scholarly journals Phosphorylation of purified bovine heart and rat liver 6-phosphofructo-2-kinase by protein kinase C and comparison of the fructose-2,6-bisphosphatase activity of the two enzymes

1986 ◽  
Vol 240 (1) ◽  
pp. 57-61 ◽  
Author(s):  
M H Rider ◽  
L Hue
Keyword(s):  
Alkaline Phosphatase ◽  
Enzyme Activity ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Exchange Reaction ◽  
Liver Enzyme ◽  
Rat Liver ◽  
Phosphorylation State ◽  
Bovine Heart ◽  
Kinase C

Purified bovine heart 6-phosphofructo-2-kinase can be phosphorylated in the presence of protein kinase C and dephosphorylated by alkaline phosphatase; changes in phosphorylation state have no effect on enzyme activity. By contrast, the rat liver enzyme is a poor substrate for protein kinase C. Unlike the liver enzyme, which is bifunctional and is phosphorylated by fructose 2,6-[2-32P]bisphosphate, the heart enzyme contains 10 times less fructose 2,6-bisphosphatase activity and is phosphorylated at a slower rate and to a lesser extent than the liver enzyme. Both rat liver and bovine heart enzymes catalyse a similar exchange reaction between [U-14C]ADP and ATP.

scholarly journals Protein kinase C phosphorylation of rat liver S-adenosylmethionine synthetase: dissociation and production of an active monomer

1994 ◽  
Vol 303 (3) ◽  
pp. 949-955 ◽  
Author(s):  
M A Pajares ◽  
C Durán ◽  
F Corrales ◽  
J M Mato
Keyword(s):  
Alkaline Phosphatase ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Rat Liver ◽  
Oligomeric State ◽  
Kinase C ◽  
Phosphatase Treatment ◽  
Key Enzyme ◽  
Adenosylmethionine Synthetase ◽  
Adomet Synthetase

The regulation of rat liver S-adenosylmethionine synthetase (AdoMet synthetase), a key enzyme in methionine metabolism, by protein kinase C (PKC) phosphorylation has been studied. Both enzyme forms, tetramer and dimer, are phosphorylated by this kinase in the same residue, Thr-342, of the sequence. Phosphorylation of the dimer leads to its dissociation, with production of a fully-active monomer. The kinetics of the monomer have been studied, and a KmMet of 931.9 microM, a KmATP of 708 microM and a Vmax of 66.8 nmol/min/mg have been calculated. Alkaline phosphatase treatment of both enzyme forms (tetramer and dimer) produces a reduction in their activity with no change in the oligomeric state. On the other hand, PKC phosphorylation of the alkaline phosphatase-treated AdoMet synthetase forms leads to the dissociation of the dimer to produce a monomer. Rephosphorylation occurs again in the same residue, Thr-342, of the sequence. The significance of AdoMet synthetase regulation by PKC phosphorylation is further discussed.

Regulation of rat Na+-K+-ATPase activity by PKC is modulated by state of phosphorylation of Ser-943 by PKA

1997 ◽  
Vol 273 (6) ◽  
pp. C1981-C1986 ◽  
Author(s):  
Xian-Jun Cheng ◽  
Jan-Olov Höög ◽  
Angus C. Nairn ◽  
Paul Greengard ◽  
Anita Aperia
Keyword(s):  
Enzyme Activity ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Response To Treatment ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Present Evidence ◽  
Cos Cells ◽  
Kinase C ◽  
Kinase A

We have previously shown that the rat Na+-K+-ATPase α1-isoform is phosphorylated at Ser-943 by protein kinase A (PKA) and at Ser-23 by protein kinase C (PKC), which in both cases results in inhibition of enzyme activity. We now present evidence that suggests that the phosphorylation of Ser-943 by PKA modulates the response of Na+-K+-ATPase to PKC. Rat Na+-K+-ATPase α1 or a mutant in which Ser-943 was changed to Ala-943 was stably expressed in COS cells. The inhibition of enzyme activity measured in response to treatment with the phorbol ester, phorbol 12,13-dibutyrate (PDBu; 10−6 M), was significantly reduced in the cells expressing the Ala-943 mutant compared with that observed in cells expressing wild-type enzyme. In contrast, for cells expressing Na+-K+-ATPase α1 in which Ser-943 was mutated to Asp-943, the effect of PDBu was slightly enhanced. The PDBu-induced inhibition was not mediated by activation of the adenosine 3′,5′-cyclic monophosphate/PKA system and was not achieved via direct phosphorylation of Ser-943. Sp-5,6-DCl-cBIMPS, a specific PKA activator, increased the phosphorylation of Ser-943, and this was associated with an enhanced response to PDBu. Thus the effect of PKC on rat Na+-K+-ATPase α1 is determined not only by the activity of PKC but also by the state of phosphorylation of Ser-943.

scholarly journals Heterogeneous activation of protein kinase C during rat liver regeneration induced by carbon tetrachloride administration

