Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.12 (PKG)
 2,515 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The stimulatory and inhibitory activities in the crude preparation of protein kinase modulator from dog heart were separated by Sephadex G-100 gel filtration, and the stimulatory modulator was further purified by DEAE-cellulose chromatography. The isolated stimulatory modulator, as the crude modulator preparation, stimulated the activity of the purified guanosine 3':5'-monophosphate (cGMP)-dependent protein kinases of both mammalian and arthropod origins in the presence of cGMP. The cGMP-dependent protein kinases were not activated by cGMP in the absence of either the isolated stimulatory modulator or the crude modulator. The stimulatory modulator, unlike the crude modulator had no effect on the activity of adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase. The stimulatory modulator was a protein since its activity was destroyed by trypsin but was resistant to hydrolysis by DNase, RNase, phospholipase C, and lysozyme. The isolated inhibitory modulator, presumably the same as the protein inhibitor of cAMP-dependent protein kinase reported by Walsh et al. (Wash. D.A., Ashby, C.D., Gonzalez, C., Calkins, D., Fischer. E.H., and Krebs, E.G. (1971) J. Biol. Chem. 246, 1977-1985), depressed the cAMP-stimulated activity of cAMP-dependent protein kinase as did the crude preparation of protein kinase modulator. The isolated inhibitory modulator, unlike the crude preparation, was without effect on cGMP-dependent protein kinase. The present findings provide evidence to support that in mammals there are separate proteins for the stimulatory and the inhibitory activities of protein kinase modulator, in contrast to the modulator from an arthropod tissue (lobster tail muscle, Donnelly et al. (Donnelly, T.E., Jr., Kuo, J.F., Reyes, P.L., Liu, Y.P., and Greengard, P. (1973) J. Biol. Chem. 248, 190-198) which has been shown to possess both activities.
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PMID:Isolation of stimulatory modulator of guanosine 3':5'-monophosphate-dependent protein kinase from mammalian heart devoid of inhibitory modulator of adenosine 3':5'-monophosphate-dependent protein kinase. 18 22

Incubation of purified cyclic guanosine 3':5'-monophospate-dependent protein kinase with [gamma-32P]ATP and Mg2+ led to formation of one 32P-labeled protein, Mr = 75,000, which corresponded to the single protein band detected after polyacrylamide gel electrophoresis in sodium dodecyl sulfate. When electrophoresis was performed without detergent, the labeled protein coincided with the position of cGMP-dependent protein kinase activity. Phosphorylation was enhanced severalfold by either histone or cAMP and was inhibited by the addition of cGMP. Low concentrations of cGMP blocked the stimulatory effects of cAMP or histone (or both). Since neither cAMP-dependent protein kinase nor cGMP-dependent phosphoprotein phosphatase activities were detected in the purified enzyme, we concluded that the cGMP-dependent protein kinase is a substrate for its own phosphotransferase activity and that other protein substrates (histone) and cyclic nucleotides modulate the process of self-phosphorylation.
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PMID:Self-phosphorylation of cyclic guanosine 3':5'-monophosphate-dependent protein kinase from bovine lung. Effect of cyclic adenosine 3':5'-monophosphate, cyclic guanosine 3':5'-monophosphate and histone. 19 21

cAMP-and cGMP-dependent protein kinases have been purified. Each enzyme demonstrates high specificity and affinity for the cyclic nucleotide with binding of two moles of nucleotide per holoenzyme and each enzyme is an ATP: phosphotransferase. The holoenzymes have similar molecular weights and demonstrate similar molecular asymmetry. A structural model relating the two enzymes is proposed. cGMP-dependent protein kinase is proposed to be a dimer composed of two identical protomers in isologous association with the chains arranged in anti-parallel fashion. cAMP-dependent protein kinase is proposed to have a similar structure with a dyad axis of symmetry but with a discontinuity in each chain. These structures account for the differing mechanisms of cyclic nucleotide activation of the two enzymes.
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PMID:A hypothesis concerning the structure of cAMP-and cGMP-dependent protein kinases. 19 41

Homogeneous cGMP-dependent protein kinase catalyzes the rapid incorporation of phosphate, specifically into the inhibitory subunit of purified cardiac troponin with a maximal incorporation of 1 mol of phosphate/mol of troponin. When troponin was incubated in the presence of both cGMP- and cAMP-dependent protein kinases, a maximal incorporation of 1 mol of phosphate/mol of troponin was observed which suggested phosphorylation of the same site by the two kinases. Both cyclic nucleotide-dependent kinases had similar Km values for troponin, but the Vmax value for the phosphorylation reaction catalyzed by cAMP-dependent protein kinase was 12-fold greater than the value obtained for cGMP-dependent protein kinase.
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PMID:Phosphorylation of cardiac troponin by guanosine 3':5'-monophosphate-dependent protein kinase. 20 26

