Soluble carrier proteins: from chemical communication to developmental biology and artificial sensing

The discovery of odorant-binding proteins (OBPs) at the early nineteen eighties raised a lot of interest being the first biochemical components of the olfactory system to be experimentally studied. About 10 years later, the identification of odorant receptors attracted the attention of scientists, leaving OBPs in the background. A generally accepted role as carriers for odorants and pheromones reduced the interest in these soluble proteins, regarded as accessory elements in the process of olfactory transduction. More recently, however, OBPs have received new attention based on (i) the recognition that some proteins of this family can act directly as nonvolatile pheromones, (ii) the possibility of investigating the structures of pheromones in species extinct or difficult to approach adopting the method of reverse chemical ecology, and (iii) the suitability of OBPs and their artificial mutants as sensing elements in electronic olfaction, as well as in other biotechnological applications. In this review, after summarizing the main structural and functional aspects of OBPs and other soluble carrier proteins both in mammals and in arthropods, we focus on their most recent uses and their potential developments.