scholarly journals Activation of adenosine 3‘,5‘-monophosphate-dependent protein kinase and its relationship to cyclic AMP and lipolysis in hamster adipose tissue.

1980 ◽  
Vol 21 (2) ◽  
pp. 250-256
Author(s):  
R J Schimmel ◽  
C A Buhlinger ◽  
R Serio
Keyword(s):  
Adipose Tissue ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Dependent Protein Kinase ◽  
Dependent Protein

scholarly journals Rat adipose-tissue glycerol phosphate acyltransferase can be inactivated by cyclic AMP-dependent protein kinase

1978 ◽  
Vol 176 (2) ◽  
pp. 607-610 ◽  
Author(s):  
H G Nimmo ◽  
B Houston
Keyword(s):  
Alkaline Phosphatase ◽  
Adipose Tissue ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Hormonal Control ◽  
Glycerol Phosphate ◽  
Dependent Protein Kinase ◽  
Phosphorylation Reaction ◽  
Dependent Protein ◽  
Rat Adipose Tissue

Rat adipose-tissue glycerol phosphate acyltransferase can be inactivated in a phosphorylation reaction catalysed by cyclic AMP-dependent protein kinase and reactivated by treatment with alkaline phosphatase. These results suggest that phosphorylation of glycerol phosphate acyltransferase may be involved in the hormonal control of esterification.

scholarly journals Studies of rat adipose-tissue microsomal glycerol phosphate acyltransferase

1984 ◽  
Vol 224 (1) ◽  
pp. 101-108 ◽  
Author(s):  
G A Nimmo ◽  
H G Nimmo
Keyword(s):  
Adipose Tissue ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Microsomal Protein ◽  
Catalytic Subunit ◽  
Glycerol Phosphate ◽  
Dependent Protein Kinase ◽  
Phosphorylated Proteins ◽  
Dependent Protein ◽  
Rat Adipose Tissue

Incubation of rat adipose-tissue microsomal fractions with iodoacetate caused an inactivation of glycerol phosphate acyltransferase that could be prevented by the presence of palmitoyl-CoA. A microsomal protein of subunit Mr 54 000 was found to react with radioactively labelled iodoacetate in the absence, but not in the presence, of palmitoyl-CoA. It is suggested that this protein is a component of glycerol phosphate acyltransferase. Incubation of rat adipose-tissue microsomal fractions with the catalytic subunit of cyclic AMP-dependent protein kinase, ATP and Mg2+ caused an inactivation of glycerol phosphate acyltransferase whose magnitude depended on the conditions used for assay of the acyltransferase. Rat adipose tissue microsomal proteins were phosphorylated by using protein kinase and [gamma-32P]ATP. One of the phosphorylated proteins was very similar, but not identical, in mobility to the Mr-54 000 protein labelled by iodoacetate. In contrast with a previous report [Sooranna & Saggerson (1976) FEBS Lett. 64, 36-39], no changes could be detected in the activity of glycerol phosphate acyltransferase in adipocytes treated with adrenaline. Adipocytes were labelled with [32P]Pi and treated with adrenaline, but no 32P was incorporated into the Mr-54000 protein labelled by iodoacetate. The results suggest that the activity of adipose-tissue microsomal glycerol phosphate acyltransferase is not directly controlled by phosphorylation.

scholarly journals β-adrenergic agents increase the phosphorylation of phosphofructokinase in isolated rat epididymal white adipose tissue

1985 ◽  
Vol 232 (3) ◽  
pp. 905-910 ◽  
Author(s):  
E M Sale ◽  
R M Denton
Keyword(s):  
Adipose Tissue ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
White Adipose Tissue ◽  
Beta Agonist ◽  
Dependent Protein Kinase ◽  
Interscapular Brown Adipose Tissue ◽  
Adrenergic Agents ◽  
Dependent Protein ◽  
Epididymal White Adipose Tissue

Pieces of rat epididymal adipose tissue were incubated in medium containing [32P]phosphate for 2 h to achieve steady-state labelling of intracellular phosphoproteins and then with or without hormones for a further 15 min. Phosphofructokinase was rapidly isolated from the tissue by use of either Blue Dextran-Sepharose chromatography or immunoprecipitation with antisera raised against phosphofructokinase purified from rat interscapular brown adipose tissue. Similar extents of incorporation of 32P into phosphofructokinase were measured by both techniques. Exposure of the tissue to adrenaline or the beta-agonist isoprenaline increased phosphorylation by about 5-fold (to about 1.4 mol of phosphate/mol of enzyme tetramer). No change in phosphorylation was detected with the alpha-agonist phenylephrine, but exposure to insulin resulted in an approx. 2-fold increase. The increased phosphorylation observed with isoprenaline was found to be associated with a decrease in the apparent Ka for fructose 2,6-bisphosphate similar to that observed on phosphorylation of phosphofructokinase purified from rat epididymal white adipose tissue with the catalytic subunit of cyclic AMP-dependent protein kinase. These results support the view [Sale & Denton (1985) Biochem. J. 232, 897-904] that an increase in cyclic AMP in adipose tissue may result in an increase in glycolysis through the phosphorylation of phosphofructokinase by cyclic AMP-dependent protein kinase.

scholarly journals Adipose-tissue phosphofructokinase. Rapid purification and regulation by phosphorylation in vitro

1985 ◽  
Vol 232 (3) ◽  
pp. 897-904 ◽  
Author(s):  
E M Sale ◽  
R M Denton
Keyword(s):  
Adipose Tissue ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Single Step ◽  
Optimal Conditions ◽  
Dependent Protein Kinase ◽  
Brown Adipose ◽  
Dependent Protein ◽  
Rapid Purification

A new procedure for the purification of phosphofructokinase using Blue Dextran-Sepharose is described. This allowed an approx. 1000-fold purification of phosphofructokinase from rat white and brown adipose tissue to be achieved in essentially a single step. The purified enzymes from both tissues were found to exhibit hyperbolic kinetics with fructose 6-phosphate, to be inhibited by ATP and citrate, and to be activated by 5′-AMP, phosphate and fructose 2,6-bisphosphate. The enzymes were phosphorylated by the catalytic subunit of cyclic AMP-dependent protein kinase, and phosphorylation was found to be associated with increases in activity when the enzymes were assayed under appropriate sub-optimal conditions. In particular, the phosphorylated enzymes exhibited less inhibition by ATP and the white-adipose-tissue enzyme was more sensitive to activation by fructose 2,6-bisphosphate. It is suggested that an increase in the cytoplasmic concentration of cyclic AMP in tissues other than liver may result in an increase in glycolysis through the phosphorylation of phosphofructokinase by cyclic AMP-dependent protein kinase.

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