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

---

Query: EC:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In isolated hepatocytes, quinacrine (150-250 microM) inhibited vasopressin-induced increases in glucose release, glycogen phosphorylase a activity and 45Ca2+ efflux; and glucagon-induced increases in glucose release and cyclic AMP formation. These results indicate that a phospholipase A2 enzyme sensitive to quinacrine is unlikely to be involved in the process by which vasopressin stimulates glycogen phosphorylase activity in the liver cell. In cells labelled with [3H]inositol, much lower concentrations of quinacrine (20-50 microM) inhibited the stimulation by vasopressin of the accumulation of [3H]inositol. The drug had little effect on vasopressin-induced accumulation of [3H]inositol mono-, bis- and tris-phosphates. In the absence of vasopressin, higher concentrations of quinacrine caused a small stimulation of glycogen phosphorylase activity, 45Ca2+ release and the formation of [3H]inositol polyphosphates. Quinacrine did not inhibit the degradation by liver homogenates of inositol 1-phosphate, inositol 4,5-bisphosphate or inositol 1,4,5-trisphosphate. It is concluded that concentrations of quinacrine comparable with those which inhibit phospholipase A2 [G.J. Blackwell, W.G. Duncombe, R.J. Flower, M.F. Parsons and J.R. Vane, Br. J. Pharmac. 59, 353-366 (1977)] inhibit the stimulation by vasopressin of inositol utilization without significantly affecting coupling between hormone receptors and adenyl cyclase or phosphoinositide-specific phosphodiesterase, the action of the phosphodiesterase, and the degradation of inositol triphosphate.
...
PMID:Effects of quinacrine on vasopressin-induced changes in glycogen phosphorylase activity, Ca2+ transport and phosphoinositide metabolism in isolated hepatocytes. 282 12

The addition of glucose to a suspension of yeast initiated glycogen synthesis and ethanol formation. Other effects of the glucose addition were a transient rise in the concentration of cyclic AMP and a more prolonged increase in the concentration of hexose 6-monophosphate and of fructose 2,6-bisphosphate. The activity of glycogen synthase increased about 4-fold and that of glycogen phosphorylase decreased 3-5-fold. These changes could be reversed by the removal of glucose from the medium and induced again by a new addition of the sugar. These effects of glucose were also obtained with glucose derivatives known to form the corresponding 6-phosphoester. Similar changes in glycogen synthase and glycogen phosphorylase activity were induced by glucose in a thermosensitive mutant deficient in adenylate cyclase (cdc35) when incubated at the permissive temperature of 26 degrees C, but were much more pronounced at the nonpermissive temperature of 35 degrees C. Under the latter condition, glycogen synthase was nearly fully activated and glycogen phosphorylase fully inactivated. Such large effects of glucose were, however, not seen in another adenylate-cyclase-deficient mutant (cyr1), able to incorporate exogenous cyclic AMP. When a nitrogen source or uncouplers were added to the incubation medium after glucose, they had effects on glycogen metabolism and on the activity of glycogen synthase and glycogen phosphorylase which were directly opposite to those of glucose. By contrast, like glucose, these agents also caused, under most experimental conditions, a detectable rise in cyclic AMP concentration and a series of cyclic-AMP-dependent effects such as an activation of phosphofructokinase 2 and of trehalase and an increase in the concentration of fructose 2,6-bisphosphate and in the rate of glycolysis. Under all experimental conditions, the rate of glycolysis was proportional to the concentration of fructose 2,6-bisphosphate. Uncouplers, but not a nitrogen source, also induced an activation of glycogen phosphorylase and an inactivation of glycogen synthase when added to the cdc35 mutant incubated at the restrictive temperature of 35 degrees C without affecting cyclic AMP concentration.
...
PMID:The control of glycogen metabolism in yeast. 1. Interconversion in vivo of glycogen synthase and glycogen phosphorylase induced by glucose, a nitrogen source or uncouplers. 283 34

