Off-response property of an acid-activated cation channel complex PKD1L3-PKD2L1.
Ligand-gated ion channels are important in sensory and synaptic transduction. The PKD1L3-PKD2L1 channel complex is a sour taste receptor candidate that is activated by acids. Here, we report that the proton-activated PKD1L3-PKD2L1 ion channels have the unique ability to be activated after the removal of an acid stimulus. We refer to this property as the off-response (previously described as a delayed response). Electrophysiological analyses show that acid-induced responses are observed only after the removal of an acid solution at less than pH 3.0. A small increase in pH is sufficient for PKD1L3-PKD2L1 channel activation, after exposure to an acid at pH 2.5. These results indicate that this channel is a new type of ion channel-designated as an 'off-channel'-which is activated during stimulus application but not gated open until the removal of the stimulus. The off-response property of PKD1L3-PKD2L1 channels might explain the physiological phenomena occurring during sour taste sensation.
Inada
Hitoshi
H
Section of Cell Signaling, Okazaki Institute for Integrative Bioscience, Higashiyama 5-1, Myodaiji, Okazaki, Aichi 444-8787, Japan. hinada@nips.ac.jp
Kawabata
Fuminori
F
Ishimaru
Yoshiro
Y
Fushiki
Tohru
T
Matsunami
Hiroaki
H
Tominaga
Makoto
M
D000143:Acids / Q000494:pharmacology*; D000818:Animals; D015220:Calcium Channels / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D015640:Ion Channel Gating / Q000187:drug effects*; D051379:Mice; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017384:Sequence Deletion; D050396:TRPP Cation Channels / Q000737:chemistry / Q000378:metabolism*
D000143:Acids; D015220:Calcium Channels; C512453:PKD1L3 protein, mouse; C486487:Pkd2l1 protein, mouse; D011956:Receptors, Cell Surface; D050396:TRPP Cation Channels