GluK2

GluK2 is a subunit of the kainate receptor family of glutamate-gated ion channels. The human subunit is encoded by GRIK2; the older name GluR6 occurs in much of the originating experimental literature. A receptor subunit is a component of an assembled channel, not a synonym for every member of the kainate receptor family.^[ref]

Deleting the gene for the subunit gave a direct test of its functional contribution. C. Mulle and colleagues generated GluR6-deficient mice and found reduced sensitivity to kainic acid in hippocampal CA3 neurons. A postsynaptic kainate current evoked by trains of mossy-fibre stimulation was absent in the mutants. The mice were also less susceptible to the tested systemic-kainate seizure challenge.^[ref]

For an experimental comparison, disappearance of a stimulus-evoked current after deleting GluK2 supports a requirement for that subunit in the tested response. It does not establish that every excitatory current in the same cell is a GluK2 current: AMPA receptors and other receptors can still contribute different components. Nor does gene deletion, by itself, specify the subunit composition of every remaining channel. Combining molecular perturbation with a precisely defined stimulation protocol makes the inference much stronger than interpreting an agonist response alone.