When an external stimulus molecule such as a taste or odor (the ligand) enters a chemosensory bristle through a pore on the bristle.s surface, it is bound by a protein. Examples of these proteins are odorant binding proteins (OBPs) or sensory appendage proteins (SAPs). The resulting chemosensory protein-ligand molecule complex then binds chmeosensory receptors (ORs, sometimes referred to as serpentine receptors or G-protein coupled receptors [GPCRs]) on the surface of neuronal cells, initiating a cascade of molecular events that result in the insect recognizing and responding to the odor. Finally, odorant degrading enzymes (ODEs) secreted by the helper cells degrade the odor molecule and re-arm the system. Note that this diagram is greatly simplified for illustrative purposes, and that in fact the proteins in the haemolymph as well as the odorant receptors can interact with one another or with other insect proteins to form multimers.
> Read more > Learn more