ABSTRACT
This chapter provides the main types of cellular receptors; ligand gated ion channels, transducer type receptors, and steroid receptorsIon channels are opening and closing all of the time, not just when a ligand binds to the receptor. When a ligand binds to the receptor, it increases the probability of the ion channel being open rather than closed. The ligand-gated ion channel on skeletal muscle is known as a nicotinic receptor. It is opened when acetylcholine released from a nerve terminal innervating the muscle binds to the receptor. Muscarinic receptors are receptors for acetylcholine and they receive innervation from the parasympathetic nervous system. One common feature of all of the receptors appears to be autophosphorylation. It is believed that binding of the ligand to the receptor causes clustering of the two or more receptors and the tyrosine kinase activity of one phosphorylates the other receptor and vice versa – a bit like mutual masturbation really.
