RT Journal Article SR Electronic T1 Genetic Variants of the Human H+/Dipeptide Transporter PEPT2: Analysis of Haplotype Functions JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 1088 OP 1096 DO 10.1124/jpet.104.073098 VO 311 IS 3 A1 Julia Pinsonneault A1 Carsten Uhd Nielsen A1 Wolfgang Sadée YR 2004 UL http://jpet.aspetjournals.org/content/311/3/1088.abstract AB PEPT2 is a high-affinity H+/dipeptide transporter expressed in kidney, brain, lung, and mammary gland. The physiological role of PEPT2 in kidney is to reabsorb small peptides generated by luminal peptidases. PEPT2 is also a transporter for peptide-like drugs such as penicillins and cephalosporins. We have conducted a haplotype analysis of 27 single nucleotide polymorphisms located in or near exons of the human gene encoding hPEPT2 (SLC15A2), using genotyping data from 247 genomic DNA samples from the Coriell collection. Our analysis reveals that hPEPT2 has a >6-kilobase sequence block with at least 10 abundant polymorphisms in almost complete linkage disequilibrium. As a result, only two main hPEPT2 variants exist (hPEPT2*1 and *2) with several phased amino acid substitutions, present in substantial frequencies in all ethnic groups tested. When expressed in Chinese hamster ovary cells, hPEPT2*1 and *2 displayed similar Vmax values for glycyl-sarcosine (Gly-Sar), but they differed significantly in their Km values (83 ± 16 and 233 ± 38 μM, respectively). Moreover, hPEPT2*1 and *2 differed in their pH sensitivity for H+/Gly-Sar transport. In addition, hPEPT2*1 and *2 generated varying levels of mRNA in nine heterozygous kidney tissue samples, including one allele expressing no detectable mRNA, suggesting the presence of cis-acting polymorphisms affecting transcription or mRNA processing. The results indicate that polymorphisms in the gene encoding hPEPT2 can alter substrate transport and therefore could affect drug disposition in vivo. The American Society for Pharmacology and Experimental Therapeutics