Regulation of phosphate transport in proximal tubules

Homeostasis of inorganic phosphate (P-i) is primarily an affair of the kidneys. Reabsorption of the bulk of filtered P-i occurs along the renal proximal tubule and is initiated by apically localized Na+-dependent P-i cotransporters. Tubular P-i reabsorption and therefore renal excretion of P-i is controlled by a number of hormones, including phosphatonins, and metabolic factors. In most cases, regulation of P-i reabsorption is achieved by changing the apical abundance of Na+/Pi cotransporters. The regulatory mechanisms involve various signaling pathways and a number of proteins that interact with Na+/P-i cotransporters.