Their diverse functions include regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and cell volume.

[8] KCNE1 slows the activation of KCNQ1 5-10 fold, increases its unitary conductance 4-fold, eliminates its inactivation, and alters the manner in which KCNQ1 is regulated by other proteins, lipids and small molecules.

The association of KCNE1 with KCNQ1 was discovered 8 years after Takumi and colleagues reported the isolation of a fraction of RNA from rat kidney that, when injected into Xenopus oocytes, produced an unusually slow-activating, voltage-dependent, potassium-selective current.

KCNE1 increased both their peak currents in oocyte expression studies, and slowed the activation of the latter.,[10][11] KCNE1 also regulates hERG, which is the Kv α subunit that generates ventricular IKr.

This appears to be a mechanism for ensuring that homomeric N-type channels do not reach the cell surface, as this mode of suppression by KCNE1 or KCNE2 is relieved by co-expression of same-subfamily delayed rectifier (slowly inactivating) α subunits.

Thus, Kv1.1 rescued Kv1.4, Kv3.1 rescued Kv3.4; in each of these cases the resultant channels at the membrane were heteromers (e.g., Kv3.1-Kv3.4) and displayed intermediate inactivation kinetics to those of either α subunit alone.,[13][14] KCNE1 also regulates the gating kinetics of Kv2.1, Kv3.1 and Kv3.2, in each case slowing their activation and deactivation, and accelerating inactivation of the latter two.,[15][16] No effects were observed upon oocyte co-expression of KCNE1 and Kv4.2,[17] but KCNE1 was found to slow the gating and increase macroscopic current of Kv4.3 in HEK cells.

[18] In contrast, channels formed by Kv4.3 and the cytosolic ancillary subunit KChIP2 exhibited faster activation and altered inactivation when co-expressed with KCNE1 in CHO cells.

[23] The interaction of KCNE1 with an alpha helix in the S6 KvLQT1 domain contributes to the higher affinity this channel has for benzodiazepine L7 and chromanol 293B by repositioning amino acid residues to allow for this.

[30] The intracellular C-terminal domain of KCNE1 is thought to sit on the KCNQ1 S4-S5 linker, a segment of KCNQ1 crucial for communicating S4 status to the pore and thus control activation.