KCNJ5

Official Full Name

potassium inwardly rectifying channel subfamily J member 5

Organism

Homo sapiens

GeneID

3762

Background

This gene encodes an integral membrane protein which belongs to one of seven subfamilies of inward-rectifier potassium channel proteins called potassium channel subfamily J. The encoded protein is a subunit of the potassium channel which is homotetrameric. It is controlled by G-proteins and has a greater tendency to allow potassium to flow into a cell rather than out of a cell. Naturally occurring mutations in this gene are associated with aldosterone-producing adenomas. [provided by RefSeq, Aug 2017]

Synonyms

CIR; GIRK4; KATP1; LQT13; KIR3.4;

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Detailed Information

Recent Research

KCNJ5 gene, encodes GIRK4 (cytogenetic location: 11q24.3). GIRK4 is a member of the family of G protein-activated inwardly-rectifying potassium channels. GIRK4 contains the pore domain signature sequence GlyTyrGly that is conserved in K⁺selective channels. The channel is expressed at the plasma membrane in various different tissues, including the heart, peripheral and central neurons, various endocrine tissues, as well as non-excitable structures, such as blood platelets, and exists both as a homotetramer and as a hetero tetrameric complex with GIRK1. GIRK channels form transmembrane permeation pathways or pores with a high selectivity for K⁺ thereby preferentially allowing K⁺ to flow into the cell.

Some reports have shown that somatic mutations of KCNJ5 affect the function of the GIRK4 channel, The adenoma-associated gain-of-function mutations of KCNJ5 are localized in or close to the ion selectivity filter and confer a pathological Na⁺ and Ca2⁺ permeability to the mutated channels. Activity of the mutated KCNJ5 leads to influx of cations, thereby, to membrane depolarization. The depolarization results in activation of voltage-gated Ca2⁺ channels. The increased cytosolic Ca2⁺ activity ultimately promotes aldosterone secretion and adenoma formation.

Mutations of the KCNJ5 K⁺ channel gene have been identified as causative of familial and sporadic forms of primary aldosteronism (PA) and Aldosterone-producing adenoma (APA) in humans. PA is the most common form of secondary hypertension, with a prevalence of 5% to 15% among hypertensive patients and is characterized by the autonomous hypersecretion of aldosterone. Somatic APA mutations in the KCNJ5 gene were first identified by Choi et al. The cortisol production pathway is down-regulated in KCNJ5-mutated APA tissue, resulting in highly autonomous aldosterone production. Subsequently, Boulkroun et al determined a 34% prevalence of KCNJ5 mutations in a large European cohort of 380 APA. In patients with APA, the KCNJ5 mutations are remarkably more prevalent in female than in male individuals (>70%) and the mutation carriers are significantly younger compared with noncarriers.

References:

Williams T A, et al. KCNJ5 Mutations: Sex, Salt and Selection. Hormone & Metabolic Research, 2015, 47(13):953-958.
Kitamoto T, et al. Comparison of cardiovascular complications in patients with and without KCNJ5 gene mutations harboring aldosterone-producing adenomas. Journal of Atherosclerosis & Thrombosis, 2015, 22(2):191-200.
Tauber P, et al. Pharmacology and Pathophysiology of Mutated KCNJ5 Found in Adrenal Aldosterone-Producing Adenomas. Endocrinology, 2014, 155(4):1353-1362.

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