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Na+, Cl-, and pH dependence of the human choline transporter (hCHT) in Xenopus oocytes: the proton inactivation hypothesis of hCHT in synaptic vesicles.
Iwamoto H, Blakely RD, De Felice LJ.
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The recent cloning of the human choline transporter (hCHT) has allowed its expression in Xenopus laevis oocytes and the simultaneous measurement of choline transport and choline-induced current under voltage clamp. hCHT currents and choline transport are evident in cRNA-injected oocytes and significantly enhanced by the hCHT trafficking mutant L530A/V531A. The charge/choline ratio of hCHT varies from 10e/choline at -80 mV to 3e/choline at -20 mV, in contrast with the reported fixed stoichiometry of the Na+-coupled glucose transporter in the same gene family. Ion substitution shows that the choline uptake and choline-induced current are Na+ and Cl- dependent; however, the reversal potential of the induced current suggests a Na+-selective mechanism, consigning Cl- to a regulatory role rather than a coupled, cotransported-ion role. The hCHT-specific inhibitor hemicholinium-3 (HC-3) blocks choline uptake and choline-induced current; in addition, HC-3 alone reveals a constitutive, depolarizing leak current through hCHT. We show that external protons reduce hCHT current, transport, and binding with a similar pKa of 7.4, suggesting proton titration of residue(s) that support choline binding and transport. Given the localization of the choline transporter to synaptic vesicles, we propose that proton inactivation of hCHT prevents acetylcholine and proton leakage from the acidic interior of cholinergic synaptic vesicles. This mechanism would allow cholinergic, activity-triggered delivery of silent choline transporters to the plasma membrane, in which normal pH would reactivate the transporters for choline uptake and subsequent acetylcholine synthesis.
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,
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,
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,
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Pubmed
,
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Increased acetylcholine synthesis and release following presynaptic activity in a sympathetic ganglion.
1983,
Pubmed Dani,
Cellular mechanisms of nicotine addiction.
2001,
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2003,
Pubmed
,
Xenbase Díez-Sampedro,
Na+-to-sugar stoichiometry of SGLT3.
2001,
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,
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1998,
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1997,
Pubmed
,
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2004,
Pubmed Ferguson,
Lethal impairment of cholinergic neurotransmission in hemicholinium-3-sensitive choline transporter knockout mice.
2004,
Pubmed Ferguson,
Vesicular localization and activity-dependent trafficking of presynaptic choline transporters.
2003,
Pubmed Galli,
Patch-clamp and amperometric recordings from norepinephrine transporters: channel activity and voltage-dependent uptake.
1998,
Pubmed Galli,
Drosophila serotonin transporters have voltage-dependent uptake coupled to a serotonin-gated ion channel.
1997,
Pubmed
,
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Sodium-dependent norepinephrine-induced currents in norepinephrine-transporter-transfected HEK-293 cells blocked by cocaine and antidepressants.
1995,
Pubmed Geerlings,
Calcium- and syntaxin 1-mediated trafficking of the neuronal glycine transporter GLYT2.
2001,
Pubmed Guyenet,
Inhibition by hemicholinium-3 of (14C)acetylcholine synthesis and (3H)choline high-affinity uptake in rat striatal synaptosomes.
1973,
Pubmed Haga,
Choline uptake systems of rat brain synaptosomes.
1973,
Pubmed Hirayama,
Protons drive sugar transport through the Na+/glucose cotransporter (SGLT1).
1994,
Pubmed
,
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2002,
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2005,
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2005,
Pubmed
,
Xenbase Keller,
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2000,
Pubmed Kuhar,
Sodium-dependent, high affinity choline uptake.
1978,
Pubmed Kusano,
Cholinergic and catecholaminergic receptors in the Xenopus oocyte membrane.
1982,
Pubmed
,
Xenbase Li,
Voltage-dependent transient currents of human and rat 5-HT transporters (SERT) are blocked by HEPES and ion channel ligands.
2002,
Pubmed
,
Xenbase Loo,
Role of Cl- in electrogenic Na+-coupled cotransporters GAT1 and SGLT1.
2000,
Pubmed
,
Xenbase Lowenstein,
Rapid regulation of [3H]hemicholinium-3 binding sites in the rat brain.
1986,
Pubmed Mackenzie,
Relationships between Na+/glucose cotransporter (SGLT1) currents and fluxes.
1998,
Pubmed
,
Xenbase Mager,
Ion binding and permeation at the GABA transporter GAT1.
1996,
Pubmed
,
Xenbase Mager,
Conducting states of a mammalian serotonin transporter.
1994,
Pubmed
,
Xenbase Marchbanks,
Relationship of choline uptake to acetylcholine synthesis and release.
1979,
Pubmed Nakata,
Ultrastructural localization of high-affinity choline transporter in the rat neuromuscular junction: enrichment on synaptic vesicles.
2004,
Pubmed Nelson,
The significance of molecular slips in transport systems.
2002,
Pubmed Nguyen,
Kinetic parameters for the vesicular acetylcholine transporter: two protons are exchanged for one acetylcholine.
1998,
Pubmed Okuda,
Identification and characterization of the high-affinity choline transporter.
2000,
Pubmed Okuda,
High-affinity choline transporter.
2003,
Pubmed Okuda,
Functional characterization of the human high-affinity choline transporter.
2000,
Pubmed
,
Xenbase Parsons,
Acetylcholine transport, storage, and release.
1993,
Pubmed Petersen,
Ionic interactions in the Drosophila serotonin transporter identify it as a serotonin channel.
1999,
Pubmed
,
Xenbase Prasad,
Structure and function of mammalian sodium-dependent multivitamin transporter.
2000,
Pubmed Quick,
Regulating the conducting states of a mammalian serotonin transporter.
2003,
Pubmed
,
Xenbase Ramsey,
Serotonin transporter function and pharmacology are sensitive to expression level: evidence for an endogenous regulatory factor.
2002,
Pubmed
,
Xenbase Renick,
The mammalian brain high-affinity L-proline transporter is enriched preferentially in synaptic vesicles in a subpopulation of excitatory nerve terminals in rat forebrain.
1999,
Pubmed Ribeiro,
Constitutive high-affinity choline transporter endocytosis is determined by a carboxyl-terminal tail dileucine motif.
2005,
Pubmed Ribeiro,
The "ins" and "outs" of the high-affinity choline transporter CHT1.
2006,
Pubmed Sandberg,
Characterization of [3H]hemicholinium-3 binding associated with neuronal choline uptake sites in rat brain membranes.
1985,
Pubmed Sarter,
Choline transporters, cholinergic transmission and cognition.
2005,
Pubmed Simon,
High affinity choline uptake: ionic and energy requirements.
1976,
Pubmed Simon,
Impulse-flow regulation of high affinity choline uptake in brain cholinergic nerve terminals.
1975,
Pubmed Sonders,
Multiple ionic conductances of the human dopamine transporter: the actions of dopamine and psychostimulants.
1997,
Pubmed
,
Xenbase Tan,
A leucine-based motif mediates the endocytosis of vesicular monoamine and acetylcholine transporters.
1998,
Pubmed Wadiche,
Ion fluxes associated with excitatory amino acid transport.
1995,
Pubmed
,
Xenbase Wright,
The sodium/glucose cotransport family SLC5.
2004,
Pubmed Wright,
Surprising versatility of Na+-glucose cotransporters: SLC5.
2004,
Pubmed Yamamura,
Choline: high-affinity uptake by rat brain synaptosomes.
1972,
Pubmed
