Role of a guanine nucleotide binding protein, G alpha 2, in regulation of adenylate cyclase in Dictyostelium discoideum.
Two substances, cAMP and 2,3-dimercapto-1-propanol (BAL) are known to induce transient activation of adenylate cyclase in Dictyostelium discoideum. A frigid mutant (HC85) has a deletion in a gene for G alpha 2, a guanine nucleotide binding protein and cannot activate the cyclase in response to cAMP. We found that BAL induced activation in the frigid mutant. This result suggests that the BAL-induced activation is independent of G alpha 2 and that BAL mimics a role of activated G alpha 2. We also found that cAMP promoted the BAL-induced activation. This result suggests that cAMP plays a role in activation through a mechanism in which G alpha 2 is not involved. We lastly showed that continuous cAMP stimulation could not inhibit the BAL-induced activation in the frigid mutant. Since the cAMP-induced inhibition observed in the wild type strain (NC4) proceeds with the time course identical to the cAMP-induced adaptation (Oyama, submitted), this result suggests that G alpha 2 is involved in adaptation of adenylate cyclase.
Oyama
M
M
Department of Botany, Faculty of Science, Kyoto University, Japan.
Kubota
K
K
Okamoto
K
K
D000262:Adenylyl Cyclases / Q000378:metabolism*; D002872:Chromosome Deletion; D004023:Dictyostelium / Q000201:enzymology* / Q000235:genetics; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005800:Genes, Fungal; D007700:Kinetics; D008954:Models, Biological
D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases