Probably participates in establishing action potential waveform and excitability of neuronal and muscle tissues. 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. Blocked by external barium or cesium. Homomultimeric and heteromultimeric association with KCNJ4/Kir2.3. Association, via its PDZ-recognition domain, with LIN7A, LIN7B, LIN7C, DLG1, CASK and APBA1 plays a key role in its localization and trafficking (By similarity). S-nitrosylation increases the open probability and inward rectifying currents. Belongs to the inward rectifier-type potassium channel (TC 1.A.2.1) family. KCNJ2 subfamily.