TRPM4 is activated by calcium ions and passively transports monovalent cations across the plasma membrane, resulting in depolarization of the cell (Launay et al. 2002, and inferred from mouse homologs). 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), however Ishimaru et al. (2006) reported that Trpm5, Pkd2l1, and Pkd1l3 but not other Trp channels were specifically and robustly expressed in mouse circumvallate taste cells.. TRPM4 is less sensitive to calcium than TRPM5 is (inferred from mouse homologs).