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)

Partially purified rabbit skeletal muscle phosphorylase phosphatase (EC 3.1.3.17; phosphoprotein phosphohydrolase) was inactivated when it was incubated with exogenous cyclic AMP-dependent protein kinase (EC 2.7.1.37; ATP:protein phosphotransferase), cyclic AMP, and ATP-Mg. Subsequent separation of the phosphatase by acrylamide gel electrophoresis or sucrose density centrifugation resulted in reactivation of the enzyme. The phosphatase decreased in molecular weight from approximately 70,000 to 52,000, and a phosphorylated inhibitor with molecular weight of 26,000 was found. Reactivation of phosphatase also occurred when it was incubated with MnCl2 or trypsin. The inhibitor was effective at less than 10(-8) M and was relatively heat stable. Its activity was destroyed by tryptic digestion and by dephosphorylation by a Mn-stimulated phosphatase. These observations support the possibility that phosphorylase phosphatase activity is controlled by cyclic AMP-dependent protein kinase and a Mn-stimulated phosphatase by a reaction involving phosphorylation and dephosphorylation of a protein phosphatase inhibitor.
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PMID:Inactivation of rabbit muscle phosphorylase phosphatase by cyclic AMP-dependent kinas. 17 49

Partial separation of protein kinase activity from rhodopsin in isolated bovine retinal photoreceptor outer segments was accomplished by mild ultrasonic treatment followed by ultracentrifugation. Residual kinase activity in the rhodopsin-rich sediment was destroyed by chemical denaturation which did not affect the spectral properties of the rhodopsin. The retinal outer segment kinase was found to be specific for rhodopsin, since in these preparations it alone of several bovine protein kinases was capable of phosphorylating rhodopsin in the light. The phosphorylation reaction apparently requires a specific conformation of the rhodopsin molecule since it is abolished by heat denaturation of rhodopsin, and it is greatly reduced or abolished by treatment of the visual pigment protein with potassium alum after the rhodopsin has been "bleached" by light. When kinase and rhodopsin or opsin fractions were prepared from dark-adapted and bleached outer segments and the resultant fractions were mixed in various combinations of bleached and unbleached preparations, the observed pattern of light-activated phosphorylation was consistent only with the interpretation that a conformational change in the rhodopsin molecule in the light exposes a site on the visual pigment protein to the kinase and ATP. These results rule out the possibility of a direct or indirect (rhodopsin-mediated) light activation of the kinase. Finally, phosphorylation of retinal outer segment protein in monochromatic lights of various wavelengths followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicates that both rhodopsin and the higher molecular weight visual pigment protein reported by several laboratories have the same action spectrum for phosphorylation. This result is consistent with the suggestion that the higher molecular weight species is a rhodopsin dimer.
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PMID:Mechanism and specificity of rhodopsin phosphorylation. 17 16

In the absence of added hemin, protein synthesis in rabbit reticulocyte lysates proceeds at maximal linear rates for several minutes and then ceases abruptly. Inhibition involves the action of a translational inhibitor whose formation is regulated by hemin. Addition of the isolated inhibitor to hemin-supplemented lysates produces an inhibition of protein chain initiation similar to that observed in heme-deficiency. The inhibitor has been purified over 300-fold and contains a protein kinase activity that copurifies with the inhibitory function. With calf thymus histone II as the phosphate receptor, the inhibitor-associated protein kinase requires ATP as the phosphorylating agent. Cycle AMP stimulates kinase activity 5- to 8-fold; the concentration of cycle AMP required for halfmaximal activity is 4 X 10-8 M. Preincubation of the inhibitor in the presence of cyclic AMP significantly reduces cyclic AMP-dependent phosphorylation and inhibitory activity. The corresponding protein kinase activity from hemin-supplemented lysates displays reduced cyclic AMP-dependency and little or no inhibitory activity. These findings suggest that the protein kinase activity associated with the purified translational inhibitor is involved in the mechanism of inhibition of initiation observed in hemedeficient reticulocyte lysates.
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PMID:Association of a cyclic AMP-dependent protein kinase with a purified translational inhibitor isolated from hemin-deficient rabbit reticulocyte lysates. 17 78

Experiments with cold exposure confirmed previous studies indicating that the endogenous protein acitvator of phosphodiesterase (PDEA) isolated by Cheung participates in the in vivo regulation of 3':5'-cyclic adenosine monophosphate (cAMP) in adrenal medulla. This activator of cAMP phosphodiesterase (PDE) (3':5'-cyclic-AMP 5'-nucleotidohydrolase, EC 3.1.4.17) is present in the particulate as well as the soluble fractions of rat brain. It was found that a purified cAMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37), in the presence of ATP and cAMP, stimulates 3-fold the release of PDEA from the particulate fraction of rat brain and adrenal medulla. The substrate for this phosphorylation could be either a membrane protein that binds PDEA or PDEA itself. In vivo evidence, however, obtained by injecting rats intraventricularly with [gamma-32P]ATP, indicates that the PDEA does not contain radioactive phosphate in its structure. Also, PDEA could not be phosphorylated by protein kinase in vitro. The following mechanism is postulated: when the intracellular content of cAMP increases it activates a protein kinase which phosphorylates a PDEA-binding membrane protein and releases PDEA. In turn this binds to activator-deficient high Km PDE and decreases its Km to facilitate the hydrolysis of the increased concentration of cAMP.
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PMID:Regulation of transsynaptically elicited increase of 3':5'-cyclic AMP by endogenous phosphodiesterase activator. 17 3

