Phosphate transport in the kidney.

In kidneys of mammals, filtered phosphate ions (Pi) are reabsorbed along the proximal tubules. Transcellular transport of phosphate is initiated by several apically localized sodium-dependent Pi cotransporters (Na/Pi-cotransporters) that belong to the SLC 20 (SLC20A2) and 34 (SLC34A1, SLC34A3) families. Apical abundance of these Na/Pi-cotransporters is adjusted by numerous hormones/phosphatonins and metabolic factors in order to adjust the extent of renal Pi reabsorption according to body needs. Acute hormonal regulation of Pi reabsorption occurs mainly by a change of the abundance of SLC34A1 (NaPi-IIa) via modulation of the interaction of NaPi-IIa with the PDZ-protein NHERF1.