ION-CHANNEL-LINKED RECEPTORS

Binding to an ion-channel-linked receptor causes a conformational change in the trans-membrane protein, which opens up the ion-channel allowing ions to flow into the cell. The ligand-gated ion-channels comprise two, three or four trans-membrane proteins, each with a number of sub-units. The size of the ion-channel and the amino acids that make up the structural protein determine the ions involved. Opening cationic ionchannels involving sodium, potassium or calcium ions leads to excitatory effects. The anionic channels, such as the chloride ion-channel, are inhibitory. Neurotransmitters that bind to ion-channel-linked receptors include acetylcholine, glutamic acid, g-aminobutyric acid and serotonin.

Both acetylcholine and serotonin also bind to G-protein-linked receptors. A number of drugs target these receptors and the ion-channels themselves.