function:This potassium channel 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. This receptor plays a crucial role in regulating the heartbeat. ,similarity:Belongs to the inward rectifier-type potassium channel family. ,subunit:Associates with GIRK2 , GIRK3 or GIRK4 to form a G-protein activated heteromultimer pore-forming unit. The resulting inward current is much larger. ,
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