DISSECTION OF THE CAMP-INDUCED CYTOSOLIC CALCIUM RESPONSE IN DICTYOSTELIUM-DISCOIDEUM - THE ROLE OF CAMP RECEPTOR SUBTYPES AND G-PROTEIN SUBUNITS

The cAMP signaling cascade leading to changes in [Ca2+](i) in Dictyost elium discoideum was analyzed using cell lines overexpressing single c AMP receptor subtypes (cAR1-cAR3) or lacking the G(alpha 2) or G(beta) Subunit of the G protein. Imaging of fura2-destran-loaded amoebae rev ealed cAMP-induced [Ca2+](i) changes characteristic for each receptor subtype activated. Cells expressing distinct subtypes sort to defined zones during multicellular development suggesting involvement of the s pecific [Ca2+](i) transients in patterning processes. Whereas generati on of the [Ca2+](i) increase was G(alpha 2)-independent, only few cell s devoid of Gp displayed a [Ca2+](i) change after stimulation indicati ng its participation in the regulation of the calcium homeostasis. (C) 1998 Federation of European Biochemical Societies.