Signal Transduction in Dictyostelium fgd A Mutants with a Defective Interaction between Surface cAMP Receptors and a GTP-binding Regulatory Protein

Fanja Kesbeke, B. Ewa Snaar-Jagalska, Peter J. M. van Haastert

Research output: Contribution to journalArticleAcademic

74 Citations (Scopus)
203 Downloads (Pure)


Transmembrane signal transduction was investigated in four Dictyostelium discoideum mutants that belong to the fgd A complementation group. The results show the following. (a) Cell surface cAMP receptors are present in fgd A mutants, but cAMP does not induce any of the intracellular responses, including the activation of adenylate or guanylate cyclase and chemotaxis. (b) cAMP induces down-regulation and the covalent modification (presumably phosphorylation) of the cAMP receptor. (c) The inhibitory effects of GTPγS and GDPβS on cAMP binding are reduced; the stimulatory effect of cAMP on GTPγS binding is lost in fgd A mutants. (d) Basal high-affinity GTPase activity is reduced 40% and the stimulatory effect of cAMP is decreased from 40% in wild type to 30% in fgd A. (e) GTP-mediated stimulation and inhibition of adenylate cyclase is normal in mutant membranes. The results suggest a defective interaction between cell surface cAMP receptors and a specific G-protein in fgd A mutants. This interaction appears to be essential for nearly all signal transduction pathways in Dictyostelium discoideum.
Original languageEnglish
Number of pages8
JournalThe Journal of Cell Biology
Issue number2
Publication statusPublished - 1988

Cite this