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 recent observation that ammonium sulfate stabilizes cell-surface [3H]cyclic AMP binding in Dictyostelium discoideum (Van Haastert, P., and Kien, E. (1983) J. Biol. Chem. 258, 9636-9642) led us to attempt to identify the surface cAMP receptor by photoaffinity labeling with 8-azido-[32P]cAMP using this stabilization technique. 8-azido-[32P]cAMP specifically labeled a polypeptide which migrates as a closely spaced doublet (Mr = 40,000 to 43,000) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Greater than 60% of the labeled polypeptide was found associated with membranes. This protein was distinguished from the cytosolic regulatory subunit of the cAMP-dependent protein kinase (Mr = 41,000) by differences in developmental regulation, specificity, and subcellular localization. No kinase regulatory subunit was detected in membranes by western blot analysis. Our preliminary observations show that labeling of this doublet correlates closely with cAMP-binding activity, suggesting that it is the surface receptor which mediates chemotaxis and cAMP signaling.
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PMID:Specific photoaffinity labeling of the cAMP surface receptor in Dictyostelium discoideum. 609 28

An adenosine cyclic 3',5'-monophosphate (cAMP) dependent protein kinase has recently been shown to exist in Dictyostelium discoideum and to be developmentally regulated. In this report we have followed the chromatographic behavior of both the holoenzyme and its subunits. A cAMP-dependent holoenzyme could be obtained from the 100000 g soluble fraction after passage through DE-52 cellulose (pH 7.5) and Sephacryl S300. Under conditions of low pH the holoenzyme could be further purified by flat-bed electrofocusing (pI = 6.8). Application of the holoenzyme to electrofocusing at high pH resulted in dissociation of the holoenzyme into a cAMP binding component (pI = 6.1) and a cAMP-independent catalytic activity (pI = 7.4). Dissociation of the holoenzyme into subunits also occurred during histone affinity chromatography and gel filtration chromatography (S300) in the presence of a dissociating buffer. Although the subunit structure was clearly evident during chromatography, the holoenzyme could not be dissociated by simple addition of cAMP to the extract. The catalytic subunit could be purified further by CM-Sephadex, DE-52 cellulose (pH 8.5), histone affinity, and hydrophobic chromatography. The regulatory subunit was further purified by DE-52 cellulose (pH 8.5) and cAMP affinity chromatography. Proof that the cAMP binding activity and the cAMP-independent catalytic activity were in fact the regulatory and catalytic subunits was shown by reconstitution of the cAMP-dependent holoenzyme from the purified subunits. By using these separation procedures, one can obtain from extracts of Dictyostelium the subunits that are free of each other as well as free of any endogenous protein substrates.
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PMID:Chromatographic behavior of cyclic AMP dependent protein kinase and its subunits from Dictyostelium discoideum. 609 60

The distribution of adenosine 3',5'-monophosphate (cyclic AMP) in fields of aggregating amoebae of Dictyostelium discoideum was examined by a novel isotope dilution-fluorographic technique. Cellular cyclic AMP was visualized by its competition with exogenous 3H-labeled cyclic AMP for high-affinity binding sites on protein kinase immobilized on a Millipore filter used to blot the monolayer. The cyclic AMP was distributed in spiral or concentric circular wave patterns which centered on the foci of the aggregations. These patterns were correlated with those of cell shape change that propagate through the monolayers: cells in regions of high concentrations of cyclic AMP were elongated (presumably moving up a cyclic AMP gradient), whereas those in regions of low cyclic AMP concentrations were randomly directed. The highest cyclic AMP concentrations were about 10(-6)M. The widths of the regions of elevated cyclic AMP were about 0.3 to 1 millimeter which, assuming a wave velocity of 300 micrometers per minute, suggests that a cell signals for about 1 to 3 minutes. These observations support the hypothesis that the aggregation process in Dictyostelium is mediated by the periodic relay of cyclic AMP signals and suggest a simple scheme for the dynamics of the aggregation process.
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PMID:Adenosine 3',5'-monophosphate waves in Dictyostelium discoideum: a demonstration by isotope dilution--fluorography. 625 34

