Constitutively active, non-selective divalent cation- conducting channel that is permeable to Ca(2+), Mn(2+), and Mg(2+), with a high permeability for Ca(2+). However, can be enhanced by increasing temperature and by ligands, including the endogenous neurosteroid pregnenolone sulfate and sphingosine-1 and suppressed by intracellular Mg(2+) (PubMed:12672799, PubMed:12672827, PubMed:32343227). Implicated in a variety of cellular processes, including insulin/peptide secretion, vascular constriction and dilation, noxious heat sensing, inflammatory and spontaneous pain sensitivity. In neurons of the dorsal root ganglia, functions as thermosensitive channel for the detection of noxious heat and spontaneous pain. Suggested to function as an ionotropic steroid receptor in beta-cell, indeed pregnenolone sulfate leads to Ca(2+) influx and enhanced insulin secretion. Mediates Zn(2+) uptake into the lumen of pancreatic beta cell secretory granules, thereby regulating insulin secretion (By similarity). Forms heteromultimeric ion channels with TRPM1 which are permeable for Ca(2+) and Zn(2+) ions (PubMed:21278253). Exists as multiple splice variants which differ significantly in their biophysical properties (By similarity). {ECO:0000250|UniProtKB:J9SQF3, ECO:0000269|PubMed:12672799, ECO:0000269|PubMed:12672827, ECO:0000269|PubMed:21278253, ECO:0000269|PubMed:32343227}. This is the function of ENSG00000083067 (TRPM3, transient receptor potential cation channel subfamily M member 3).