Multifunctional transporter that transports L-glutamate as well as multiple ions such as chloride, proton, potassium, sodium and phosphate (PubMed:29642010, PubMed:25433636, PubMed:33440152, PubMed:29273736). At the synaptic vesicle membrane, mainly functions as an uniporter which transports preferentially L-glutamate but also phosphate from the cytoplasm into synaptic vesicles at presynaptic nerve terminals of excitatory neural cells (PubMed:25433636, PubMed:29642010, PubMed:15103023, PubMed:15118123). The L-glutamate or phosphate 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 (PubMed:29642010). 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 (PubMed:25433636, PubMed:29273736, PubMed:29642010). Moreover, may function as a K(+)/H(+) antiport allowing to maintain the electrical gradient and to decrease chemical gradient and therefore sustain vesicular glutamate uptake (By similarity). The vesicular K(+)/H(+) antiport activity is electroneutral (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 (PubMed:33440152, PubMed:29642010). The symporter activity is driven by an inside negative membrane potential and is electrogenic (PubMed:29642010). Is necessary for synaptic signaling of visual-evoked responses from photoreceptors (PubMed:17611277). chloride(in) = chloride(out) 3 Na(+)(out) + phosphate(out) = 3 Na(+)(in) + phosphate(in) L-glutamate(out) = L-glutamate(in) phosphate(in) = phosphate(out) H(+)(out) + K(+)(in) = H(+)(in) + K(+)(out) Chloride channel activity is allosterically activated by lumenal H(+) and Cl(-) leading to synaptic vesicles acidification. The L-glutamate transport activity is allosterically activated by lumenal H(+) and Cl(-). The allosteric activation by H(+) efficiently prevents non-vesicular efflux across the plasma membrane, thereby restricting L-glutamate transport activity to acidic membranes such as synaptic vesicles. Interacts with SHANK3. Expressed in hippocampus (at protein level). Expressed in the molecular layer of the cerebellum and in retina. Expression in brain increases progressively from four days to adulthood. Oscillates diurnally in synaptic vesicles (at protein level). Mice begin to die 3 weeks after birth. They exhibit a progressive neurological phenotype including blindness, loss of coordination and enhanced startle response. Glutamatergic neurotransmission is drastically reduced due to a decrease in the reserve pool of synaptic vesicles and reduced quantal size. Visual signaling from photoreceptors to retinal output neurons is impaired while photoentrainment and pupillary light responses remain intact. Belongs to the major facilitator superfamily. Sodium/anion cotransporter family. VGLUT subfamily. Martineau M. et al. show that may function as a L-glutamate/H(+) antiporter (PubMed:29273736). However, according to Eriksen J. et al., H(+) is an allosteric activator (By similarity).