Mammals rely heavily on olfaction to interact adequately with each other and with their environment. They make use of seven-transmembrane G-protein-coupled receptors to identify odorants and pheromones. These receptors are present on dendrites of olfactory sensory neurons located in the main olfactory or vomeronasal sensory epithelia, and pertain to the odorant, trace amine-associated receptor and vomeronasal type 1 (ref. 4) or 2 (refs 5-7) receptor superfamilies. Whether these four sensor classes represent the complete olfactory molecular repertoire used by mammals to make sense of the outside world is unknown. Here we report the expression of formyl peptide receptor-related genes by vomeronasal sensory neurons, in multiple mammalian species. Similar to the four known olfactory receptor gene classes, these genes encode seven-transmembrane proteins, and are characterized by monogenic transcription and a punctate expression pattern in the sensory neuroepithelium. In vitro expression of mouse formyl peptide receptor-like 1, 3, 4, 6 and 7 provides sensitivity to disease/inflammation-related ligands. Establishing an in situ approach that combines whole-mount vomeronasal preparations with dendritic calcium imaging in the intact neuroepithelium, we show neuronal responses to the same molecules, which therefore represent a new class of vomeronasal agonists. Taken together, these results suggest that formyl peptide receptor-like proteins have an olfactory function associated with the identification of pathogens, or of pathogenic states.

Pheromone-binding proteins (PBPs) are small helical proteins found in sensorial organs, particularly in the antennae, of moth and other insect species. They were proposed to solubilize and carry the hydrophobic pheromonal compounds through the antennal lymph to receptors, participating thus in the peri-receptor events of signal transduction. The x-ray structure of Bombyx mori PBP (BmorPBP), from male antennae, revealed a sixhelix fold forming a cavity that contains the pheromone bombykol. We have identified a PBP (LmaPBP) from the cockroach Leucophaea maderae in the antennae of the females, the gender attracted by pheromones in this species. Here we report the crystal structure of LmaPBP alone or in complex with a fluorescent reporter (aminonaphthalen sulfonate, ANS) or with a component of the pheromonal blend, 3-hydroxy-butan-2-one. Both compounds bind in the internal cavity of LmaPBP, which is more hydrophilic than BmorPBP cavity. LmaPBP structure ends just after the sixth helix (helix F). BmorPBP structure extends beyond the sixth helix with a stretch of residues elongated at neutral pH and folding as a seventh internalized helix at low pH. These differences between LmaPBP and BmorPBP structures suggest that different binding and release mechanism may be adapted to the hydrophilicity or hydrophobicity of the pheromonal ligand.The sexual behavior of insects, and in particular the mate choice, is triggered by small volatile molecules called pheromones. In Lepidoptera, more than in other insect species, olfaction is preeminent compared with other senses. This feature has led to the development of large antennae, which allow the males to perceive the sexual pheromone blend emitted by females and to respond to it (1). In this family of insects, pheromone-binding proteins (PBPs) 1 produced in males antennae and secreted in the antennal lymph have been proposed to accommodate pheromones and ferry them from the air/antenna interface to their receptors. PBPs are acidic proteins containing an average of 120 -150 amino acids with 6 conserved cysteines involved in three disulfide bridges (1-3). The crystal structure of a PBP from Bombyx mori (BmorPBP) has been solved in complex with bombykol (4), unique until now of this class of proteins. In addition, the structure of a functionally related chemosensory protein (CSP) has been reported recently (5, 6). BmorPBP three-dimensional structure revealed a six ␣-helices fold, which delineates a buried cavity containing the hydrophobic pheromone, bombykol, a C16 long chain alkene alcohol. Two three-dimensional structures of the apoprotein were further solved by NMR (7,8). The one at low pH (pH 4.5) revealed that the C terminus (residues 125-137) has switched from an elongated stretch conformation to an ␣-helix. Amazingly, this seventh helix occupies the internal cavity filled with bombykol in the structure of the complex (7). In contrast, the other apoform, solved at neutral pH, exhibits a three-dimensional structure close to that observed by x-ray diffraction in the complex, c...

Single-pass sequences were obtained from the 5P P-ends of a total of 1794 rose petal cDNA clones. Cluster analysis identified 242 groups of sequences and 635 singletons indicating that the database represents a total of 877 genes. Putative functions could be assigned to 1151 of the transcripts. Expression analysis indicated that transcripts of several of the genes identified accumulated specifically in petals and stamens. The cDNA library and expressed sequence tag database described here represent a valuable resource for future research aimed at improving economically important rose characteristics such as flower form, longevity and scent. ß