Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.11 (AMPK)
 12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An adenosine 3':5'-monophosphate-dependent protein kinase II (ATP:protein phosphotransferase, EC 2.7.1.37) was partially purified from the cytosol fraction of an exponentially growing culture of Tetrahymena pyriformis. Protein kinase II represented approximately 90% of the cytosolic protein kinase activity. The enzyme had a high degree of substrate specificity for calf thymus and Tetrahymena histones as compared to casein, protamine and phosvitin. The enzyme incorporated the terminal phosphate of ATP into serine and threonine residues of all the histone fractions. The apparent Km of the enzyme for adenosine 3':5'-monophosphate (cyclic AMP) was 1-10-minus 8 M. Protein kinase II was also activated by other cyclic nucleotides with apparent Km values in the range 2.k-10-minus 6 M. Ther specific activity of the cyclic AMP-dependent protein kinase of Tetrahymena decreases markedly from initial high values during the transition from the lag to early log phase of growth. This is followed by a shrp increase in the activity of the enzyme as the log phase of growth progresses. The specific activity of the enzyme increases rapidly during the heat-induced synchronization of Tetrahymena cells. The capacity for rapid phosphorylation of multiple classed of organelle-specific phosphoproteins and the level of cyclic AMP were maximal in Tetrahymena during the earliest phase of growth. These results demonstrate that the cell cycle of Tetrahymena may be coordinated by marked variations in the level of cyclic AMP which in turn regulate the cyclic AMP-dependent protein kinase.
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PMID:Changes in cyclic AMP-dependent protein dinase activity in Tetrahymena pyriformis during the growth cycle. 16 17

Cyclic adenosine 3',5'-monophosphate (cAMP) dependent protein kinase and proteins specifically binding cAMP have been extracted from calf thymus nuclei and analyzed for their abilities to bind to DNA. Approximately 70% of the cAMP-binding activity in the nucleus can be ascribed to a nuclear acidic protein with physical and biochemical characteristics of the regulatory (R) subunit of cAMP-dependent protein kinase. Several peaks of protein kinase activity and of cAMP-binding activity are resolved by affinity chromatography of nuclear acidic proteins on calf thymus DNA covalently linked to aminoethyl Sephrarose 4B. When an extensively purified protein kinase is subjected to chromatography on the DNA column in the presence of 10(-7) M cAMP, the R subunit of the kinase is eluted from the column at 0.05 M NaCl while the catalytic (C) subunit of the enzyme is eluted at 0.1-0.2 M NaCl. When chromatographed in the presence of histones, the R subunit is retained on the column and is eluted at 0.6-0.9 M NaCl. In the presence of cAMP, association of the C subunit with DNA is enhanced, as determined by sucrose density gradient centrifugation of DNA-protein kinase complexes. cAMP increases the capacity of the calf thymus cAMP-dependent protein kinase preparation to bind labeled calf thymus DNA, as determined by a technique employing filter retention of DNA-protein complexes. This protein kinase preparation binds calf thymus DNA in preference to salmon DNA, Escherichia coli DNA, or yeast RNA. Binding of protein kinases to DNA may be part of a mechanism for localizing cyclic nucleotide stimulated protein phosphorylation at specific sites in the chromatin.
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PMID:DNA binding by cyclic adenosine 3',5'-monophosphate dependent protein kinase from calf thymus nuclei. 16 89

Both E. coli and calf thymus DNA polymerase can be phosphorylated by cAMP-dependent protein kinase and phosphorylation appears to stimulate the DNA polymerase reaction. Conversely, dephosphorylation of the polymerase molecule, by a protein phosphatase, inhibits the polymerase reaction.
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PMID:Phosphorylation of DNA polymerase. 17 41

The properties of purified mammalian adenosine 3':5'-cyclic monophosphate (cAMP)- and guanosine 3':5'-cyclic monophosphate (cGMP)-dependent protein kinases were compared. Several physical characteristics of the two enzymes were similar, including size, shape, affinity for cyclic nucleotide binding, and K(m) for ATP. In addition, the amino acid composition of the two proteins indicated a close composition homology (70-90%). Both cyclic nucleotide-dependent protein kinases catalyzed phosphorylation of rat liver pyruvate kinase (EC 2.7.1.40) and fructose 1,6-diphosphatase (EC 3.1.3.11), rabbit skeletal muscle glycogen synthase (EC 2.4.1.11) and phosphorylase b kinase (EC 2.7.1.38), and calf thymus histone H(2)b. The phosphorylation of several synthetic peptides and of trypsin-sensitive and trypsin-insensitive sites in glycogen synthase suggested similar recognition sites on the protein substrates for the two kinases. The cAMP-dependent protein kinase was the better catalyst with each protein or peptides substrate. The results suggest that the two enzymes evolved from a common ancestral protein.
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PMID:Adenosine 3':5'-cyclic monophosphate- and guanosine 3':5'-cyclic monophosphate-dependent protein kinases: possible homologous proteins. 19 77

