Ionotropic glutamate receptor (By similarity). L-glutamate acts as an excitatory neurotransmitter at many synapses in the central nervous system. Binding of the excitatory neurotransmitter L-glutamate induces a conformation change, leading to the opening of the cation channel, and thereby converts the chemical signal to an electrical impulse. The receptor then desensitizes rapidly and enters a transient inactive state, characterized by the presence of bound agonist (By similarity). Independent of its ionotropic glutamate receptor activity, acts as a thermoreceptor conferring sensitivity to cold temperatures (By similarity). Functions in dorsal root ganglion neurons (By similarity). Cold receptor activity activated by temperatures between 10-19 degrees Celsius. Belongs to the glutamate-gated ion channel (TC 1.A.10.1) family. GRIK2 subfamily.