A Ligand-Gated Ion Channel (Such as the Nicotinic Acetylcholine Receptor)

A ligand-gated ion channel (such as the nicotinic acetylcholine receptor) is:

A) a charged lipid in the membrane bilayer that allows ions to pass through.
B) a membrane protein that permits a ligand to pass through the membrane only when opened by the appropriate ion.
C) a membrane protein that permits an ion to pass through the membrane only when opened by the appropriate ligand.
D) a molecule that binds to the membrane thereby allowing ions to pass through.
E) always requires a second ligand to close the channel once it is opened.