadium in ascidians. (C) 2003 Elsevier Science B.V. All rights reserved.