The SLC20A2 gene provides instructions for making a protein called sodium-dependent phosphate transporter 2 (PiT-2). This protein is highly active in nerve cells (neurons) in the brain. It plays a major role in regulating the levels of a molecule called phosphate in cells (phosphate homeostasis). Specifically, the PiT-2 protein uses positively charged sodium atoms (ions) to transport phosphate in out and of cell membranes. Phosphate is needed for many cellular functions including the breakdown of substances (metabolic processes), signaling between cells, and the production of DNA building blocks (nucleic acids) and fats.