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J Biol Chem
2009 Jun 26;28426:17846-57. doi: 10.1074/jbc.M109.008060.
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The functional roles of the His247 and His281 residues in folate and proton translocation mediated by the human proton-coupled folate transporter SLC46A1.
Unal ES
,
Zhao R
,
Chang MH
,
Fiser A
,
Romero MF
,
Goldman ID
.
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This report addresses the functional role of His residues in the proton-coupled folate transporter (PCFT; SLC46A1), which mediates intestinal folate absorption. Of ten His residues, only H247A and H281A mutations altered function. The folic acid influx Kt at pH 5.5 for H247A was downward arrow 8.4-fold. Although wild type (WT)-PCFT Ki values varied among the folates, Ki values were much lower and comparable for H247-A, -R, -Q, or -E mutants. Homology modeling localized His247 to the large loop separating transmembrane domains 6 and 7 at the cytoplasmic entrance of the translocation pathway in hydrogen-bond distance to Ser172. The folic acid influx Kt for S172A-PCFT was decreased similar to H247A. His281 faces the extracellular region in the seventh transmembrane domain. H281A-PCFT results in loss-of-function due to approximately 12-fold upward arrow in the folic acid influx Kt. When the pH was decreased from 5.5 to 4.5, the WT-PCFT folic acid influx Kt was unchanged, but the Kt decreased 4-fold for H281A. In electrophysiological studies in Xenopus oocytes, both WT-PCFT- and H281A-PCFT-mediated folic acid uptake produced current and acidification, and both exhibited a low level of folate-independent proton transport (slippage). Slippage was markedly increased for the H247A-PCFT mutant. The data suggest that disruption of the His247 to Ser172 interaction results in a PCFT conformational alteration causing a loss of selectivity, increased substrate access to a high affinity binding pocket, and proton transport in the absence of a folate gradient. The His281 residue is not essential for proton coupling but plays an important role in PCFT protonation, which, in turn, augments folate binding to the carrier.
Abramson,
Structure and mechanism of the lactose permease of Escherichia coli.
2003, Pubmed
Abramson,
Structure and mechanism of the lactose permease of Escherichia coli.
2003,
Pubmed
Alexov,
Incorporating protein conformational flexibility into the calculation of pH-dependent protein properties.
1997,
Pubmed
Andrews,
When is a heme transporter not a heme transporter? When it's a folate transporter.
2007,
Pubmed
Boll,
A cluster of proton/amino acid transporter genes in the human and mouse genomes.
2003,
Pubmed
,
Xenbase
Carvelli,
Dopamine transporter/syntaxin 1A interactions regulate transporter channel activity and dopaminergic synaptic transmission.
2008,
Pubmed
Chang,
Slc26a9--anion exchanger, channel and Na+ transporter.
2009,
Pubmed
,
Xenbase
Chang,
Entry to "formula tunnel" revealed by SLC4A4 human mutation and structural model.
2008,
Pubmed
,
Xenbase
Chen,
Yeast SMF1 mediates H(+)-coupled iron uptake with concomitant uncoupled cation currents.
1999,
Pubmed
,
Xenbase
Choi,
An electroneutral sodium/bicarbonate cotransporter NBCn1 and associated sodium channel.
2000,
Pubmed
,
Xenbase
Cohen,
Group-specific reagents in protein chemistry.
1968,
Pubmed
Crane,
The gradient hypothesis and other models of carrier-mediated active transport.
1977,
Pubmed
Decoursey,
Voltage-gated proton channels and other proton transfer pathways.
2003,
Pubmed
DeFelice,
Transporters as channels.
2007,
Pubmed
Fairman,
An excitatory amino-acid transporter with properties of a ligand-gated chloride channel.
1995,
Pubmed
,
Xenbase
Fairman,
Arachidonic acid elicits a substrate-gated proton current associated with the glutamate transporter EAAT4.
1998,
Pubmed
,
Xenbase
Fei,
A novel H(+)-coupled oligopeptide transporter (OPT3) from Caenorhabditis elegans with a predominant function as a H(+) channel and an exclusive expression in neurons.
