Max-Planck Institut für Verhaltensphysiologie, 82319-Seewiesen, Germany.
How a chemical stimulus is transduced into electrical information propagated to the brain is one of the open question in insect olfaction. Following the identification of the alpha-subunit of a G-protein belonging to the Gq/11 family (Laue et al., Cell Tissue Research, 288, 149-158, 1997) here we report about the identification of the second-messenger producing enzyme Phospholipase C (PLCbeta) and of a Protein Kinase C (PKC) in isolated sensilla trichodea of Antheraea polyphemus, containing the outer dendrites of pheromone receptor neurons. Western blots with homogenates of isolated hairs revealed a 110 kDa protein recognized by an antiserum raised against the Drosophila PLCbeta pl21. No immunoreactive bands were found with anti-PLCgamma or with anti-PLCdelta 1 antisera. To identify PKC we performed Western blots with different antisera generated against synthetic peptides mimicking different conserved regions of PKCs. Only one of these antisera, raised against a synthetic peptide mimicking the C-terminal of vertebrate PKC and called PKCconsensus, was immunoreactive with a protein with an apparent molecular weight of 80 kDa. Incubation of homogenized isolated pheromone-sensitive hairs with the main sex pheromone component, (E,Z)6-11 hexadecadienyl acetate, resulted in a 6-fold increase in the activity of a DAG-dependent PKC compared to controls without pheromone. In contrast, incubation with pheromone did not affect the activity of cAMP-dependent PKA.These data provide evidence that the highly sensitive pheromone perception of moths is mediated by the IP3 transduction pathway.