Final answer:
The five types of muscarinic acetylcholine receptors are called M1-M5, highlighting their role in the cholinergic system and specificity to muscarine and acetylcholine.
Step-by-step explanation:
The 5 types of muscarinic acetylcholine receptors are called M1-M5. These receptors play key roles in the cholinergic system and are a subset of acetylcholine receptors which are G protein-coupled receptors. Unlike their counterpart, the nicotinic receptors which are ligand-gated ion channels, the muscarinic receptors are differentiated by their ability to bind to muscarine — a substance found in certain mushrooms — as well as acetylcholine but not nicotine, showcasing their substance specificity.