The actions of cyclic AMP are subject to several levels of post-receptor modulation in cardiac tissue. Isoproterenol and prostaglandin E1 both stimulate cAMP accumulation, but only isoproterenol causes activation of particulate cAMP-dependent protein kinase, leading to activation of phosphorylase kinase and glycogen phosphorylase, and inhibition of glycogen synthase. Through the use of isolated, adult ventricular myocytes, we have determined that the hormone-specific activation of glycogen phosphorylase is due to subcellular compartmentation of cAMP. There is some evidence that cyclic nucleotide phosphodiesterases, whose activity is stimulated by alpha 1-adrenergic agonists in isolated myocytes, may have a role in compartmentation. Phosphoinositide hydrolysis is stimulated by alpha 1 and muscarinic agonists, presumably leading to activation of protein kinase C, which in turn has multiple effects on hormone-sensitive adenylate cyclase.
...
PMID:Post-receptor modulation of the effects of cyclic AMP in isolated cardiac myocytes. 284 10

The opioid peptides [Leu]enkephalin and dynorphin-(1-13) were shown to enhance glycogen breakdown when added directly to hepatocytes. This was the result of a concerted effect on the enzymes of glycogen metabolism, with a stimulation of glycogen phosphorylase activity and a simultaneous decrease in glycogen synthase I activity. The latter only became significant when the enzyme was activated by incubating the cells in presence of 20 mM- or 40 mM-glucose. The effect of the opioid peptides was independent of an increase in cyclic AMP or any change in the activity ratio of the cyclic AMP-dependent protein kinase and was abolished by depleting the cells of Ca2+. Both [Leu]enkephalin and dynorphin-(1-13) produced a significant decrease in cyclic AMP formation, suggesting that in liver, as in neuronal tissue, they may act by inhibiting adenylate cyclase activity.
...
PMID:The stimulation of glycogenolysis in isolated hepatocytes by opioid peptides. 287 34

Activities of two key enzymes of glycogen metabolism have been measured after an acute administration of cortisol to 3d-old chickens. Glycogen synthase activity is enhanced 2-3 hours after a cortisol injection, and this activation is blocked by use of protein synthesis inhibitors. Glycogen phosphorylase activity is enhanced at an early stage, and this effect is not suppressed by protein synthesis inhibitors. Liver cAMP levels are not increased concomitantly with this early activation of glycogen phosphorylase; indeed they are depleted. These results point to the existence of an effect of cortisol previous to and independent of its nuclear interaction, and not mediated by an activation of the membrane adenylate cyclase.
...
PMID:Two independent effects of cortisol on chicken liver. 303 Jul 82

Membrane-bound adenylate cyclase in Neurospora crassa is activated by glucagon. Half-maximal effect is observed at hormone concentrations of about 10 nM. After solubilization of the enzyme with Lubrol-PX, the glucagon effect is lost. Incubation of neurospora cells with glucagon leads to a decrease in the activity of glycogen synthetase (EC 2.4.1.11) and to an increase in the activity of glycogen phosphorylase (EC 2.4.1.1) and in the rate of glycogenolysis.
...
PMID:Activation of membrane-bound adenylate cyclase by glucagon in Neurospora crassa. 426 8

Prostaglandin E(1) (PGE(1)) at a concentration of 1 ng/ml antagonized theophylline, and norepinephrine induced release of glycerol and free fatty acids (FFA) in human fat cell preparations. Insulin at higher doses also inhibited theophylline-stimulated lipolysis. The N(6)-2-0'dibutyryl derivative of cyclic adenosine monophosphate (DCAMP) stimulated lipolysis. Prostaglandin E(1) did not significantly inhibit the lipid mobilizing effects of DCAMP. Changes in glycogen phosphorylase activity after treatment with theophylline, norepinephrine, DCAMP, and PGE(1) paralleled those of lipolysis. These results suggest that in man as in experimental animals lipolysis and phosphorylase activity are regulated through processes involving cyclic AMP and that PGE(1) appears to exert its antilipolytic effect in human fat cells, as in rat fat cells, by interfering at the level of adenyl cyclase with the accumulation of cyclic AMP.
...
PMID:Hormonal regulation of lipolysis and phosphorylase activity in human fat cells. 430 1

