DISTRIBUTION OF 2 GABA RECEPTOR-LIKE SUBUNITS IN THE DROSOPHILA CNS

Previously we have described the distribution of the Rdl GABA receptor subunit in the Drosophila CNS. Knowing that Rdl can coassemble with L CCH3 (a Drosophila GABA receptor-like subunit showing sequence similar ity to vertebrate beta subunit GABA(A) receptors) in baculovirus infec ted insect cells, we compared the localization of these two receptor s ubunits in order to identify any potential overlap in their spatial or temporal distribution. The two subunits show very different patterns of localization. Early in development LCCH3 is found in the majority o f developing neuroblasts and later is localized to the cell bodies of the embryonic nerve cord and brain, and the neuronal cell bodies surro unding the adult brain. In contrast, Rdl receptor subunits appear conf ined to the neuropil in all developmental stages. These results have t wo important implications. Firstly, they suggest that although these t wo subunits can coassemble in heterologous expression systems, they ma y not be found in the same tissues in the nervous system. Secondly, pr oduction of LCCH3 before neuronal differentiation leads us to speculat e on the role of that LCCH3 containing receptors in the developing ner vous system.