2000,
Pubmed
,
Xenbase
Fei,
Identification of the histidyl residue obligatory for the catalytic activity of the human H+/peptide cotransporters PEPT1 and PEPT2.
1997,
Pubmed
,
Xenbase
Fiser,
Modeller: generation and refinement of homology-based protein structure models.
2003,
Pubmed
Foltz,
Kinetics of bidirectional H+ and substrate transport by the proton-dependent amino acid symporter PAT1.
2005,
Pubmed
,
Xenbase
Fry,
Rapid formation of poly-gamma-glutamyl derivatives of methotrexate and their association with dihydrofolate reductase as assessed by high pressure liquid chromatography in the Ehrlich ascites tumor cell in vitro.
1982,
Pubmed
Galić,
The loop between helix 4 and helix 5 in the monocarboxylate transporter MCT1 is important for substrate selection and protein stability.
2003,
Pubmed
,
Xenbase
Galli,
Norepinephrine transporters have channel modes of conduction.
1996,
Pubmed
Galli,
Patch-clamp and amperometric recordings from norepinephrine transporters: channel activity and voltage-dependent uptake.
1998,
Pubmed
Geller,
Hereditary folate malabsorption: family report and review of the literature.
2002,
Pubmed
Georgescu,
Combining conformational flexibility and continuum electrostatics for calculating pK(a)s in proteins.
2002,
Pubmed
Guan,
Lessons from lactose permease.
2006,
Pubmed
Gunshin,
Cloning and characterization of a mammalian proton-coupled metal-ion transporter.
1997,
Pubmed
,
Xenbase
Helmlinger,
Interstitial pH and pO2 gradients in solid tumors in vivo: high-resolution measurements reveal a lack of correlation.
1997,
Pubmed
Honig,
Classical electrostatics in biology and chemistry.
1995,
Pubmed
Horne,
Transport of methotrexate in basolateral membrane vesicles from rat liver.
1992,
Pubmed
Huang,
Structure and mechanism of the glycerol-3-phosphate transporter from Escherichia coli.
2003,
Pubmed
Humphrey,
VMD: visual molecular dynamics.
1996,
Pubmed
Jardetzky,
Simple allosteric model for membrane pumps.
1966,
Pubmed
Kjelsberg,
Constitutive activation of the alpha 1B-adrenergic receptor by all amino acid substitutions at a single site. Evidence for a region which constrains receptor activation.
1992,
Pubmed
Lam-Yuk-Tseung,
Iron transport by Nramp2/DMT1: pH regulation of transport by 2 histidines in transmembrane domain 6.
2003,
Pubmed
Lasry,
A novel loss-of-function mutation in the proton-coupled folate transporter from a patient with hereditary folate malabsorption reveals that Arg 113 is crucial for function.
2008,
Pubmed
Lemieux,
Eukaryotic major facilitator superfamily transporter modeling based on the prokaryotic GlpT crystal structure.
2007,
Pubmed
Liman,
Subunit stoichiometry of a mammalian K+ channel determined by construction of multimeric cDNAs.
1992,
Pubmed
,
Xenbase
Loland,
Generation of an activating Zn(2+) switch in the dopamine transporter: mutation of an intracellular tyrosine constitutively alters the conformational equilibrium of the transport cycle.
2002,
Pubmed
Mackenzie,
Divalent metal-ion transporter DMT1 mediates both H+ -coupled Fe2+ transport and uncoupled fluxes.
2006,
Pubmed
,
Xenbase
McGuffin,
The PSIPRED protein structure prediction server.
2000,
Pubmed
Meredith,
Molecular modeling of PepT1--towards a structure.
2006,
Pubmed
Metzner,
Mutational analysis of histidine residues in the human proton-coupled amino acid transporter PAT1.
2008,
Pubmed
Miles,
Modification of histidyl residues in proteins by diethylpyrocarbonate.
1977,
Pubmed
Müller-Berger,
Roles of histidine 752 and glutamate 699 in the pH dependence of mouse band 3 protein-mediated anion transport.
