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:2.7.11.11 (AMPK)
12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Treatment of 3T3-L1 cells with 0.1-1.0 nM insulin results in rapid (5-15 min) activation of a soluble protein kinase that phosphorylates serine residues in ribosomal protein S6. The insulin-stimulated kinase activity is detectable in confluent, nongrowing preadipocytes and adipocytes. In the presence of 2 micrograms of cycloheximide per ml, preconfluent 3T3-L1 cells also respond to insulin by acquiring an S6 kinase activity whose properties are the same as those of the enzyme activity elicited by insulin alone in growth-inhibited cells. The principal insulin-stimulated S6 kinase has a Mr of approximately equal to 50,000-60,000; there is a variable amount of activity that sediments with a Mr of about 80,000. The soluble enzyme exhibits optimal activity between pH 8 and pH 9, requires Mg2+ (10-20 mM), and is inhibited by Ca2+ (0.5 mM), Mn2+ (0.05 mM), and NaF (30 mM). GTP cannot substitute for ATP in the phosphotransferase reaction; cAMP, cGMP, phosphatidylserine plus diolein, the cAMP-dependent protein kinase inhibitor, and heparin (0.7 micrograms/ml) are without effect. Although treatment of 3T3-L1 cells with insulin does not influence the activity or the subcellular distribution of the phospholipid and Ca2+-dependent protein kinase C, exposure to the phorbol tumor promoter phorbol 12-myristate 13-acetate (PMA) results in translocation of protein kinase C to the membrane and activation of a soluble phospholipid and Ca2+-independent S6 protein kinase that has the same magnitude of activity and sedimentation behavior as the insulin-induced activity. Trypsin treatment of either 3T3-L1 cytosolic extracts or partially purified 3T3-L1 protein kinase C generates a small amount of S6 kinase activity of Mr 50,000. This activity, resolved by sucrose gradient centrifugation, is less active than that elicited by either insulin or PMA and, unlike the activities generated by insulin and PMA, is associated with histone kinase activity. The data suggest that the S6 kinase elicited by either insulin or PMA is neither protein kinase C, its phospholipid, and Ca2+-independent proteolytic derivative nor the result of proteolytic activation of an inactive proenzyme that can be reproduced by trypsin treatment of cell extracts in vitro.
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PMID:Activation of S6 kinase activity in 3T3-L1 cells by insulin and phorbol ester. 389 33

The nuclear protein kinase NI (NI kinase) was purified from NB-15 mouse neuroblastoma cells by phosphocellulose column and casein affinity column chromatography. The purified NI kinase exhibited (i) an apparent subunit molecular weight of about 37,000, (ii) autophosphorylation, and (iii) insensitivity to inhibition by heparin. When NI kinase was added to heat-treated neuroblastoma nuclei in the presence of [gamma-32P] ATP, two proteins with apparent subunit molecular weights of 11,000 and 10,000 were prominently phosphorylated. Other protein kinases tested including the nuclear protein kinase NII, Type I cAMP-dependent protein kinase, and protein kinase C did not catalyze the phosphorylation of these two proteins. The NI kinase-catalyzed phosphorylation of these two proteins was completely inhibited by 1 mM spermine. In contrast, 10 mM putrescine, 2 mM spermidine, 5 mM arginine, and 10 mM NH4Cl, had no inhibitory effect on this phosphorylation reaction. Our study also indicated that the phosphorylation of the 11,000- and 10,000-dalton proteins occurred in the nuclear matrix fraction but not in heterogeneous nuclear ribonucleoproteins, high mobility group proteins, or histone fractions. We have previously reported that spermine specifically inhibits the endogenous phosphorylation of an 11,000-dalton nuclear protein in various mammalian cell lines (Chen, K. Y., and Verma, R. (1984) Biochem. Biophys. Res. Commun. 118, 710-716). The present study suggests that the 11,000- and 10,000-dalton nuclear proteins may be native substrates of nuclear protein kinase NI and that their phosphorylation can be affected by physiological concentrations of spermine.
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PMID:Spermine inhibits the phosphorylation of the 11,000- and 10,000-dalton nuclear proteins catalyzed by nuclear protein kinase NI in NB-15 mouse neuroblastoma cells. 394 52

Polyamine-dependent protein kinase (P kinase) in nuclear and cytosol fraction of pig epidermal cells were extracted. Two different protein kinases were purified from nuclei. One was cAMP-dependent protein kinase (A kinase) and another was P kinase. P kinase phosphorylated acidic non-histone protein only, while A kinase phosphorylated both exogenous histone and non-histone proteins. Among polypeptides phosphorylated by P kinase, a 180 kilodalton (K) polypeptide seemed to be a specific substrate for P kinase. In cytosol, the fraction containing P kinase exhibited multiple polypeptide bands on SDS -PAGE, including four major polypeptide bands and several minor polypeptide bands. One of minor polypeptide bands (80 K) was phosphorylated by P kinase. Authentic ornithine decarboxylase (ODC) added exogenously was also phosphorylated by P kinase. A 80 K polypeptide of ODC was comigrated with the polypeptide phosphorylated by P kinase on SDS -PAGE. Kinetic study revealed that the ODC activity decreased as ODC was phosphorylated.
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PMID:[Studies on polyamine-dependent protein kinase in pig epidermal cells]. 398 33

