Cloning and functional characterization of the human sodium-dependent vitamin C transporters hSVCT1 and hSVCT2

FEBS Lett. 1999 Nov 5;460(3):480-4. doi: 10.1016/s0014-5793(99)01393-9.

R Daruwala ¹, J Song, W S Koh, S C Rumsey, M Levine

Affiliations

Affiliation

1 Molecular and Clinical Nutrition Section, Bldg. 10, Rm. 4D52, MSC 1372, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-1372, USA.

PMID: 10556521 DOI: 10.1016/s0014-5793(99)01393-9

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.

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