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Insect olfactory receptor complex functions as a ligand-gated ionotropic channel
1Department of Integrated Biosciences, The University of Tokyo, Chiba, Japan. touhara@k.u-tokyo.ac.jp
Annals of the New York Academy of Sciences
|August 19, 2009
Summary
Insect olfactory receptors (ORs) form novel ligand-activated cation channels, distinct from vertebrate mechanisms. This finding reveals a unique insect strategy for detecting odors and pheromones.
Area of Science:
- Molecular Biology
- Neuroscience
- Biochemistry
Background:
- Insect olfaction relies on olfactory receptors (ORs) and a co-receptor (Or83b) forming heteromeric complexes.
- The precise function and signaling pathway of these OR complexes remain incompletely understood.
Purpose of the Study:
- To investigate the functional properties of heteromeric insect OR complexes.
- To elucidate the ion channel activity and signaling mechanism of insect ORs upon odorant stimulation.
Main Methods:
- Heterologous expression of insect OR complexes (silk moth, fruit fly, mosquito) in cell lines.
- Measurement of ion flux and conductance using calcium imaging and patch-clamp electrophysiology.
- Assessment of G protein involvement in OR-mediated signaling.
Main Results:
- Heteromeric insect ORs function as ligand-activated, nonselective cation channels.
- Odorant or pheromone stimulation induced cation influx and conductance in expressing cells.
- G protein-mediated signaling was found to be negligible in this process.
- Single-channel recordings confirmed direct ligand-gated channel activity.
Conclusions:
- Insect ORs represent a novel class of ligand-gated ion channels.
- Insect olfactory transduction is distinct from vertebrate mechanisms.
- This ion channel activity is a unique insect adaptation for olfactory sensing.
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