Muscarinic acetylcholine receptor M4

Muscarinic acetylcholine receptor M4 is one of the five types of muscarinic receptors (M1-M5) that belong to a larger family of G protein-coupled receptors. The M4 receptor, like the other muscarinic receptors, is activated by the neurotransmitter acetylcholine.

Structure

The M4 receptor is a protein that spans the cell membrane. It is composed of seven transmembrane alpha helices, with the N-terminus located outside the cell and the C-terminus inside the cell. The receptor also has three extracellular loops and three intracellular loops. The third intracellular loop interacts with the G protein.

Function

The M4 receptor is primarily found in the central nervous system, particularly in the striatum, a part of the brain involved in movement and reward. When activated by acetylcholine, the M4 receptor inhibits the activity of adenylate cyclase, reducing the production of cyclic AMP. This leads to a decrease in neuronal excitability and neurotransmitter release.

Clinical significance

The M4 receptor has been implicated in several neurological and psychiatric disorders, including schizophrenia, Parkinson's disease, and drug addiction. Drugs that target the M4 receptor are currently being developed for the treatment of these conditions.

See also

• Muscarinic acetylcholine receptor
• G protein-coupled receptor
• Acetylcholine
• Striatum