scholarly journals Fructose 2,6-bisphosphate and 6-phosphofructo-2-kinase during liver regeneration

1990 ◽  
Vol 270 (3) ◽  
pp. 645-649 ◽  
Author(s):  
J L Rosa ◽  
F Ventura ◽  
J Carreras ◽  
R Bartrons
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Total Activity ◽  
Glycogen Level ◽  
Dependent Protein Kinase ◽  
Phosphorylated Form ◽  
Dependent Protein

Glycogen and fructose 2,6-bisphosphate levels in rat liver decreased quickly after partial hepatectomy. After 7 days the glycogen level was normalized and fructose 2,6-bisphosphate concentration still remained low. The ‘active’ (non-phosphorylated) form of 6-phosphofructo-2-kinase varied in parallel with fructose 2,6-bisphosphate levels, whereas the ‘total’ activity of the enzyme decreased only after 24 h, similarly to glucokinase. The response of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase from hepatectomized rats (96 h) to sn-glycerol 3-phosphate and to cyclic AMP-dependent protein kinase was different from that of the enzyme from control animals and similar to that of the foetal isoenzyme.

scholarly journals Cyclic AMP-dependent protein kinase phosphorylates rabbit reticulocyte elongation factor-2 kinase and induces calcium-independent activity

1993 ◽  
Vol 293 (1) ◽  
pp. 31-34 ◽  
Author(s):  
N T Redpath ◽  
C G Proud
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Elongation Factor ◽  
Total Activity ◽  
Dependent Protein Kinase ◽  
Calcium Calmodulin Dependent ◽  
Elongation Factor 2 ◽  
Eukaryotic Elongation Factor ◽  
Dependent Protein ◽  
Phosphopeptide Mapping

The catalytic subunit of cyclic AMP-dependent protein kinase (PKA) phosphorylated purified calcium/calmodulin-dependent eukaryotic elongation factor-2 (eEF-2) kinase, isolated from rabbit reticulocyte lysates. It maximally incorporated about 1 mol of phosphate/mol of eEF-2 kinase. The Km of eEF-2 kinase for PKA was calculated to be 7 microM. Phosphorylation of eEF-2 kinase by PKA induced calcium-independent activity which amounted to 40-50% of the total activity measured in the presence of calcium. Furthermore, the level of calcium-independent activity induced by phosphorylation by PKA was similar to that induced by the calcium-stimulated autophosphorylation of eEF-2 kinase. Phosphopeptide mapping of eEF-2 kinase labelled by autophosphorylation and by PKA revealed a number of common phosphopeptides. This suggests that PKA may phosphorylate the same site(s) which are phosphorylated autocatalytically and which are responsible for the induction of calcium-independent activity. The possible implications these findings have for the control of translation are discussed.

scholarly journals Early events in the response of fast skeletal muscle to chronic low-frequency stimulation. Polyamine biosynthesis and protein phosphorylation

1982 ◽  
Vol 206 (2) ◽  
pp. 211-219 ◽  
Author(s):  
C Mastri ◽  
S Salmons ◽  
G H Thomas
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Low Frequency ◽  
Total Activity ◽  
Dependent Protein Kinase ◽  
Polyamine Biosynthesis ◽  
Cytoplasmic Proteins ◽  
Phosphorylation Pattern ◽  
Dependent Protein

The concentrations of putrescine, spermidine and spermine and the activities of ornithine decarboxylase (ODC) and S-adenosyl-L-methionine decarboxylase (SAM-D) were investigated in fast muscle subjected to chronic low-frequency electrical stimulation. Both ODC and SAM-D activities increased markedly between 18 and 48 h of stimulation. Changes in enzyme activities were followed by phasic elevations in the concentrations of putrescine, spermidine and spermine. Peak levels were reached first by putrescine at 3-4 days, followed by spermidine at about 9 days and then by spermine at about 11 days. A possible relationship was sought between these events and changes produced in vitro in the phosphorylation pattern of cytoplasmic proteins and the total activity of cyclic AMP-dependent protein kinase. However, during the early stages of stimulation, no prominent changes were seen either in the phosphorylation pattern or in the activity of cyclic AMP-dependent protein kinase. These characteristics changed significantly at a later stage (by 12 days of stimulation) and became indistinguishable from those of slow muscle by 3 to 4 weeks of stimulation.

scholarly journals Antiserum against the catalytic subunit of adenosine 3′:5′-cyclic monophosphate-dependent protein kinase. Reactivity towards various protein kinases

1980 ◽  
Vol 192 (1) ◽  
pp. 223-230 ◽  
Author(s):  
G Schwoch ◽  
A Hamann ◽  
H Hilz
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinases ◽  
Rat Liver ◽  
Catalytic Subunit ◽  
Type Ii ◽  
Dependent Protein Kinase ◽  
Subunit C ◽  
Bovine Heart ◽  
Dependent Protein

An antiserum against the catalytic subunit C of cyclic AMP-dependent protein kinase, isolated from bovine heart type II protein kinase, was produced in rabbits. Reaction of the catalytic subunit with antiserum and separation of the immunoglobulin G fraction by Protein A-Sepharose quantitatively removed the enzyme from solutions. Comparative immunotitration of protein kinases showed that the amount of antiserum required to eliminate 50% of the enzymic activity was identical for pure catalytic subunit, and for holoenzymes type I and type II. The reactivity of the holoenzymes with the antiserum was identical in the absence or the presence of dissociating concentrations of cyclic AMP. Most of the holoenzyme (type II) remains intact when bound to the antibodies as shown by quantification of the regulatory subunit in the supernatant of the immunoprecipitate. Titration with the antibodies also revealed the presence of a cyclic AMP-independent histone kinase in bovine heart protein kinase I preparations obtained by DEAE-cellulose chromatography. Cyclic AMP-dependent protein kinase purified from the particulate fraction of bovine heart reacted with the antiserum to the same degree as the soluble enzyme, whereas two cyclic AMP-independent kinases separated from the particle fraction neither reacted with the antiserum nor influenced the reaction of the antibodies with the cyclic AMP-dependent protein kinase. Immunotitration of the protein kinase catalytic subunit C from rat liver revealed that the antibodies had rather similar reactivities towards the rat liver and the bovine heart enzyme. This points to a relatively high degree of homology of the catalytic subunit in mammalian tissues and species. Broad applicability of the antiserum to problems related to cyclic AMP-dependent protein kinases is thus indicated.

Synthetic fragments of protamines as model substrates for rat liver cyclic AMP-dependent protein kinase

1981 ◽  
Vol 662 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Flavio Meggio ◽  
Gavino Chessa ◽  
Gianfranco Borin ◽  
Lorenzo A. Pinna ◽  
Ferdinando Marchiori
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Rat Liver ◽  
Dependent Protein Kinase ◽  
Dependent Protein
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