9.B.432.  The Odorant Binding Protein (OBP) Family 

The proteins of this family are usually of ~140 aas or larger (up to ~300 aas) and have an N-terminal TMS and possibly one of two more failly hydrophilic TMSs nearer the C-terminus of the proteins.  These proteins bind ordorant molecules and serve as receptors, allowing a response to the odorant (Rihani et al. 2021).  The survival of insects depends on their ability to detect molecules present in their environment. Odorant-binding proteins (OBPs) form a family of proteins involved in chemoreception. While OBPs were initially found in olfactory appendages, these proteins have been discovered in other chemosensory and non-chemosensory organs. OBPs can bind, solubilize and transport hydrophobic stimuli to chemoreceptors across the aqueous sensilla lymph. In addition to this broadly accepted 'transporter role', OBPs can buffer sudden changes in odorant levels and are involved in hygro-reception. The physiological roles of OBPs expressed in other body tissues, such as mouthparts, pheromone glands, reproductive organs, digestive tract and venom glands, remain to be investigated. A review by Rihani et al. 2021 provides a panorama on the varied structural aspects, binding properties, tissue expression and functional roles of insect OBPs.

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