A Temperature-Sensitive Change in the Energy of Activation of Hormone-Stimulated Hepatic Adenylyl Cyclase
- 1 June 1973
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 70 (6), 1785-1789
- https://doi.org/10.1073/pnas.70.6.1785
Abstract
We describe an abrupt increase (at 32 degrees ) in the energy of activation for the reaction of hepatic adenylyl cyclase in the presence of glucagon or epinephrine. This increase is not seen in the presence of fluoride, prostaglandin E(1), or 1-propanol, or in the absence of cyclase stimulators. The change in energy of activation found with hormones is abolished by 1-propanol. This change does not represent differences in hormone or substrate binding at different temperatures, but seems to reflect interactions among elements of the cyclase stimulation sequence. Similar changes in energy of activation were not observed for alkaline phosphatase, cyclic AMP-phosphodiesterase, 5'-nucleotidase, or ouabain-sensitive ATPase. Since the mole fraction of cholesterol in liver membranes is sufficiently high to preclude a phase change in bulk membrane lipids, our observation suggests either that cyclase is restricted to cholesterol-poor membrane regions or that the change in its energy of activation is largely restricted to protein components of the cyclase apparatus. The data are compatible with fundamental differences in the stimulation process(es) for the hormones (glucagon and epinephrine) as compared with those for fluoride and prostaglandin E(1).Keywords
This publication has 33 references indexed in Scilit:
- Digitonin Effects on Photoreceptor Adenylate CyclaseScience, 1972
- Selectively Blocked and Des-Histidine-Glucagons: Preparation and Effects on Hepatic Adenylate Cyclase ActivityEndocrinology, 1972
- The Effect of Phospholipid Fatty Acid Composition on Membranous Enzymes in Escherichia coliJournal of Biological Chemistry, 1972
- SOLUBILIZATION OF MYOCARDIAL ADENYL CYCLASE: LOSS OF HORMONE RESPONSIVENESS AND ACTIVATION BY PHOSPHOLIPIDS*Annals of the New York Academy of Sciences, 1971
- A Specific, Reversible, Macromolecular Inhibitor of Hepatic Glucagon Responsive Adenyl CyclaseEndocrinology, 1971
- Adenyl cyclase in hepatic parenchymal and reticuloendothelial cellsBiochemical and Biophysical Research Communications, 1971
- Adenyl cyclase. Kinetic properties and nature of fluoride and hormone stimulation.1971
- Characterization of adenyl cyclase from the testis of chinook salmonBiochemistry, 1971
- Adenyl cyclase of rat cerebral cortex. Activation of sodium fluoride and detergents.1971
- Effects of Calcium on ACTH Stimulation of the Adrenal: Separation of Hormone Binding from Adenyl Cyclase ActivationNature, 1970