ACTIVATION OF PROTEIN-KINASE A-INDEPENDENT PATHWAYS BY GS-ALPHA IN DROSOPHILA

One of the best-described transmembrane signal transduction mechanisms is based on receptor activation of the alpha subunit of the heterotri meric G protein G(s), leading to stimulation of adenylyl cyclase and t he production of cAMP. Intracellular cAMP is then thought to mediate i ts effects largely, if not entirely, by activation of protein kinase A and the subsequent phosphorylation of substrates which in turn contro l diverse cellular phenomena, In this report we demonstrate, by two di fferent methods, that reduction or elimination of protein kinase A act ivity had no effect on phenotypes generated by activation of G(s) alph a pathways in Drosophila wing epithelial cells, These genetic studies show that the G(s) alpha pathway mediates its primary effects by a nov el pathway in differentiating wing epithelial cells. This novel pathwa y may in part be responsible for some of the complex, cell-specific re sponses observed following activation of this pathway in different cel l types.