This receptor is controlled by G proteins. 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). Associates with GIRK1 to form a G-protein-activated heteromultimer pore-forming unit (By similarity). Interacts (via PDZ-binding motif) with SNX27 (via PDZ domain); the interaction is required when endocytosed to prevent degradation in lysosomes and promote recycling to the plasma membrane. The PDZ-binding motif specifically binds the PDZ domain of SNX27: the specificity for SNX27 is provided by the 2 residues located upstream (Glu-388 and Ser-389) of the PDZ-binding motif (PubMed:17828261, PubMed:21422294). Belongs to the inward rectifier-type potassium channel (TC 1.A.2.1) family. KCNJ9 subfamily.