Calcium-activated non selective (CAN) cation channel that mediates membrane depolarization. While it is activated by increase in intracellular Ca(2+), it is impermeable to it. Mediates transport of monovalent cations (Na(+) > K(+) > Cs(+) > Li(+)), leading to depolarize the membrane. It thereby plays a central role in cadiomyocytes, neurons from entorhinal cortex, dorsal root and vomeronasal neurons, endocrine pancreas cells, kidney epithelial cells, cochlea hair cells etc. Participates in T-cell activation by modulating Ca(2+) oscillations after T lymphocyte activation, which is required for NFAT-dependent IL2 production. Involved in myogenic constriction of cerebral arteries. Controls insulin secretion in pancreatic beta-cells. May also be involved in pacemaking or could cause irregular electrical activity under conditions of Ca(2+) overload. Affects T-helper 1 (Th1) and T-helper 2 (Th2) cell motility and cytokine production through differential regulation of calcium signaling and NFATC1 localization. Enhances cell proliferation through up-regulation of the beta-catenin signaling pathway. Essential for the migration but not the maturation of dendritic cells (By similarity). Plays a role in keratinocyte differentiation (By similarity). Gating is voltage-dependent and repressed by decavanadate. Calmodulin-binding confers the Ca(2+) sensitivity. ATP is able to restore Ca(2+) sensitivity after desensitization. Phosphatidylinositol 4,5-bisphosphate (PIP2)-binding strongly enhances activity, by increasing the channel's Ca(2+) sensitivity and shifting its voltage dependence of activation towards negative potentials. Activity is also enhanced by 3,5-bis(trifluoromethyl)pyrazole derivative (BTP2) (By similarity). Homotetramer. Additional isoforms may exist. Isoform 1 is highly expressed in the testis with a moderate expression in the brain, spleen and thymus. Isoform 2 is only expressed in the brain and spleen. Phosphorylation by PKC leads to increase the sensitivity to Ca(2+). Sumoylated. Desumoylated by SENP1. Probably non-functional. Belongs to the transient receptor (TC 1.A.4) family. LTrpC subfamily. TRPM4 sub-subfamily. Chimeric cDNA.