Regulation of guanylate cyclase by a guanine nucleotide binding protein, G alpha 2, in Dictyostelium discoideum.
Binding of cyclic AMP (cAMP) to the cell surface receptor induces a transient activation of guanylate cyclase in Dictyostelium discoideum. A frigid mutant (HC85) which lacks G alpha 2, a guanine nucleotide binding protein, does not respond to cAMP. We found that 2,3-dimercapto-1-propanol (BAL) induced a continuous activation both in the frigid and in its parents. Therefore, the BAL-induced continuous activation of guanylate cyclase is independent of G alpha 2. We also found that cAMP enhanced the BAL-induced continuous activation in the frigid mutant. This result suggests that an unidentified signal transduction mechanism from the cAMP-receptor besides the one involving G alpha 2 plays a role in the enhancement of activation. Lastly, we found that the BAL-induced continuous activation was terminated by cAMP in the parental strain, but not in the frigid mutant. Therefore, the cAMP-induced suppression on the BAL-induced continuous activation is mediated through G alpha 2.
Department of Botany, Faculty of Science, Kyoto University, Japan.
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M
Oyama
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Kubota
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K
Okamoto
D003080:Cold Temperature; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology; D004023:Dictyostelium / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D004112:Dimercaprol / Q000494:pharmacology; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006162:Guanylate Cyclase / Q000378:metabolism*; D007700:Kinetics; D009154:Mutation
D004112:Dimercaprol; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; D006162:Guanylate Cyclase