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)

The response of the Na efflux in unpoisoned barnacle fibers to 10 mM theophylline is biphasic; i.e., inhibition is followed by stimulation. The stimulatory response is unaffected by ouabain. Fibers pretreated with ouabain show no transitory inhibition when 10 mM theophylline is applied, but show prompt stimulation the magnitude of which is comparable to that observed with unpoisoned fibers. The same holds true for lower concentrations of theophylline. Prior injection of 500 mM EGTA completely abolishes the biphasic action of 10 mM theophylline. External application of 10 mM theophylline following removal of external Ca2+ fails to bring about a biphasic effect. Ca2+ restoration, however, results in a moderate rise in the Na efflux. External application of 10 mM theophylline stimulates the Na efflux into Ca2+-free artificial seawater (ASW) when the test fibers are pretreated with ouabain. Injection of the protein inhibitor of Walsh leads to reduced stimulation by 10 mM theophylline of the Na efflux in unpoisoned fibers. Injection of the protein inhibitor of Corbin into unpoisoned fibers leads to reduced stimulation by 10 mM theophylline. Injection of cAMP into ouabain-poisoned fibers, following internal application of Corbin's inhibitor and external application of 10 mM theophylline, fails to cause a marked rise in the ouabain-insensitive Na efflux. Injection of Corbin's inhibitor into ouabain-poisoned fibers, following the onset of peak stimulation by 10 mM theophylline, fails to reduce the Na efflux. Fibers injected with 1 mM and 100 mM EGTA and exposed to 10 mM theophylline show a marked reduction in the response of the ouabain-insensitive Na efflux to injected cAMP when the concentration of theophylline is 10 mM. A poor response to injected cAMP is also seen in fibers bathed in Ca-free ASW containing 10 mM theophylline. Theophylline (10 mM) fails to cause an enhanced stimulation of the ouabain-insensitive Na efflux into Ca-free 3 mM-HEPES ASW or 10 mM-Ca2+ -3mM-HEPES ASW following the addition of protons to the bathing medium. An enhanced response is similarly not observed with injected cAMP following the addition of theophylline to the bathing medium. Injection of 8-fluorotheophylline, 3-isobutyl-1-methylxanthine and doxantrazole leads to a marked reduction in the response of the ouabain-insensitive Na efflux to injected cAMP. Contraction always takes place upon injecting these substances. These results are in keeping with the theory that theophylline acts chiefly by reducing myoplasmic pCa(pCa=-log10[Ca2+]), and that a reduced pCa leads to stimulation of the ouabain-insensitive Na efflux as the result of activation of the cGMP-dependent protein kinase system by newly formed cGMP.
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PMID:Mode of action of theophylline on sodium efflux in barnacle muscle fibers. 20 85

Calcium transport by cardiac sarcoplasmic reticulum (SR) was compared in hyperthyroid (HT) and euthyroid (ET) rats. Both Ca2+ uptake (97 +/- 3.1 nmol/mg per min in HT vs. 63 +/- 2.9 nmol/mg per min in ET, P less than 0.01) and CA2+ -stimulated ATPase activity (61 +/- 4.1 vs. 37 +/- 1.6 nmol Pi/mg per min, P less than 0.01) were higher in the thyroxine-treated animals. These changes were accompanied by enhanced cyclic AMP-dependent phosphorylation of cardiac SR in hyperthyroid rats (180 +/- 4.3 pmol Pi/mg per min vs. 117 +/- 4.2 pmol Pi/mg per min, P less than 0.01). SDS-polyacrylamide gel electrophoresis of cardiac SR showed that phosphorylation of a 22,000-dalton protein (phospholamban) primarily accounted for the differences between the two groups. There was no difference in the rate of SR dephosphorylation by endogenous phosphoprotein phosphatase between HT and ET rats. Differences in cyclic AMP-dependent phosphorylation between the two groups were blunted in the presence of excess exogenous cyclic AMP-dependent protein kinase. These results suggest that increased levels or activity of endogenous cyclic AMP-dependent protein kinases may partially explain enhanced calcium transport by the cardiac SR of hyperthyroid animals.
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PMID:Enhanced phosphorylation of myocardial sarcoplasmic reticulum in experimental hyperthyroidism. 20 50

The role of adenosine 3',5'-monophosphate (cyclic AMP)-dependent membrane phosphorylation in the regulation of microsomal calcium transport in rat aortic smooth muscle was studied. Cyclic AMP-dependent protein kinase augmented the phosphorylation of serine residues in a microsomal protein component with a molecular weight of about 44,000 (determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and the majority of 32P incorporation was in serine residue(s). The phosphorylated protein had stability characteristics of a phosphoester. The phosphorylated substrate was not extracted from the trichloroacetic acid (TCA) precipitate with organic solvents or by suspension in hot TCA; and the demonstrated hydroxylamine insensitivity suggested that the substrate was not lipid or nucleic acid. Intrinsic phosphoprotein phosphatase cleaved the labeled phosphate from the cyclic AMP-stimulated microsomes in the first 5 min of incubation. Microsomes phosphorylated in the presence of 1 micron cyclic AMP or 1 micron cyclic AMP plus 0.1 mg/ml protein kinase exhibited enhanced calcium uptake. We suggest that reversible phosphorylation of microsomal membranes may play an important role in the regulation of aortic microsomal calcium transport by cyclic AMP.
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PMID:Role of cyclic AMP in rat aortic microsomal phosphorylation and calcium uptake. 20 57

