The nicotinic acetylcholine receptor is a vital part of the nervous system, and is crucial for voluntary muscle contraction. It is a tunnel that regulates ion flow between a cell and its exterior. Similar channels control many other body systems. The receptor is made up of water (grey) enclosed by five protein sub-units (green/orange). The narrowest part of the water column is the gate. When the neurotransmitter chemical acetylcholine binds to the receptor it opens, allowing metal ions to pass through it.
Image created by loading the crystal structure of the receptor and water density on a 3D grid into VMD 1.8.3. Rendered directly with Raster3D 2.7c