TRPM5

Monovalent cation-selective ion channel activated by intracellular Ca(2+) in a voltage- and temperature-dependent manner (PubMed:14634208). Mediates the transport of Na(+), K(+) and Cs(+) ions equally well (PubMed:14634208). Activated directly by increase in intracellular Ca(2+), but is impermeable to it (PubMed:14634208). The activation mechanism of TRPM5 involves a multistep process. TRPM5 activation involves ligand binding (i.e., tastant molecule, glucose stimulation) to Gq/G-protein coupled receptors (GPCR) and leads to the breakdown of phosphatidylinositol bisphosphate (PIP2) into diacylglycerol (DAG) and inositol trisphosphate (IP3), IP3 binds to its receptors in the endoplasmic reticulum and cause calcium release. Simultaneously with the intracellular Ca(2+) release, DAG activates the protein kinase C (PKC), which phosphorylates the TRPM5 channel. This phosphorylation combined with the bound Ca(2+), leads to a robust inward current allowing the entry of sodium ions (Na+) into the cell. This ion influx depolarizes the cell membrane, generating action potentials that propagate TRPM5 signals. Is a key player in sensing sweet, umami and bitter stimuli (By similarity). Involved in insulin secretion by pancreatic beta cells (By similarity).