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)

The tyrosine-3-monooxygenase activity [L-tyrosine, tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating); EC 1.14.16.2] of rat adrenal medulla is induced 20-24 hr after the injection of reserpine (16 mumol/kg intraperitoneally). This and other inducing stimuli increase the 3': 5'-cyclic AMP (cAMP) content in the medulla for longer than 60 min and activate the cAMP-dependent protein kinase (ATP: protein phosphotransferase; EC 2.7.1.37) for several hours. Corticotropin (ACTH), dopamine, and propranolol do not induce the monooxygenase, but elicit an increase in the cAMP content of the medulla which fails to activate protein kinase and lasts less than 1 hr. A high- and low-molecular-weight protein kinase are separated by gel filtration from the 20,000 X g pellet extract of adrenal medulla homogenate. The activity of the low-molecular-weight enzyme is expressed as its ability to phosphorylate histone. The protein kinase activity of the pellet is increased between 3 and 17 hr after reserpine injection. Our evidence indicates that this increase is due to a translocation from cytosol to subcellular structures of a kinase that utilizes lysine-rich histone as phosphate acceptor. The protein kinase activity that is extracted from a purified nuclear fraction prepared from the adrenal medulla of rats injected 7 hr previously with reserpine is greater than that extracted from medulla of saline-treated rats.
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PMID:Activation and nuclear translocation of protein kinase during transsynaptic induction of tyrosine 3-monooxygenase. 0 93

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

There appear to be two classes of protein kinases in rat heart and adipose tissue, types I and II. Type I elutes from DEAE-cellulose at smaller than 0.1 M NaCl and type II at greater than 0.1 M NaCl. The type I enzyme is more readily dissociated by salt or histone than is the type II enzyme. If the type I kinase is first dissociated by cAMP, the subunits reassociate very slowly at 0 degrees C on removal of the cAMP by Sephadex G-25 chromatography, whereas those of type II reassociate very rapidly. Rat heart contains mostly type I and a small amount of type II enzyme, whereas adipose tissue contains almost exclusively the type II enzyme. The adipose tissue enzyme resembles the heart type II kinase in all of the above properties, although the two enzymes are not identical as indicated by slight differences in elution patterns from DEAE-cellulose columns. Incubation of rat epididymal adipose tissue with low concentrations of epinephrine (0.11 muM) increases glycerol production and the fraction of the protein kinase in the active form (activity ratio). The change in cAMP under these conditions is not statistically significant. The presence of insulin inhibits the epinephrine effect on glycerol production and protein kinase but has no measurable effect on cAMP levels. Incubation of adipose tissue with high epinephrine concentrations (11 muM) increases the cAMP level, the protein kinase activity ratio, and glycerol production. Under these conditions insulin decreases the cAMP level and kinase activity ratio but does not reduce glycerol production. The data suggest that very small changes in the tissue cAMP level, undetectable by the assay method, are magnified during the stepwise activation of glycerol output aided possibly by cooperative effects between cAMP and protein kinase. The procedure developed for determining the state of activation of the cAMP-dependent protein kinase in adipose tissue must be modified by reducing the salt concentration of the buffers in order to carry out similar studies in the heart. This reflects the different types of protein kinase in the two tissues. The addition of charcoal to crude extracts of heart prevents protein kinase activation by added cyclic AMP. Charcoal should therefore prevent any activation that could occur if any sequestered cAMP were released during homogenization. Charcoal addition thereby provides a means to distinguish intracellular cAMP activation of the kinase from that which might occur following cell rupture. If epinephrine-perfused hearts are homogenized in the presence of charcoal, epinephrine stimulation of the protein kinase is only slightly decreased. This indicates that the protein kinase is activated intracellularly by cAMP and suggests that all of the cAMP in the cell is available to the protein kinase; i.e., cAMP is not released during homogenization.
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PMID:Hormonal regulation of adenosine 3',5'-monophosphate-dependent protein kinase. 16 70

