Glaeser H, Mandery K, Sticht H, Fromm MF, König J (2010) Relevance of conserved lysine and arginine residues in transmembrane helices for the transport activity of organic anion transporting polypeptide 1B3. J Biol Chem 276:9626-9630Įlens L, Capron A, Kerckhove VV, Lerut J, Mourad M, Lison D, Wallemacq P, Haufroid V (2007) 1199G>A and 2677G>T/A polymorphisms of ABCB1 independently affect tacrolimus concentration in hepatic tissue after liver transplantation. Biochemistry 41:9215–9221Ĭui Y, König J, Leier I, Buchholz U, Keppler D (2001) Hepatic uptake of bilirubin and its conjugates by the human organic anion transporter SLC21A6. Science 301:610–615Ĭhan BS, Bao Y, Schuster VL (2002) Role of conserved transmembrane cationic amino acids in the prostaglandin transporter PGT. Gastroenterology 120:1689–1699Ībramson J, Smirnova I, Kasho V, Verner G, Kaback HR, Iwata S (2003) Structure and mechanism of the lactose permease of Escherichia coli. J Biol Chem 274:17159–17163Ībe T, Unno M, Onogawa T, Tokui T, Kondo TN, Nakagomi R, Adachi H, Fujiwara K, Okabe M, Suzuki T, Nunoki K, Sato E, Kakyo M, Nishio T, Sugita J, Asano N, Tanemoto M, Seki M, Date F, Ono K, Kondo Y, Shiiba K, Suzuki M, Ohtani H, Shimosegawa T, Iinuma K, Nagura H, Ito S, Matsuno S (2001) LST-2, a human liver-specific organic anion transporter, determines methotrexate sensitivity in gastrointestinal cancers. In conclusion, the conserved amino acids R57, K361 and R580 seem to be part of the substrate binding sites and/or translocation pathways in OATP1B1.Ībe T, Kakyo M, Tokui T, Nakagomi R, Nishio T, Nakai D, Nomura H, Unno M, Suzuki M, Naitoh T, Matsuno S, Yawo H (1999) Identification of a novel gene family encoding human liver-specific organic anion transporter LST-1. Mutations at intracellular K90, H92 and R93 mainly affected V max values for estradiol-17β-glucuronide uptake. In addition, R580K reduced the V max values for all three substrates to <25% of wild-type OATP1B1. The largest changes were seen for estradiol-17β-glucuronide, while estrone-3-sulfate and bromosulfophthalein transport were less affected. Mutations of several amino acids resulted in substrate-dependent effects. A lysine at position 580 (R580K) rescued the expression of R580A. Two of the mutants had low surface expression levels: R181K at 10% and R580A at 30% of wild-type OATP1B1. We made mutants and measured surface expression and uptake of estradiol-17β-glucuronide, estrone-3-sulfate and bromosulfophthalein in HEK293 cells. Based on this model, we tested the hypothesis that these positive amino acids are important for OATP1B1 function. A putative model of OATP1B3 with a “positive binding pocket” containing conserved positively charged amino acids was predicted (Meier-Abt et al. OATP1B1 and 1B3 are related transporters mediating uptake of numerous compounds into hepatocytes.