Inward rectifier potassium channel that forms the pore of ATP-sensitive potassium channels (KATP), regulating potassium permeability as a function of cytoplasmic ATP and ADP concentrations in many different cells (PubMed:29286281, PubMed:34815345). 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. Can be blocked by extracellular barium (By similarity). In pancreatic cells, it forms KATP channels with ABCC8/SUR1 (PubMed:29286281, PubMed:34815345). Can form cardiac and smooth muscle-type KATP channels with ABCC9. {ECO:0000250, ECO:0000269|PubMed:17855752, ECO:0000269|PubMed:28842488, ECO:0000269|PubMed:29286281, ECO:0000269|PubMed:34815345, ECO:0000269|PubMed:9831708}. This is the function of KCNJ11 (potassium inwardly rectifying channel subfamily J member 11, Ensembl gene identifier ENSG00000187486).