A protein kinase which depends on the simultaneous presence of Ca2+ and the modulator protein for its histone phosphorylation activity has been demonstrated in rabbit skeletal muscle and partially purified. The purified enzyme was not activated by cAMP, cGMP, or incubation with trypsin. Nor was the enzyme inhibited by the protein inhibitor of cAMP-dependent protein kinase. In addition to histone, myosin light chains and phosphorylase kinase served as substrates for the protein kinase, and their phosphorylation also depended on the presence of Ca2+ and the modulator protein. The phosphorylation of phosphorylase kinase was accompanied with a marked activation of the enzyme. The results suggest that the protein kinase has multiple functions and may be involved in the mediation of Ca2+ effects in many biological processes. It is proposed that this enzyme be designated as the modulator-dependent protein kinase. The modulator-dependent protein kinase may be identical to the myosin light chain kinase; chicken gizzard light chain kinase has been shown activatable by the modulator protein (Dabrowska, R., Sherry, J. M. F., Aramatorio, D. K., and Hartshorne, D. J. (1978) Biochemistry 17, 253-258).
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PMID:The modulator-dependent protein kinase. A multifunctional protein kinase activatable by the Ca2+-dependent modulator protein of the cyclic nucleotide system. 20 40

Two inhibitors of cyclic AMP phosphodiesterase (3':5'-cyclic-AMP 5'-nucleotidohydrolase, EC 3.1.4.17), theophylline and papaverine, inhibit the maturation of Xenopus laevis oocytes induced by four different stimuli: human chorionic gonadotropin, progesterone, testosterone, and lanthanum ions. Addition of 1 mM cyclic AMP to the medium delays maturation by approximately 2 hr. Papaverine, theophylline, and cyclic AMP inhibit amino acid incorporation into oocyte proteins by 50% or more but do not inhibit amino acid uptake. The capacity of theophylline to block maturation and protein synthesis is reversed in a parallel fashion by addition of 1-5 mM calcium ion to the medium. Addition of papaverine, theophylline, and cycloheximide to oocytes at different times after hormonal treatment shows that the step sensitive to blockage by the three drugs is coincident and precedes germinal vesicle breakdown by about 1.5 hr. Theophylline and papaverine do not increase endogenous cyclic AMP levels in oocytes but do block the decrease of cyclic AMP levels observed 3 hr after progesterone treatment. Both drugs inhibit oocyte cyclic AMP phosphodiesterase measured in vivo and severely inhibit the stimulus of calcium uptake caused by progesterone and human chorionic gonadotropin. These results suggest that cyclic AMP, theophylline, and papaverine may block oocyte maturation by inhibiting protein synthesis, possibly via a cyclic AMP-dependent protein kinase as shown in reticulocytes [Datta, A., De Haro, C., Sierra, J. & Ochoa, S. (1977) Proc. Natl. Acad. Sci., USA 74, 1463-1467].
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PMID:Amphibian oocyte maturation and protein synthesis: related inhibition by cyclic AMP, theophylline, and papaverine. 20 89

Filamin is a high molecular weight actin-binding protein found in large quantities in smooth muscle and other non-muscle cells. We have studied the phosphorylation of filamin in a mammalian smooth muscle, the guinea pig vas deferens. Intact vas deferens incorporated [32P]orthophosphate into filamin. Incubation of particulate fractions of vas deferens with [gamma-32P]ATP resulted in 32P-labeling of filamin. Cyclic AMP stimulated this phosphorylation, whereas cyclic GMP and Ca2+ had no effect. Purified vas deferens filamin can be phosphorylated by purified cyclic AMP-dependent protein kinase. We have compared cyclic AMP and cyclic GMP effects on phosphorylation in smooth muscle. Cyclic GMP stimulated phosphorylation of two particulate proteins, G-I (Mr = 130,000) a protein previously described by Casnellie, J. E., and Greengard, P. (1974) Proc. Natl. Acad, Sci. U.S.A. 71, 1891-1895 and G-III (Mr = 240,000). Both proteins and the kinase responsible for their phosphorylation appear to be membrane-bound. Phosphorylation of both proteins is stimulated by cyclic GMP (Ka = 3 x 10(-8) M), cyclic AMP (Ka = 3 x 10(-7) M), and to a lesser degree by Ca2+. In contrast, filamin phosphorylation is due to a soluble kinase stimulated only by cyclic AMP (Ka = 3 x 10(-7) M) and not by cyclic GMP or Ca2+.
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PMID:Cyclic AMP-dependent phosphorylation of filamin in mammalian smooth muscle. 20 8