An increase in activity of disulphide reductase system (DRS) in supernatant of liver tissue was caused by 3',5'-AMP, ATP, GTP, UTP, Mg2+, Ca2+, EDTA, protamine, noradrenaline and F-. The effect was connected with arsenite resistant fraction of DRS. After rapid homogenization the effect of noradrenaline disappeared and the effects of ATP, GTP, UTP and Ca2+ were distinctly decreased. Treatment with adsorbents prevented the effects of 3',5,-AMP, ATP and EDTA and markedly decreased the effects of protamine and Mg2+. A protein inhibitor of protein kinase prevented completely the activation of DRS with 3',5'-AMP, ATP, GTP, UTP and noradrenaline and distinctly decreased the effect of protamine, Mg2+ and Ca2+ but did not alter the influence of EDTA. Addition of 2',3'-AMP blocked the effect of 3',5-AMP, ATP and Mg2+ but did not influence the effect of protamine and EDTA. The data obtained suggest that protein kinase participated in activation of DRS by most of the regulators.
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PMID:[Study of mechanisms of regulation of disulphide reductase in mouse liver]. 17 2

A single cyclic AMP-dependent protein kinase (EC 2.7.1.37) has been isolated from human platelets by using DEAE-cellulose ion-exchange chromatography and Sephadex G-150 gel filtration. The molecular weight of the protein kinase was estimated to be 86 490. In the presence of cyclic AMP, the protein kinase could be dissociated into a catalytic subunit of molecular weight 50 000, and either one regulatory subunit of molecular weight 110 000 or two regulatory subunits of molecular weights 110 000 and 38 100, depending on the pH used. Recombination of either of the regulatory subunits with the catalytic subunit restored cyclic AMP-dependency in the catalytic subunit. The apparent Km for ATP in the presence of 10 muM Mg2+ was 4 muM (plus cyclic AMP) and 4.3 muM (minus cyclic AMP). The concentration of cyclic AMP needed for half-maximal stimulation of the protein kinase was 0.172 muM and apparent dissociation constants of 3.7 nM (absence of MgATP) and 0.18 muM (presence of MgATP) were exhibited by the "protein kinase-cyclic AMP complex". The enzyme required Mg2+ for maximum activity and showed a pH optimum of 6.2 with histone as substrate. In addition to four major endogenous platelet protein acceptors of apparent molecular weights 45 000, 28000, 18 500, and 11 100, the platelet protein kinase also phosphorylated the exogenous acceptor proteins thrombin, collagen and histone, all capable of inducing platelet aggregation. Prothrombin, a nonaggregating agent, was not phosphorylated.
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PMID:Adenosine cyclic 3',5'-monophosphate-dependent protein kinase from human platelets. 17 39

1. Cyclic-AMP dependent protein kinases, resolved by chromatography on DEAE-cellulose and hydroxylapatite, catalysed the phosphorylation of rat liver pyruvate kinase and calf thymus histones by [gamma32P]ATP. [32P]phosphopeptides, from acid hydrolysates of pyruvate kinase phosphorylated by the different protein kinase fractions, displayed identical electrophoretic patterns. Phosphorylation inhibited pyruvate kinase activity. 2. Full activity was restored when phosphorylated pyruvate kinase was dephosphorylated by a histone phosphatase from the soluble fraction of rat liver. These results are consistent with the hypothesis that pyruvate kinase is regulated by phosphorylation-dephosphorylation reactions.
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PMID:Regulation in vitro of rat liver pyruvate kinase by phosphorylation-dephosphorylation reactions, catalyzed by cyclic-AMP dependent protein kinases and a histone phosphatase. 17 40

