Summary.
The proton coupled amino acid transporter PAT1 expressed in intestine, brain, and other organs accepts L- and D-proline, glycine, and L-alanine but also pharmaceutically active amino acid derivatives such as 3-amino-1-propanesulfonic acid, L-azetidine-2-carboxylic acid, and cis-4-hydroxy-D-proline as substrates. We systematically analyzed the structural requirements for PAT1 substrates by testing 87 amino acids, proline homologs, indoles, and derivatives. Affinity data and effects on membrane potential were determined using Caco-2 cells. For aliphatic amino acids, a blocked carboxyl group, the distance between amino and carboxyl group, and the position of the hydroxyl group are affinity limiting factors. Methylation of the amino group enhances substrate affinity. Hetero atoms in the proline template are well tolerated. Aromatic α-amino acids display low affinity. PAT1 interacts strongly with heterocyclic aromatic acids containing an indole scaffold. The structural requirements of PAT1 substrates elucidated in this study will be useful for the development of prodrugs.
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References
CM Anderson DS Grenade M Boll M Foltz KA Wake DJ Kennedy LK Munck S Miyauchi PM Taylor FC Campbell BG Munck H Daniel V Ganapathy DT Thwaites (2004) ArticleTitleH+/Amino acid transporter 1 (PAT1) is the imino acid carrier: An intestinal nutrient/drug transporter in human and rat Gastroenterology 127 1410–1422 Occurrence Handle15521011 Occurrence Handle1:CAS:528:DC%2BD2cXhtVKisrzF Occurrence Handle10.1053/j.gastro.2004.08.017
M Boll H Daniel B Gasnier (2004) ArticleTitleThe SLC36 family: proton-coupled transporters for the absorption of selected amino acids from extracellular and intracellular proteolysis Pflugers Arch 447 776–779 Occurrence Handle12748860 Occurrence Handle1:CAS:528:DC%2BD2cXhtVygsLo%3D Occurrence Handle10.1007/s00424-003-1073-4
M Boll M Foltz CM Anderson C Oechsler G Kottra DT Thwaites H Daniel (2003a) ArticleTitleSubstrate recognition by the mammalian proton-dependent amino acid transporter PAT1 Mol Membr Biol 20 261–269 Occurrence Handle1:CAS:528:DC%2BD3sXmtVelurc%3D Occurrence Handle10.1080/0968768031000100759
M Boll M Foltz I Rubio-Aliaga H Daniel (2003b) ArticleTitleA cluster of proton/amino acid transporter genes in the human and mouse genomes Genomics 82 47–56 Occurrence Handle1:CAS:528:DC%2BD3sXktlOht7k%3D Occurrence Handle10.1016/S0888-7543(03)00099-5
M Boll M Foltz I Rubio-Aliaga G Kottra H Daniel (2002) ArticleTitleFunctional characterization of two mammalian electrogenic proton-dependent amino acid cotransporters J Biol Chem 277 22966–22973 Occurrence Handle11959859 Occurrence Handle1:CAS:528:DC%2BD38XltVGrs7w%3D Occurrence Handle10.1074/jbc.M200374200
Z Chen YJ Fei CM Anderson KA Wake S Miyauchi W Huang DT Thwaites V Ganapathy (2003) ArticleTitleStructure, function and immunolocalization of a proton-coupled amino acid transporter (hPAT1) in the human intestinal cell line Caco-2 J Physiol 546 349–361 Occurrence Handle12527723 Occurrence Handle1:CAS:528:DC%2BD3sXitVWrurg%3D Occurrence Handle10.1113/jphysiol.2002.026500
TN Faria JK Timoszyk TR Stouch BS Vig CP Landowski GL Amidon CD Weaver DA Wall RL Smith (2004) ArticleTitleA novel high-throughput PepT1 transporter assay differentiates between substrates and antagonists Mol Pharmacol 1 67–76 Occurrence Handle1:CAS:528:DC%2BD2cXitFWiug%3D%3D Occurrence Handle10.1021/mp034001k
M Foltz M Boll L Raschka G Kottra H Daniel (2004) ArticleTitleA novel bifunctionality: PAT1 and PAT2 mediate electrogenic proton/amino acid and electroneutral proton/fatty acid symport FASEB J 18 1758–1760 Occurrence Handle15345686 Occurrence Handle1:CAS:528:DC%2BD2cXpslehtLo%3D
M Foltz C Oechsler M Boll G Kottra H Daniel (2004) ArticleTitleSubstrate specificity and transport mode of the proton-dependent amino acid transporter mPAT2 Eur J Biochem 271 3340–3347 Occurrence Handle15291811 Occurrence Handle1:CAS:528:DC%2BD2cXntFeltbk%3D Occurrence Handle10.1111/j.1432-1033.2004.04268.x
V Ganapathy M Brandsch FH Leibach (1994) Intestinal transport of amino acids and peptides LR Johnson (Eds) Physiology of the gastrointestinal tract EditionNumber3 Raven Press New York 1773–1794
M Goodman A Felix L Moroder C Toniolo (Eds) (2002) Houben-Weyl: methods of organic chemistry NumberInSeriesE22A Thieme Stuttgart
DJ Kennedy KM Gatfield JP Winpenny V Ganapathy DT Thwaites (2005) ArticleTitleSubstrate specificity and functional characterisation of the H+/amino acid transporter rat PAT2 (SLC36A2) Br J Pharmacol 114 28–41 Occurrence Handle10.1038/sj.bjp.0706029
