Human placental Na+-dependent multivitamin transporter. Cloning, functional expression, gene structure, and chromosomal localization

We have cloned the human Na+-dependent multivitamin transporter (SMVT), which transports the water-soluble vitamins pantothenate, biotin, and lipoate, from a placental choriocarcinoma cell line (JAR). The cDNA codes for a protein of 635 amino acids with 12 transmembrane domains and 4 putative sites...

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Bibliographic Details
Published in:The Journal of biological chemistry 1999-05, Vol.274 (21), p.14875-14883
Main Authors: Wang, H, Huang, W, Fei, Y J, Xia, H, Yang-Feng, T L, Leibach, F H, Devoe, L D, Ganapathy, V, Prasad, P D
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Base Sequence
Biological Transport, Active
Biotin - metabolism
Carrier Proteins - biosynthesis
Carrier Proteins - genetics
Carrier Proteins - isolation & purification
Choriocarcinoma
Chromosome Mapping
Cloning, Molecular
DNA, Complementary - genetics
Female
Humans
Membrane Glycoproteins - biosynthesis
Membrane Glycoproteins - genetics
Membrane Glycoproteins - isolation & purification
Molecular Sequence Data
Pantothenic Acid - metabolism
Placenta
Symporters
Tumor Cells, Cultured
Uterine Neoplasms
Xenopus laevis
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Summary:We have cloned the human Na+-dependent multivitamin transporter (SMVT), which transports the water-soluble vitamins pantothenate, biotin, and lipoate, from a placental choriocarcinoma cell line (JAR). The cDNA codes for a protein of 635 amino acids with 12 transmembrane domains and 4 putative sites for N-linked glycosylation. The human SMVT exhibits a high degree of homology (84% identity and 89% similarity) to the rat counterpart. When expressed in HRPE cells, the cDNA-induced transport process is obligatorily dependent on Na+ and accepts pantothenate, biotin, and lipoate as substrates. The relationship between the cDNA-specific uptake rate of pantothenate or biotin and Na+ concentration is sigmoidal with a Na+:vitamin stoichiometry of 2:1. The human SMVT, when expressed in Xenopus laevis oocytes, induces inward currents in the presence of pantothenate, biotin, and lipoate in a Na+-, concentration-, and potential-dependent manner. We also report here on the structural organization and chromosomal localization of the human SMVT gene. The SMVT gene is approximately 14 kilobase pairs in length and consists of 17 exons. The SMVT gene is located on chromosome 2p23 as evidenced by somatic cell hybrid analysis and fluorescence in situ hybridization.
ISSN:0021-9258
DOI:10.1074/jbc.274.21.14875