KCNQ1

Official Full Name

potassium voltage-gated channel subfamily Q member 1

Organism

Homo sapiens

GeneID

3784

Background

This gene encodes a voltage-gated potassium channel required for repolarization phase of the cardiac action potential. This protein can form heteromultimers with two other potassium channel proteins, KCNE1 and KCNE3. Mutations in this gene are associated with hereditary long QT syndrome 1 (also known as Romano-Ward syndrome), Jervell and Lange-Nielsen syndrome, and familial atrial fibrillation. This gene exhibits tissue-specific imprinting, with preferential expression from the maternal allele in some tissues, and biallelic expression in others. This gene is located in a region of chromosome 11 amongst other imprinted genes that are associated with Beckwith-Wiedemann syndrome (BWS), and itself has been shown to be disrupted by chromosomal rearrangements in patients with BWS. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Aug 2011]

Synonyms

LQT; RWS; WRS; LQT1; SQT2; ATFB1; ATFB3; JLNS1; KCNA8; KCNA9; Kv1.9; Kv7.1; KVLQT1;

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Detailed Information

Recent Research

The KCNQ1 (KvLQT1 or Kv7.1) gene encodes for the pore-forming alpha subunit of a voltage-gated potassium channel that enables a K⁺ current after electrical depolarization of the cell membrane. KCNQ1 has six transmembrane segments (S1-S6) and forms tetrameric channels with a central pore domain (composed of S5-S6) and four peripheral voltage sensing domains (composed of S1-S4) (Fig.1). The pore domain includes K⁺ conduction pathway with activation gate (S6). Mutations of positively charged residues in the fourth transmembrane domain (S4) in KCNQ1 strongly alter or abolish voltage gating, supporting the notion that S4 acts as the voltage sensor in KCNQ1 channels. In the case of depolarization, the outward motion of S4 in each subunit mediates the voltage sensing, and it is assumed that the S6 gate is opened to allow the potassium ions to penetrate.

Figure 1 Topology of Kv7.1 and KCNE and model for electro-mechanical coupling.

The KCNQ1 channel is expressed in various tissues, such as inner ear, myocardium, stomach, intestine and pancreas. In these tissues, it mainly contributes to the regulation of electric activity or to maintain K⁺ homeostasis needed for electrolyte and hormone transport. These two functional roles of KCNQ1 are probably the easiest to understand in the heart and inner ear, respectively. KCNQ1 in complex with the KCNE1 (MinK) β-subunit form the cardiac I Ks channel which plays an important role in regulating cardiac action potential duration. The outward K⁺ current through the I Ks channel is one of the main K⁺ repolarization currents in the human heart, which leads to the termination of cardiac action potential. Cardiac dysfunction I Ks channels cause pathological changes in the duration of cardiac action potential, which can lead to severe arrhythmia and sudden cardiac death. In general, loss-of-function of the cardiac I Ks channel tends to prolong the cardiac action potential duration which can cause a prolonged QT interval in the ECG (long QT syndrome), which is characterized by a prolongation of the QT interval on the electrocardiogram. It is a disorder caused by abnormal ventricular repolarization that increases the risk of sudden death from cardiac arrhythmias.

KCNQ1 is also co-expressed with KCNE1 in the inner ear. K⁺ flux through the inner ear I Ks channel is important to maintain the endolymph K⁺ homeostasis and the endocochlear potential. Dysfunctional I Ks channels in the inner ear can result in decreased hearing ability or congenital deafness. KCNQ1 is also suggested to associate with KCNE1 or other KCNE subunits in other epithelial tissues such as pancreas, kidney, colon and intestine, stomach, thyroid gland and airways where these KCNQ1–KCNE complexes contribute to K⁺ homeostasis and/or maintain the proper membrane potential for transepithelial transport of, for instance, Cl⁻ and gastric acid.

References:

Liin S I, et al. The KCNQ1 channel - remarkable flexibility in gating allows for functional versatility: KCNQ1 channel gating flexibility. The Journal of Physiology, 2015, 593(12).
Barro-Soria R, et al. KCNE1 divides the voltage sensor movement in KCNQ1/KCNE1 channels into two steps. Nature Communications, 2014, 5.

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