High-affinity transporter for external inorganic phosphate. Mainly expressed in roots, especially in the stele of the primary root, the pericycle and trichoblasts of secondary roots. To a lower extent, present in hydathodes and vascular tissues of young leaves. In roots by phosphate starvation. Although related to the sugar transporter family, it does not transport sugars. Belongs to the major facilitator superfamily. phosphate:H(+) symporter (TC 2.A.1.9) family.