Enables group III metabotropic glutamate receptor activity. Involved in detection of mechanical stimulus involved in sensory perception of pain; glutamatergic synaptic transmission; and regulation of synaptic vesicle exocytosis. Located in neuron projection; neuronal cell body; and presynaptic membrane. Is integral component of plasma membrane. Is active in GABA-ergic synapse and glutamatergic synapse. Is integral component of presynaptic active zone membrane. Used to study Parkinsonism; epilepsy; and visual epilepsy. Human ortholog(s) of this gene implicated in attention deficit hyperactivity disorder; autistic disorder; and schizophrenia. Orthologous to human GRM8 (glutamate metabotropic receptor 8). [provided by Alliance of Genome Resources, Apr 2022]