Enables inorganic phosphate transmembrane transporter activity and sodium:phosphate symporter activity. Involved in several processes, including neurotransmitter loading into synaptic vesicle; phosphate ion transport; and regulation of synaptic vesicle endocytosis. Located in excitatory synapse and presynaptic active zone. Is integral component of synaptic vesicle membrane. Is active in synaptic vesicle membrane. Biomarker of sciatic neuropathy and transient cerebral ischemia. Orthologous to human SLC17A7 (solute carrier family 17 member 7). [provided by Alliance of Genome Resources, Apr 2022]