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)

A study is presented of the effect of the bile salt ursodeoxycholate (UDC) on protein phosphorylation by [gamma-32P]ATP in the cytosol from rat hepatocytes. Gel electrophoresis and corresponding autoradiograms of cytosolic proteins show that UDC promotes phosphorylation of at least eight different protein bands. Four of them (the 36, 60, 64 and 76 kDa) are phosphorylated by Ca2+ and phospholipid-dependent protein kinase (PKC); three (the 31, 51 and 71 kDa) are phosphorylated by cAMP-dependent protein kinase (PKA) and one protein band, with molecular weight of 34 kDa, apparently contains substrates of both PKC and PKA. Data are reported indicating that UDC can directly affect the intrinsic activity of protein kinases.
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PMID:Ursodeoxycholate promotes protein phosphorylation in the cytosol of rat hepatocytes. 906 73

This study was designed to test the hypothesis that 8-Br-cAMP and 8-Br-cGMP dependent relaxation of phorbol dibutyrate stimulated contractions of intact rat aorta are independent of changes in the level of myosin light chain phosphorylation. Phorbol dibutyrate stimulated contraction with a concomitant increase in myosin light chain phosphorylation in normal tissues and without an increase in myosin light chain phosphorylation in calcium-depleted tissues. Phorbol dibutyrate stimulated contractions in normal CaCl2-containing physiological salt solution were relaxed in a concentration-dependent manner by 8-Br-cAMP and 8-Br-cGMP. Phorbol dibutyrate-induced contractions in the absence of Ca2+ were only relaxed by 8-Br-cGMP; 8-Br-cAMP had no effect. The relaxation induced by 8-Br-cGMP was associated with a decrease in myosin light chain phosphorylation suggesting that cGMP-dependent protein kinase may alter the activity of either the myosin light chain kinase or phosphatase. The relaxation induced by 8-Br-cAMP was not associated with a decrease in phosphorylation suggesting that cAMP-dependent protein kinase may uncouple myosin light chain phosphorylation from force.
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PMID:Cyclic AMP and cyclic GMP relax phorbol ester-induced contractions of rat aorta by different mechanisms. 919 89

1. The effects of 17 alpha-estradiol on KCl (60 mM), CaCl2 (30 microM to 10 mM) and vanadate (0.3 mM)-induced contractions in rat uterus have been assayed. Furthermore, the effect of 17 alpha-estradiol on calmodulin-stimulated cAMP-phosphodiesterase activity was also studied. 2. 17 alpha-estradiol relaxed the tonic contraction induced by KCl (60 mM) in a concentration-dependent way (IC50, 8.3 +/- 0.7 microM), and CaCl2 (0.1 to 10 mM) counteracted it. 3. CaCl2 (30 microM to 10 mM) produced concentration-dependent contraction of rat uterus in a calcium-free medium supplemented with 60 mM of KCl (EC50: 0.2 +/- 0.01 mM). 17 alpha-estradiol (8 microM) antagonized the contraction induced by CaCl2, increasing the EC50 value up to 0.7 +/- 0.1 mM (P < 0.01). 4. 17 alpha-estradiol (0.1 to 1 mM) relaxed in a concentration-dependent way the tonic contraction induced by vanadate in rat uterus incubated in a calcium-free medium and EDTA supplemented. The maximal relaxation achieved with 1 mM of 17 alpha-estradiol was 52.2 +/- 2.8%. 5. 17 alpha-estradiol (1 to 100 microM) did not modify the basal activity of cAMP-phosphodiesterase but inhibited the calcium plus calmodulin stimulated activity. The maximal inhibition achieved was 43 +/- 5.4%. 6. The relaxing effect of 17 alpha-estradiol on KCl (60 mM)-induced tonic contraction was unmodified with the antioestrogen tamoxifen (0.1 and 1 microM), the inhibitor of tirosine kinase (genistein, 10 microM) and the cAMP-dependent protein kinase inhibitor (Rp-adenosine 3',5'-monophosphothioate, triethylamine salt, 100 microM). However, the effect was antagonized with the inhibitor of transcription (actinomycin D, 5 micrograms/ml,), the inhibitor of protein synthesis (cycloheximide, 10 and 100 micrograms/ml), and the inhibitor of ornithine decarboxilase (alpha-difluoromethyl-ornithine, 10 mM). 7. Our results suggest that polyamines contribute to the relaxant effect of 17 alpha-estradiol in rat uterine smooth muscle behaving, presumably, as mediators of the transcriptional component involved in the effect of 17 alpha-estradiol.
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PMID:Partial contribution of polyamines to the relaxant effect of 17 alpha-estradiol in rat uterine smooth muscle. 945 84

