Human Na+-dependent vitamin C transporter 1 (hSVCT1): Primary structure, functional characteristics and evidence for a non-functional splice variant

Haiping Wang, Binita Dutta, Wei Huang, Lawrence D Devoe, Frederick H. Leibach, Vadivel Ganapathy, Puttur D Prasad

Research output: Contribution to journalArticle

109 Scopus citations

Abstract

We report here on the cloning and functional characterization of human Na+-dependent vitamin C transporter 1 (SVCT1). The human SVCT1 cDNA, obtained from a Caco2 cell cDNA library, encodes a protein of 598 amino acids with 12 putative transmembrane domains. The SVCT1-specific transcript, 2.4 kb in size, is expressed in kidney, liver, small intestine, thymus and prostate. When expressed heterologously in HRPE cells, SVCT1 mediates the transport of ascorbate, the reduced form of vitamin C, in a Na+-dependent manner. The transporter is specific for ascorbate with a K(t) of ~75 μM. The relationship between the cDNA-specific uptake rate of ascorbate and Na+ concentration is sigmoidal with a Na+:ascorbate stoichiometry of 2:1, indicating that the transport process is electrogenic. In Caco2 cells and in normal human intestine, SVCT1 also exists as a non-functional splice variant with a four amino acid sequence inserted between E-155 and V-156. The splice variant results from the use of a donor site 12 bp downstream of the normal donor site. Copyright (C) 1999.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1461
Issue number1
DOIs
StatePublished - Nov 9 1999

Keywords

  • Ascorbate transport
  • Human
  • Intestine
  • Na-dependent vitamin C transporter 1
  • Na-dependent vitamin C transporter 1 splice variant
  • Primary structure

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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