GRIK5

GRIK5 is a gene that encodes the kainate receptor subunit 5, a member of the ionotropic glutamate receptor (iGluR) family. Kainate receptors are ligand-gated ion channels that mediate excitatory neurotransmission in the central nervous system. The GRIK5 subunit contributes to the properties of kainate receptors, influencing their ligand sensitivity and ion conductance.

GRIK5 subunits assemble with other kainate receptor subunits (such as GRIK1–GRIK4) to form functional receptors. Although homomeric assembly of GRIK5 is uncommon, heteromeric combinations involving GRIK5 and other subunits determine receptor pharmacology, trafficking, and synaptic localization. These receptors are permeable to sodium and, depending on subunit composition, can also allow calcium influx, contributing to fast excitatory transmission and presynaptic modulation of neurotransmitter release.

Expression studies show that GRIK5 is present in multiple brain regions, with notable expression in areas such as the hippocampus, cortex, and amygdala, and its expression can be developmentally regulated. Through kainate receptors, GRIK5 participates in synaptic plasticity processes that underlie learning and memory and can influence overall neuronal network excitability and seizure susceptibility in experimental models.

Genetic and expression analyses have explored associations between GRIK5 and neurological or psychiatric conditions, including epilepsy and schizophrenia, though findings vary across studies. As with other iGluR subunits, changes in GRIK5 expression or function can affect excitatory signaling in neural circuits.

In research contexts, GRIK5 serves as a molecular target to study kainate receptor physiology and pharmacology. The encoded protein features the characteristic domains of iGluR subunits, including an extracellular N-terminus, a ligand-binding domain, and transmembrane segments that form the ion-conducting pore.