We analyze the conditions under which sustained oscillations develop in a biochemical system regulated autocatalytically by reversible, covalent enzyme modification. The analysis applies, for example, to the situation where adenylate cyclase (or guanylate cyclase) is activated through phosphorylation by a cAMP (or cGMP)-dependent protein kinase. The model then provides a non-allosteric mechanism for the periodic generation of cAMP or cGMP pulses. For certain parameter values close to those that produce oscillations, the system is excitable since it can amplify in a pulsatory manner suprathreshold perturbations. The results on excitable and oscillatory behavior are discussed in relation with the mechanism of cAMP relay and oscillation in the slime mold Dictyostelium discoideum.
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PMID:Metabolic oscillations in biochemical systems controlled by covalent enzyme modification. 626 42

Cyclic AMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) in Dictyostelium discoideum was shown to be developmentally controlled. No activity was measured in vegetative cells, but activity increased rapidly during differentiation. A simple procedure for the isolation of the catalytic subunit of the kinase from aggregating cells is presented. The cyclic AMP-dependent holoenzyme could be reconstituted by adding purified D. discoideum cyclic AMP-binding protein. Molecular weight, kinetic parameters, pH dependence and affinity for cyclic AMP were determined for the enzyme. Most properties are similar to those of cyclic AMP-dependent kinase from mammalian cells.
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PMID:Isolation and properties of cyclic AMP-dependent protein kinase from Dictyostelium discoideum. 631 30

A cyclic-AMP-independent nuclear protein kinase has been purified from Dictyostelium discoideum amoebae. The purification procedure involves chromatography of DEAE-Sephadex, phosphocellulose and heparin-Sepharose. The purified enzyme phosphorylates threonine and serine of acidic proteins as casein and phosvitin. Phosphorylation of casein is stimulated by spermine. The kinase requires Mg2+ and can utilize both ATP and GTP as phosphoryl donors. Heparin is a potent inhibitor of the enzyme, being the protein kinase activity fully inhibited at concentrations of 0.5 micrograms/ml. One polypeptide of molecular mass 38 kDa was the major protein band present in the purified kinase preparation as estimated by NaDodSO4 denaturing polyacrylamide gel electrophoresis. This band belongs to the protein kinase because it is the only one that is observed associated with the protein kinase activity when the enzyme preparation is centrifuged in glycerol gradients. The 38-kDa polypeptide is also the major product of autophosphorylation of the enzyme preparation. The enzymatic properties allow to classify the enzyme as a type-II casein kinase. However, its structural properties are different from the mammalian type-II casein kinases and make the D. discoideum enzyme more similar to the plants type-II casein kinases.
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PMID:Purification and properties of cAMP-independent nuclear protein kinase from Dictyostelium discoideum. 632 82

The cAMP-dependent protein kinase of the cellular slime mold, Dictyostelium discoideum, is developmentally regulated; there is an approximately 4-fold increase in activity during development. The incorporation of [3H]leucine into the enzyme demonstrates that there is de novo synthesis of the cAMP-dependent protein kinase. The activities of the catalytic and regulatory subunits increase in parallel. The maximal rate of increase of cAMP-dependent protein kinase activity precedes "tip" formation, a stage of development characterized by a sharp increase in mRNA complexity. The high level of cAMP-dependent protein kinase activity, attained at this stage of development, persists when aggregates are dispersed and the amoebae are kept in suspension without added cAMP. The synthesis of the developmentally regulated mRNAs under these conditions is dependent on exogenous cAMP. The increase in cAMP-dependent protein kinase activity during development does not require sustained cell-cell contact insofar as it occurs in single cell suspensions of amoebae. Furthermore, the increase does not require exogenous cAMP, although added cAMP stimulates the synthesis of the enzyme to a level higher than that found, when cAMP is not added. These observations support the hypothesis that in D. discoideum cAMP-dependent protein kinase mediates the effects of cAMP on development.
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PMID:A cytosolic cyclic AMP-dependent protein kinase in Dictyostelium discoideum. II. Developmental regulation. 632 17

