1 Physiology Institute, Hohenheim University, Garbenstrasse 30, 70395 Stuttgart, Germany.
2 INRA, Unité de Recherche Santé Végétale, 33883 Villenave d'Ornon, France.
3 Department of Medicinal Chemistry, University of Utah, Salt Lake City, UT 84112, USA.
Pheromone sensing in insects starts when pheromone molecules enter the sensillar hair and have to be transported to the neuronal membrane receptors. The sensory neurons are surrounded by an aqueous lymph which constitutes a hydrophilic barrier for hydrophobic pheromones. Soluble acidic low molecular weight proteins (OBPs) are believed to mediate the specific transport of hydrophobic pheromones at the periphery of chemosensing neurons within the sensillar lymph. In moths, a particular class of proteins, the Pheromone Binding Proteins (PBPs) may retain the specific function of pheromone sensing. In species using multicomponent pheromone, two PBPs have been cloned and checked for binding labeled pheromone analogs in presence or not of native pheromone. We discuss the funtion of PBPs as specific filters of pheromone molecules and the structures important for pheromone-PBP interactions. In addition, we will describe a novel family of putative chemosensory proteins, structurally distinct of PBPs, characterized by a higher diversity and more general tissue-distribution among phylogenetically distinct insects.