OTOP1 and polycystic kidney disease 2: The polycystic kidney disease 1 and polycystic kidney disease 2–like proteins PKD2L1 and PKD1L3 have been identified as sour taste‐related receptors in human taste cells (Ishimaru et al., 2006), and potential ion‐channel OTOP1 was present in taste cells in mouse that express Pkd2l1.