In order to uncover the role of G proteins in the integrative functioning and development of the nervous system, we have begun a multidisciplinary study of the G proteins present in the fruit fly, Drosophila melanogaster. In this report, we describe the distribution of 3 different G protein α-subunits in the adult Drosophila CNS as determined by immunocytochemical localization using affinity-purified antibodies generated to synthetic oligopeptide sequences unique to each α-subunit. Western blot analysis of membranes prepared from Drosophila heads indicates that antibodies specific for the Drosophila Goα and Gsα homologs recognize the appropriate protein species predicted by molecular cloning (Quan et al., 1989; Thambi et al., 1989). The Giα homolog could not be detected in head membranes by Western blotting, consistent with the negligible levels of expression observed for Giα on Northern blots of head mRNA (Provost et al., 1988). However, a Drosophila Giα fusion protein could be detected by these antibodies following expression in E. coli. Immunolocalization studies revealed that the Goα and Gsα homologs are expressed at highest levels in neuropils and at intermediate levels in the cortex of all brain and thoracic ganglion areas. Only the lamina contained low levels of these α-subunits in the CNS. Additionally, Gsα appears to be associated with the cell membranes of neuronal cell bodies, while Goα has a more diffuse distribution, suggesting its presence in the cytoplasm as well as cell membranes. In contrast to the wide distribution of Goα and Gsα, Giα has a surprisingly restricted distribution in the CNS. It is present at high levels only in photoreceptor cell terminations, glomerulae of the antennal lobes, and the ocellar retina. Little or no Giα was detected in other brain regions or in the thoracic ganglion. Giα, then, appears to be uniquely associated with some primary sensory afferents and r terminations, suggesting the presence of specific receptor and/or effector systems which mediate the transmission of primary sensory information in Drosophila.
|Original language||English (US)|
|Number of pages||11|
|Journal||Journal of Neuroscience|
|State||Published - 1990|
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