Three protein kinases (ATP:protein phosphotransferase, EC 2.7.1.37) were detected when the soluble fraction of rabbit kidney medulla was chromatographed on DEAE-cellulose with a linear NaC1 gradient. The first two kinases eluted (Peak 1 and Peak II) were cyclic-AMP-dependent, wheras Peak III was cyclic-AMP-independent. A procedure was developed to separate the catalytic subunit of Peak II cyclic-AMP-dependent protein kinase (representing the bulk of the histone kinase activity) from Peak III protein kinase. In contrast to the catalytic subunit, Peak III protein kinase phosphorylated casein more rapidly than histone. Peak III was insensitive to the heat-stable protein inhibitor of cyclic-AMP-dependent protein kinases and appeared to have a higher requirement for ATP than did the catalytic subunit. Peak III catalyzed the conversion of glycogen synthase (UDPglucose:glycogen alpha-4-glucosyltransferase, EC 2.4.1.11) from the I (glucose-6-phosphate-independent) to the D (glucose-6-phosphate-dependent) form. This conversion was dependent on Mg-2+ and ATP and was unaffected by cyclic AMP, cyclic GMP, or the protein inhibitor. Glycogen synthase I in the soluble fraction of kidney medulla could be converted to the D form by endogenous glycogen synthase I kinase if Mg-2+ and ATP were added. Most of this glycogen synthase I kinase activity was unaffected by cyclic AMP or by the protein inhibitor, suggesting that Peak III may be of major importance in the regulation of glycogen synthase in vivo.
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PMID:Isolation of a glycogen synthase I kinase that is independent of adenosine 3':5'-monophosphate. 16 80

In crude extracts of adipose tissue the protein kinase dissociates slowly at 30 degrees into regulatory and catalytic subunits in the presence of 700 mug per ml of histone or 0.5 M NaCl. If the kinase is first dissociated by adding 10 muM adenosine 3':5'-monophosphate (cAMP), reassociation occurs instantaneously after removal of the cAMP by Sephadex G-25 chromatography. In contrast, in crude xtracts of heart, the protein kinase dissociates rapidly in the presence of 700 mug per ml of histone or 0.5 M NaCl and reassociates slowly after removal of cAMP. These differences are accounted for by the existence of two types of protein kinases in these tissues, referred to as types I and II. DEAE-cellulose chromatography of extracts of adipose tissue produces only one peak of cAMP-dependent protein kinase activity (type II) which elutes between 0.15 and 0.25 M NaCl. Similar chromatography of heart extracts resolves enzyme activity into two peaks; a type I enzyme which elutes between 0.05 and 0.1 M and predominates (greater than 75% of total activity), and a type II enzyme which elutes between 0.15 and 0.25 M NaCl. The dissociation properties of the types I and II enzymes from heart and adipose tissue are retained after partial purification by DEAE-cellulose and Sepharose 6B chromatography. Rechromatography of the separated peaks of the cardiac enzymes does not change the elution pattern. Sucrose density gradient centrifugation and gel filtration studies indicate that the molecular weights of these enzymes are very similar. The type II enzyme isolated by DEAE-cellulose chromatography of heart extracts resembles the adipose tissue enzyme, i.e. it undergoes slow dissociation at 30 degrees in the presence of histone or 0.5 M NaCl. The adipose tissue kinase and the heart type II kinase are not identical, however, since they do not elute at exactly the same point on DEAE-cellulose columns. A survey of several tissues indicates the presence of type I and II protein kinases similar to the enzymes in adipose tissue and heart as determined by DEAE-cellulose chromatography of crude extracts and by dissociation of the enzymes with histone. The presence of MgATP prevents dissociation of type I enzyme from heart by 0.5 M NaCl or histone. The profile of the enzyme on DEAE-cellulose, however, is not changed...
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PMID:The distribution and dissociation of cyclic adenosine 3':5'-monophosphate-dependent protein kinases in adipose, cardiac, and other tissues. 16 86

