The protein encoded by this gene is a member of thetransient receptor potential (TRP) family of non-selective cationchannels. It is expressed in the retina, in a subset ofbipolar cells termed ON bipolar cells.[8][9] These cells formsynapses with eitherrods orcones, collecting signals from them. In the dark, the signal arrives in the form of theneurotransmitter glutamate, which is detected by aG protein-coupled receptor (GPCR) signal transduction cascade. Detection of glutamate by the GPCRMetabotropic glutamate receptor 6 results in closing of the TRPM1 channel. At the onset of light, glutamate release is halted and mGluR6 is deactivated; this results in opening of the TRPM1 channel, influx of sodium and calcium, anddepolarization of the bipolar cell.[10][11]
In addition to the retina, TRPM1 is also expressed inmelanocytes, which are melanin-producing cells in the skin. The expression of TRPM1 is inversely correlated withmelanoma aggressiveness, suggesting that it might suppressmelanomametastasis.[12] However, subsequent work showed that amicroRNA located in anintron of theTRPM1 gene, rather than the TRPM1 protein itself, is responsible for the tumor suppressor function.[13][14] The expression of both TRPM1 and the microRNA are regulated by theMicrophthalmia-associated transcription factor.[15][16][17][13]
^"Human PubMed Reference:".National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:".National Center for Biotechnology Information, U.S. National Library of Medicine.
^Hunter JJ, Shao J, Smutko JS, Dussault BJ, Nagle DL, Woolf EA, Holmgren LM, Moore KJ, Shyjan AW (Nov 1998). "Chromosomal localization and genomic characterization of the mouse melastatin gene (Mlsn1)".Genomics.54 (1):116–23.doi:10.1006/geno.1998.5549.PMID9806836.
^Duncan LM, Deeds J, Hunter J, Shao J, Holmgren LM, Woolf EA, Tepper RI, Shyjan AW (Apr 1998). "Down-regulation of the novel gene melastatin correlates with potential for melanoma metastasis".Cancer Research.58 (7):1515–20.PMID9537257.
^Clapham DE, Julius D, Montell C, Schultz G (Dec 2005). "International Union of Pharmacology. XLIX. Nomenclature and structure-function relationships of transient receptor potential channels".Pharmacological Reviews.57 (4):427–50.doi:10.1124/pr.57.4.6.PMID16382100.S2CID17936350.
^Schneider FM, Mohr F, Behrendt M, Oberwinkler J (2015). "Properties and functions of TRPM1 channels in the dendritic tips of retinal ON-bipolar cells".Eur J Cell Biol.94 (7–9):420–7.doi:10.1016/j.ejcb.2015.06.005.PMID26111660.
