RT Journal Article SR Electronic T1 Genetic Polymorphisms in Human Proton-Dependent Dipeptide Transporter PEPT1: Implications for the Functional Role of Pro586 JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 437 OP 445 DO 10.1124/jpet.104.065912 VO 310 IS 2 A1 Eric Y. Zhang A1 Dong-Jing Fu A1 Youngeen A. Pak A1 Trent Stewart A1 Nitai Mukhopadhyay A1 Steven A. Wrighton A1 Kathleen M. Hillgren YR 2004 UL http://jpet.aspetjournals.org/content/310/2/437.abstract AB The human proton-dependent dipeptide transporter (PEPT1, gene SLC15A1) is important for intestinal absorption of di- and tripeptides and a variety of peptidomimetic compounds. Using a DNA polymorphism discovery panel of 44 ethnically diverse individuals, nine nonsynonymous and four synonymous coding-region single-nucleotide polymorphisms (SNPs) were identified in PEPT1. HeLa cells were transiently transfected with plasmids constructed by site-directed mutagenesis for each of the nine nonsynonymous variants. Quantitative polymerase chain reaction showed that the mRNA transcription level of all of the mutants was comparable with the mRNA transcription level of the reference sequence in transfected HeLa cells. Functional analysis in transiently transfected HeLa cells revealed that all nonsynonymous variants retained similar pH-dependent activity and Kt values for [glycyl-1,2-14C]glycylsarcosine (Gly-Sar) uptake as the reference PEPT1. In addition, a group of seven peptide-like drugs showed inhibitory effect on Gly-Sar uptake by these variants comparable with the reference, suggesting conserved drug recognition. Of the nine nonsynonymous SNPs, a single SNP (P586L) demonstrated significantly reduced transport capacity as evidenced by a much lower Vmax value. This was consistent with lower immunoactive protein level (Western analysis) and lower plasma membrane expression (immunocytochemical analysis). Therefore, Pro586 may have profound effect on PEPT1 translation, degradation, and/or membrane insertion. The American Society for Pharmacology and Experimental Therapeutics