Functional analysis of human sodium-phosphate transporter 4 (NPT4/SLC17A3) polymorphisms.

We analyzed the functional properties of five nonsynonymous single nucleotide polymorphisms (SNPs) in the sodium-phosphate transporter NPT4 gene (SLC17A3) using the Xenopus oocyte expression system. NPT4 variants carrying SNP V257F, G279R, or P378L exhibited reduced transport of [(14)C]para-aminohippurate, [(3)H]bumetanide, [(3)H]estrone sulfate, and [(14)C]urate, when each variant clone was expressed in the plasma membrane of oocytes. This study suggests the possibility that the genetic variation of NPT4 contributes to inter-individual differences in disposition of anionic drugs such as diuretics as well as certain endogenous organic anions such as urate.