The TRPM1 gene codes for a member of the transient receptor potential (TRP) channel family that is important in cellular and somatosensory perception. The encoded protein is expressed in the bipolar cells and the melanocytes. The TRPM1 protein acts as a channel that transports cations in and out of bipolar cells. TRPM1 channels are involved in the pathway that is used to see in low light. When the TRPM1 channel is open, it allows cations to flow in and out of bipolar cells, which prevent visual signals from being sent in the bright-light conditions. While in the low-light conditions, the TRPM1 channels are triggered by the visual signals from rod cells to close, which causes visual signals to be transmitted. The channel may also play a role in Ca2+-dependent signaling related to melanocyte proliferation, differentiation, and/or survival.
Defects in this protein are the cause of congenital stationary night blindness type 1C (CSNB1), an autosomal recessive non-progressive retinal disorder, characterized by impaired night vision, nystagmus and myopia. Mutations in TRPM1 have been reported to account for at least half of the autosomal recessive CSNB1 cases in the Caucasian and Japanese population.