Nicotinic Acetylcholine receptor
A receptor that responds to binding from the neurotransmitter acetylcholine and activated by the ligand nicotine. It is a ligand-gated ion channel which can be found on plasma membranes of neurons or postsynaptic membranes of the neuromuscular junction. When acetyl choline is released by the Presynaptic membrane it diffuses across the synapse and binds to the receptor. The ligand gate is made up of 5 sub units (2 Alpha units, 1 Beta, 1 Gamma and 1 Delta) where the acetylcholine binds to the alpha sub-unit making the gate more permeable. This requires two Aceytlcholine molecules to do so as there are two alpha sub units. The gate is now open so Sodium ions can flow into the post synaptic membrane and Potassium ions can flow out causing rapid Depolarisation. This then ultimately leads to a Muscle contraction.