The heat-stable protein (protein kinase modulator), partially purified from fresh bovine heart, possessed the ability to inhibit and stimulate adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase and guanosine 3':5'-monophosphate (cGMP)-dependent protein kinase activities, respectively. The inhibitory activity of protein kinase modulator on cAMP-dependent protein kinase was abolished almost completely by trypsin treatment, while the ability to stimulate cGMP-dependent protein kinase activity was resistant to trypsin. Fractionation by a linear potassium phosphate gradient on DEAE-cellulose column did not clearly separate both activities. Phosphorylation of cardiac microsomal component, "phospholamban" (molecular weight = 22,000), was inhibited almost completely by the saturating amounts of protein kinase modulator. This inhibition of phospholamban phosphorylation by protein kinase modulator was accompanied by a decreased Ca uptake rate that had been stimulated by cAMP-dependent protein kinase. These findings indicate that protein kinase modulator is functional in controlling the cAMP-dependent protein kinase-catalyzed phosphorylation of phospholamban and the rate of calcium transport, lending further support for the previously proposed mechanism, in which phospholamban is assumed to serve as a regulator of calcium transport in cardiac sarcoplasmic reticulum.
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PMID:Effect of protein kinase modulator on cAMP-dependent protein kinase-catalyzed phosphorylation of phospholamban and stimulation of calcium transport in cardiac sarcoplasmic reticulum. 20 86

A heat-stable protein which inhibits cAMP dependent protein kinase was prepared from the bovine thyroid 100,000 X g supernatant. This protein inhibited the cAMP-dependent protein kinase both from bovine thyroid cytosol and bovine thyroid plasma membranes. The inhibitory effect was noncompetitive with histone as substrate of the cytosolic enzyme. The stimulatory modulator for cGMP-dependent protein kinase was separated from the 100,000 X g supernatant by Sephadex G-100 gel filtration. The stimulatory modulator had no stimulating effect on cAMP-dependent phosphorylation, and the inhibitory modulator of cAMP-dependent enzyme had no effect on cGMP-requiring phosphorylations. The inhibitory modulator may regulate cAMP-dependent protein kinase activity in cytosol and plasma membrane, and the stimulatory modulator for cGMP-dependent protein kinase may have a role in thyroid function independent of the cAMP-requiring system.
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PMID:Cyclic nucleotide-dependent protein kinase modulators in thyroid tissue. 22 Dec

The rat cerebellum contains a significant amount of cGMP-dependent protein kinase, cAMP-dependent and cyclic nucleotide-independent protein kinase, and a large concentration of protein kinase inhibitors. These inhibitors are thermostable proteins which can be separated by gel chromatography into two molecular forms: the type 1 and type 2 inhibitors of protein kinase (14). The type 1 inhibitor blocks the rat cerebellar cAMP-dependent protein kinase activity while the type 2 inhibitor blocks the cGMP-dependent protein kinase, the cAMP-dependent protein kinase, and the cyclic nucleotide-independent protein kinases. The activity of the type 2 inhibitor increased or decreased in opposite direction to changes of cerebellar cGMP content generated by injection of 10 mg/kg harmaline 2.5 mg diazepam. No changes of type 1 inhibitor were observed under these conditions. The drug-induced shift of type 2 inhibitor of protein kinase was not mediated by changes in protein synthesis because it persisted after pretreatment with cycloheximide. These results are compatible with the hypothesis that cGMP modulates phosphorylation in cerebellum by changing the relationship between cGMP-dependent protein kinase and type 2 inhibitor content.
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PMID:Action of harmaline and diazepam on the cerebellar content of cyclic GMP and on the activities of two endogenous inhibitors of protein kinase. 22 76

Elevation of either cAMP or cGMP causes smooth muscle relaxation. Whether these effects are mediated through cAMP-dependent protein kinase (cAK), cGMP-dependent protein kinase (cGK), or both is unknown. Pig coronary arteries were treated with sodium nitroprusside (SNP) or atrial natriuretic factor (ANF), relaxants which elevate cGMP, and with isoproterenol or forskolin, relaxants which elevate cAMP. Incubation of the arteries with 10 microM SNP produced a 3.3-fold increase in cGMP without altering cAMP; the cGK activity ratio (-cGMP/+cGMP) in these extracts was increased by 2.6-fold as determined by a newly developed assay, while the cAK activity ratio (-cAMP/+cAMP) was unchanged. The increase in cGK activity ratio by SNP was concentration-dependent and was nearly maximal at 30 s. Treatment of the tissue with 10 nM ANF also increased the cGK activity ratio (2.3-fold), but not that of cAK. 100 microM isoproterenol caused a 2.9-fold elevation of cAMP with no change in cGMP, but both cAK and cGK activity ratios were increased (2.3- and 1.6-fold, respectively). The increase in the cGK activity ratio could be mimicked by cAMP addition to control tissue extracts at the concentration measured in extracts of the isoproterenol-treated tissue. Forskolin (1 and 10 microM) also increased the cGK activity ratio (1.9- and 4.9-fold). The increases in cGK activity observed in extracts suggest that moderate elevation of either cGMP or cAMP causes intracellular cGK activation, thus producing relaxation of vascular smooth muscle.
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PMID:Direct evidence for cross-activation of cGMP-dependent protein kinase by cAMP in pig coronary arteries. 130 58

