title: Natural ligands of porcine olfactory binding proteins.
abstract: Knowledge of endogenous ligands of olfactory binding proteins is a prerequisite for studying their role in odor and pheromone transduction. Here, we report the extraction, derivatization, and characterization by gas chromatography-mass spectrometry of the natural ligands of pig, Sus scrofa (L.), Von Ebner's Gland protein (VEG) and odorant binding protein (OBP). We identified two isoforms (VEG1 and VEG2), which differed only by the linkage of an O-N-acetylglucosamine (O-GlcNac) group on VEG1. The natural ligands of VEG1 were characterized as two isomers of testosterone, whereas ligands of VEG2 and OBP were fatty acids or their derivatives. Our findings suggest that the binding specificity of VEG1 for steroids is governed by the presence of an O-GlcNac moiety on the protein. This specificity was confirmed by the binding of radiolabeled testosterone only by VEG1 in an in-gel binding assay. This is the first evidence for a post-translational modification in the process of odorant discrimination by olfactory binding proteins.
authors.affiliation: INRA, UMR 8576 CNRS/Université Lille1, Unité de Glycobiologie Structurale et Fonctionnelle, 59655, Villeneuve d'Ascq Cedex, France.
authors.forename: Chrystelle
authors.initials: C
authors.lastname: Le Danvic
authors.forename: Gaelle
authors.initials: G
authors.lastname: Guiraudie-Capraz
authors.forename: Djamel
authors.initials: D
authors.lastname: Abderrahmani
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Zanetta
authors.forename: Patricia
authors.initials: P
authors.lastname: Nagnan-Le Meillour
mesh_terms: D000117:Acetylglucosamine / Q000737:chemistry; D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry; D008024:Ligands; D054835:Lipocalin 1 / Q000737:chemistry*; D019308:Palmitic Acid / Q000737:chemistry; D020033:Protein Isoforms / Q000737:chemistry; D018035:Receptors, Odorant / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D034421:Sus scrofa; D013739:Testosterone / Q000494:pharmacology
chemical_list: D008024:Ligands; D054835:Lipocalin 1; D020033:Protein Isoforms; D018035:Receptors, Odorant; C045648:odorant-binding protein; D019308:Palmitic Acid; D013739:Testosterone; D000117:Acetylglucosamine