Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Differentiation of 3T3-L1 fibroblasts to adipocyte-like cells was accompanied by a 19-fold increase in neutral triglyceride lipase activity, a 12-fold increase in diglyceride lipase activity, a 10-fold increase in monoglyceride lipase activity, and a 280-fold increase in cholesterol esterase activity. In contrast, acid acylhydrolase activities did not increase during differentiation. The rate of glycerol release from unstimulated intact cells increased by more than 1 order of magnitude upon differentiation. Isoproterenol (1 microM) and 1-methyl-3-isobutylxanthine (0.1 mM) further stimulated this rate of glycerol release 3-fold. The neutral triglyceride lipase activity in cell-free preparations of differentiated cells was activated 105% by cyclic AMP-dependent protein kinase. Neutral cholesterol esterase, diglyceride lipase, and monoglyceride lipase were also activated (117%, 10%, and 37+, respectively) by cyclic AMP-dependent protein kinase. In contrast, protein kinase had no effect on any of the four lysosomal acid acylhydrolase activities. Thus, hormone-sensitive lipase, the most characteristic and functionally important enzyme of adipose tissue, has been characterized in differentiated 3T3-L1 cells. The 3T3-L1 cell should be a valuable model system in which to study regulation of hormone-sensitive lipase, particularly its long-term regulation.
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PMID:Hormone-sensitive lipase in differentiated 3T3-L1 cells and its activation by cyclic AMP-dependent protein kinase. 626 67

The possible role of cyclic AMP-mediated phosphorylation events in the regulation of exocrine secretion after beta-adrenergic stimulation was examined in vitro in dispersed acinar cell aggregates from rat parotid gland. l-Isoproterenol, a beta-adrenergic agonist, stimulated endogenous activity of cyclic AMP-dependent protein kinase, alterations in the 32P content of 3 parotid phosphoproteins (increased 32P in 2, Mr = 27,000 and 14,000; decreased 32P in the remaining, Mr = 13,600), and amylase secretion in a dose-dependent manner. All responses were half-maximal within a range of l-isoproterenol concentrations of approximately 4 X 10(-8) to 5 X 10(-7) M. Examination of the time course of these 3 processes revealed that by 30 s after addition of l-isoproterenol, significant elevations in cyclic AMP-dependent protein kinase activity and alterations in the 32P content of the 3 parotid proteins had occurred, whereas secretion of amylase from cells was first detected 1-2 1/2 min after hormonal stimulation. Dibutyryl cyclic AMP (2 mM) elicited the same changes in parotid protein 32P content as l-isoproterenol. Our results support the concept of a role for cyclic AMP-regulated protein phosphorylation in the sequence of cellular events leading to exocrine protein secretion from the rat parotid gland following beta-adrenergic stimulation.
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PMID:beta-Adrenergic regulation of protein phosphorylation and its relationship to exocrine secretion in dispersed rat parotid gland acinar cells. 627 99

Both isoproterenol and prostaglandin E1 increased the activation state of cyclic AMP-dependent protein kinase in cultured myocytes; however, only isoproterenol enhanced phosphorylase activity and contractile state. Following the incubation of intact myocytes with 32PO3-(4), 32 phosphoproteins were resolved from total cellular proteins by electrophoresis in sodium dodecyl sulfate polyacrylamide gels followed by autoradiography. Isoproterenol stimulated 32PO3-(4) incorporation into 16 proteins, including 2 phosphoproteins not observed under control conditions. By contrast, prostaglandin E1 neither caused a measurable change in the protein phosphorylation pattern nor interfered with isoproterenol's capacity to do so. Isoproterenol stimulated myocyte protein phosphorylation in either the presence or absence of extracellular Ca2+. The results suggest that the regulation of protein phosphorylation following adenylate cyclase stimulation is: (1) an agonist-specific process and not due solely to a random accumulation of intracellular cycle AMP and activation of protein kinase; (2) the Ca2+ mobilization component of beta-receptor activation does not account for the paradoxical effects of isoproterenol and prostaglandin E1; (3) activation of cyclic AMP-dependent protein kinase does not always result in an enhancement of protein phosphorylation.
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PMID:Evidence for selective regulation of the phosphorylation of myocyte proteins by isoproterenol and prostaglandin E1. 627 3

