In the kidney, probably plays a major role in potassium homeostasis. Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. Their voltage dependence is regulated by the concentration of extracellular potassium; as external potassium is raised, the voltage range of the channel opening shifts to more positive voltages. The inward rectification is mainly due to the blockage of outward current by internal magnesium. This channel is activated by internal ATP and can be blocked by external barium. Inhibited by WNK3. Interacts with SGK1 and SLC9A3R2/NHERF2. Phosphorylation at Ser-44 by SGK1 is necessary for its expression at the cell membrane. In the kidney and pancreatic islets. Lower levels in skeletal muscle, pancreas, spleen, brain, heart and liver. Phosphorylation at Ser-44 by SGK1 is necessary for its expression at the cell membrane. The disease is caused by variants affecting the gene represented in this entry. Belongs to the inward rectifier-type potassium channel (TC 1.A.2.1) family. KCNJ1 subfamily.