scholarly journals Effects of phosphorylation on the kinetic properties of rat liver fructose-1,6-bisphosphatase

1984 ◽  
Vol 222 (1) ◽  
pp. 125-130 ◽  
Author(s):  
D W Meek ◽  
H G Nimmo
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Rat Liver ◽  
Kinetic Properties ◽  
Purification Procedure ◽  
Dependent Protein Kinase ◽  
Fructose 1,6 Bisphosphatase ◽  
Dependent Protein ◽  
A Subunit ◽  
Fructose 1,6 Bisphosphate

A new purification procedure for rat liver fructose-1,6-bisphosphatase that involves use of Procion Red-Sepharose is described. The purified enzyme was homogeneous, had a subunit Mr of 40 000-41 000 and seemed to be undegraded. The enzyme could be phosphorylated by cyclic AMP-dependent protein kinase with a stoicheiometry of one per subunit. Phosphorylation caused a 2-fold decrease in the Km of the enzyme for fructose 1,6-bisphosphate, but did not affect its allosteric responses to AMP, Mg2+ and fructose 2,6-bisphosphate.

scholarly journals Comparison of purified bovine heart and rat liver 6-phosphofructo-2-kinase. Evidence for distinct isoenzymes

1985 ◽  
Vol 231 (1) ◽  
pp. 193-196 ◽  
Author(s):  
M H Rider ◽  
D Foret ◽  
L Hue
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Liver Enzyme ◽  
Rat Liver ◽  
Rat Heart ◽  
Kinetic Properties ◽  
Dependent Protein Kinase ◽  
Bovine Heart ◽  
Dependent Protein

Rat liver and bovine heart 6-phosphofructo-2-kinase were purified by the same procedure. Compared with the liver enzyme, the heart enzyme had a smaller apparent Mr, different kinetic properties, was not inactivated by cyclic AMP-dependent protein kinase, and contained less fructose-2,6-bisphosphatase activity. These differences suggest that heart and liver 6-phosphofructo-2-kinase are distinct isoenzymes. Likewise, 6-phosphofructo-2-kinase from rat heart and skeletal muscle was not inactivated on treatment with cyclic AMP-dependent protein kinase.

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.

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.

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