Enables phosphate transmembrane transporter activity. Involved in phosphate ion transmembrane transport and wing disc dorsal/ventral pattern formation. Located in mitochondrion. Is active in mitochondrial membrane. Is expressed in several structures, including adult head; adult heart; embryonic/larval midgut primordium; gut section; and larval muscle cell. Orthologous to human SLC25A3 (solute carrier family 25 member 3).