Like the AMPA receptor and the NMDA receptor, the kainate receptor belongs to the ionotropic glutamate receptors. It is a ligand-gated ion channel receptor type named after the prototype kainate (kainic acid) for the main excitatory transmitter glutamate. Ionotropic receptors activate membrane channels where ions can pass through when open. Kainate receptors have large transmembrane pores that are permeable to small cations. Thus, they are non-selective cationic channels. While the receptor channel is passable for Na+, K+, Ca2+ and Cs+, it is not permeable for anions.