Novel vanadium-binding proteins (Vanabins) identified in cDNA libraries and the genome of the ascidian Ciona intestinalis
BBA_1630_64-70_2003.pdf 584 KB
Ascidians, especially those belonging to the suborder Phlebobranchia, can accumulate high levels of vanadium. Vanadium-binding proteins (vanabins) were first isolated from a vanadium-accumulating ascidian, Ascidia sydneiensis samea, and then the vanabins were cloned, their expression was studied, and metal-binding assays were conducted. In order to unravel the mechanism of vanadium accumulation, we searched for vanabin-like genes in other animals, including other ascidians. A database search revealed five groups of cDNAs that encoded vanabin-like proteins in another ascidian, Ciona intestinalis. The genes encoding C. intestinalis vanabins, CiVanabin1 to CiVanabin5, were clustered in an 8.4-kb genomic region. The direction of transcription of each gene was identical and each gene had a single intron. All the C. intestinalis vanabins were cysteine rich, and the repetitive pattern of cysteines closely resembled that of A. sydneiensis samea vanabins. Using immobilized metal ion affinity chromatography, we found that a recombinant protein of at least one of the C. intestinalis vanabins (CiVanabin5) bound to vanadium(IV) ions.
Biochimica et biophysica acta
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Copyright (c) 2003 Elsevier B.V.
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Graduate School of Science