Volume 33 reviews the current understanding of ion channel regulation by signal transduction pathways. Ion channels are no longer viewed simply as the voltage-gated resistors of biophysicists or the ligand-gated receptors of biochemists. They have been transformed during the past 20 years into signaling proteins that regulate every aspect of cell physiology. In addition to the voltage-gated channels, which provide the ionic currents to generate and spread neuronal activity, and the calcium ions to trigger synaptic transmission, hormonal secretion, and muscle contraction, new gene families of...