TRPM5 is activated by calcium ions and passively transports monovalent cations across the plasma membrane, resulting in depolarization of the cell (Prawitt et al. 2003). In mice, Trpm4 and Trpm5 are involved in sodium signals in type II taste cells and are required for perception of sweet, bitter, and umami tastes (Dutta Banik et al. 2018). TRPM5 is more sensitive to calcium than TRPM4 is (inferred from mouse homologs).
sodium channel activity of TRPM5 tetramer [plasma membrane]