Low-affinity transporter for external inorganic phosphate (Pi). NH4(+)(in) = NH4(+)(out) Slightly repressed during arbuscular mycorrhiza (AM) formation after inoculation with AM fungi (e.g. Glomus intraradices). 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.