Molecular bases of insect odorant receptor function: specificity and evolution

Insect odorant receptors (ORs) are a class of chemoreceptors that insects use to detect volatile cues in their environment. In recent years, major advances in the field of structural biology have made it possible to obtain the first structures of insect ORs. In this review, we place molecular evidence of OR function into the context of their three-dimensional structure, focusing on both tuning ORs and their co-receptor, Orco, as well as their interaction. We also used AlphaFold2 to model the structures of several deorphanized receptors and mapped the experimentally identified residues important for function, revealing putative functional hotspots. We discuss several efficient methods for functional evolution studies and propose emerging technologies that may open avenues for further research and innovation.