Potassium channel that plays an important role in a number of tissues, including heart, inner ear, stomach and colon (By similarity). Associates with KCNE beta subunits that modulates current kinetics (By similarity). Induces a voltage-dependent by rapidly activating and slowly deactivating potassium-selective outward current (By similarity). 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). When associated with KCNE3, forms the potassium channel that is important for cyclic AMP-stimulated intestinal secretion of chloride ions (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 (By similarity). When associated with KCNE4, inhibits voltage-gated potassium channel activity (By similarity). When associated with KCNE5, this complex only conducts current upon strong and continued depolarization (By similarity). Tetramer. Heterotetramer with KCNE1; targets to the membrane raft. Interacts (via C-terminus) with CALM; forms an heterotetramer in a calcium-independent manner. Interacts with KCNE2; form a heterooligomer complex that targets to the membrane raft and 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. Interacts with KCNE3; alters membrane raft localization. Interacts with KCNE4; impairs KCNQ1 localization in lipid rafts and inhibits voltage-gated potassium channel activity. Interacts with KCNE5; impairs KCNQ1 localization in lipid rafts and only conducts current upon strong and continued depolarization. Expressed only in rectal gland and heart. Faintly expressed in intestine. Undetectable in kidney, brain, testis, liver and gills. The segment S4 is probably the voltage-sensor and is characterized by a series of positively charged amino acids at every third position. The coiled-coil domain mediates tetramerization. The segment S6 is involved in the inhibition of voltage-gated potassium channel activity by KCNE4. The C-terminal assembly domain promotes self-interactiona; allows functional channel. Belongs to the potassium channel family. KQT (TC 1.A.1.15) subfamily. Kv7.1/KCNQ1 sub-subfamily.