S Kowalczuk A Bröer M Munzinger N Tietze K Klingel S Bröer (2005) ArticleTitleMolecular cloning of the mouse IMINO system: an Na+- and Cl−-dependent proline transporter Biochem J 386 417–422 Occurrence Handle15689184 Occurrence Handle1:CAS:528:DC%2BD2MXitVegs70%3D Occurrence Handle10.1042/BJ20050100
L Metzner J Kalbitz M Brandsch (2004) ArticleTitleTransport of pharmacologically active proline derivatives by the human proton-coupled amino acid transporter hPAT1 J Pharmacol Exp Ther 309 28–35 Occurrence Handle14718599 Occurrence Handle1:CAS:528:DC%2BD2cXivFamtrw%3D Occurrence Handle10.1124/jpet.103.059014
L Metzner G Kottra K Neubert H Daniel M Brandsch (2005) ArticleTitleSerotonin, L-tryptophan, and tryptamine are effective inhibitors of the amino acid transport system PAT1 FASEB J 19 1468–1473 Occurrence Handle16126914 Occurrence Handle1:CAS:528:DC%2BD2MXpvFSltbw%3D Occurrence Handle10.1096/fj.05-3683com
PL Nicklin WJ Irwin IF Hassan M Mackay (1992) ArticleTitleProline uptake by monolayers of human intestinal absorptive (Caco-2) cells in vitro Biochim Biophys Acta 1104 283–292 Occurrence Handle1547265 Occurrence Handle1:CAS:528:DyaK38XhsVyqs7s%3D Occurrence Handle10.1016/0005-2736(92)90042-K
M Palacin R Estevez J Bertran A Zorzano (1998) ArticleTitleMolecular biology of mammalian plasma membrane amino acid transporters Physiol Rev 78 969–1054 Occurrence Handle9790568 Occurrence Handle1:CAS:528:DyaK1cXntFOhurg%3D
G Ranaldi K Islam Y Sambuy (1994) ArticleTitleD-Cycloserine uses an active transport mechanism in the human intestinal cell line Caco 2 Antimicrob Agents Chemother 38 1239–1245 Occurrence Handle8092820 Occurrence Handle1:CAS:528:DyaK2cXkt1Khsb4%3D
C Sagne C Agulhon P Ravassard M Darmon M Hamon S El Mestikawy B Gasnier B Giros (2001) ArticleTitleIdentification and characterization of a lysosomal transporter for small neutral amino acids Proc Natl Acad Sci USA 98 7206–7211 Occurrence Handle11390972 Occurrence Handle1:CAS:528:DC%2BD3MXkslWmt7Y%3D Occurrence Handle10.1073/pnas.121183498
B Steffansen CU Nielsen B Brodin AH Eriksson R Andersen S Frokjaer (2004) ArticleTitleIntestinal solute carriers: an overview of trends and strategies for improving oral drug absorption Eur J Pharm Sci 21 3–16 Occurrence Handle14706808 Occurrence Handle1:CAS:528:DC%2BD2cXovFSn Occurrence Handle10.1016/j.ejps.2003.10.010
H Takanaga B Mackenzie Y Suzuki MA Hediger (2005) ArticleTitleIdentification of a mammalian proline transporter (SIT1, SLC6A20) with characteristics of classical system IMINO J Biol Chem 1 67–76
DT Thwaites G Armstrong BH Hirst NL Simmons (1995a) ArticleTitleD-Cycloserine transport in human intestinal epithelial (Caco-2) cells: mediation by a H+-coupled amino acid transporter Br J Pharmacol 115 761–766 Occurrence Handle1:CAS:528:DyaK2MXmsl2itb0%3D
DT Thwaites L Basterfield PMJ McCleave SM Carter NL Simmons (2000) ArticleTitleGamma-aminobutyric acid (GABA) transport across human intestinal epithelial (Caco-2) cell monolayers Br J Pharmacol 129 457–464 Occurrence Handle10711343 Occurrence Handle1:CAS:528:DC%2BD3cXht1ynsb0%3D Occurrence Handle10.1038/sj.bjp.0703069
DT Thwaites GT McEwan CD Brown BH Hirst NL Simmons (1994) ArticleTitleL-Alanine absorption in human intestinal Caco-2 cells driven by the proton electrochemical gradient J Membr Biol 140 143–151 Occurrence Handle7932648 Occurrence Handle1:CAS:528:DyaK2cXktlWkt70%3D
DT Thwaites GT McEwan BH Hirst NL Simmons (1995b) ArticleTitleH+-coupled alpha-methylaminoisobutyric acid transport in human intestinal Caco-2 cells Biochim Biophys Acta 1234 111–118 Occurrence Handle10.1016/0005-2736(94)00268-T
DT Thwaites GT McEwan NL Simmons (1995c) ArticleTitleThe role of the proton electrochemical gradient in the transepithelial absorption of amino acids by human intestinal Caco-2 cell monolayers J Membr Biol 145 245–256 Occurrence Handle1:CAS:528:DyaK2MXms1egtb4%3D
DT Thwaites GTA McEwan CDA Brown BH Hirst NL Simmons (1993a) ArticleTitleNa+-independent, H+-coupled transepithelial ß-alanine absorption by human intestinal Caco-2 cell monolayers J Biol Chem 268 18438–18441 Occurrence Handle1:CAS:528:DyaK3sXlsFKrs74%3D
DT Thwaites GTA McEwan MJ Cook BH Hirst NL Simmons (1993b) ArticleTitleH+-coupled (Na+-independent) proline transport in human intestinal (Caco-2) epithelial cell monolayers FEBS Lett 333 78–82 Occurrence Handle1:CAS:528:DyaK3sXmsVKntbw%3D Occurrence Handle10.1016/0014-5793(93)80378-8
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Metzner, L., Neubert, K. & Brandsch, M. Substrate specificity of the amino acid transporter PAT1. Amino Acids 31, 111–117 (2006). https://doi.org/10.1007/s00726-005-0314-6
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DOI: https://doi.org/10.1007/s00726-005-0314-6