An ion channel comprises of a solitary protein or complex of protein that extends through the lipid bilayer of the plasma membrane and form a channel that makes possible the movement of ions through it based on their electrochemical gradient. They acts as a pores in the plasma membrane and allows the selective passage of ions such as potassium ions, sodium ions, and calcium ions, by means of which electrical signals in the form of ions (charged particles) travels in and out of the cell. Ion channels also render many other crucially essential functions including chemical signalling, transcellular transport (involves the transportation of solutes by a cell through a cell) , regulation of pH and cell volume. Abnormal functioning of ion channels can cause diseases in many tissues. The collection of human diseases related with defects in ion channels is increasing. Ion channels are specific for calcium (Ca+2), sodium(Na+), potassium(K+) or chloride(Clâˆ'). A cell membrane may have a quite few thousand ion channels particular for each of these ions.
The following disorders result from abnormal ion channels:
Cystic Fibrosis and Chloride Channels - it is an inherited illness distinguished by the build up of thick, sticky mucus that can harm many of the body's organs. The most general signs and symptoms of the illness involve successive damage to the respiratory system and long term troubles with the digestive system. The characteristics of the disorder and their intensity vary among affected persons. Cystic fibrosis results due to the mutations occurred in the CFTR gene. CFTR gene renders the information for the production of channels that transfer the chloride (Clâˆ') ions that are negatively charged in and out of the cell. Chloride is a constituent of sodium chloride (NaCl), a common salt found in sweat and also has significant functions in cells. For instance, the flow of chloride ions assists to regulate the movement of water in tissues, which is essential for the production of thin, freely flowing mucus.
Mutations occurring in CFTR gene interrupt the function of the chloride channels, obstructing them from controlling the movement of chloride ions and water across plasma membranes. As a consequence, cells lining the passages of the pancreas, lungs etc, generate mucus that is uncommonly sticky and thick. The sticky mucus blocks the airways and several ducts, generating the typical signs and symptoms of cystic fibrosis.
Long- QT Syndrome and Potassium Channels - it is a condition concerned with heart rhythm that can severely cause speedy, chaotic heartbeats. In the heart cells, the malfunctioning ion channels interrupt electrical activity, causing a fatal disturbance to the heart rhythm. In the cells of the inner ear, the abnormal ion channels increase the extracellular concentration of potassium ions, and can impairing hearing. Some causes of long- QT syndrome are caused not by faulty ion channels, but by the proteins, known as ankyrins, that hold the channels in place within the cell membrane.
Hyperkalemic Periodic Paralysis and Sodium Channels - it is a disorder that causes events of severe muscle weakness, generally commencing in infancy or early childhood. Frequently, these events include a short-term inability to move muscles in the arms and legs. Elements that can activate attacks include rest after exercise, foods rich in potassium, stress, fatigue, and fasting.
The SCN4A gene renders information for generating a protein that plays a vital role in muscles utilized for movement especially skeletal muscles. For the general movement of the body, these muscles must relax and tense in a coordinated fashion. Contractions of muscles are triggered by the movement of certain positively charged ions, such as sodium, into muscle cells. The SCN4A protein forms channels that regulate the movement of sodium ions (Na+) into these cells.
Mutations occurring in SCN4A gene modify the normal configuration and function of sodium channels. The modified channels cannot control accurately, the movement of sodium ions into muscle cells, which decreases the capacity of skeletal muscles to contract. As muscle contraction is essential for movement, an interruption in normal ion transport results in the events of weakness of muscle or paralysis.
Diseases that are caused by faulty ion channel proteins are termed as channelopathy and the discoveries in this field offer a new viewpoint on how defective ion channels can cause disorders in humans.
About Author / Additional Info: