Cloning and functional expression of a cDNA encoding a mammalian sodium- dependent vitamin transporter mediating the uptake of pantothenate, biotin, and lipoate

Puttur D Prasad, Haiping Wang, Ramesh Kekuda, Takuya Fujita, You Jun Fei, Lawrence D Devoe, Frederick H. Leibach, Vadivel Ganapathy

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Abstract

Previous studies have shown that a Na± dependent transport system is responsible for the transplacental transfer of the vitamins pantothenate and biotin and the essential metabolite lipoate. We now report the isolation of a rat placental cDNA encoding a transport protein responsible for this function. The cloned cDNA, when expressed in HeLa cells, induces Na + - dependent pantothenate and biotin transport activities. The transporter is specific for pantothenate, biotin, and lipoate. The Michaelis-Menten constant (K(t)) for the transport of pantothenate and biotin in cDNA-transfected cells is 4.9 ± 1.1 and 15.1 ± 1.2 μM, respectively. The transport of both vitamins in cDNA-transfected cells is inhibited by lipoate with an inhibition constant (K(i)) of approximately 5 μM. The nucleotide sequence of the cDNA (sodium-dependent multivitamin transporter (SMVT)) predicts a protein of 68.6 kDa with 634 amino acids and 12 potential transmembrane domains. Protein data base search indicates significant sequence similarity between SMVT and known members of the Na + -dependent glucose transporter family. Northern blot analysis shows that SMVT transcripts are present in all of the tissues that were tested. The size of the principal transcript is 3.2 kilobases. SMVT represents the first Na + -dependent vitamin transporter to be cloned from a mammalian tissue.

Original languageEnglish (US)
Pages (from-to)7501-7508
Number of pages8
JournalJournal of Biological Chemistry
Volume273
Issue number13
DOIs
StatePublished - Mar 27 1998

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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