Acetylcholinesterase (AChE) is an enzyme that breaks down and deactivates acetylcholine (ACh) after it is released by terminal buttons. AChE is located naturally in the postsynaptic membrane and breaks down ACh into its base components of acetate and choline. Reuptake is used to take choline back to the terminal buttons which recycle it and use it to make more ACh. AChE is used as an insecticide and as a medical treatment for myasthenia gravis in humans. Myasthenia gravis is a disease which causes an individual's immune system to attack ACh receptors that are on muscles. This makes the individual gradually weaker and unable to move normally.