Humanether a` go-go potassium channels (hEAG1) open in response to membrane depolarization and they are inhibited by Ca 2+ ⁄calmodulin (CaM), presumably binding to the C-terminal domain of the channel sub-units. Deletion of the cytosolic N-terminal domain resulted in complete abolition of Ca 2+ ⁄CaM sensitivity suggesting the existence of further CaM binding sites.