The amino acid glutamate is the main excitatory neurotransmitter stored in the synaptic vesicles. The excitatory neurons release glutamate by exocytosis into the synaptic cleft in response to neuronal stimulation. The solute carrier family 17 (SLC17) belongs to the vesicular glutamate transporter family, which is involved in the accumulation of glutamate in synaptic vesicles. SLC17A7/VGLUT1 is predominantly expressed in the brain. Glutamatergic neurotransmission is drastically impaired in neurons of mice lacking the slc17a7 gene. After weaning, the mice show a progressive neurologic phenotype including blindness, uncoordination, and an enhanced startle response.