Inward rectifying potassium channel that is activated by phosphatidylinositol 4,5-bisphosphate and that probably participates in controlling the resting membrane potential in electrically excitable cells. 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 (By similarity). Homotetramer. Forms heteromer with KCNJ4. 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). Phosphatidylinositol 4,5-bisphosphate binding to the cytoplasmic side of the channel triggers a conformation change leading to channel opening. Belongs to the inward rectifier-type potassium channel (TC 1.A.2.1) family. KCNJ12 subfamily.