FEBS Letters ◽  
1989 ◽  
Vol 254 (1-2) ◽  
pp. 59-65 ◽  
Author(s):  
Yutaka Sasaki ◽  
Norio Hayashi ◽  
Toshifumi Ito ◽  
Hideyuki Fusamoto ◽  
Nobuhiro Sato ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Carbon Tetrachloride ◽  
Protein Kinase ◽  
Liver Regeneration ◽  
Rat Liver ◽  
Rat Liver Regeneration ◽  
Kinase C ◽  
Carbon Tetrachloride Administration

scholarly journals Bombesin and epidermal growth factor stimulate the mitogen-activated protein kinase through different pathways in Swiss 3T3 cells

1993 ◽  
Vol 289 (1) ◽  
pp. 283-287 ◽  
Author(s):  
L Pang ◽  
S J Decker ◽  
A R Saltiel
Keyword(s):  
Enzyme Activity ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Map Kinase ◽  
3T3 Cells ◽  
Kinase C ◽  
Mitogen Activated Protein ◽  
Epidermal Growth ◽  
Swiss 3T3 ◽  
Stimulation Of

Both bombesin and epidermal growth factor (EGF) are potent mitogens in Swiss 3T3 cells that nonetheless have dissimilar receptor structures. To explore possible common intracellular events involved in the stimulation of cellular growth by these two peptides, we have evaluated the regulation of the mitogen-activated protein (MAP) kinase. Exposure of Swiss 3T3 cells to bombesin, EGF or the protein kinase C activator phorbol 12-myristate 13-acetate (PMA) causes the rapid and transient stimulation of the enzyme activity. Pretreatment of cells with the protein kinase inhibitor H-7, or down-regulation of cellular protein kinase C by prolonged exposure to PMA, causes a decrease of over 90% in the activation of MAP kinase by bombesin. In contrast, these treatments have no effect on the stimulation of MAP kinase by EGF. The stimulation of MAP kinase activity by bombesin is dose-dependent, occurring over a narrow concentration range of the peptide. Both EGF and bombesin stimulate the phosphorylation of an immunoprecipitable MAP kinase protein migrating at 42 kDa on SDS/PAGE. Phosphoamino acid analysis of this phosphorylated protein reveals that EGF and bombesin stimulate phosphorylation on tyrosine, threonine and serine residues. Tyrosine phosphorylation of the enzyme, as evaluated by antiphosphotyrosine blotting of the immunoprecipitated protein, reveals that the time course of phosphorylation by both mitogens correlates with stimulation of enzyme activity. These results provide further evidence for the convergence of discrete pathways emanating from tyrosine kinase and G-protein-linked receptors in the regulation of MAP kinase.

Dephosphorylation of activated protein kinase C contributes to downregulation by bryostatin

1996 ◽  
Vol 271 (1) ◽  
pp. C304-C311 ◽  
Author(s):  
H. W. Lee ◽  
L. Smith ◽  
G. R. Pettit ◽  
J. Bingham Smith
Keyword(s):  
Alkaline Phosphatase ◽  
Protein Synthesis ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Bryostatin 1 ◽  
Rapid Loss ◽  
Renal Epithelial Cells ◽  
Kinase C ◽  
Phosphatase Treatment ◽  
Pkc Alpha

We show that bryostatin 1 (Bryo) rapidly produces an inactive, incompetent 76-kDa form of protein kinase C-alpha (PKC-alpha) in the LLC-MK2 line of renal epithelial cells. Bryo, like phorbol 12-myristate 13-acetate (PMA), acutely activated PKC, as indicated by autophosphorylation and translocation of PKC-alpha, the predominant PMA-sensitive isoform expressed by the cells. Bryo concomitantly increased the 32P labeling of 80-kDa PKC-alpha by autophosphorylation and produced a 76-kDa form of PKC-alpha that lacked detectable 32P. The 76-kDa form was in the particulate rather than the cytosolic fraction, which suggests that it was produced from activated kinase. Alkaline phosphatase treatment of immunoprecipitated PKC-alpha converted the 80-kDa form to 76 kDa, but it had no effect on the mobility of the 76-kDa form, suggesting that it was not phosphorylated. Pulse-chase labeling of PKC-alpha with [35S]Met/Cys indicated that there is a precursor-product relationship between the 80- and 76-kDa forms, respectively. Inhibition of protein synthesis had no effect on the production of 76-kDa PKC-alpha by Bryo. PMA also produced 76-kDa PKC-alpha but was less potent and efficacious than Bryo. Bryo produced a more rapid loss of 80-kDa PKC-alpha protein and total Ca(2+)- and phospholipid-dependent PKC activity than PMA. The 76-kDa form is inactive and incompetent because it lacked detectable 32P under conditions that strongly autophosphorylated the 80-kDa form. We suggest that dephosphorylation predisposes PKC to proteolysis, and greater production of the 76-kDa form explains the more efficient downregulation of the kinase by Bryo vs. PMA.

Sign in / Sign up

Export Citation Format

Share Document