Identification of a Drosophila G protein α subunit (dG_qα-3) expressed in chemosensory cells and central neurons

We have identified another Drosophila GTP-binding protein (G protein) α subunit, dG_qα-3. Transcripts encoding dG_qα-3 are derived from alternative splicing of the dGqα locus previously shown to encode two visual-system-specific transcripts [Lee, Y.-J., Dobbs, M.B., Verardi, M.L. & Hyde, D.R. (1990) Neuron 5, 889-898]. Immunolocalization studies using dG_qα-3 isoform-specific antibodies and LacZ fusion genes show that dG_qα-3 is expressed in chemosensory cells of the olfactory and taste structures, including a subset of olfactory and gustatory neurons, and in cells of the central nervous system, including neurons in the lamina ganglionaris. These data are consistent with a variety of roles for dG_qα-3, including mediating a subset of olfactory and gustatory responses in Drosophila, and supports the idea that some chemosensory responses use G protein-coupled receptors and the second messenger inositol 1,4,5-trisphosphate.