KCNJ5

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. It may associate with two other G-protein-activated potassium channels to form a heteromultimeric pore-forming complex. [provided by RefSeq]

potassium inwardly-rectifying channel, subfamily J, member 5

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. Can be blocked by external barium.

Membrane repolarization during atrial cardiac muscle cell action potentialManual Assertion Based On ExperimentIMP: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 conductionManual Assertion Based On ExperimentIMP:BHF-UCL
Regulation of ion transmembrane transportManual Assertion Based On ExperimentIBA:GO_Central
Ventricular cardiac muscle cell membrane repolarization1 PublicationIC:BHF-UCL

Membrane

Long QT syndrome 13 (LQT13):
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 exercise or emotional stress, and can present with a sentinel event of sudden cardiac death in infancy.
Hyperaldosteronism, familial, 3 (HALD3):
A form of hyperaldosteronism characterized by hypertension secondary to massive adrenal mineralocorticoid production. HALD3 patients present with childhood hypertension, elevated aldosteronism levels, and high levels of the hybrid steroids 18-oxocortisol and 18-hydroxycortisol. Hypertension and aldosteronism are not reversed by administration of exogenous glucocorticoids and patients require adrenalectomy to control hypertension.
Somatic mutations in KCNJ5 have been found in aldosterone-producing adrenal adenomas and can be responsible for aldosteronism associated with cell autonomous proliferation. APAs are typically solitary, well circumscribed tumors diagnosed between ages 30 and 70. They come to medical attention due to new or worsening hypertension, often with hypokalemia. The precise role of KCNJ5 mutations in APA is under debate. They produce increased sodium conductance and cell depolarization, which in adrenal glomerulosa cells produces calcium entry, the signal for aldosterone production and cell proliferation. However, they may not be causative of APA development but may be a consequence of tumorigenesis, playing only a contributory role toward aldosterone overproduction and tumor growth (PubMed:22275527). Somatic mutations in KCNJ5 have not been found in non-aldosterone secreting adrenal adenomas suggesting that they are specifically associated with APA (PubMed:22275527 and PubMed:22848660).
Mutations in KCNJ5 are involved in the pathogenesis of hypertension without primary aldosteronism but with increased aldosterone response to ACTH stimulation.

Cytoplasmic: 1-86
Helical: 87-111
Extracellular: 112-135
Helical: 136-147
Pore-forming: 148-154
Extracellular: 155-163
Helical: 164-185
Cytoplasmic: 186-419