Reply to: “Direct actions of GLP-1 analogues on AMP-activated protein kinase activity are distinct from cyclic AMP accumulation”

Purified zymogen granules were prepared from rat pancreas by using an iso-osmotic Percoll gradient. In the presence of [gamma-32P]ATP, phosphorylation of several granule proteins was induced by Ca2+, most notably a Mr-13 000 protein, whereas addition of cyclic AMP was without effect. When phosphatidylserine was also added, Ca2+ increased the phosphorylation of additional proteins, with the largest effect on a protein of Mr 62 000. Purified granules were also able to phosphorylate exogenous substrates. Ca2+-induced phosphorylation of lysine-rich histone was enhanced over 3-fold in the presence of phosphatidylserine, and cyclic AMP-activated protein kinase activity was revealed with mixed histone as substrate. The concentrations of free Ca2+ and cyclic AMP required for half-maximal phosphorylation of both endogenous and exogenous proteins were 1-3 microM and 57 nM respectively. Treatment of granules with 0.25 M-KCl resulted in the release of phosphatidylserine-dependent kinase activity into a high-speed granule supernatant. In contrast, granule-protein substrates of Ca2+-activated kinase activity were resistant to KCl extraction, and in fact were present in purified granule membranes. Kinase activity activated by cyclic AMP was not extracted by KCl treatment. It is concluded that phosphorylation of integral membrane proteins in the zymogen granule can be induced by one or more Ca2+-activated protein kinases. Such a reaction is a potential mechanism by which exocytosis may be regulated in the exocrine pancreas by Ca2+-mediated secretagogues.

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Evidence for Ecto-Protein Kinase Activity That Phosphorylates Kemptide in a Cyclic AMP-dependent Mode

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)71713-4 ◽

1989 ◽

Vol 264 (24) ◽

pp. 14549-14555 ◽

Cited By ~ 1

Author(s):

D Kübler ◽

W Pyerin ◽

O Bill ◽

A Hotz ◽

J Sonka ◽

...

Keyword(s):

Protein Kinase ◽

Cyclic Amp ◽

Kinase Activity ◽

Protein Kinase Activity

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Regulation of protein kinase by vasopressin in renal medulla in situ

AJP Renal Physiology ◽

10.1152/ajprenal.1977.232.1.f50 ◽

1977 ◽

Vol 232 (1) ◽

pp. F50-F57

Author(s):

T. P. Dousa ◽

L. D. Barnes

Keyword(s):

Protein Kinase ◽

Cyclic Amp ◽

Kinase Activity ◽

Kinase Inhibitor ◽

Renal Medulla ◽

Protein Kinase Activity ◽

Kinase Activation ◽

Heat Stable ◽

Protein Kinase Activation ◽

Heat Stable Protein

Results of this study demonstrate that vasopressin activates protein kinase in intact renal medullary cells as detected by measurement of the (-cyclic AMP/+cyclic AMP) protein kinase activity ratios in freshly prepared tissue extracts (40,000 X g supernates) from bovine renal medullary slices. The activation of protein kinase was specific for vasopressin since parathyroid hormone, histamine, angiotensin II, or the inactive analog of vasopressin did not activate protein kinase. There was a direct correlation between the extent of protein kinase activation and the elevation in tissue levels of cyclic AMP elicited by increasing doses of vasopressin or with an increase in incubation time. The elevation of tissue cyclic AMP level and maximum activation of protein kinase reached maximum level at a vasopressin concentration of about 2 X 10(-9) M. Incubation of slices with vasopressin caused a dose-dependent decrease in the cyclic AMP-dependent protein kinase activity in the 40,000 X g supernate of homogenate from the renal medullary slices. This effect of vasopressin was specific for protein kinase since activity of lactate dehydrogenase or a specific [3H]colchicine-binding activity was not affected, and the decrease in the protein kinase was not due to the accumulation of a heat-stable protein kinase inhibitor. There was an increase in protein kinase was not due to the accumulation of a heat-stable protein kinase inhibitor. There was an increase in protein kinase activity extracted from 40,000 X g pellets of homogenate prepared from slices exposed to vasopressin. Results thus provide evidence that cyclic AMP-mediated protein kinase activation in the intact cells is an integral part of cellular response of the mammalian renal medulla to vasopressin.

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5′-AMP-activated protein kinase activity is elevated early during primary brain tumor development in the rat

International Journal of Cancer ◽

10.1002/ijc.25558 ◽

2010 ◽

Vol 128 (9) ◽

pp. 2230-2239 ◽

Cited By ~ 29

Author(s):

Taichang Jang ◽

Joy M. Calaoagan ◽

Eunice Kwon ◽

Steven Samuelsson ◽

Lawrence Recht ◽

...

Keyword(s):

Brain Tumor ◽

Protein Kinase ◽

Kinase Activity ◽

Tumor Development ◽

Primary Brain Tumor ◽

Protein Kinase Activity ◽

Amp Activated Protein Kinase

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The role of protein kinase activation in the control of steroidogenesis by adrenocorticotrophic hormone in the adrenal cortex

Biochemical Journal ◽

10.1042/bj1360993 ◽

1973 ◽

Vol 136 (4) ◽

pp. 993-998 ◽

Cited By ~ 29

Author(s):

Malcolm C. Richardson ◽

Dennis Schulster

Keyword(s):

Protein Kinase ◽

Cyclic Amp ◽

Adrenal Cortex ◽

Kinase Activity ◽

Protein Kinase Activity ◽

Adrenocorticotrophic Hormone ◽

Dependent Protein Kinase ◽

Kinase Activation ◽

Protein Kinase Activation ◽

Dependent Protein

A method has been developed for investigation of the effect of adrenocorticotrophic hormone (ACTH) on the state of activation of a cyclic AMP-dependent protein kinase within cells of the adrenal cortex. Enzyme activity was measured in terms of the quantity of32P transferred from [γ-32P]ATP to histone under conditions in which bound cyclic AMP did not dissociate from the regulatory subunit of the protein kinase ACTH (1×10-2i.u./ml) caused a rapid and complete activation of the cyclic AMP-dependent protein kinase activity within 2min of hormone addition to the isolated cells. In response to a range of ACTH concentrations a sigmoid log dose–response curve for protein kinase activation was obtained, with half-maximal stimulation attained at about 1×10-3i.u./ml. However, some low doses of ACTH that elicited a marked (but submaximal) steroidogenic response failed to cause a clear stimulation of protein kinase activity in isolated adrenal cells. Theophylline (2mm) potentiated the effect of ACTH on protein kinase activity. The results implicate an important role for protein kinase in ACTH action on the adrenocortical cell.

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