1995,
Pubmed
,
Xenbase
Müller-Berger,
Inhibition of mouse erythroid band 3-mediated chloride transport by site-directed mutagenesis of histidine residues and its reversal by second site mutation of Lys 558, the locus of covalent H2DIDS binding.
1995,
Pubmed
,
Xenbase
Pao,
Major facilitator superfamily.
1998,
Pubmed
Petrey,
GRASP2: visualization, surface properties, and electrostatics of macromolecular structures and sequences.
2003,
Pubmed
Qiu,
Identification of an intestinal folate transporter and the molecular basis for hereditary folate malabsorption.
2006,
Pubmed
,
Xenbase
Qiu,
Rodent intestinal folate transporters (SLC46A1): secondary structure, functional properties, and response to dietary folate restriction.
2007,
Pubmed
,
Xenbase
Raghunand,
Plasmalemmal pH-gradients in drug-sensitive and drug-resistant MCF-7 human breast carcinoma xenografts measured by 31P magnetic resonance spectroscopy.
1999,
Pubmed
Rai,
Multiple mapping method: a novel approach to the sequence-to-structure alignment problem in comparative protein structure modeling.
2006,
Pubmed
Rai,
MMM: a sequence-to-structure alignment protocol.
2006,
Pubmed
Said,
Folate transport in intestinal brush border membrane: involvement of essential histidine residue(s).
1993,
Pubmed
Sali,
Comparative protein modelling by satisfaction of spatial restraints.
1993,
Pubmed
Schron,
pH modulation of the kinetics of rabbit jejunal, brush-border folate transport.
1991,
Pubmed
Schron,
The transmembrane pH gradient drives uphill folate transport in rabbit jejunum. Direct evidence for folate/hydroxyl exchange in brush border membrane vesicles.
1985,
Pubmed
Sharina,
Role of the C-terminus and the long cytoplasmic loop in reduced folate carrier expression and function.
2002,
Pubmed
Sippl,
Recognition of errors in three-dimensional structures of proteins.
1993,
Pubmed
Sonders,
Channels in transporters.
1996,
Pubmed
Steel,
Stoichiometry and pH dependence of the rabbit proton-dependent oligopeptide transporter PepT1.
1997,
Pubmed
,
Xenbase
Tao,
The conserved histidine 295 does not contribute to proton cotransport by the glutamate transporter EAAC1.
2005,
Pubmed
Thwaites,
H+-coupled nutrient, micronutrient and drug transporters in the mammalian small intestine.
2007,
Pubmed
Unal,
N-linked glycosylation and its impact on the electrophoretic mobility and function of the human proton-coupled folate transporter (HsPCFT).
2008,
Pubmed
WIDDAS,
Inability of diffusion to account for placental glucose transfer in the sheep and consideration of the kinetics of a possible carrier transfer.
1952,
Pubmed
Xu,
A spontaneous, recurrent mutation in divalent metal transporter-1 exposes a calcium entry pathway.
2004,
Pubmed
Yang,
Mutation of Aspartate 555 of the Sodium/Bicarbonate Transporter SLC4A4/NBCe1 Induces Chloride Transport.
2009,
Pubmed
,
Xenbase
Yang,
Characterization of the pH of folate receptor-containing endosomes and the rate of hydrolysis of internalized acid-labile folate-drug conjugates.
2007,
Pubmed
Zhao,
Antifolate resistance in a HeLa cell line associated with impaired transport independent of the reduced folate carrier.
2004,
Pubmed
Zhao,
A role for the proton-coupled folate transporter (PCFT-SLC46A1) in folate receptor-mediated endocytosis.
2009,
Pubmed
Zhao,
The proton-coupled folate transporter: impact on pemetrexed transport and on antifolates activities compared with the reduced folate carrier.
2008,
Pubmed
,
Xenbase
Zhao,
The spectrum of mutations in the PCFT gene, coding for an intestinal folate transporter, that are the basis for hereditary folate malabsorption.
2007,
Pubmed