Polysphondylium pallidum is a cellular slime mold in which, unlike in Dictyostelium discoideum, cAMP is not the chemotactic agent. The occurrence of a cAMP-dependent protein kinase in D. discoideum was demonstrated earlier and we suggested that it may mediate the intracellular effects of cAMP on the development of the organism, particularly since an increase in the amount of the enzyme during development was noted. In D. discoideum cAMP plays a dual role insofar as it serves both as chemotactic agent and as second messenger; it was of interest therefore, to determine whether a cAMP-dependent protein kinase occurred in P. pallidum. We found a cAMP-dependent protein kinase in P. pallidum using Kemptide as substrate. The regulatory subunit of the enzyme has an apparent molecular weight of 41,000 and seems to be similar in its properties with that isolated earlier from D. discoideum. The cAMP-dependent protein kinase catalytic subunits from the two species are also similar. Furthermore, there is a developmentally regulated, parallel, two- to threefold increase in the two subunits of the cAMP-dependent protein kinase in P. pallidum. The increase occurs before aggregates are formed. These findings are compatible with a role of the intracellular cAMP and of the cAMP-dependent protein kinase in the development of P. pallidum.
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PMID:An increase of cAMP-dependent protein kinase during development in Polysphondylium pallidum. 654 35

A cAMP-dependent protein kinase was isolated and partially purified from Dictyostelium discoideum. The cytosolic holoenzyme has an apparent Mr = 160,000-180,000; its activity was stimulated significantly by cAMP when Kemptide served as substrate. The enzyme was dissociated and the regulatory subunit purified by affinity chromatography on 8-aminoethylamino-cAMP. Only one type of regulatory subunit was found; it has an apparent Mr = 41,000 and is a substrate for the in vitro phosphorylation by the homologous catalytic subunit and by purified bovine catalytic subunit. Antibody against the regulatory subunit was prepared. The D. discoideum catalytic subunit was separated from cAMP-independent protein kinase by chromatofocusing. The apparent molecular weight of the catalytic subunit of the D. discoideum cAMP-dependent protein kinase is 33,000 and its pI is 6.4. The enzyme catalyzed the phosphorylation of bovine RII but not of RI regulatory subunit and was inhibited by high concentrations of the inhibitor of mammalian cAMP-dependent protein kinase. The evolution of the functional domains of cAMP-dependent protein kinases is discussed on the basis of a comparison of the analogous D. discoideum and vertebrate enzymes.
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PMID:A cytosolic cyclic AMP-dependent protein kinase in Dictyostelium discoideum. I. Properties. 670 57

Residues 40-300 of the mammalian catalytic (C) subunit of cAMP-dependent protein kinase define a conserved bilobal catalytic core shared by all eukaryotic protein kinases. Contiguous to the core is an extended amphipathic alpha-helix (A helix). Trp30, a prominent feature of this helix, fills a deep hydrophobic pocket between the two lobes on the surface opposite to the active site. The C subunit in Dictyostelium discoideum shows sequence conservation of residues 40-350 with the mouse enzyme but contains an N-terminal extension of 332 residues. A sequence corresponding to the A helix contiguous to the core is absent. However, we have now identified a remote A-helix motif (residues 77-98). When the core of the Dictyostelium C subunit was modeled, based on the mouse C subunit, complementarity between this putative A helix and the surface of the core was found to be conserved. Analysis of other protein kinases reveals that the A-helix motif is not restricted to cAMP-dependent protein kinase. In the Src-related family of protein kinases, for example, an A helix is very likely contiguous to the core, thus serving as a linker between the conserved catalytic core and the Src homology 2 domain. We predict that an A-helix motif complementary to the core will be a conserved feature of most eukaryotic protein kinases.
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PMID:A conserved helix motif complements the protein kinase core. 750 72


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