Inward rectifier potassium channel 4 (KCNJ4)

Inward rectifier potassium channel 4 (KCNJ4) is an integral membrane protein and member of the Kir2 subfamily of inward rectifier potassium channels. These channels transport potassium more efficiently into cells than out, contributing to the resting membrane potential and excitability of cardiac myocytes and neurons. KCNJ4 is most strongly expressed in heart and brain, especially at excitatory synapses and cardiac myocytes. Functionally, it helps stabilize cellular electrical activity and participates in repolarization phases of action potentials. In cancer, notably lung adenocarcinoma, KCNJ4 expression is upregulated and correlates with worse prognosis, implicating it in cell proliferation and migration via MAPK/ERK pathway. Drugs such as carvedilol inhibit KCNJ4 by interfering with PIP2-channel interaction, and channel activity can be blocked by barium or cesium ions. Although no direct disease-causing mutations in KCNJ4 have been identified, related inward rectifier potassium channels are linked to cardiac and neurological diseases.

Other names

Kir2.3IRK3HIRIRK-3HIRK2HRK1Hippocampal inward rectifierinward rectifier K(+) channel Kir2.3potassium channel, inwardly rectifying subfamily J member 4potassium voltage-gated channel subfamily J member 4

Channel inhibition (blocking K⁺ conductance via direct channel block or interference with PIP2-channel interaction)