Synthetic polypeptides were employed as substrates in kinetic analyses of the reaction mechanism for the catalytic subunit of a cyclic AMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) from calf thymus. This enzyme preparation was shown to catalyze the transfer of phosphate from ATP to histone H1 from calf thymus, as well as to two synthetic polypeptides, Arg-Lys-Ala-Ser-Gly-Pro (H1-6) and Arg-Arg-Lys-Ala-Ser-Gly-Pro (H1-7), corresponding to the amino acid sequence about serine-38 in calf H1. A related, basic heptapeptide corresponding to a sequence from pig liver pyruvate kinase, Leu-Arg-Arg-Ala-Ser-Leu-Gly (K), was also a substrate. The stoichiometry of peptide phosphorylation was established in each case as the transfer of 1 mol of phosphate from the gamma position of MgATP to the serine hydroxyl of 1 mol of the peptide. Steady-state, initial-velocity, kinetic parameters were determined for each substrate, using various concentrations of ATP. Under the conditions used, all synthetic peptides reacted with greater maximum velocities than whole histone H1. Nevertheless, the K(m) for H1, 54 muM, was lower than the K(m) values of the synthetic substrates. The most efficient substrate was peptide K, which had a V(max) of 50.6 mumol/min per mg of kinase and a K(m) of 63 muM. In the absence of peptide substrate no ATPase activity was detectable at a sensitivity of 0.05% of the rate of peptide phosphorylation, suggesting that ATP is not cleaved to form an unstable phosphoenzyme complex. The data are consistent with a sequential reaction mechanism involving a ternary complex between enzyme, polypeptide substrate, and ATP.
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PMID:Studies on the mechanism of phosphorylation of synthetic polypeptides by a calf thymus cyclic AMP-dependent protein kinase. 20 Sep 11

A cyclic AMP-like substance has been isolated from higher plant tissues which can be quantitated with the use of a radioimmunoassay similar to that described by A. L. Steiner, D. M. Kipnis, R. Utiger, and C. Parker [(1969) Proc. Natl. Acad. Sci. USA 64, 367-373]. This compound has been extensively purified and is chromatographically distinct from authentic cyclic AMP. This cyclic AMP-like compound inhibited beef heart 3':5'-cyclic-nucleotide phosphodietsterase (3':5'-cyclic-nucleotide 5'-nucleotidohydrolase, EC 3.1.4.17), with half-maximal inhibition occurring at a concentration of 7.6 X 10(-10) M cyclic AMP equivalents. The compound also inhibited cyclic AMP-dependent protein kinase (ATP:protein phosphotransferase; EC 2.7.1.37) from bovine heart, with half-maximal inhibition of mixed histone phosphorylation occurring at 8.0 X 10(-11) M cyclic AMP equivalents. Equipotent inhibition of phosphorylation and associated trace ATPase activity were observed with the purified catalytic subunit of cyclic AMP-dependent protein kinase from calf thymus with a synthetic heptapeptide as substrate. Moreover, steady-state kinetic analysis of this inhibition in the latter system showed it to be nonlinear and noncompetitive versus MgATP.
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PMID:Inhibition of mammalian protein kinase and phosphodiesterase activities by a cyclic AMP-like compound isolated from higher plants. 21 43

The synthesis of cytoplasmic proteins and the activity of cAMP-dependent protein kinase were studied in the thyroid gland and thymus of intact and irradiated (0.05 Gr) embryos and chicks. The increase in labeled amino acid incorporation into proteins of irradiated chicken endocrine organs during postnatal development was more apparent in thyrocytes. Stimulation of protein kinase activity in the thyroid gland and thymus was observed at the same periods of time. It was supposed that minor doses of ionizing radiation stimulate synthetic processes as well as phosphorylation of proteins responsible for differentiation of avian endocrine organs.
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PMID:[Change in protein synthesis and enzyme activity in avian endocrine glands during ontogenesis]. 208 16