The purpose of this investigation was to examine the effects of beta-adrenergic and muscarinic cholinergic agonists on protein phosphorylation in intact frog atrium. beta-Adrenergic agonists increase and muscarinic agonists decrease 32P incorporation into a 165,000-dalton (165K) protein within less than 1 min. The concentrations of isoproterenol that produce increases in 32P incorporation into the 165K protein and in systolic tension are similar. Further, the changes in 32P incorporation and tension produced by isoproterenol occur with similar time courses. Carbamylcholine decreases tension somewhat more quickly and at lower concentrations than it decreases 32P incorporation, however. Isoproterenol-stimulated 32P incorporation is thought to be mediated by cAMP-dependent protein kinase because bath application of dibutyryl cAMP, cholera toxin, or phosphodiesterase inhibitors increase 32P incorporation into the 165K protein in intact atria. When heart homogenates are incubated in the presence of [gamma-32P]ATP, cAMP stimulates the incorporation of 32P into the 165K protein. cGMP is much less effective. We suggest that carbamylcholine decreases 32P incorporation into the 165K protein by a mechanism independent of cAMP levels because carbamylcholine inhibits the stimulation of 32P incorporation into the 165K band produced by 8-bromo cAMP in intact cells. Phosphorylation of the 165K protein occurs in cardiac muscle but not in other tissues. We hypothesize that the 165K protein is C-protein, because the 165K- and C-proteins have similar solubilities and are associated with the myofibril. Further, antibodies produced against the 165K protein bind to C-protein purified from rabbit heart and also bind to the same region of the myofibril where C-protein is found.
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PMID:Effects of cholinergic and adrenergic agonists on phosphorylation of a 165,000-dalton myofibrillar protein in intact cardiac muscle. 627 7

Microassay procedures for cAMP-dependent protein kinase and phosphorylase were developed which detected these activities in less than 25 micrograms of frozen-dried epidermis from a punch biopsy of skin without homogenization. Using these procedures, the activation of cAMP-dependent protein kinase and phosphorylase by beta-adrenergic stimulation in mouse skin was studied in vivo. Cyclic AMP-dependent protein kinase was stimulated by isoproterenol and inhibited by propranolol. Isoproterenol stimulation also activated phosphorylase a in mouse skin. In normal epidermis and uninvolved and involved epidermis from psoriatic patients no significant differences were found in the activities of cAMP-dependent kinase and phosphorylase a. In all experiments we observed that the unstimulated activity ratios of phosphorylase a/total phosphorylase were around 20-30%; these values were much lower than those hitherto reported and show a preponderance of phosphorylase b rather than a. We suggest that in previous reports where phosphorylase a domination was found, phosphorylase b to a activation occurred during homogenization. The data also suggest that in the steady state no obvious defect in basic activities of cAMP-dependent protein kinase and phosphorylase is observed in psoriatic skin.
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PMID:Measurement of adenosine 3',5'-monophosphate-dependent protein kinase and phosphorylase activities in in vivo conditions. 628 82