It is evident from the above review that during the last two decades a great deal of interest in investigating the action of serotonin in parasitic worms has been shown by parasitologists as well as by scientists from several other disciplines. What we have initially reported concerning the effect of serotonin on motility and carbohydrate metabolism of F. hepatica has been pursued on several other parasitic worms. The studies so far indicate that serotonin stimulates motility of every species tested among the phylum Platyhelminthes. The indoleamine also stimulates glycogenolysis in the few flatworm parasites that have been investigated. The information in nematodes is scanty and the role of serotonin in these parasites is still open for experimentation. Recent biochemical investigations on F. hepatica and S. mansoni demonstrated that serotonin and related compounds utilize a common class of receptors in plasma membrane particles which I designate as 'serotonin receptors'. These receptors are linked to an adenylate cyclase that catalyses the synthesis of the second messenger, cyclic 3',5'-AMP. Serotonin and its congeners increase the concentration of cyclic AMP in intact parasites whereas antagonists inhibit such an effect. Cyclic AMP stimulates glycogenolysis, glycolysis and some rate-limiting glycolytic enzymes. It activates a protein kinase that may be involved in activation of glycogen phosphorylase and phosphofructokinase. Serotonin-activated adenylate cyclase in S. mansoni is activated early in the life of the schistosomule. The possibility is discussed that the availability of cyclic AMP through serotonin activation in these parasites may be a prelude to the development processes that take place in the parasite. The different components of the serotonin-activated adenylate cyclase in the parasite are the same as those that have been previously described for the host. Binding characteristics of the receptors indicate that the receptors in F. hepatica appear to be different from those that have been described in the host. The discovery of these receptors and their differences from those in the host offer a new site which is amenable to pharmacological manipulation. The search for new agents that influence serotonin receptors in these parasites could be included in a strategy for the development of new chemotherapeutic agents against these parasites.
...
PMID:Serotonin receptors in parasitic worms. 615 76

alpha-Adrenergic receptors have been grouped into two major subtypes, termed alpha 1- and alpha 2-receptors. Radioligand binding techniques have been utilized to measure the number of alpha 1- and alpha 2-receptors in a variety of tissues. [3H]Dihydroergocryptine labels the entire alpha-receptor population; the alpha-receptor subtypes may be delineated by constricting competition curves with unlabeled selective antagonists and analyzing the data with computer modeling techniques. Alternatively, alpha 1- and alpha 2-receptors may be directly identified with selective radioligands such as [3H]prazosin and [3H]yohimbine, respectively. For example, rat liver membranes have been shown to contain alpha 1- (80%) and alpha 2- (20%) receptors; the alpha 1-receptors activate glycogen phosphorylase. Radioligands have also been used to probe the mechanism by which alpha 2-receptors may inhibit adenylate cyclase activity. Agonist competition curves with [3H]dihydroergocryptine at eht human platelet's alpha 2-receptor may be resolved into two affinity components, interconvertible by guanine nucleotides. These data suggest the agonist-promoted association of the alpha 2-receptor with an additional membrane component. More direct evidence in favor of this possibility was indicated by the increase in sedimentation velocity of solubilized agonist-labeled receptor on sucrose density gradients.
...
PMID:Agonist interactions with alpha-adrenergic receptors. 617 29

Changes in the contents of adenine nucleotides, creatine phosphate, inorganic phosphate, creatine, glucose-6-phosphate and glycogen and the activity of adenylate cyclase, creatine kinase, glycogen phosphorylase 31:51-AMP-phosphodiesterase and glycogen synthetase in muscles and of blood catecholamines were studied in adult rats before loading, immediately after the cessation of the muscular activity, and at rest. Adenine nucleotides are established to play a regulatory role in catabolic and anabolic processes nucleotides are established to play a regulatory role in catabolic and anabolic processes related to the muscular activity. It is established that compensation and supercompensation of the working losses of muscular creatine phosphate and glycogen are due to activation of anabolic processes under conditions of higher phosphorylation of the adenylic system.
...
PMID:[Dependence of creatine kinase and glycogen synthetase activities of skeletal muscles on state of adenine nucleotide phosphorylation and cAMP metabolism]. 624 97


<< Previous 1 2 3 4 Next >>

---