The protein kinase activities of a transplantable, insulin-producing hamster islet cell tumor were characterized using gel filtration, sucrose density gradient centrifugation and acrylamide gel electrophoresis. The post-microsomal supernatant fluid contains 70-80% of the protein kinase activity present in crude homogenates. A cAMP-dependent protein kinase, PK I (Mr 170,000), represents 25% of the soluble protein kinase activity assayed with protamine as substrate. It dissociates in the presence of cAMP into a cAMP-binding protein, R2 (Mr 90,000) and a catalytic subunit C (Mr 33,000). The dissociation induced by cAMP seems to be facilitated by the addition of Mg2+ and ATP. The regulatory subunit, R2, changes its gel filtration pattern in the presence of 0.5 M NaCl suggesting dissociation into a smaller subunit, R1 (Mr 44,000). By analogy with purified beef heart protein kinase (Erlichman et al., 1973) and skeletal muscle protein kinase, PK I. The presence in crude homogenates of a free cAMP-binding protein indistinguishable from the R2 derived by dissociation of PK I, suggests that PK I is partially dissociated in vivo. A cAMP-independent (casein) kinase (Mr 210,000) elutes with PK I on columns of Sepharose 6B. Another cAMP-independent protein kinase, PK II (Mr 88,000), is the predominatn form of soluble protein kinase accounting for approximately 75% of the soluble protein kinase activity detected using protaimine as substrate. This cAMP-independent protein kinase changes its gel filtration pattern in the presence of 0.5 M NaCl giving rise to a form which appears to have the same Mr (33,000) as the catalytic subunit of PK I. Studies comparing the catalytic subunit C of PK I with PK II and its salt-induced smaller molecular form demonstrate facile association of C with the cAMP-binding protein of purified bovine heart protein kinase to yield a hybrid holoenzyme, whereas PK II and its smaller form fail to recombine in this fashion. The 33,000 dalton forms derived from PK I (by cAMP) and PK II (by salt) also show different substrate specificities. It would appear, therefore, that pK II is a cAMP-independent protein kinase unrelated to PK I.
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PMID:Characterization of the protein kinases in a transplantable islet cell tumor of the Syrian hamster. 17 65

Effects of cyclic adenosine 3':5'-monophosphate (cyclic AMP)-dependent protein kinase were studied in sarcoplasmic reticulum prepared from cardiac and slow and fast (white) skeletal muscle. Cyclic AMP-dependent protein kinase failed to catalyze phosphorylation of fast skeletal muscle microsomes as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cyclic AMP-dependent protein kinase was without effect on calcium uptake by these microsomes. Treatment of cardiac microsomes obtained from dog, cat, rabbit, and guinea pig with cyclic AMP-dependent protein kinase and ATP resulted in phosphorylation of a 22,000-dalton protein component in the amounts of 0.75, 0.25, 0.30, and 0.14 nmol of phosphorus/mg of microsomal protein, respectively. Calcium uptake by cardiac microsomes was stimulated 1.8- to 2.5-fold when microsomes were treated with cyclic AMP-dependent protein kinase. Protein kinases partially purified from bovine heart and rabbit skeletal muscle were both effective in mediating these effects on phosphorylation and calcium transport in dog cardiac sarcoplasmic reticulum. Slow skeletal muscle sarcoplasmic reticulum also contains a protein with a molecular weight of approximately 22,000 that can be phosphorylated by protein kinase. Phosphorylation of this component ranged from 0.005 to 0.016 nmol of phosphorous/mg of microsomal protein in dog biceps femoris. A statistically significant increase in calcium uptake by these membranes was produced by the protein kinase. Increases in protein kinase-catalyzed phosphorylation of a low molecular weight microsomal component and in calcium transport by sarcoplasmic reticulum of cardiac and slow skeletal muscle may be related to the relaxation-promoting effects of epinephrine seen in these types of muscle. Conversely, the absence of a relaxation-promoting effect of epinephrine in fast skeletal muscle may be associated with the lack of effect of cyclic AMP and protein kinase on calcium transport by the sarcoplasmic reticulum of this type of muscle.
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PMID:Effects of adenosine 3':5'-monophosphate-dependent protein kinase on sarcoplasmic reticulum isolated from cardiac and slow and fast contracting skeletal muscles. 17 60

Testicular and cauda epididymal sperm were obtained via catheters previously implanted in the rete testis and proximal vas deferens of bulls and were used to examine the relationships among sperm motility, cyclic adenosine 3':5'-monophosphate (cAMP) level, adenine nucleotide levels, and rates of glucose and oxygen consumption. Testicular, cauda epididymal, and ejaculated sperm contain cAMP-stimulated protein kinase, adenylate cyclase, and nucleotide phosphodiesterase. Treatment of the nonmotile testicular sperm with phosphodiesterase inhibitors resulted in a doubling of cellular cAMP concentration and a 25% increase in their glucose consumption. No change in motility, ATP level, or rate of oxygen consumption was observed. Sperm in neat cauda epididymal semen had flagellating tails but no progressive motility. Dilution of these sperm into glucose-containing buffer resulted in an increase in intracellular cAMP concentration and a decrease in ATP level with concomitant increases in ADP and AMP levels. These biochemical changes occurred within 30 s after dilution and apparently preceded the initiation of progressive motility by most cells. Since sperm in neat cauda epididymal semen became progressively motile when diluted with neat cauda epididymal plasma as well as accessory sex gland fluid or buffer, composition of the fluid surrounding the sperm is not responsible for the initiation of progressive motility upon dilution nor does cauda epididymal plasma contain an inhibitory factor. Perhaps release from contact immobilization provides the stimulation for the initial acquisition of progressive motility by cauda epididymal sperm. We conclude that during epididymal passage sperm develop from a cell physically unresponsive to changes in cAMP concentration to a form which initiates progressive motility upon changes in cAMP concentration.
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PMID:Adenine nucleotide changes at initiation of bull sperm motility. 17 61


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