Relaxation of smooth muscle cells induced by activation of beta-adrenoceptors was investigated in intact and skinned muscles of the guinea-pig mesenteric artery.1. In concentrations over 10(-7) M, isoprenaline reduced the resting tone of intact preparations and also the amplitude of K contractions. When Ca was applied after previous superfusion with Ca-free solution, the amount of Ca accumulated into storage sites was increased by isoprenaline in polarized and depolarized ([K](o) 128 mM) muscles. The amount of Ca stored increased even further when procaine and isoprenaline were applied simultaneously during store loading.2. Isoprenaline increased the concentration of cyclic AMP as determined by radioimmunoassay. Application of isoprenaline at a concentration of 10(-7) M increased cyclic AMP from 2.2+/-0.3 to 2.8+/-0.6 p-mole/mg wet weight and at 10(-6) M increased it to 4.5+/-0.8 p-mole/mg wet weight after 5 min incubation (n = 4).3. Application of cyclic AMP (3 x 10(-6) M) with cyclic AMP-dependent protein kinase (50 mug/ml.) had no effect on the pCa-tension relationship in the skinned muscles. However, an increased concentration of cyclic AMP (> 10(-5) M) suppressed the Ca-induced concentration only in the presence of protein kinase. This protein kinase (50 mug/ml.) alone had no effect on the Ca-induced contraction.4. In skinned fibres, the Ca store could be loaded by applying low concentrations of Ca. If cyclic AMP (3 x 10(-6) M) with protein kinase (50 mug/ml.) was applied during the loading procedure, the amount of Ca accumulated by the store increased if the loading solution contained 10(-6) M-Ca applied for 2 min or less, but if the loading solution was applied for 3 min, or if higher Ca concentrations were used, the presence of cyclic AMP with protein kinase decreased the store size, suggesting that a Ca-induced Ca-release mechanism was also being activated.5. In skinned muscles, accumulation of Ca into the store site in the presence of cyclic AMP (3 x 10(-6) M) with protein kinase (50 mug/ml.) was further accelerated by simultaneous applications of procaine (5 mM), as here the Ca-induced Ca-release mechanism was suppressed.6. These results indicate that activation of beta-adrenoceptors by isoprenaline increases the amount of cyclic AMP in the intact muscles, and leads to an increase in Ca accumulation into the store site. In the skinned muscles, the Ca-induced Ca-release mechanism is activated by cyclic AMP and the Ca receptor for contraction (leiotonin C or calmodulin) is somewhat suppressed. These effects of exogenously applied cyclic AMP require the presence of protein kinase. The relaxation following beta-adrenoceptor activation is more likely to involve Ca extrusion from the cell and accumulation of Ca in internal storage sites than suppression of the binding of calmodulin with the myosin light chain kinase.
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PMID:Mechanisms of relaxation induced by activation of beta-adrenoceptors in smooth muscle cells of the guinea-pig mesenteric artery. 628 50

1. The phosphorylation by cAMP and protein kinase I of rat cardiac sarcolemma (SL) and sarcoplasmic reticulum (SR) isolated from the same homogenate, was compared. 2. In both fractions, the phosphate incorporation is strongly dependent on the ATP and the membrane protein concentration. 3. SDS-gel electrophoresis reveals that in the SL preparation a protein of Mr = 24,500 and a glycoprotein of Mr = 17,500 are mainly phosphorylated, while in the SR fraction the main phosphate incorporation is found in a protein having a Mr = 37,000. 4. Isoprenaline stimulates the phosphorylation of SL but not of SR. Propranolol abolished that stimulatory action of isoprenaline completely, suggesting that the beta-adrenoceptor is involved.
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PMID:Comparison of cyclic AMP-dependent phosphorylation of sarcolemma and sarcoplasmic reticulum from rat cardiac ventricle muscle. 630 38

