Voltage-gated KCNQ1 potassium channels are expressed abundantly in heart but are also found in multiple other tissues.Differential co-assembly with single transmembrane KCNE beta subunits in different cell types gives rise to a variety of biophysical properties, hence endowing distinct physiological roles for KCNQ1-KCNEx complexes.Mutations in either KCNQ1 or KCNE1 genes result in diseases in brain, heart and the respiratory system.In addition to complexities arising from existence of five KCNE subunits, KCNE1 to KCNE5, recent studies in heterologous systems have suggested unorthodox stoichiometric dynamics in subunit assembly is dependent on KCNE expression levels.