Molecular and functional characterization of an I(h)-channel from lobster olfactory receptor neurons.
We isolated a cDNA named PAIH encoding a member of the I(h)-channel family expressed in olfactory receptor neurons (ORNs) of the spiny lobster Panulirus argus. Functional expression of recombinant PAIH in HEK293 cells generated a slowly activating, noninactivating inward current under whole-cell voltage-clamp to hyperpolarizing voltage steps, the amplitude and activation rate of which increase with increasing hyperpolarization. The channel is weakly selective for K+. Intracellular cAMP or cGMP shifts activation of the current to less negative potentials in a concentration-dependent manner. Finally, the channel is blocked by the I(h)-channel blocker ZD7288. An I(h)-channel sharing the properties of the recombinant channel occurs in cultured lobster ORNs. PAIH immunoreactivity localizes the protein to the transduction compartment of the ORNs in situ, and selectively applying the blocker to the transduction compartment reduces spontaneous activity in the ORN. Collectively, these results implicate for the first time a functional role for an I(h)-channel in olfactory signal transduction.
Gisselmann
Günter
G
Ruhr-Universität-Bochum, Lehrstuhl für Zellphysiologie, Universitätsstr.150, D-44780 Bochum, Germany. Guenter.Gisselmann@ruhr-uni-bochum.de
Marx
Thomas
T
Bobkov
Yuriy
Y
Wetzel
Christian H
CH
Neuhaus
Eva M
EM
Ache
Barry W
BW
Hatt
Hanns
H
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D003001:Cloning, Molecular / Q000187:drug effects / Q000379:methods; D054815:Cyclic Nucleotide-Gated Cation Channels; D004305:Dose-Response Relationship, Drug; D006801:Humans; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D007473:Ion Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008969:Molecular Sequence Data; D018034:Olfactory Receptor Neurons / Q000187:drug effects / Q000502:physiology*; D033521:Palinuridae / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D015221:Potassium Channels; D011743:Pyrimidines / Q000494:pharmacology
D054815:Cyclic Nucleotide-Gated Cation Channels; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D007473:Ion Channels; D015221:Potassium Channels; D011743:Pyrimidines; C082246:ICI D2788; D015124:8-Bromo Cyclic Adenosine Monophosphate