UniProt ID: Q1L8X9 |
FUNCTION: Multifunctional transporter that transports L-glutamate as well as multiple ions such as chloride, sodium and phosphate. At the synaptic vesicle membrane, mainly functions as an uniporter that mediates the uptake of L-glutamate into synaptic vesicles at presynaptic nerve terminals of excitatory neural cells. The L-glutamate uniporter activity is electrogenic and is driven by the proton electrochemical gradient, mainly by the electrical gradient established by the vacuolar H(+)-ATPase across the synaptic vesicle membrane (By similarity). In addition, functions as a chloride channel that allows a chloride permeation through the synaptic vesicle membrane that affects the proton electrochemical gradient and promotes synaptic vesicles acidification (By similarity). At the plasma membrane, following exocytosis, functions as a symporter of Na(+) and phosphate from the extracellular space to the cytoplasm allowing synaptic phosphate homeostasis regulation. The symporter activity is electrogenic (By similarity). Moreover, operates synergistically with SLC18A3/VACHT under a constant H(+) gradient, thereby allowing striatal vesicular acetylcholine uptake (By similarity). {ECO:0000250|UniProtKB:Q7TSF2, ECO:0000250|UniProtKB:Q8NDX2}. CATALYTIC ACTIVITY: Reaction=L-glutamate(out) = L-glutamate(in); Xref=Rhea:RHEA:66336, ChEBI:CHEBI:29985; Evidence={ECO:0000250|UniProtKB:Q8NDX2}; CATALYTIC ACTIVITY: Reaction=3 Na(+)(out) + phosphate(out) = 3 Na(+)(in) + phosphate(in); Xref=Rhea:RHEA:71255, ChEBI:CHEBI:29101, ChEBI:CHEBI:43474; Evidence={ECO:0000250|UniProtKB:Q8NDX2}; CATALYTIC ACTIVITY: Reaction=chloride(in) = chloride(out); Xref=Rhea:RHEA:29823, ChEBI:CHEBI:17996; Evidence={ECO:0000250|UniProtKB:Q7TSF2}; ACTIVITY REGULATION: The L-glutamate uniporter activity exhibits a biphasic dependence on chloride concentration. Chloride channel activity is allosterically activated by lumenal H(+) and Cl(-) leading to synaptic vesicles acidification. The glutamate transport activity is allosterically activated by lumenal H(+) and Cl(-), preventing non- vesicular L-glutamate release. {ECO:0000250|UniProtKB:Q7TSF2}. SUBCELLULAR LOCATION: Cytoplasmic vesicle, secretory vesicle, synaptic vesicle membrane {ECO:0000250|UniProtKB:Q7TSF2}. Cell membrane {ECO:0000250|UniProtKB:Q8NDX2}; Multi-pass membrane protein {ECO:0000250|UniProtKB:Q8NDX2}. Synapse, synaptosome {ECO:0000250|UniProtKB:Q7TSF2}. SIMILARITY: Belongs to the major facilitator superfamily. Sodium/anion cotransporter family. VGLUT subfamily. {ECO:0000305}. |
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