In voltage dependent channels, the electrical expression of their function is the ionic current which can be studied at the macroscopic level (the ionic current) and at the microscopic level (the single channel recording). But in addition to the ionic current, in these molecules the rearrangement of internal dipoles and charged groups under the influence of the external electric field produce gating currents. These currents are a direct expression of molecular rearrangements relevant to the operation (or gating) of the channel molecule.

With the advent of molecular cloning techniques, we have been able to carry out these studies with a detail not possible before by recording gating currents of cloned Shaker K+ and Sodium channels and describing their electrical properties with high resolution. Thus, we can modify the molecule to probe the role of specific amino acids in the voltage dependence and charge movement of the channel.