ion channels

Definition: Ion channels are transmembrane glycoprotein pores important in cell excitability, which is mediated by the ion flow in and out of cells.

Channels can exist in three different states: open, closed (resting state), or inactivated (refractory period after opening of the channel, during which the channel will not let ions pass through). Channels are composed of different subunits, with each subunit encoded by a different gene.

There are two major classes of ion channels:

 voltage-gated ion channel
 ligand-gated ion channel

Types

 voltage-gated ion channels

• voltage-gated cation channels
  • calcium channels
  • K+ channels (potassium channels)
    • voltage-dependent K+ channels

 transmitted-gated ion channels

 gap junctions

Localization

 mitochondrial ion channels

Pathology: channelopathies