Inward rectifier potassium channel that mediates potassium uptake into the cell. 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 may be achieved by the blockage of outward current by cytoplasmic divalent metal ions and polyamines. Complements an E.coli mutant that is defective in K(+) uptake. Homotetramer. A conformation change implying rotational movement of the cytoplasmic domains plays an important role in channel opening and closing. Release of polyamines from their binding sites on the cytoplasmic domain may block the ion permeation pathway, preventing the efflux of intracellular potassium ions. Belongs to the inward rectifier-type potassium channel (TC 1.A.2.1) family. KCNJ11 subfamily.