Illustration of an AMPA (a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor) neurotransmitter receptor. This glutamate receptor is the most common neurotransmitter receptor in the central nervous system. It mediates fast excitatory synaptic transmissions. It is a transmembrane protein with the upper part of the receptor, which recognises and binds glutamate, located on the outside of the cell. The lower part is located in the cell membrane and forms a channel after binding glutamate, through which cations pass.