ACD-5 forms a homomeric proton-sensing channel localised to the apical membrane . Acid-sensing members of the DEG/ENaC family can form homomeric or heteromeric channels that are activated and/or inhibited by low pH ( Zhang and Canessa, 2002 ; Wang et al., 2008 ; Elkhatib et al., 2019 ). Many, but not all, are blocked by the anti-hypertensive amiloride; indeed, in some cases amiloride can potentiate currents ( Canessa et al., 1994 ; Fechner et al., 2021 ; Besson et al., 2017 ...