beta-Adrenergic receptors and the activities of adenylate cyclase, phosphodiesterase and protein kinase were examined in two human glioma cell lines, U 251 and LM, as well as in rat C6 glioma. [3H]Dihydroalprenolol binding to beta-adrenergic receptors was specific, saturable and of high affinity in each cell line. The dissociation constant (Kd) and maximal binding (Bmax) extrapolated from Scatchard curves were Kd = 17.4 +/- 3.2 nM and Bmax = 1110 +/- 197 fmol/mg protein for the U-251 cells; Kd = 14.4 +/- 2.2 nM and Bmax = 655 +/- 105 fmol/mg protein for the LM cells; and Kd = 5.6 +/- 1.1 nM and Bmax = 454 +/- 80 fmol/mg protein for the C6 glioma cells. L-Isoproterenol stimulated cyclic AMP formation in all 3 cell lines. beta-Adrenergic agonists also increased calcium-dependent and calcium non-dependent phosphodiesterase activity in these tumor cells. Cytosolic protein kinase in the 3 cell lines phosphorylated exogenous histone as a substrate. The phosphorylation was enhanced by cyclic AMP. Cytosolic protein kinase also phosphorylated endogenous cytosolic macromolecules. The phosphorylated proteins had molecular weights of 30,000, 51,000 and 90,000 in the two human glioma cell lines. The present results indicate that human glioma cell lines have functional beta-adrenergic receptors linked to adenylate cyclase. These beta-receptors can also regulate phosphodiesterase activity and cyclic AMP in human glioma cells can activate protein kinase and induce the phosphorylation of specific proteins.
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PMID:The beta-adrenergic receptor system in human glioma-derived cell lines: the mode of phosphodiesterase induction and the macromolecules phosphorylated by cyclic AMP-dependent protein kinase. 632 58

Previous in vitro studies demonstrated that ATP-citrate lyase is phosphorylated by cyclic AMP-dependent protein kinase at peptide A, containing a phosphoserine residue, and by ATP-citrate lyase kinase at peptide B, containing both phosphoserine and phosphothreonine residues (Ramakrishna, S., Pucci, D. L., and Benjamin, W. B. (1983) J. Biol. Chem. 258, 4950-4956). In the present study, trypsin-digested, radiolabeled ATP-citrate lyase from rat epididymal fat pads was analyzed by high performance liquid chromatography. Phosphorylation occurred at three amino acid residues within two different peptide sequences; one (peptide a) contained phosphoserine and the other (peptide b) contained phosphoserine and phosphothreonine. The retention times and molecular weights were the same for peptides a and A and peptides b and B. Isoproterenol action increased peptide a phosphorylation and, to a lesser extent, peptide b phosphorylation. Insulin action also increased peptide a phosphorylation, but did not increase peptide b phosphorylation.
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PMID:ATP-citrate lyase phosphorylation in rat adipose tissue. 663 Feb 12

1. Single ventricular myocytes were enzymatically isolated, incubated with the A1-purinergic and beta-adrenergic receptor-specific agonists N6-cyclopentyladenosine (CPA) and isoprenaline (Iso), and then rapidly skinned. Ca2+ sensitivity of isometric tension and unloaded shortening velocity (Vo) were measured, and protein kinase A (PKA)-specific phosphorylations of troponin I (TnI) and C-protein were assessed by back-phosphorylation of cell suspensions with [gamma-32P]-ATP. 2. Isoprenaline treatment decreased the Ca2+ sensitivity of isometric tension relative to propranolol-treated controls, as did simultaneous stimulation with Iso and CPA (Iso + CPA). CPA alone had no effect on Ca2+ sensitivity. Vo was greater in Iso-treated cells than in paired controls, while Vo was significantly less than control in both Iso + CPA-treated and CPA-treated cells. 3. Phosphorylation of TnI and C-protein was increased by Iso treatment and also when Iso and CPA were simultaneously applied. CPA alone caused a significant decrease in the phosphorylation state of these two proteins. 4. From these results we conclude that A1-purinergic receptor stimulation does not inhibit beta-adrenergic receptor-mediated phosphorylation of myofilament proteins, nor does it alter the Ca2+ sensitivity of isometric tension at the level of the myofilaments. However, A1-receptor stimulation does decrease Vo at the level of the myofilaments by a mechanism that is independent of beta-adrenergically mediated phosphorylation of TnI and C-protein.
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PMID:Slowing of shortening velocity of rat cardiac myocytes by adenosine receptor stimulation regardless of beta-adrenergic stimulation. 747 28


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