Glutamate ionotropic receptor kainate type subunit 2, also known as ionotropic glutamate receptor 6 or GluR6, is a protein that in humans is encoded by the GRIK2 (or GLUR6) gene.

This gene encodes a subunit of a kainate glutamate receptor. This receptor may have a role in synaptic plasticity, learning, and memory. It also may be involved in the transmission of visual information from the retina to the hypothalamus. The structure and function of the encoded protein is influenced by RNA editing. Alternatively spliced transcript variants encoding distinct isoforms have been described for this gene. It has been discovered that this is a key protein, which enables mammals to feel cold sensations.

Homozygosity for a GRIK2 deletion-inversion mutation is associated with non-syndromic autosomal recessive mental retardation.

GRIK2 has been shown to interact with:

Pre-mRNA for several neurotransmitter receptors and ion channels are substrates for ADARs, including AMPA receptor subunits (GluR2, GluR3, GluR4) and kainate receptor subunits (GluR5, GluR6). Glutamate-gated ion channels are made up of four subunits per channel, with each subunit contributing to the pore loop structure. The pore loop structure is similar to that found in K⁺ channels (e.g. the human K_v1.1 channel, whose pre-mRNA is also subject to A to I RNA editing). The diversity of ionotropic glutamate receptor subunits, as well as RNA splicing, is determined by RNA editing events of the individual subunits, explaining their extremely high diversity.

The type of RNA editing that occurs in the pre-mRNA of GluR6 is Adenosine to Inosine (A to I) editing.

A to I RNA editing is catalyzed by a family of adenosine deaminases acting on RNA (ADARs) that specifically recognize adenosines within double-stranded regions of pre-mRNAs and deaminate them to inosine. Inosines are recognised as guanosine by the cell's translational machinery. There are three members of the ADAR family ADARs 1–3 with ADAR1 and ADAR2 being the only enzymatically active members. ADAR1 and ADAR2 are widely expressed in tissues, while ADAR3 is restricted to the brain, where it is thought to have a regulatory role. The double-stranded regions of RNA are formed by base-pairing between residues close to region of the editing site, with residues usually in a neighboring intron, though they can occasionally be located in an exonic sequence. The region that forms base pairs with the editing region is known as an Editing Complementary Sequence (ECS).

ADARs bind interact directly with the dsRNA substrate via their double-stranded RNA binding domains. If an editing site occurs within a coding sequence, the result could be a codon change. This can lead to translation of a protein isoform due to a change in its primary protein structure. Therefore, editing can also alter protein function. A to I editing occurs in a noncoding RNA sequences such as introns, untranslated regions (UTRs), LINEs, and SINEs (especially Alu repeats). The function of A to I editing in these regions is thought to involve creation of splice sites and retention of RNAs in the nucleus amongst others.