The function of TRPM1 (transient receptor potential cation channel subfamily M member 1, ENSG00000134160) is as follows. Constitutively open nonselective divalent cation-conducting channels which mediate the influx of Ca(2+), Mg(2+), Mn(2+), Ba(2+), and Ni(2+) into the cytoplasm, leading to membrane depolarization (PubMed:11535825, PubMed:19436059, PubMed:21278253). Impermeable to zinc ions (PubMed:21278253). In addition, forms heteromultimeric ion channels with TRPM3 which are permeable for calcium and zinc ions (PubMed:21278253). Plays an essential role for the depolarizing photoresponse of retinal ON bipolar cells (PubMed:19878917, PubMed:19896109). In the dark, tonic release of glutamate activates the G protein-coupled receptor for glutamate, GRM6, its activation induces the release of G(o) protein and the beta-gamma G protein dimer. Both subunits can interact and inactivate the TRPM1 channel. A light onset, induces decrease in glutamate release and deactivation of GRM6 leading to channel opening and membrane depolarization (By similarity). May play a role in metastasis suppression (PubMed:9537257). {ECO:0000250|UniProtKB:Q2TV84, ECO:0000269|PubMed:11535825, ECO:0000269|PubMed:19436059, ECO:0000269|PubMed:19878917, ECO:0000269|PubMed:19896109, ECO:0000269|PubMed:21278253, ECO:0000269|PubMed:9537257}.