Fig. 1

TMC4 is a novel voltage-dependent chloride channel that is specifically expressed in the posterior part of the tongue and is responsible for the salt response of the glossopharyngeal nerve. A Location of the circumvallate papillae (CvP), foliate papillae (FoP), and fungiform papillae (FuP) on a mouse tongue. Surrounding epithelia (Epi) means to the epithelia of the tongue that does not contain taste papillae. B In situ hybridization of Tmc4 mRNA is specifically detected in the CvP and FoP, but barely detected in the FuP. C Representative I-V relationship of the currents using step pulses (the holding potential was -60 mV, and stimulated from − 100 to + 100 mV [∆10 mV] for 400 ms) under different bath solutions. The mouse TMC4-mediated outward current is not affected by the bath application of N-methyl-D-glucamine (NMDG)-Cl, NaCl, or amiloride (epithelial sodium channel inhibitor), but is significantly reduced by the anion channel inhibitor, 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB). D) Integral glossopharyngeal nerve response of wild-type (WT) or Tmc4-deficient mice to NaCl solutions (30, 50, 100, and 300 mM). The asterisks (^*, ^****) indicate statistical differences: p < 0.05 and p < 0.0001, respectively. Significance was evaluated using two-way ANOVA with Bonferroni correction (n = 6–7 for WT and n = 5–6 for KO)