1. We used patch clamp to study whole-cell K+ currents activated by calcitonin gene-related peptide (CGRP) in smooth muscle cells freshly dissociated from pig coronary arteries. 2. CGRP (50 nM) activated an inward current at -60 mV in symmetrical 140 mM K+ that was blocked by glibenclamide (10 microM), an inhibitor of ATP-sensitive potassium (KATP) channels. CGRP-induced currents were larger in cells dialysed with 0.1 mM ATP than with 3.0 mM ATP. 3. Forskolin (10 microM) activated a glibenclamide-sensitive current, as did intracellular dialysis with cAMP (100 microM). The catalytic subunit of cAMP-dependent protein kinase (protein kinase A, PKA), added to the pipette solution, activated equivalent currents in five out of twelve cells. 4. CGRP-induced currents were reduced by the PKA inhibitors adenosine 3',5'-cyclic monophosphorothioate, RP-isomer, triethylammonium salt (Rp-cAMPS; 100 microM) and N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulphonamide+ ++ dihydrochloride (H-89; 1 microM), and abolished by inclusion of a PKA inhibitor peptide in the pipette solution. 5. The beta-adrenergic agonist isoprenaline (10 microM) also activated a glibenclamide-sensitive K+ current. 6. CGRP-induced currents were unaffected by the inhibitor of cGMP-dependent protein kinase (PKG) KT5823 (1 microM). Sodium nitroprusside (10 microM) did not activate a glibenclamide-sensitive current in cells held at -60 mV, but did activate an outward current at +60 mV that was abolished by KT5823, or by 100 nM iberiotoxin (an inhibitor of BKCa channels). 7. Our findings suggest that CGRP activates coronary KATP channels through a pathway that involves adenylyl cyclase and PKA, but not PKG.
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PMID:ATP-sensitive K+ channel activation by calcitonin gene-related peptide and protein kinase A in pig coronary arterial smooth muscle. 949 Aug 26

1. We examined the effects of noradrenaline on steady-state intracellular pH (pHi) and the recovery of pHi from internal acid loads imposed by the NH4+ prepulse technique in hippocampal CA1 neurones acutely dissociated from adult rats. 2. Under nominally HCO3--free conditions, acid extrusion was accomplished by a Na+-dependent mechanism, probably the amiloride-insensitive variant of the Na+-H+ exchanger previously characterized in both fetal and adult rat hippocampal neurones. In the presence of external HCO3-, acid extrusion appeared to be supplemented by a Na+-dependent HCO3--Cl- exchanger, the activity of which was dependent upon the absolute level of pHi. 3. Noradrenaline evoked a concentration-dependent and sustained rise in steady-state pHi and increased rates of pHi recovery from imposed intracellular acid loads. The effects of noradrenaline were not dependent upon the presence of external HCO3- but were blocked by substituting external Na+ with N-methyl-D-glucamine, suggesting that noradrenaline acts to increase steady-state pHi by increasing the activity of the Na+-H+ exchanger. 4. The effects of noradrenaline on steady-state pHi and on rates of pHi recovery from imposed acid loads were mimicked by beta1- and beta2-, but not alpha-, adrenoceptor agonists. The beta-adrenoceptor antagonist propranolol blocked the ability of noradrenaline to increase both steady-state pHi and rates of pHi recovery from acid loads. 5. The effects of noradrenaline on steady-state pHi and on pHi recovery rates following acid loads were not dependent on changes in [Ca2+]i. However, the effects of noradrenaline were blocked by pre-treatment with the adenylate cyclase inhibitor 2',5'-dideoxyadenosine and the cAMP-dependent protein kinase inhibitors Rp-adenosine-3',5'-cyclic monophosphorothioate (sodium salt; Rp-cAMPS) and N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulphonamide (H-89). 6. Forskolin, an activator of endogenous adenylate cyclase, and 3-isobutyl-1-methylxanthine, a phosphodiesterase inhibitor, mimicked the ability of noradrenaline to increase both steady-state pHi and rates of pHi recovery from imposed acid loads, as did Sp-cAMPS, a selective activator of cAMP-dependent protein kinase. The effect of forskolin on steady-state pHi was blocked by pre-treatment with Rp-cAMPS whereas the effect of Sp-cAMPS was enhanced by pre-treatment with the protein phosphatase inhibitor, okadaic acid. 7. Noradrenaline also increased steady-state pHi and rates of pHi recovery from imposed acid loads in cultured postnatal rat hippocampal neurones. In this preparation, the effects of noradrenaline were occluded by 18-24 h pre-treatment with cholera toxin. 8. We conclude that noradrenaline increases the activity of the Na+-H+ exchanger in rat hippocampal neurones, probably by inducing an alkaline shift in the pHi dependence of the antiport, thereby raising steady-state pHi. The effects of noradrenaline are mediated by beta-adrenoceptors via a pathway which involves the alpha-subunit of the stimulatory G-protein Gs (Gsalpha), adenylate cyclase, cAMP and the subsequent activation of cAMP-dependent protein kinase which, in turn, may phosphorylate the exchange mechanism.
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PMID:Effects of noradrenaline on intracellular pH in acutely dissociated adult rat hippocampal CA1 neurones. 976 38

