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Cloning and functional characterization of the human sodium‐dependent vitamin C transporters hSVCT1 and hSVCT2
Author(s) -
Daruwala Rushad,
Song Jian,
Koh Woo S.,
Rumsey Steve C.,
Levine Mark
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)01393-9
Subject(s) - transporter , dehydroascorbic acid , open reading frame , biochemistry , ascorbic acid , amino acid , complementary dna , vitamin c , cdna library , xenopus , sodium , chemistry , biology , microbiology and biotechnology , peptide sequence , gene , food science , organic chemistry
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 μM and of hSVCT2 for ascorbate was 21.3 μM. 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.