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
- Amino Acid Sequence
- Animals
- Ascorbic Acid / metabolism*
- Base Sequence
- Biological Transport
- Bucladesine / pharmacology
- Carrier Proteins / biosynthesis
- Carrier Proteins / chemistry*
- Carrier Proteins / genetics*
- Carrier Proteins / physiology
- Cloning, Molecular
- Female
- Humans
- Molecular Sequence Data
- Oocytes / metabolism
- Organic Anion Transporters, Sodium-Dependent*
- Protein Biosynthesis
- Proteins / chemistry*
- Proteins / genetics*
- Proteins / physiology
- Sodium / physiology*
- Sodium-Coupled Vitamin C Transporters
- Symporters*
- Tetradecanoylphorbol Acetate / pharmacology
- Xenopus laevis
Substances
- Carrier Proteins
- Organic Anion Transporters, Sodium-Dependent
- Proteins
- Sodium-Coupled Vitamin C Transporters
- Symporters
- Bucladesine
- Sodium
- Tetradecanoylphorbol Acetate
- Ascorbic Acid
Associated data
- GENBANK/AJ269477
- GENBANK/AJ269478