Ion Channels

Ion channels are pore-forming membrane proteins that control the flow of ions (small charged molecules) in and out of the cell. There are many different types of ion channels and how they control the flow of ions may vary. A typical ion channel is only one or two atoms wide at its narrowest point, and conducts a specific type of ions, such as potassium or sodium. These ions are conveyed single file through the membrane. In some ion channels, ions have to pass through a "gate", which opens or closes depending on chemical or electrical signals, temperature, or mechanical force, depending on the type of ion channel.

The ion channel proteins are composed of various regions, which carry out specific functions. One part of the protein forms the pore where the ions pass, whereas other regions are responsible for opening and closing of the pore, for interacting with the membrane, and for binding regulatory molecules called ligands – which in turn will influence the activity of the ion channel.

Between 5 and 10 different types of ion channels can be found in a single cell membrane. Ion channels are involved in, among other things, nerve impulses and conduction across synapses, and are thus important parts of the nervous system. Ion channels are also involved in a myriad of other biological processes, such as cardiac, skeletal, and smooth muscle contraction, T-cell activation, and pancreatic beta-cell insulin release. Dysfunction of one or more of the ion channels may cause or contribute to disease, thus ion channels are prime targets in the search for new pharmaceutical drugs.

Channelopathies – Ion Channel Disorders

If one or more of the ion channels fail to function, the result is cell damage or even damage to entire systems in the body. Disorders caused by dysfunctional ion channels are called channelopathies. This is a highly diverse group of disorders, ranging from rather common ones to rare ones and from the less serious conditions to the very serious. For example, several types of epilepsy, some types of migraines, as well as myotonias, arrythmias, cystic fibrosis, and type II diabetes have all been related to dysfunctional ion channels.