Cyclic nucleotide levels, protein phosphotransferase activities, and cyclic nucleotide-binding proteins have been determined and partially characterized in the mouse lymphosarcoma P1798. This system is used as a model to understand the function of these activities in a rapidly proliferating cell. Adenosine 3':5'-monophosphate (cAMP) concentrations are 5-fold higher in the lymphosarcoma cells than in thymocytes. In both the thymocytes and malignant tissue, cAMP concentrations are increased by physiological concentrations of epinephrine and prostaglandin. The guanosine 3':5'-monophosphate (cGMP) level in the lymphosarcoma is 0.1 pmole/10(6) cells and is not modified by acetylcholine, prostaglandin F2alpha, or concanavalin A. Four protein phosphotransferase activities have been identified in the lymphosarcoma. These are the cAMP-dependent protein kinase type I and II isozymes and a "histone kinase" and a "phosvitin kinase"; neither of the latter two is regulated by cyclic nucleotides. Characterization of these enzymes was based on fractionation by DE 52 chromatography, substrate specificity, interaction with the protein inhibitor of cAMP-dependent protein kinases, and sucrose gradient sedimentation rates. Both the cAMP-dependent protein phosphotransferase activity and the phosvitin phosphotransferase activity are 2-to 4-fold elevated in the lymphosarcoma cells in comparison to thymocytes. cAMP binding is associated with both the type I and II isozymes and with a fraction tentatively designated as the regulatory subunit of these enzymes. cGMP also binds to this later fraction and to the partially purified fraction containing the type IcAMP-dependent enzyme. The histone phosphotransferase activity of this fraction is also stimulated by cGMP, but studies of the number of binding sites and of absorption to cAMP and cGMP affinity resins indicated that this fraction contains more than one species of cyclic nucleotide-binding protein.
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PMID:Protein phosphotransferase activities and cyclic nucleotide action in proliferating lymphocytes. 18 45

Phosphorylase kinase was found to be activated and phosphorylated at 10mM Mg2+ by the cAMP-dependent protein kinase-catalyzed reaction ot much higher levels than observed previously when reactions were carried out in 1 to 2 mM Mg2+ (Cohen, P. (1973) Eur. J. Biochem. 34, 1; Hayakawa, T., Perkin, J.P., and Krebs, E.G. (1973) Biochemistry 12, 574). That the reaction at 10 mM Mg2+ is protein kinase-catalyzed is supported by several observations: (a) the reaction is facilitated by the addition of protein kinase; (b) the reaction depends on cAMP when protein kinase holoenzyme is uded; (c) the reaction is not inhibited by 1 mM ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetate which is known to inhibit autoactivation and autophosphorylation of phosphorylase kinase; and (d) the protein inhibitor of protein kinase inhibits this reaction. The phosphorylation and activation of phosphorylase kinase seem to occur in two phases. At low Mg2+ only the first phase is manifested and involves the incorporation of 2 mol of phosphate, 1 mol into each of Subunits A and B. At high Mg2+ additional sites are phosphorylated almost exclusively on Subunit A, with phosphate incorporation approaching the final level of 7 to 9 mol. Enzyme activity at high Mg2+ is 2 to 3 times higher than that observed when activation is studied at low Mg2+. The observation that both casein and type II histone are phosphorylated to the same extent at 1 mM and 10 mM Mg2+ suggested that high Mg2+ may be altering the conformation of phosphorylase kinase thus rendering more phosphorylation sites accessible to protein kinase. Since the phosphorylation of phosphorylase kinase by either the protein kinase-catalyzed or autocatalytic reaction can result in the incorporation of 7 to 9 mol of phosphate, the finding that only about seven sites become phosphorylated by both mechanisms acting together suggest that activation by these two mechanisms may involve common phosphorylation sites.
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PMID:Effect of Mg2+ concentration on the cAMP-dependent protein kinase-catalyzed activation of rabbit skeletal muscle phosphorylase kinase. 18 21

