Multifunctional transporter that transports L-glutamate as well as multiple ions such as chloride, proton, potassium, sodium and phosphate (PubMed:11001057, PubMed:10938000, PubMed:18080752, PubMed:19169251, PubMed:8202535, PubMed:27133463, PubMed:25433636, PubMed:33440152, PubMed:29642010, PubMed:11698619). 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:29642010, PubMed:11001057, PubMed:10938000, PubMed:11698619, PubMed:18080752). 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:10938000, PubMed:27133463, PubMed:25433636, PubMed:29642010, PubMed:19169251). 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 (PubMed:25433636). The vesicular K(+)/H(+) antiport activity is electroneutral (PubMed:25433636). 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:8202535, 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 (By similarity). L-glutamate(out) = L-glutamate(in) chloride(in) = chloride(out) 3 Na(+)(out) + phosphate(out) = 3 Na(+)(in) + phosphate(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 (PubMed:27133463). The L-glutamate transport activity is allosterically activated by lumenal H(+) and Cl(-) (PubMed:27133463, PubMed:19169251). 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 (PubMed:27133463). Interacts with SHANK3. Expressed in the cerebellum, cerberal cortex and hippocampus. Isoform 2 is expressed specifically in retina. Expression of isoform 2 increases sharply during the first ten days of postnatal life, and also increases with increasing numbers of rhodopsin cells in the retina. Induced within cerebellar granule cells by exposure to N-methyl-D-aspartate (NMDA). 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 (By similarity). However, according to Eriksen J. et al., H(+) is an allosteric activator (PubMed:27133463).