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首页> 外文期刊>The Journal of Nutritional Biochemistry >Transcuprein is a macroglobulin regulated by copper and iron availability.
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Transcuprein is a macroglobulin regulated by copper and iron availability.

机译：Transcuprein是一种巨球蛋白，受铜和铁可用性的调节。

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Transcuprein is a high-affinity copper carrier in the plasma that is involved in the initial distribution of copper entering the blood from the digestive tract. To identify and obtain cDNA for this protein, it was purified from rat plasma by size exclusion and copper-chelate affinity chromatography, and amino acid sequences were obtained. These revealed a 190-kDa glycosylated protein identified as the macroglobulin alpha < sub>1-inhibitor III, the main macroglobulin of rodent blood plasma. Albumin (65 kDa) copurified in variable amounts and was concluded to be a contaminant (although it can transiently bind the macroglobulin). The main macroglobulin in human blood plasma ( alpha < sub>2-macroglobulin), which is homologous to alpha < sub>1-inhibitor III, also bound copper tightly. Expression of alpha < sub>1I3 (transcuprein) mRNA by the liver was examined in rats with and without copper deficiency, using quantitative polymerase chain reaction methodology and Northern blot analysis. Protein expression was examined by Western blotting. Deficient rats with 40% less ceruloplasmin oxidase activity and liver copper concentrations expressed about twice as much alpha < sub>1I3 mRNA, but circulating levels of transcuprein did not differ. Iron deficiency, which increased liver copper concentrations by threefold, reduced transcuprein mRNA expression and circulating levels of transcuprein relative to what occurred in rats with normal or excess iron. We conclude that transcupreins are specific macroglobulins that not only carry zinc but also carry transport copper in the blood, and that their expression can be modulated by copper and iron availability.
机译：Transcuprein是血浆中的高亲和力铜载体，与从消化道进入血液的铜的初始分布有关。为了鉴定和获得该蛋白质的cDNA，通过大小排阻和铜螯合亲和层析从大鼠血浆中纯化该cDNA，获得氨基酸序列。这些发现揭示了一种190kDa的糖基化蛋白，被鉴定为啮齿类动物血浆的主要巨球蛋白-巨球蛋白α 1 -抑制剂III。白蛋白（65 kDa）以不同的量共纯化，并被认为是一种污染物（尽管它可以瞬时结合巨球蛋白）。与α 1 抑制剂III同源的人血浆中的主要巨球蛋白（α 2 -巨球蛋白）也与铜紧密结合。使用定量聚合酶链反应法和Northern印迹分析法检测缺铜和缺铜大鼠的肝脏中α 1 I3（transcuprein）mRNA的表达。通过蛋白质印迹检查蛋白质表达。铜蓝蛋白氧化酶活性降低且肝铜浓度降低40％的缺损大鼠表达的α 1 I3 mRNA大约是后者的两倍，但转铁蛋白的循环水平没有差异。相对于含铁正常或过量的大鼠，铁缺乏症使肝脏铜浓度增加了三倍，从而降低了transcuprein mRNA表达和transcuprein循环水平。我们得出的结论是，transcupreins是特定的巨球蛋白，不仅携带锌，而且还携带血液中的转运铜，并且它们的表达可以受到铜和铁可用性的调节。

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