There is broad species variation in the type of cAMP-dependent protein kinase isozyme present in supernatant fractions of heart homogenates as determined by DEAE-cellulose chromatography, Isozyme I, which elutes at less than 0.1 M NaCl, is predominant in mouse and rat hearts; while isozyme II, which elutes at greater than 0.1 M NaCl, is the predominant type in beef and guinea pig. Human and rabbit hearts contain about equal amounts of the two types. The type I heart kinases are more easily dissociated into free regulatory and catalytic subunits by incubation with histone than are the type II kinases, and the separated regulatory and catalytic subunits of isozyme II of rat heart reassociate more rapidly than the subunits of isozyme I under the conditions used. The data from several experiments using rat heart indicate that the basal activity ratio of the protein kinase in crude extracts (approximately 0.15) is due mainly to basal endogenous cAMP and that cAMP elevation accounts entirely for the epinephrine effect on the enzyme. Addition of epinephrine and 1-methyl-3-isobutylxanthine to the perfusate causes a rapid (1 min) increase in cAMP, active supernatant protein kinase, and active phosphorylase in perfused hearts of both rat (mainly isozyme I) and guinea pig (mainly isozyme II). The elevation percentage in cAMP is about the same in the two species, but the increase in active protein kinase is greater in rat heart. If hearts from either animal are perfused continually (10 min) with epinephrine (0.8 muM) and 1-methyl-3-isobutylxanthine (10 muM), the cAMP level, active protein kinase, and active phosphorylase remain elevated. Likewise, all parameters return rapidly to the basal levels when epinephrine and 1-methyl-3-isobutylxanthin are removed. Most of the epinephrine effect on the rat heart supernatant kinase is retained at 0 degrees if cAMP is removed by Sephadex G-25 chromatography, although this procedure completely reverses the epinephrine effect in the guinea pig heart. The epinephrine effect on the rabbit heart kinase (approximately equal amounts of isozymes I and II) is partially reversed by Sephadex G-25. These species differences can be accounted for by differences in association-dissociation behavior of the isozymes in vitro. The data suggest that epinephrine causes activation of both isozymes. The activity present in the particulate fraction comprises nearly half of the total cAMP-dependent protein kinase activity in homogenates of rabbit heart. Triton X-100 extracts of low speed particulate fractions from hearts of each species tested, including rat heart, contain predominantly or entirely the type II isozyme, suggesting differences in intracellular distribution of the isozymes. The binding of the protein kinase to the particulate fraction is apparently due to the properties of the regulatory subunit component. Differences in topographical distribution of the isozymes could provide for differences in either physiological regulation or substrate specificity.
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PMID:Characterization and regulation of heart adenosine 3':5'-monophosphate-dependent protein kinase isozymes. 19 Feb 20

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

A thermostable inhibition of ATP-protein phosphotransferase (EC 2.7.1.37) (protein kinase) which is present in crude tissue extracts has been resolved by gel chromatography (Sephadex G-100) into two molecular forms. These two forms will be referred to as type I and type II inhibitor. The type I inhibitor (Mr approximately or equal to 24,000) is specific for cAMP-dependent protein kinase and corresponds to the inhibitor described earlier (Walsh, D. A., Ashby, C. D., Gonzalez, C., Calkins, D., Fisher, E. H., and Krebs, E. G. (1971) J. Biol. Chem. 246, 1977-1985). The type II inhibitor (Mr approximately or equal to 15,000) competes for the enzyme with various substrate proteins (histone, alpha-casein, and Leu-Arg-Arg-Ala-Ser-Leu-Gly (kemptide). The type II inhibitor blocks protein phosphorylation catalyzed by several types of protein kinases (cAMP- and cGMP-dependent or cyclic nucleotide-independent protein kinases). The type II inhibitor from rat brain has been purified 1500-fold; this protein is thermostable, has acidic characteristics, and does not require Ca2+ ions for its activity. Different ratios and concentrations of type I and type II inhibitors of protein kinase are found in rat skeletal muscle, pancreas, cerebellum and corpus striatum, and in lobster tail muscle.
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PMID:Endogenous protein kinase inhibitors. Purification, characterization, and distribution in different tissues. 19 48


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