PHEROMONE BINDING-PROTEINS OF THE MOTH MAMESTRA-BRASSICAE - SPECIFICITY OF LIGAND-BINDING

Several isoforms of pheromone-binding proteins (PBP) and general odora nt-binding proteins (GOBP) were previously characterized in the antenn ae of the cabbage armyworm Mamestra brassicae L. (Lepidoptera: Noctuid ae), In further investigations, we used two-dimensional electrophoresi s and Western-blotting with antibodies raised against the PBPs of the male: this method revealed more proteins,vith molecular weight and iso electric points similar to those of OBPs and confirmed the high level of microdiversity suspected for this family of proteins, The binding o f the tritiated major pheromone compound, Z11-16:Ac, with male and fem ale antennal extracts and purified PBPs from male antennae was studied , Only the two isoforms Mbra-1 and Mbra-1' (N-terminus: SKELI) bound t he labelled pheromone, whereas no binding was observed with the Mbra-2 (N-terminus: SQEIM), In female antennal extracts, binding was shown b etween Z11-16:Ac and the proteins Mbra-1 and GOBP2, These results cons titute an unambiguous demonstration of the binding specificity of a PB P to a pheromonal ligand, supporting the hypothesis of active particip ation of PBPs in odor discrimination, as a filter for odorants, prior to the receptor activation. (C) 1997 Elsevier Science Ltd.