The IKs channel response to cAMP is modulated by the KCNE1:KCNQ1 stoichiometry

The delayed potassium rectifier current, IKs, is assembled from tetramers of KCNQ1 and varying numbers of KCNE1 accessory subunits, in addition to calmodulin. This channel complex is important in the response of the cardiac action potential to sympathetic stimulation, during which IKs is enhanced. This is likely due to channels opening more quickly, more often, and to greater sublevel amplitudes during adrenergic stimulation. KCNQ1 alone is unresponsive to cAMP, and thus KCNE1 is required for a functional effect of PKA phosphorylation.

https://ift.tt/2NJ4EnO