Regulation of Adenylyl Cyclase from Isolated Pancreatic Islets by Prostaglandins and Guanosine 5′-Triphosphate

David G. Johnson; W. Joseph Thompson; Robert H. Williams

doi:10.1021/bi00706a022

Regulation of Adenylyl Cyclase from Isolated Pancreatic Islets by Prostaglandins and Guanosine 5′-Triphosphate

David G. Johnson, W. Joseph Thompson, Robert H. Williams

Medicine

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Abstract

Adenylyl cyclase activity of homogenates or membrane preparations from isolated rat pancreatic islets was slightly activated by 10 μm prostaglandin E₁ (PGE₁) or GTP. However, when both PGE₁ and GTP were used in combination, adenylyl cyclase activity was increased twofold to a level that was 70% of that obtained with 10 mm sodium fluoride. In the presence of GTP (20 μm) PGE₁ stimulation was evident at 0.2 μm and maximal at 10 μm. Prostaglandins E₂, F₂, and A₁ (0.1 or 10 μm) had no effect on basal enzyme activity, but PGE₂ or PGA₁(10 μm) increased activity slightly in the presence of GTP (20 μm). Kinetic analysis indicated that PGE₁ plus GTP increased both the apparent Michaelis constant for ATP and the maximum velocity of adenylyl cyclase. Neither compound had any effect on the activity of cyclic nucleotide phosphodiesterase in pancreatic islet homogenates.

Original language	English (US)
Pages (from-to)	1920-1924
Number of pages	5
Journal	Biochemistry
Volume	13
Issue number	9
DOIs	https://doi.org/10.1021/bi00706a022
State	Published - Apr 1 1974

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Biochemistry

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title = "Regulation of Adenylyl Cyclase from Isolated Pancreatic Islets by Prostaglandins and Guanosine 5′-Triphosphate",

abstract = "Adenylyl cyclase activity of homogenates or membrane preparations from isolated rat pancreatic islets was slightly activated by 10 μm prostaglandin E1 (PGE1) or GTP. However, when both PGE1 and GTP were used in combination, adenylyl cyclase activity was increased twofold to a level that was 70% of that obtained with 10 mm sodium fluoride. In the presence of GTP (20 μm) PGE1 stimulation was evident at 0.2 μm and maximal at 10 μm. Prostaglandins E2, F2, and A1 (0.1 or 10 μm) had no effect on basal enzyme activity, but PGE2 or PGA1(10 μm) increased activity slightly in the presence of GTP (20 μm). Kinetic analysis indicated that PGE1 plus GTP increased both the apparent Michaelis constant for ATP and the maximum velocity of adenylyl cyclase. Neither compound had any effect on the activity of cyclic nucleotide phosphodiesterase in pancreatic islet homogenates.",

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T1 - Regulation of Adenylyl Cyclase from Isolated Pancreatic Islets by Prostaglandins and Guanosine 5′-Triphosphate

AU - Johnson, David G.

AU - Thompson, W. Joseph

AU - Williams, Robert H.

PY - 1974/4/1

Y1 - 1974/4/1

N2 - Adenylyl cyclase activity of homogenates or membrane preparations from isolated rat pancreatic islets was slightly activated by 10 μm prostaglandin E1 (PGE1) or GTP. However, when both PGE1 and GTP were used in combination, adenylyl cyclase activity was increased twofold to a level that was 70% of that obtained with 10 mm sodium fluoride. In the presence of GTP (20 μm) PGE1 stimulation was evident at 0.2 μm and maximal at 10 μm. Prostaglandins E2, F2, and A1 (0.1 or 10 μm) had no effect on basal enzyme activity, but PGE2 or PGA1(10 μm) increased activity slightly in the presence of GTP (20 μm). Kinetic analysis indicated that PGE1 plus GTP increased both the apparent Michaelis constant for ATP and the maximum velocity of adenylyl cyclase. Neither compound had any effect on the activity of cyclic nucleotide phosphodiesterase in pancreatic islet homogenates.

AB - Adenylyl cyclase activity of homogenates or membrane preparations from isolated rat pancreatic islets was slightly activated by 10 μm prostaglandin E1 (PGE1) or GTP. However, when both PGE1 and GTP were used in combination, adenylyl cyclase activity was increased twofold to a level that was 70% of that obtained with 10 mm sodium fluoride. In the presence of GTP (20 μm) PGE1 stimulation was evident at 0.2 μm and maximal at 10 μm. Prostaglandins E2, F2, and A1 (0.1 or 10 μm) had no effect on basal enzyme activity, but PGE2 or PGA1(10 μm) increased activity slightly in the presence of GTP (20 μm). Kinetic analysis indicated that PGE1 plus GTP increased both the apparent Michaelis constant for ATP and the maximum velocity of adenylyl cyclase. Neither compound had any effect on the activity of cyclic nucleotide phosphodiesterase in pancreatic islet homogenates.

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Regulation of Adenylyl Cyclase from Isolated Pancreatic Islets by Prostaglandins and Guanosine 5′-Triphosphate

Abstract

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