Glucagon-(19-29) exerts a biphasic action on the liver plasma membrane Ca2+ pump which is mediated by G proteins
| Autor: | B. Roche, Françoise Pecker, Catherine Pavoine, M. Dufour, Sophie Lotersztajn, Dominique Bataille, Dung Le-Nguyen, V. Brechler |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
medicine.medical_specialty
Cholera Toxin GTP' G protein Guanosine Diaphragm pump Calcium-Transporting ATPases Biology medicine.disease_cause Pertussis toxin Biochemistry Glucagon chemistry.chemical_compound GTP-Binding Proteins Internal medicine medicine Animals Magnesium Virulence Factors Bordetella Molecular Biology Guanosine 5'-O-(3-Thiotriphosphate) Cholera toxin Cell Membrane Rats Inbred Strains Cell Biology Thionucleotides Peptide Fragments Rats Kinetics Endocrinology chemistry Liver Pertussis Toxin Biophysics Adenylate Cyclase Toxin Sodium Fluoride Calcium Female Guanosine Triphosphate Adenylyl Cyclases |
| Zdroj: | The Journal of biological chemistry. 265(17) |
| ISSN: | 0021-9258 |
| Popis: | We have recently shown that nanomolar concentrations of glucagon-(19-29), which can derive from native glucagon by proteolytic cleavage of the dibasic doublet Arg17-Arg18, inhibit the Ca2+ pump in liver plasma membrane vesicles independently of adenylyl cyclase activation (Mallat, A., Pavoine, C., Dufour, M., Lotersztajn, S., Bataille, D., and Pecker, F. (1987) Nature 325, 620-622). We report here that the regulation of the Ca2+ pump by glucagon-(19-29) is dependent on guanine nucleotides. In the presence of 10 microM guanosine 5'-3-O-(thio) triphosphate (GTP gamma S) or 75 microM GTP, glucagon-(19-29) caused a biphasic regulation of the Ca2+ pump. ATP-dependent Ca2+ transport was inhibited in the presence of 10 pM to 1 nM glucagon-(19-29), while higher concentrations of the peptide (1-100 nM) reversed the inhibition caused by lower ones. GTP gamma S alone, at high concentrations (100 microM), reproduced the inhibitory effect of glucagon-(19-29) and induced a 40% inhibition of the basal activity of the Ca2+ pump which was reversed by low concentrations of glucagon-(19-29) (10 pM to 1 nM). Treatment of rats with cholera toxin resulted in a 70% increase in the basal activity of the Ca2+ pump, a loss of sensitivity to GTP gamma S and to the biphasic regulation by glucagon-(19-29). Treatment with pertussis toxin did not affect the response of the Ca2+ pump to GTP gamma S and glucagon-(19-29). We conclude that glucagon-(19-29) can exert a biphasic effect on the Ca2+ pump which is mediated by G protein(s) sensitive to cholera toxin. |
| Databáze: | OpenAIRE |
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