Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new assay procedure for triglyceride lipase [EC 3.1.1.3] was developed in which radioactive triolein was dissolved in ethanol and directly added to the reaction mixture in the absence of serum and albumin. In the rat adipose tissue there appeared to be a triglyceride lipase measurable with this assay in addition to the two previously defined lipases, lipoprotein lipase [EC 3.1.1.34] and hormone-sensitive lipase. The enzyme was active in the absence of serum and was strongly inhibited by albumin. The molecular weight was estimated to be about 42,000. Adenosine 3',5'-monophosphate-dependent protein kinase [EC 2.7.1.27] was unable to activate the enzyme. The three species of lipases mentioned above behaved differently upon chromatography on a Sepharose 4B column, and were distinguishable from each other in their physical and kinetic properties. The physiological roles of the new species of lipase remain to be explored.
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PMID:Studies on triglyceride lipases from rat adipose tissue. 1 45

This paper describes the stimulation by cyclic nucleotide dependent protein kinases on the Ca2+ uptake by isolated endoplasmic reticulum (ER) vesicles from the bovine main pulmonary artery. This ER fraction has previously been shown to be highly enriched in phospholamban, a protein kinase substrate that has been well characterized in cardiac sarcoplasmic reticulum (SR), where its phosphorylation is accompanied by an increased rate of Ca2+ uptake. As previously observed for the phosphorylation of phospholamban, the stimulation of the rate of Ca uptake was as high with cGMP dependent protein kinase as with cAMP dependent protein kinase. The effect of phosphorylation of the ER membranes from smooth muscle on the Ca2+ uptake was smaller than that seen in cardiac SR, and it was only observed if albumin was included during the isolation of the membranes. This relatively small effect is probably not due to a lower ratio of phospholamban to Ca2(+)-transport enzyme in the ER membranes as compared to cardiac SR. Several alternative explanations are discussed.
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PMID:Effects of cyclic nucleotide dependent protein kinases on the endoplasmic reticulum Ca2+ pump of bovine pulmonary artery. 216 83

We have recently reported the existence of two forms of glycogen phosphorylase (1,4-alpha-D-glucan: orthophosphate-alpha-glucosyltransferase; EC 2.4.1.1) in Dictyostelium discoideum. During development the activity of the glycogen phosphorylase b form decreased as the activity of the a form increased. The total phosphorylase activity remained constant. The physical and kinetic properties of the Dictyostelium enzyme were similar to those of the mammalian enzyme. In mammals, cAMP regulates the conversion of the two forms by a cAMP dependent protein kinase (cAMPdPK). We report here that if cAMP is added to a single cell suspension, the Dictyostelium phosphorylase activity becomes independent of 5'AMP and a 104 kd peptide appears. We also show the effect of several cAMP analogs on the phosphorylase activity in these single-cell suspensions. The cAMP analogs were selected on the basis of their affinities for the membrane-bound cAMP receptor or the cytoplasmic cAMPdPK. We found that relatively low levels, 100 microM, of cAMP or 2'd-cAMP added to aggregation-competent cells in shaking culture caused a loss of phosphorylase b activity and the appearance of phosphorylase a activity. The analog, 2'd-cAMP, has a high affinity for the cAMP receptor but a low affinity for the cAMPdPK. Two other analogs, Bt2-cAMP and 8-Br-cAMP, which have low affinities for the cAMP receptor but high affinities for the cAMPdPK, required high levels (500 microM) for 'b' to 'a' conversion. cDNAs to three cAMP-regulated genes--PL3, D11, and D3--were used as controls in the above experiments. In order to determine if intracellular levels of cAMP were involved in the regulation of phosphorylase activity, both the phosphorylase and the PL3, D11 and D3 mRNA levels were examined in cells suspended in a glucose/albumin mixture--a medium in which adenylate cyclase is inhibited. Under these conditions, neither gene regulation nor a change in the phosphorylase b to a activity occurred in response to added extra cellular cAMP. The results suggest that an intracellular increase in cAMP is involved in the regulation of the two forms of glycogen phosphorylase in Dictyostelium.
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PMID:Regulation of the two forms of glycogen phosphorylase by cAMP and its analogs in Dictyostelium discoideum. 217 98

