Ion channel

An ion channel is a [pore complex]? in the membrane of a biological cell. It lets specific ions pass through the membrane, and can be turned on and of by regulatory signals, either chemical or electrical ones. They are especially important in neurons at the synapses.

Ion channel structure

Although ion channels vary depending on the ion they let pass (for example, Na⁺, K⁺, Cl^-), and the type of regulation, the known ion channels have a basic structure in common. They consist of four subunits with six transmembrane helices each, together forming a (closed) pore. On activation, these helices change structure, opening the pore.

See also : transmembrane receptor