Auxiliary subunits of voltage-gated ion channels

The voltage-gated Na super(+), Ca super(2+), and K super(+) channels are responsible for the generation of action potentials in neurons and other excitable cells. Voltage-gated ion channels all contain principal subunits (designated alpha or alpha 1) that are members of a common channel gene family and are responsible for the voltage-gated ion conductance which is the defining characteristic of these proteins. However, in nearly every case studied to date, the principal subunits of the voltage-gated ion channels are expressed in cells as a specific protein complex with one or more auxiliary subunits, which strongly influence the activation, inactivation, or modulation of the principal subunits when coexpressed in heterologous cells. This review focuses on the molecular properties and functional roles of these important ion channel components.