Ion flow through protein channels is one of the fundamental mechanisms of transmembrane signaling. Ion channels are involved in processes as diverse as development, hormone secretion, salt balance and memory. Abnormalities in channel function underlie a wide range of neural, muscular, cardiovascular and renal diseases. In order to understand the roles of ion channels under normal and pathological conditions, it is necessary to know how they regulate the flow of specific ions across the membrane and how other proteins affect their function. We address these questions by combining state of the art electrophysiological, molecular and imaging techniques, both in cultured cells and in native tissues.