Drosophila odorant receptors are both ligand-gated and cyclic-nucleotide-activated cation channels

摘要: In many organisms, from worms to humans, olfactory cues are detected by large families of seven transmembrane-spanning receptors, which have until now been classified as G protein-coupled receptors. Insects, however, evolved a surprisingly simple and efficient sense smell in the odorant receptors require second component — ion-channel-forming chaperone protein Or83b for correct function. first two related papers, Sato et al. show that these heteromeric form ligand-gated cation channels not dependent on messengers, speculate other proteins may similar ion channel activity. Wicher that, addition direct activation, ligand binding causes activation. This work has implications search insect receptor inhibitors possible use controlling host seeking behaviour disease carrying insects such mosquito. Olfactory G-protein-coupled insects, (Or83b) The papers shows From worm man, signals perceived volatile ligands receptors1 belong (GPCR) family2. They couple heterotrimeric G-proteins, most induce cAMP production3. messenger then activates cyclic-nucleotide-gated depolarize neuron, thus providing signal further neuronal processing. Recent findings, challenged this concept transduction because their lack any sequence similarity GPCRs4, composed conventional (for example, Or22a), dimerized with ubiquitously expressed protein5, Drosophila6. structure akin GPCRs, but an inverted orientation plasma membrane4,7. However, neurons8, perception is modified mutations affecting pathway9. Here we application odorants mammalian cells co-expressing Or22a results non-selective currents activated means ionotropic metabotropic pathway, subsequent increase intracellular Ca2+ concentration. Expression alone leads functional directly responding odorants, being or cGMP. Insect well complexes odorant-sensing units cyclic-nucleotide-activated channels. Thereby, they provide rapid transient sensitive prolonged signalling.