Cyclic adenosine monophosphate (AMP) has numerous important effects on cell structure and function, but its role in endothelial cells is unclear. Since cyclic AMP has been shown to affect transmembrane transport, cell growth and morphology, cellular adhesion, and cytoskeletal organization, it may be an important determinant of endothelial barrier properties. To test this we exposed bovine pulmonary artery endothelial cell monolayers to substances known to increase cyclic AMP and measured their effect on endothelial permeability to albumin and endothelial cell cyclic AMP concentrations. Cholera toxin (CT), a stimulant of the guanine nucleotide binding subunit of adenylate cyclase, led to a concentration-dependent 2-6-fold increase in cyclic AMP which was associated with a 3-10-fold reduction in albumin transfer across endothelial monolayers. The effect was not specific to albumin as similar barrier-enhancing effects were also noted with an unrelated macromolecule, fluorescein isothiocyanate (FITC)-dextran (MW 70,000). Barrier enhancement with cyclic AMP elevation was also observed with forskolin, a stimulant of the catalytic subunit of adenylate cyclase. The temporal pattern of barrier enhancement seen with these agents paralleled their effects on increasing cyclic AMP, and the barrier enhancement could be reproduced by incubation with either dibutyryl cyclic AMP or Sp-cAMPS, cyclic AMP-dependent protein kinase agonists. Furthermore, the forskolin effect on barrier enhancement was partially reversed with Rp-cAMPS, an antagonist of cyclic AMP-dependent protein kinase. Since endothelial actin polymerization may be an important determinant of endothelial barrier function, we sought to determine whether the cyclic AMP-induced effects were associated with increases in the polymerized actin pool (F-actin). Both cholera toxin and forskolin led to apparent endothelial cell spreading and quantitative increases in endothelial cell F-actin fluorescence. In conclusion, increased endothelial cell cyclic adenine nucleotide activity was an important determinant of endothelial barrier function in vitro. The barrier enhancement was associated with increased endothelial apposition and increases in F-actin, suggesting that influences on cytoskeletal assembly may be involved in this process.
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PMID:Role of cyclic adenosine monophosphate in the induction of endothelial barrier properties. 254 Feb 9

Cyclic AMP-stimulated mRNA levels in cultured rat hepatocytes were inhibited by three different inhibitors of cAMP-dependent protein kinase activity: (i) Rp-cAMPS, a cAMP analog with a sulfur substitution at the equatorial oxygen of the cyclic monophosphate; (ii) H8, an isoquinoline sulfonamide derivative; and (iii) PKI, a 20-amino acid synthetic peptide of the Walsh protein kinase inhibitor. These inhibitors specifically blocked the cAMP-stimulated increase in mRNA for tyrosine aminotransferase and phosphoenolpyruvate carboxykinase; they had no effect on the level of albumin mRNA which is not cAMP regulated. These results provide functional evidence that kinase activity involving protein phosphorylation is required in cAMP-mediated gene expression in mammalian cells.
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PMID:Catalytic subunit of cAMP-dependent protein kinase is essential for cAMP-mediated mammalian gene expression. 283 Jan 34

The expression of the tyrosine aminotransferase (TAT) gene of the rat was analyzed in primary hepatocytes. The TAT gene remains active in primary cultured cells at a level similar to that in liver cells. Expression can be induced by glucocorticoids and cAMP, glucocorticoids lead to a 8-10-fold increase in TAT mRNA level, cAMP to a 20-30-fold increase. The elevation of the TAT mRNA is preceeded by a rise in the relative rate of transcription of the gene. Surprisingly transcription of the albumin gene, which steadily declines with the age of the culture, can also strongly be stimulated by glucocorticoids in primary hepatocytes. cAMP antagonists, which act as competitive inhibitors of the cAMP-dependent protein kinase, prevent induction of transcription of the tyrosine aminotransferase gene by cAMP suggesting that the effect of cAMP on expression of the tyrosine aminotransferase gene is mediated by a cAMP-dependent protein kinase. The cAMP antagonist does not interfere with induction by glucocorticoids which suggests that phosphorylation of the glucocorticoid receptor by the cAMP-dependent protein kinase is not required for its function. We thus conclude that the two inducers affect transcription by independent mechanisms.
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PMID:Transcription activation of the tyrosine aminotransferase gene by glucocorticoids and cAMP in primary hepatocytes. 288 94