After bacteriophage T7 infection, a protein kinase (EC 2.7.1.37; ATP:protein phosphotransferase) activity can be demonstrated in E. coli in vivo by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Cell-free extracts catalyzed the transfer of the terminal phosphoryl group of [(gamma)-(32)P]ATP to endogenous protein acceptor or to added histone. The bond between phosphate and protein shows the characteristics of serine phosphate: it is stable in 1 N HCl (100 degrees ) and cleaved by 1 N KOH (37 degrees ) and by alkaline phosphatase treatment. Moreover, after partial acid hydrolysis, radiophosphate migrates with marker O-phosphoserine on polyethyleneimine-cellulose thin-layer chromatograms. Enzyme activity in uninfected cells is negligible. Ultraviolet irradiation of the phage genome prevents the appearance of the protein kinase; irradiation of the host genome does not. The enzyme activity occurs 4 min after infection and its gene maps in the early region (promoter proximal to gene 1). Ribosomal proteins are phosphorylated in vivo and are substrates in vitro. Enzyme activity in vitro is not changed by addition of cyclic AMP or cyclic GMP.
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PMID:Protein kinase induction in Escherichia coli by bacteriophage T7. 459 95

A protein kinase activity fraction was defined in cytosols and membranes of mammary tissue isolated from rats during pregnancy lactation, and weaning. By partial purification on DEAE-cellulose columns, it was shown that this protein kinase activity is cAMP independent and that its preferential substrate is casein and not histone. This protein kinase activity is inhibited by the bioflavonoid quercetin at doses that do not inhibit cAMP-dependent protein kinase activity. The enzyme requires Mg2+ and is inactive in the presence of 10 mM Ca+2; these properties distinguish this activity from casein kinase activity found in the Golgi fraction and involved in milk protein processing. By following the physiological cycle of mammary gland development during pregnancy, lactation, and weaning, we found a close correlation between proliferation, expressed as the DNA content per gland, and quercetin-inhibited cytosolic protein kinase activity. Moreover, changes in this phosphorylating activity preceded the glandular growth changes. There was a less significant correlation between the growth process and protein kinase activity in the membrane fraction. The cytosolic cAMP-dependent protein kinase activity showed (only partial) correlation with growth only during pregnancy. Cytosolic progesterone receptor levels in mammary tissue were used as an estrogenic marker. Tissue growth correlated with progesterone receptor levels during pregnancy, where estrogens are the predominant hormones affecting tissue proliferation. However, no such correlation was found during lactation and weaning, when PRL is the major hormone affecting mammary gland growth. These results suggest that quercetin-inhibitable protein kinase activity is not merely another estrogenic marker, but represents more general regulatory activity which might be connected to growth processes of breast tissue.
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PMID:Protein kinase activity in the rat mammary gland during pregnancy, lactation, and weaning: a correlation with growth but not with progesterone receptor levels. 609 41

The cyr2 mutant of yeast, Saccharomyces cerevisiae, required cAMP for growth at 35 degrees C. The cyr2 mutation was suppressed by the bcy1 mutation which resulted in deficiency of the regulatory subunit of cAMP-dependent protein kinase. The DEAE-Sephacel elution profile of cyr2 cAMP-dependent protein kinase was markedly different from that observed for the wild-type enzyme. With histone as substrate, the cAMP-dependent protein kinase activity of cyr2 cells showed 100-fold greater Ka value for activation by cAMP at 35 degrees C than that of the wild-type cells, while the Kd value for cAMP of the mutant enzyme was not altered. The electrophoretic character, molecular weight, and pI value of the regulatory subunit of the mutant enzyme were the same as those of the wild-type enzyme. When histone, trehalase, and glutamate dehydrogenase were used as substrate, the free catalytic subunit of the mutant enzyme showed a markedly decreased affinity for ATP and was more thermolabile compared to that of the wild-type enzyme. The results indicated that the cyr2 phenotype was produced by a structural mutation in the cyr2 gene coding for the catalytic subunit of cAMP-dependent protein kinase in yeast.
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PMID:Characterization of cyclic AMP-requiring yeast mutants altered in the catalytic subunit of protein kinase. 609 37

