Potassium channel that plays an important role in a number of tissues, including heart, inner ear, stomach and colon (, ). Associates with KCNE beta subunits that modulates current kinetics (  , ). Induces a voltage-dependent current by rapidly activating and slowly deactivating potassium-selective outward current (  , ). Promotes also a delayed voltage activated potassium current showing outward rectification characteristic (By similarity). During beta-adrenergic receptor stimulation participates in cardiac repolarization by associating with KCNE1 to form the I(Ks) cardiac potassium current that increases the amplitude and slows down the activation kinetics of outward potassium current I(Ks) (By similarity) (  ). Muscarinic agonist oxotremorine-M strongly suppresses KCNQ1/KCNE1 current . When associated with KCNE3, forms the potassium channel that is important for cyclic AMP-stimulated intestinal secretion of chloride ions . This interaction with KCNE3 is reduced by 17beta-estradiol, resulting in the reduction of currents (By similarity). During conditions of increased substrate load, maintains the driving force for proximal tubular and intestinal sodium ions absorption, gastric acid secretion, and cAMP-induced jejunal chloride ions secretion (By similarity). Allows the provision of potassium ions to the luminal membrane of the secretory canaliculus in the resting state as well as during stimulated acid secretion (By similarity). When associated with KCNE2, forms a heterooligomer complex leading to currents with an apparently instantaneous activation, a rapid deactivation process and a linear current-voltage relationship and decreases the amplitude of the outward current . When associated with KCNE4, inhibits voltage-gated potassium channel activity . When associated with KCNE5, this complex only conducts current upon strong and continued depolarization . Also forms a heterotetramer with KCNQ5; has a voltage-gated potassium channel activity . Binds with phosphatidylinositol 4,5-bisphosphate . KCNQ1-KCNE2 channel associates with Na(+)-coupled myo-inositol symporter in the apical membrane of choroid plexus epithelium and regulates the myo-inositol gradient between blood and cerebrospinal fluid with an impact on neuron excitability.
Non-functional alone but modulatory when coexpressed with the full-length isoform 1.
Subcellular locations: Cell membrane, Cytoplasmic vesicle membrane, Early endosome, Membrane raft, Endoplasmic reticulum, Basolateral cell membrane, Apical cell membrane
Colocalized with KCNE3 at the plasma membrane . Upon 17beta-oestradiol treatment, colocalizes with RAB5A at early endosome . Heterotetramer with KCNQ5 is highly retained at the endoplasmic reticulum and is localized outside of lipid raft microdomains . During the early stages of epithelial cell polarization induced by the calcium switch, it is removed from the plasma membrane to the endoplasmic reticulum, where it is retained, and redistributed to the basolateral cell surface in a PI3K-dependent manner at a later stage . Colocalizes with SLC5A3 at the apical membrane of choroid plexus epithelium.
Abundantly expressed in heart, pancreas, prostate, kidney, small intestine and peripheral blood leukocytes. Less abundant in placenta, lung, spleen, colon, thymus, testis and ovaries.