Calcitonin gene-related peptide (CGRP) plays a significant role in the non-adrenergic non-cholinergic (NANC) regulation of intestinal tract motility. In this work, the contractile properties of enzymatically isolated circular smooth muscle cells (SMC) from human colon in response to CGRP were evaluated. Relaxation by CGRP (1 microM) was determined in cells maximally contracted by carbachol (CCh, 1 nM). Simultaneously, cGMP contents of SMC were measured by radioimmunoassay. CCh-induced contraction was inhibited by 1 microM CGRP (maximum: 69+/-5% within 60 sec); similarly, exposure of cells to sodium nitroprussiate (SNP), 1 microM, fully inhibited contraction (maximum: 89+/-8% within 30 sec). In the same time-course as for relaxation, CGRP and sodium nitroprussiate caused significant increase in intracellular cGMP levels (2- and 10-fold that of the basal level, respectively, P < 0.01). The nitric oxide synthase (NOS) inhibitor, L-N5(I-iminoethyl)ornithine, dihydrochloride, (L-NIO), 1 microM, partly inhibited SMC relaxation induced by CGRP (78.26%); the protein kinase inhibitor, N-(2-aminoethyl)-5-isoquinolinesulfonamide hydrochloride (H9), 1 microM, and the selective cAMP-dependent protein kinase inhibitor, adenosine-3',5'-monophosphorothioate triethylammonium salt, Rp isomer, (Rp-cAMP(S)), 1 microM, also caused inhibition of relaxation (70.30% and 28.6%, respectively). In parallel, the increase in cGMP caused by CGRP was partly reduced by L-NIO (65.47%) and by H9 (55%). In conclusion, the nitric oxide generation following exposure of human colonic SMC to sodium nitroprussiate causes relaxation through the cGMP pathway; on the other hand, exposure of SMC to CGRP causes relaxation in part by activation of nitric oxide synthase and guanylate cyclase and in part through the cAMP pathway.
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PMID:Calcitonin gene-related peptide-induced relaxation of isolated human colonic smooth muscle cells through different intracellular pathways. 980 18

cAMP mediates many of the effects of vasopressin, prostaglandin E2, and beta-adrenergic agents upon salt and water transport in the renal collecting duct. The present studies examined the role of cAMP-dependent protein kinase (PKA) in mediating these effects. PKA is a heterotetramer comprised of two regulatory (R) subunits and two catalytic (C) subunits. The four PKA isoforms may be distinguished by their R subunits that have been designated RIalpha, RIbeta, RIIalpha, and RIIbeta. Three regulatory subunits, RIalpha, RIIalpha, and RIIbeta, were detected by immunoblot and ribonuclease protection in both primary cultures and fresh isolates of rabbit cortical collecting ducts (CCDs). Monolayers of cultured CCDs grown on semipermeable supports were mounted in an Ussing chamber, and combinations of cAMP analogs that selectively activate PKA type I vs. PKA type II were tested for their effect on electrogenic ion transport. Short-circuit current (Isc) was significantly increased by the PKA type II-selective analog pairs N6-monobutyryl-cAMP plus 8-(4-chlorophenylthio)-cAMP or N6-monobutyryl-cAMP plus 8-chloro-cAMP. In contrast the PKA type I-selective cAMP analog pair [N6-monobutyryl-cAMP plus 8-(6-aminohexyl)-amino-cAMP] had no effect on Isc. These results suggest PKA type II is the major isozyme regulating electrogenic ion transport in the rabbit collecting duct.
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PMID:Type II cAMP-dependent protein kinase regulates electrogenic ion transport in rabbit collecting duct. 1019 23