Affinities of the catalytic subunit (C1) of Saccharomyces cerevisiae cAMP-dependent protein kinase and of mammalian cGMP-dependent protein kinase were determined for the protein kinase inhibitor (PKI) peptide PKI(6-22)amide and seven analogues. These analogues contained structural alterations in the N-terminal alpha-helix, the C-terminal pseudosubstrate portion, or the central connecting region of the PKI peptide. In all cases, the PKI peptides were appreciably less active as inhibitors of yeast C1 than of mammalian C alpha subunit. Ki values ranged from 5- to 290-fold higher for the yeast enzyme than for its mammalian counterpart. Consistent with these results, yeast C1 exhibited a higher Km for the peptide substrate Kemptide. All of the PKI peptides were even less active against the mammalian cGMP-dependent protein kinase than toward yeast cAMP-dependent protein kinase, and Kemptide was a poorer substrate for the former enzyme. Alignment of amino acid sequences of these homologous protein kinases around residues in the active site of mammalian C alpha subunit known to interact with determinants in the PKI peptide [Knighton, D. R., Zheng, J., Ten Eyck, L. F., Xuong, N-h, Taylor, S. S., & Sowadski, J. M. (1991) Science 253, 414-420] provides a structural basis for the inherently lower affinities of yeast C1 and cGMP-dependent protein kinase for binding peptide inhibitors and substrates. Both yeast cAMP-dependent and mammalian cGMP-dependent protein kinases are missing two of the three acidic residues that interact with arginine-18 in the pseudosubstrate portion of PKI. Further, the cGMP-dependent protein kinase appears to completely lack the hydrophobic/aromatic pocket that recognizes the important phenylalanine-10 residue in the N-terminus of the PKI peptide, and binding of the inhibitor by the yeast protein kinase at this site appears to be partially compromised.
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PMID:Structural basis for the low affinities of yeast cAMP-dependent and mammalian cGMP-dependent protein kinases for protein kinase inhibitor peptides. 131 Jun 17

Vasodilators capable of elevating cAMP or cGMP inhibit the activation of human platelets and stimulate the phosphorylation of a 46-kDa protein (vasodilator-stimulated phosphoprotein, VASP) mediated by cAMP-dependent protein kinase (PKA) and cGMP-dependent protein kinase (PKG). The availability of purified proteins and specific antisera against VASP, PKG and the catalytic subunit of PKA enabled us to measure and estimate the concentration of these regulatory proteins in intact human platelets. In addition, the rate of PKA- and PKG-mediated VASP phosphorylation in intact human platelets was estimated. For these calculations, a homogeneous population of human platelets and a homogeneous intracellular distribution of proteins and second messengers was assumed. Unstimulated washed human platelets contain 4.4 microM cAMP and 3.1 microM catalytic subunit of PKA, which is equivalent to 6.2 microM cAMP-binding sites due to PKA. Unstimulated washed human platelets also contain 0.4 microM cGMP and 7.3 microM PKG monomer, equivalent to 14.6 microM cGMP-binding sites due to the PKG. The intracellular concentration of VASP in platelets was estimated to be 25 microM. Treatment of washed human platelets with 10 microM (or 10 mM) prostaglandin E1 (PGE1) elevated the intracellular cAMP concentration to 27 microM (10 microM with 10 nM PGE1) within 30 s, accompanied by a rapid, up to 55% (35%), conversion of VASP from the dephosphorylated form (46-kDa protein) to the phosphorylated form (50-kDa protein). Treatment of washed human platelets with 100 microM (or 1 microM) sodium nitroprusside elevated the platelet cGMP level to 4 microM (0.9 microM with 1 microM sodium nitroprusside) within 2 min, accompanied by a less-rapid VASP phosphorylation of 45% (27% with 1 microM sodium nitroprusside). PGE1 and sodium nitroprusside had no significant effect on human platelet cGMP or cAMP levels, respectively. The results suggest for human platelets that relatively small increase in cAMP levels are required for activation of most of PKA, whereas even several-fold increases in platelet cGMP levels are capable of stimulating only a small fraction of total PKG. This interpretation was also supported by phosphorylation experiments with purified VASP, PKG and catalytic subunit of PKA. The results also support the hypothesis that in human platelets both cAMP/PKA- and cGMP/PKG-regulated VASP phosphorylation are components of an efficient and sensitive signal-transduction pathway, most likely involved in the inhibition of platelet activation.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Concentration and regulation of cyclic nucleotides, cyclic-nucleotide-dependent protein kinases and one of their major substrates in human platelets. Estimating the rate of cAMP-regulated and cGMP-regulated protein phosphorylation in intact cells. 131 68


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