Filamin is a high molecular weight protein that binds to actin filaments in cells. It is found in large amounts in several different cells and tissues, including smooth muscle, fibroblasts, platelets, and macrophages. It is immunologically related to the previously described macrophage high molecular weight actin-binding protein but clearly different from erythrocyte spectrin. Filamin is a phosphoprotein; it is phosphorylated in vivo in intact tissues and cells. It can be phosphorylated in vitro with endogenous kinases; cyclic AMP stimulates this phosohorylation. Furthermore, the purified protein can be phosphorylated by purified cyclic AMP-dependent protein kinase. In smooth muscle homogenates, the stimulation of filamin phosphorylation by cyclic AMP is specific. Cyclic GMP and Ca2+ do not increase its phosphorylation, although they do stimulate phosphorylation of other proteins.
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PMID:Cyclic AMP-dependent phosphorylation of the actin-binding protein filamin. 20 86

Epinephrine rapidly activates phosphorylase in hepatocytes, mainly by a mechanism(s) involving alpha-adrenergic and not beta-adrenergic receptors. The alpha-adrenergic mechanism does not involve accumulation of cAMP or activation of cAMP-dependent protein kinase. It is impaired when hepatocytes are depleted of calcium by EGTA treatment and is rapidly restored by readdition of calcium. Basal phosphorylase is also lowered by calcium deficiency and rapidly increased by calcium but not other divalent cations. The divalent cation ioniphore A23187 increases phosphorylase a levels in hepatocytes in a calcium-dependent manner. Calcium deficiency does not modify the effects of glucagon, cAMP, or beta-adrenergic activation on phosphorylase. Activation of alpha-adrenergic receptors rapidly increases 45Ca fluxes in hepatocytes. Glucagon produces similar effects, but supraphysiological concentrations are required. The hypothesis is advanced that alpha-adrenergic activation of phosphorylase involves alterations in cell calcium such that there is an increase in cytosolic Ca2+ concentration leading to increased phosphorylase kinase activity. Epinephrine induces greater cAMP accumulation in calcium-depleted cells than in normal cells. The effect is mediated by alpha-adrenergic and not beta-adrenergic receptors. Calcium deficiency also cuases cAMP accumulation in hepatocytes incubated with phenylephrine but does not modify the responses of the cells to isoproterenol, glucagon, or cAMP. Low concentrations of calcium rapidly reverse alpha-adrenergic receptor-mediated cAMP accumulation in calcium-depleted cells. The hypothesis is advanced that calcium normally exerts an inhibitory effect on a linkage between alpha-adrenergic receptors and adenylate cyclase in hepatocytes.
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PMID:Mechanisms of catecholamine actions on liver carbohydrate metabolism. 20 89

The recently discovered heat-stable inhibitor protein of the Ca2+-activated cyclic nucleotide phosphodiesterase (Sharma, R. K., Wirch, E. & Warg, J. H. (1978) J. Biol. Chem., in press) has been purified 238 214-fold from bovine brain extract using an affinity column of the modulator protein--Sepharose 4B conjugate. The purified sample appears to be homogeneous as judged by sodium dodecyl sulphate (SDS) gel electrophoresis. The protein band has a mobility corresponding to that of a polypeptide of molecular weight 68 000. Since the heat-stable inhibitor protein has a molecular weight of 70 000 under nondenaturing conditions, it suggests that it is a monomeric protein. The protein has no inhibitory activity toward the cAMP-dependent protein kinase or protein phosphatase. The purified sample has been tested for various enzyme activities which include ATPase, GTPase, cAMP phosphodiesterase, cGMP phosphodiesterase, 5'-nucleotidase, and protein kinase. None of these activities are exhibited by the purified sample.
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PMID:Purification of the heat-stable inhibitor protein of the Ca2+-activated cyclic nucleotide phosphodiesterase by affinity chromatography. 20 31

Troponin inhibitory factor, TNI, was prepared by affinity chromatography from different mammalian hearts. (i) Structure. These different TNI have the same M.W. (28000), which is higher than that found in rabbit skeletal muscle (23000). Nevertheless they differ with respect of their charge as shown by alkaline urea polyacrylamide gel electrophoresis using cardiac TNI which has previously been bound to an excess of skeletal troponin Ca2+-binding factor. These changes do not correlate with the PO4 content of TNI. They are associated with structural differences demonstrated by peptide mapping of the unfolded molecule after papain treatment. The structure of cardiac TNI from rat and rabbit differs clearly from that of crow and pig. (ii) Biological activity. These different TNI have the same inhibitory effect on skeletal actomyosin. ATPase, the same content of PO4 and the same ability to be phosphorylated in-vitro by a bovine heart c-AMP-dependent protein kinase.
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PMID:A comparative study of the cardiac troponin inhibitory factor (TNI) from mammalians. 20 99


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