PCR-coupled cDNA subtraction hybridization was adapted to identify the genes expressed in the adrenocortical tissues from high salt diet-treated rat. A novel cDNA clone, termed salt-inducible kinase (SIK), encoding a polypeptide (776 amino acids) with significant similarity to protein serine/ threonine kinases in the SNF1/AMPK family was isolated. An in vitro kinase assay demonstrated that SIK protein had autophosphorylation activity. Northern blot revealed that SIK mRNA levels were markedly augmented by ACTH treatment both in rat adrenal glands and in Y1 cells. SIK may play an important role in the regulation of adrenocortical functions in response to high plasma salt and ACTH stimulation.
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PMID:Cloning of a novel kinase (SIK) of the SNF1/AMPK family from high salt diet-treated rat adrenal. 1040 90

The Arabidopsis thaliana SOS2 and SOS3 genes are required for intracellular Na(+) and K(+) homeostasis and plant tolerance to high Na(+) and low K(+) environments. SOS3 is an EF hand type calcium-binding protein having sequence similarities with animal neuronal calcium sensors and the yeast calcineurin B. SOS2 is a serine/threonine protein kinase in the SNF1/AMPK family. We report here that SOS3 physically interacts with and activates SOS2 protein kinase. Genetically, sos2sos3 double mutant analysis indicates that SOS2 and SOS3 function in the same pathway. Biochemically, SOS2 interacts with SOS3 in the yeast two-hybrid system and in vitro binding assays. The interaction is mediated by the C-terminal regulatory domain of SOS2. SOS3 activates SOS2 protein kinase activity in a Ca(2+)-dependent manner. Therefore, SOS3 and SOS2 define a novel regulatory pathway important for the control of intracellular ion homeostasis and salt tolerance in plants.
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PMID:The Arabidopsis SOS2 protein kinase physically interacts with and is activated by the calcium-binding protein SOS3. 1072 50

Freeze tolerance by various amphibians includes cryoprotectant production in the form of glucose. Activation of the catalytic subunit of liver cAMP-dependent protein kinase (PKAc) facilitates activation of glycogenolysis, a critical biochemical process necessary for production of glucose. Here, we purified PKAc from Rana sylvatica liver to determine the extent to which cold temperature, which stimulates cryoprotectant production, affected PKAc activity and function. PKAc was purified to greater than 95% homogeneity, with a final specific activity of 71 nmol phosphate transferred/min/mg protein. The molecular weight of frog liver PKAc was 47.6 +/- 1.1 kDa and K(m) values for the phosphate acceptor kemptide and Mg-ATP were 9.0 +/- 0.1 and 51.8 +/- 1.0 microM at 22 degrees C, respectively. K(m) values for both substrates dropped significantly at 5 degrees C. The enzyme was sensitive to specific inhibitors of mammalian PKAc (PKA(i), H89) but was only moderately inhibited by high salt concentrations. Furthermore, salt inhibition was reduced at low temperature. The effect of temperature on enzyme activity indicated a conformational change in PKAc at 10 +/- 2 degrees C, with calculated activation energies of 51 +/- 4 kJ/mol at temperatures above 10 degrees C and 110 +/- 9 kJ/mol below 10 degrees C. PKAc in wood frog liver plays a crucial role in mediating the freeze-induced glycogenolysis that is responsible for the production of 200-300 mM levels of glucose as a cryoprotectant. Differential effects of low temperature on enzyme function, increased substrate affinity and reduced ion inhibition, appear to be central to this role.
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PMID:Purification and characterization of protein kinase A from liver of the freeze-tolerant wood frog: role in glycogenolysis during freezing. 1092 64


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