RT Journal Article
SR Electronic
T1 Identification and Functional Characterization of Novel Nonsynonymous Variants in the Human Multidrug and Toxin Extrusion 2-K
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1432
OP 1437
DO 10.1124/dmd.114.056887
VO 42
IS 9
A1 Kenta Nishimura
A1 Ryosuke Ide
A1 Takeshi Hirota
A1 Kana Kawazu
A1 Sho Kodama
A1 Hiroaki Takesue
A1 Ichiro Ieiri
YR 2014
UL http://dmd.aspetjournals.org/content/42/9/1432.abstract
AB This study was performed to identify genetic polymorphisms in multidrug and toxin extrusion 2-K (MATE2-K, SLC47A2), a proton/organic cation antiporter that plays a role in the transport of organic cations across the apical membrane in kidney epithelial cells into the urine, and to demonstrate their effects on MATE2-K functions in vitro. Four of the thirty single nucleotide polymorphisms (SNPs) we identified in three ethnic groups (Caucasian, African American, and Japanese) were novel [308C>G (P103R), c.487-8C>T, 818A>G (Y273C), and c.1018+14T>C]. The transport activities of the prototypical substrates, tetraethylammonium and metformin, for four nonsynonymous SNPs (P103R, P162L, G211V, and Y273C) were significantly different from those of the wild-type. In particular, transport activity was higher in P103R than in the wild-type, which is the first time elevated transport activity was demonstrated due to these coding SNPs. Kinetic analysis revealed that P103R had a higher Vmax value, whereas Y273C had a lower value than that in the wild-type. Cell surface protein expression levels were higher for P103R than for the wild-type, whereas Y273C expression was decreased. Immunofluorescence analysis revealed that the P103R protein was localized to the plasma membrane, whereas Y273C showed cytoplasmic localization. Therefore, the difference in transport activities between P103R and Y273C variants was suggested to be responsible for the different protein expression levels observed at the plasma membrane. Four nonsynonymous SNPs in this study showed relatively low allelic frequencies (0.5 to 2.1%), but these were associated with markedly reduced or increased MATE2-K function.