Transcuprein is a macroglobulin regulated by copper and iron availability.

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Liu N, Lo LS, Askary SH, Jones L, Kidane TZ, Trang T, Nguyen M, Goforth J, Chu YH, Vivas E, Tsai M, Westbrook T, Linder MC

Transcuprein is a macroglobulin regulated by copper and iron availability.

J Nutr Biochem. 2007 Sep;18(9):597-608. Epub 2007 Mar 23.

PubMed ID

17363239 [ View in PubMed

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Abstract

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(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(2)-macroglobulin), which is homologous to alpha(1)-inhibitor III, also bound copper tightly. Expression of alpha(1)I3 (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(1)I3 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.

DrugBank Data that Cites this Article

Drug Carriers

Drug	Carrier	Kind	Organism	Pharmacological Action	Actions
Copper	Alpha-2-macroglobulin	Protein	Humans	No	Binder	Details