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. Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. The inward rectification is probably due to the blockage of outward current by cytoplasmic polyamines and/or magnesium ions. Homotetramer. 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 family.