Ca2+-activated, phospholipid-dependent protein kinase (protein kinase C) is widely distributed in mammalian tissues. Accumulating evidence has revealed that protein kinase C as well as cAMP-dependent protein kinase plays important roles in various cellular functions. The purpose of this study is to examine the effect of bilirubin on protein kinase C and cAMP-dependent protein kinase activity in a cell-free system as a cause of bilirubin toxicity to the central nervous system. Bilirubin inhibited protein kinase C activity in a dose-dependent manner. This effect was markedly diminished by the addition of human serum albumin at a molar ratio of bilirubin to albumin of less than 1.0. Kinetic analysis revealed that bilirubin did not compete with phospholipid, diacylglycerol, or calcium. Bilirubin also inhibited cAMP-dependent protein kinase, but did not compete with cAMP. The inhibitory effect of bilirubin on protein kinase C seems to be irreversible because removal of bilirubin by Sephadex G-25 column chromatography did not restore the protein kinase C activity. Observations reported herein suggest that bilirubin, especially in its free form, induces an irreversible change to the catalytically active site of protein kinase C.
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PMID:Mode of inhibitory action of bilirubin on protein kinase C. 298 61

Bovine albumin was phosphorylated by both cAMP-dependent protein kinase and casein kinase I to a significant extent. Other albumins were also tested and it was found that the extent of phosphorylation varied with the species of origin of the albumin, but was between 1 and 3 mol phosphate per mole albumin for the cAMP-dependent protein kinase-catalyzed reactions. The phosphorylation occurred at and above pH 7.5 and required the presence of thiol reagents. Phosphoamino acid analyses of bovine albumin showed that it was phosphorylated on at least two serine residues. The phosphorylation could not be demonstrated in vivo.
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PMID:In vitro phosphorylation of serum albumin by two protein kinases: a potential pitfall in protein phosphorylation reactions. 346 Mar 68

Analysis of all clinical reactions (complaints) reported to CSL in the past decade has revealed that "hypotension syndrome" continues to be the predominant side effect of infusion of albumin solutions. Although the incidence of clinical reactions to albumin solutions reported to CSL is approximately 1 in every 20,000 bottles issued, the virtual elimination of PKA from SPPS has not reduced the number of adverse clinical reports received by CSL. It is concluded that factors other than PKA contamination are responsible for hypotensive effects during or after infusion of albumin solutions. Other possible causes of "hypotension syndrome" are discussed.
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PMID:Albumin solutions--their production and quality control. 360 72

Incubation of rat adipocytes with the same range of noradrenaline concentrations that stimulate lipolysis caused a rapid and stable decrease in the activity of fatty acyl-CoA synthetase. Corticotropin, glucagon and dibutyryl cyclic AMP also decreased the activity of the enzyme. The effect of noradrenaline was apparent over a wide range of concentrations for the three substrates of the enzyme. A novel fluorescence assay of fatty acyl-CoA synthetase using (1,N6-etheno)-CoA is described. The effect of noradrenaline was not abolished by inclusion of albumin in homogenization buffers, persisted through subcellular fractionation and isolation of microsomes (microsomal fractions) and even survived treatment of microsomes with Triton X-100. The effect of noradrenaline was rapidly reversed within cells by the subsequent addition of insulin or propranolol. The inclusion of fluoride in homogenization buffers did not alter the observed effect of noradrenaline. Additions of cyclic AMP-dependent protein kinase to adipocyte microsomes caused considerable phosphorylation of microsomal protein by [gamma-32P]ATP, but did not affect the activity of fatty acyl-CoA synthetase.
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PMID:Reversible inactivation by noradrenaline of long-chain fatty acyl-CoA synthetase in rat adipocytes. 388 97


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