Ionotropic glutamate receptor kainate subtype (KAR (Kainate receptor))

The ionotropic glutamate receptor kainate subtype (KAR) is a ligand-gated ion channel that responds to the neurotransmitter glutamate and mediates fast excitatory neurotransmission in the central nervous system. The receptor assembles as a tetramer from five possible subunits (GluK1–5), imparting distinct functional and pharmacological properties. KARs are involved in both pre- and post-synaptic signaling and regulation of neurotransmitter release, influencing neuronal circuit activity. They are implicated in neurological and psychiatric disorders, making them therapeutic targets for conditions like epilepsy and neurodegenerative diseases. Drugs targeting KARs act as agonists, competitive antagonists, or allosteric modulators, with perampanel as an example of an approved antiepileptic agent acting on this family. KAR dysfunction or excessive activation can result in excitotoxicity and seizure susceptibility.

Other names

Kainate receptorKainic acid receptorKARGluK1–5 (subunits: GluK1, GluK2, GluK3, GluK4, GluK5; formerly GluR5–7, KA1, KA2)

Agonists bind to and activate the receptor, allowing cation influx and excitatory synaptic transmission. Competitive antagonists block the ligand-binding site, preventing activation by glutamate. Positive allosteric modulators stabilize the closed state or alter receptor gating to enhance function. Negative allosteric modulators inhibit receptor function by stabilizing non-conducting states.