mGluR6 is specifically expressed in the retina, in a subtype of bipolar cells that depolarize in response to light, known as ON bipolar cells. These cells form synapses with photoreceptor cells, and detect the neurotransmitter glutamate via a GPCR signal transduction cascade. The glutamate receptor mGluR6 is located post-synaptically at the tips of the bipolar cell dendrites, and is responsible for initiating a signaling cascade that ultimately controls gating of the TRPM1 channel. In human patients, mutations in the GRM6 gene are associated with congenital stationary night blindness.