While clear evidence exists for the regulation of the phosphorylation of the very basic high mobility group (HMG) and histone chromatin proteins, the physiological role of their phosphorylation remains poorly understood. Elucidation of these roles has been difficult, in part, because of the inability to obtain sufficient quantities of purified phosphorylated derivatives. We have used Mono S cation-exchange chromatography to prepare milligram quantities of pure Ser 6-phosphorylated HMG 14 (Ser 6-PO4-HMG) from unphosphorylated Mono S-purified calf thymus HMG 14 following in vitro phosphorylation with cAMP-dependent protein kinase (A-kinase). In one step, this technique separates the phosphorylated derivative from A-kinase, ATP, unphosphorylated HMG 14, and a minor phosphorylated by-product which evidence suggests may be the previously reported Ser 6, 24-diphospho-HMG 14. Mono S chromatography also enhances the purity of calf thymus HMG 14 prepared by perchloric acid extraction, acetone and ethanol precipitations, and CM-Sephadex chromatography. In addition, it permits the detection of apparent microheterogenous forms of both unphosphorylated and Ser 6-PO4-HMG 14. The significant reductions in binding affinity resulting from the incorporation of phosphate groups into HMG 14 suggest that Mono S chromatography could have more general application in the isolation of phosphorylated derivatives of other basic proteins, including other chromatin-associated DNA-binding proteins which are known to undergo specific phosphorylation. It would especially be useful when the proteins and their phosphorylated derivatives bind more tightly to Mono S than the kinases used for their phosphorylation.
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PMID:A one-step preparative method for separating SER 6-phosphorylated HMG 14 from unphosphorylated HMG 14 and in vitro phosphorylation reaction components. 283 54

The ADP-ribosylation site of histone H1 from calf thymus by purified hen liver nuclear ADP-ribosyltransferase was determined and effects of the ADP-ribose X histone-H1 adduct on cAMP-dependent phosphorylation of the histone H1 were investigated. ADP-ribosylated histone H1 was prepared by incubation of histone H1, 1 mM [adenylate-32P]NAD and the purified ADP-ribosyltransferase. N-Bromosuccinimide-directed bisection of ADP-ribosylated histone H1 showed that the NH2-terminal fragment (Mr = 6000) was modified and contained serine residue 38, the site of phosphorylation by cAMP-dependent protein kinase. Digestion of the NH2-terminal fragment with cathepsin D and trypsin, and purification of this fragment, using high-performance liquid chromatography, yielded a radiolabelled single peptide corresponding to residues 29-34 of histone H1, containing the arginine residue as the ADP-ribosylation site. These results indicate that ADP-ribosylation of histone H1 occurs at the arginine residue 34, sequenced at the NH2-terminal side of the phosphate-accepting serine residue 38. Phosphorylation of histone H1 from calf thymus by cAMP-dependent protein kinase was markedly reduced when histone H1 was ADP-ribosylated. Kinetic studies of phosphorylation revealed that ADP-ribosylated histone H1 was a linear competitive inhibitor of histone H1 and a linear non-competitive inhibitor of ATP.
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PMID:Amino acid sequence of histone H1 at the ADP-ribose-accepting site and ADP-ribose X histone-H1 adduct as an inhibitor of cyclic-AMP-dependent phosphorylation. 299 55

Nuclear histone kinase activity, specifically histone H1 phosphotransferase activity, was shown to increase in synchronous Chinese hamster cells from the G1/S boundary to late G2/early M phase. Chromatin extracts purified by DEAE-Sephacel chromatography showed a cAMP-independent kinase activity that demonstrated cell cycle dependence and high specificity for histone H1 as the phosphate acceptor in the presence of [gamma-32P] ATP. This activity was purified approximately 40-fold. Using as substrates calf thymus histone H1 subfractions resolved by Bio-Rex 70 ion exchange chromatography, phosphorylation by the nuclear histone H1 kinase indicated that 32P incorporation into H1-2 was at least twice that for H1-1 and H1-3 subfractions. Both amino- and carboxy-terminal fragments generated by N-bromosuccinimide cleavage were phosphorylated. Phosphoamino acid analysis showed phosphothreonine to be approximately twice as abundant as phosphoserine. Histone H1 kinase activity was not activated by cyclic nucleotides, nor inhibited by cAMP-dependent protein kinase inhibitors or regulatory subunits. There was no effect on activity by Ca2+ alone or in the presence of calmodulin or diacylglycerol. Kinase activity was inhibited by nonhydrolyzable analogs of ATP such as adenyl-5'-yl imidodiphosphate, by 5'-p-fluorosulfonylbenzoyladenosine which binds to the ATP binding site of the enzyme, and by quercetin. Column fractions enriched in histone H1 kinase were labeled with 5'-p-fluorosulfonylbenzoyl[8-14C]adenosine, and peptides were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. One band, Mr 67,000, was specifically labeled and may represent the H1 kinase catalytic subunit.
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PMID:Histone H1 kinase in exponential and synchronous populations of Chinese hamster fibroblasts. 300 70


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