KCNJ3

Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, is controlled by G-proteins and plays an important role in regulating heartbeat. It associates with three other G-protein-activated potassium channels to form a heteromultimeric pore-forming complex that also couples to neurotransmitter receptors in the brain and whereby channel activation can inhibit action potential firing by hyperpolarizing the plasma membrane. These multimeric G-protein-gated inwardly-rectifying potassium (GIRK) channels may play a role in the pathophysiology of epilepsy, addiction, Down's syndrome, ataxia, and Parkinson's disease. Alternative splicing results in multiple transcript variants encoding distinct proteins. [provided by RefSeq, May 2012]

Full Name

Potassium Voltage-Gated Channel Subfamily J Member 3

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.

Biological Process

Membrane repolarization during atrial cardiac muscle cell action potential1 PublicationIC:BHF-UCL
Potassium ion import across plasma membraneManual Assertion Based On ExperimentIDA:BHF-UCL
Potassium ion transportManual Assertion Based On ExperimentTAS:ProtInc
Regulation of heart rate by cardiac conduction1 PublicationIC:BHF-UCL
Regulation of ion transmembrane transportManual Assertion Based On ExperimentIBA:GO_Central
Response to electrical stimulusIEA:Ensembl
Ventricular cardiac muscle cell membrane repolarization1 PublicationIC:BHF-UCL

Cellular Location

Membrane

Topology

Cytoplasmic: 1-80
Helical: 81-105
Extracellular: 106-129
Helical: 130-141
Pore-forming: 142-148
Extracellular: 149-157
Helical: 158-179
Cytoplasmic: 180-501