Visions & Reflections On the ORigin of smell: odorant receptors in insects

Olfaction, the sense of smell, depends on large, divergent families of odorant receptors that detect odour stimuli in the nose and transform them into patterns of neu- ronal activity that are recognised in the brain. The olfactory circuits in mammals and insects display striking similarities in their sensory physiology and neuroanatomy, which has suggested that odours are perceived by a conserved mecha- nism. Here I review recent revelations of significant struc- tural and functional differences between the Drosophila and mammalian odorant receptor proteins and discuss the implications for our understanding of the evolutionary and molecular biology of the insect odorant receptors.