The cAMP-dependent and cAMP-independent histone kinases have been studied in the two subcellular compartments (cytosol and particulate fraction) from placentae of different gestational age. The total protein kinase activity, as well as its distribution between the two compartments, changes during the period of gestation. The total activity is significantly increased in full-term placentae. The increase is much greater for the cAMP-dependent (400 per cent), than for the cAMP-independent (270 per cent) protein kinases. It is much higher (400 per cent) in the cytosol than in the particulate fraction (170 per cent); consequently, the particulate fraction of term placentae shows a relatively lower proportion of protein kinase activity (26 per cent of the total activity) than the corresponding fraction of young placentae (37 per cent). DEAE-cellulose chromatography revealed the presence of two cAMP-dependent protein kinase peaks which correspond to Type I and Type II isoenzymes described in many mammalian tissues (Corbin, Keely and Park, 1975). The Type II isoenzyme is predominant in both first- and third-trimester placentae. The increase in protein kinase activity in term placentae is due to the selective activation of the Type II kinase only. The activity of the Type I isoenzyme remained unchanged throughout the period of gestation. The third peak eluted from the DEAE-cellulose column corresponds to a cAMP-independent sucrose-gradient ultracentrifugation into two distinct peaks similar to those already observed in several rat tissues (Toru-Delbauffe, Ohayon and Pavlovic-Hournac, 1983). The protein kinase patterns of both young and term placentae remain stable during the incubation of the tissues 'in vitro' for three hours.
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PMID:Modification of protein kinase pattern in human placentae during gestation. 609 91

A guanosine 3':5'-monophosphate (cGMP)-dependent protein kinase was purified from bovine lung using 8-(6-aminohexylamino)-cAMP-Sepharose. The activity of the purified enzyme was highly dependent on cGMP using histone f2b as a substrate. The self-phosphorylation of the purified enzyme was strongly inhibited by cGMP and not significantly affected by cAMP. A precipitating antiserum prepared in rabbits against the cGMP-dependent protein kinase specifically inhibited the histone kinase activity and the self-phosphorylation of the purified cGMP-dependent protein kinase without affecting the cGMP binding site. This antiserum also specifically inhibited the phosphorylation of the endogenous substrate proteins by endogenous cGMP-dependent protein kinase in smooth muscle membranes, but did not cross-react detectably with catalytic subunit or regulatory subunit of type I or type II cAMP-dependent protein kinase. Conversely, anti-sera against the regulatory subunit of type I or type II cAMP-dependent protein kinase did not cross-react detectably with cGMP-dependent protein kinase. The substantial differences between the immunological properties of the cGMP-dependent and cAMP-dependent protein kinases suggest that these two enzymes have distinct physiological roles.
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PMID:Immunological distinction between guanosine 3':5'-monophosphate-dependent and adenosine 3':5'-monophosphate-dependent protein kinases. 615 53

Dark-adapted pure bovine rod outer segments (ROS) (A280/A500--2.1) can be phosphorylated in the presence of [gamma-32P]ATP and [gamma-32P]GTP. The constant levels of phosphorylation, reached within 10--15 min, are 100 +/- 30 pmol 32P/nmol of rhodopsin for [gamma-32P]ATP and 2--4 pmol 32P/nmol of rhodopsin for [gamma-32P]GTP. These processes are not controlled by 10(-4)--10(-8) cAMP, cGMP or Ca2+, but are inhibited at higher concentrations of these agents. In the presence of histone the constant level of phosphorylation is increased up to 200 +/- 30 pmol 32P/nmol of rhodopsin for [gamma-32P]ATP, but is not changed when [gamma-32P]GTP is used. 10(-5) M cAMP is found to activate the phosphorylation in the presence of histone and [gamma-32P]ATP by 5--6 times. All this evidences that ROS contains cAMP-dependent protein kinase, which utilizes ATP, but not GTP. Moreover, ROS contains cyclic nucleotides- and Ca2+-independent protein kinase. These protein kinases are the ROS endogenous enzymes. This is shown in experiments on separation of pure ROS in a sucrose density gradient.
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PMID:[Protein kinase activity of bovine retina rod outer segments]. 625 43

Interaction of cGMP-dependent protein kinase with histones H2A, H2B, H3, and H4, or poly(L-arginine) resulted in changes in enzyme conformation such that inactivation of cGMP binding and activation of basal catalytic activity (assayed without cGMP) occurred. Total kinase activity as determined by phosphorylation of exogenous substrates subsequently decreased, but autophosphorylation of the enzyme was enhanced. The reaction was specific for nucleosome core histones and poly(L-arginine); H1, troponin, and poly(L-lysine) had no effect. Inactivation of cyclic nucleotide binding sites followed pseudo-first order kinetics and, at various histone concentrations, exhibited saturation kinetics at low ionic strength (2 mM potassium phosphate, pH 6.8), but non-saturation kinetics at higher ionic strength (37.5 mM potassium phosphate, pH 6.8, 12.5 mM MgCl2). Saturation kinetics was observed with poly(L-arginine) at both low and high ionic strength. Kinetic parameters measured under saturation conditions were determined for each core histone and poly(L-arginine). Core histones and poly(L-arginine) were noncompetitive inhibitors of cGMP binding; core histones and poly(L-arginine) interacted competitively at an enzyme site designated as the poly(L-arginine) binding site. Regulatory subunits of cAMP-dependent protein kinase contain a similar poly(L-arginine) binding site. Modulator proteins bind to poly(L-arginine) or arginyl residues in histone to prevent interaction with the poly(L-arginine) binding site on the enzymes. Through this mechanism, modulator proteins maintain cyclic nucleotide dependency and full enzyme activity.
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PMID:Regulation of cyclic nucleotide-dependent protein kinase activity by histones and poly(L-arginine). 625 84


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