Involved in actively transporting phosphate into cells via Na(+) cotransport in the renal brush border membrane. The cotransport has a Na(+):Pi stoichiometry of 3:1 and is electrogenic. 3 Na(+)(out) + phosphate(out) = 3 Na(+)(in) + phosphate(in) Interacts via its C-terminal region with PDZK2. Interacts with SLC9A3R1. Localized at the brush border membranes of the proximal tubules. Belongs to the SLC34A transporter family.