KCNJ5 siRNA – G Protein-Activated Inward Rectifier Potassium Channel 4 (Mouse)

GIRK4: 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. Defects in KCNJ5 are the cause of long QT syndrome type 13 (LQT13). 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. Defects in KCNJ5 are the cause of familial hyperaldosteronism type 3 (FH3). A form of hyperaldosteronism characterized by hypertension secondary to massive adrenal mineralocorticoid production. Like patients with familial hyperaldosteronism type 1 (glucocorticoid-remediable aldosteronism), patients with FH3 present with childhood hypertension, elevated aldosteronism levels, and high levels of the hybrid steroids 18-oxocortisol and 18-hydroxycortisol. However, 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. These 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. KCNJ5 mutations produce increased sodium conductance and cell depolarization, which in adrenal glomerulosa cells produces calcium entry, the signal for aldosterone production and cell proliferation. Belongs to the inward rectifier-type potassium channel (TC 1.A.2.1) family. KCNJ5 subfamily.

Protein type: Membrane protein, integral; Channel, potassium; Membrane protein, multi-pass

Cellular Component: membrane; integral to plasma membrane; T-tubule; integral to membrane; external side of plasma membrane

Molecular Function: G-protein activated inward rectifier potassium channel activity; voltage-gated ion channel activity; inward rectifier potassium channel activity

Biological Process: potassium ion import; transport; ion transport; potassium ion transport