KCNE1 and cardiac arrhythmia: Because KV7.1 is co-assembled with KCNE1 in the native IKs channel complex in the heart (Barhanin et al., 1996; Sanguinetti et al., 1996), KV7.1 channel activators must affect the KV7.1+KCNE1 complex (referred to as KV7.1+E1) to prevent cardiac arrhythmias, such as in Long QT syndrome.