Figure 5. Inactivation of voltage-gated K channels. Channels undergo a conformational change induced by membrane depolarization to open the ion-conducting pathway. The open probability increases steeply over a narrow range of membrane potentials that is characteristic for each K channel subtype. After activation, some types of voltage-gated K channels rapidly inactivate. N-type inactivation occurs through the interaction of the amino (N)-terminus of the channel with the channel pore. A “ball-and-chain” model best describes how N-type inactivation occurs. N-type inactivation must be relieved before currents can flow through an open channel again.