Characterization of the genomic structure of the human vitamin C transporter SVCT1 (SLC23A2)

Vitamin C (L-ascorbic acid), a critical cofactor for intracellular enzymati c reactions, functions as a scavenger of free oxygen radicals and is an ess ential micronutrient. Vitamin C is actively transported into cells by one o f two closely related sodium-dependent transporters, SVCT1 or SVCT2. In thi s paper, we report the complete sequencing and gene structure of SLC23A2, t he gene encoding SVCT1. The 1797-bp cDNA sequence (open reading frame) of t he SLC23A2 gene was derived from a compact genomic sequence of 7966 bp [tra nslation initiation codon (ATG) to poly A tail], which is divided into 14 e xons. Furthermore, repetitive or masked elements constituted 17.98% of the gene; there were 4 Alu sequences and 5 MIR (Mammalian Interspersed Repetiti ve element) sequences. A search for common variants in SLC23A2, using curre nt bioinformatic tools and direct resequencing of control populations, fail ed to identify common single nucleotide polymorphisms. The start of transcr iption was mapped to a position -47 relative to the ATG; the immediate 5' s equence was determined and analyzed for possible consensus binding sites fo r known transcription factors. Our findings will serve as the foundation fo r investigation of the regulation and expression of the tissue-specific sod ium-dependent vitamin C transporter, SLC23A2.