Abstract
Two sodium-dependent vitamin C transporters, hSVCT1 and hSVCT2, were cloned from a human kidney cDNA library. hSVCT1 had a 1797 bp open reading frame encoding a 598 amino acid polypeptide. The 1953 bp open reading frame of hSVCT2 encoded a 650 amino acid polypeptide. Using a Xenopus laevis oocyte expression system, both transporters were functionally expressed. By Eadie-Hofstee transformation the apparent K(m) of hSVCT1 for ascorbate was 252.0 microM and of hSVCT2 for ascorbate was 21.3 microM. Both transporters were sodium-dependent and did not transport dehydroascorbic acid. Incubation of oocytes expressing either transporter with phorbol 12-myristate 13-acetate (PMA) inhibited ascorbate transport activity. Availability of the human transporter clones may facilitate new strategies for determining vitamin C intake.
MeSH terms
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Amino Acid Sequence
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Animals
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Ascorbic Acid / metabolism*
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Base Sequence
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Biological Transport
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Bucladesine / pharmacology
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Carrier Proteins / biosynthesis
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Carrier Proteins / chemistry*
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Carrier Proteins / genetics*
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Carrier Proteins / physiology
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Cloning, Molecular
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Female
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Humans
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Molecular Sequence Data
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Oocytes / metabolism
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Organic Anion Transporters, Sodium-Dependent*
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Protein Biosynthesis
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Proteins / chemistry*
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Proteins / genetics*
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Proteins / physiology
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Sodium / physiology*
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Sodium-Coupled Vitamin C Transporters
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Symporters*
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Tetradecanoylphorbol Acetate / pharmacology
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Xenopus laevis
Substances
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Carrier Proteins
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Organic Anion Transporters, Sodium-Dependent
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Proteins
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Sodium-Coupled Vitamin C Transporters
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Symporters
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Bucladesine
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Sodium
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Tetradecanoylphorbol Acetate
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Ascorbic Acid
Associated data
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GENBANK/AJ269477
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GENBANK/AJ269478