FunctionThis 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. Can be blocked by external barium.
Tissue specificityIslets, exocrine pancreas and heart.
Involvement in diseaseDefects in KCNJ5 are the cause of long QT syndrome type 13 (LQT13) [MIM:613485]. It is a heart disorder characterized by a prolonged QT interval on the ECG and polymorphic ventricular arrhythmias. They cause syncope and sudden death in response to excercise or emotional stress, and can present with a sentinel event of sudden cardiac death in infancy.
Sequence similaritiesBelongs to the inward rectifier-type potassium channel (TC 1.A.2.1) family. KCNJ5 subfamily.