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

Stimulation of endocytosis is a very early effect of thyrotropin on thyroid. However, the relationship of the endocytotic process to the many other thyrotropin effects on thyroid is not clearly defined. Since phagocytosis in isolated thyroid cells is a presumed model for in vivo endocytosis of colloid, we induced phagocytosis in isolated thyroid cells by incubating them at 37 degrees C with 0.109-mu diameter polystyrene microbeads; phagocytosis was confirmed in each experiment by electron microscopy and/or spectrophotometric analysis of dioxane cell extracts. Cells incubated with 50-100-mu diameter polystyrene macrobeads (too large to ingest) served as controls. Microbead-induced phagocytosis in isolated thyroid cells was consistently accompanied by increases in: (a) cyclic 3',5'-adenosine monophosphate-(14)C formation from adenine-8-(14)C (66%); (b) iodide-(131)I trapping (40%); (c) protein and RNA synthesis (30%); (d) phospholipogenesis (50%); (e) alpha-aminoisobutyric acid-1-(14)C uptake (15%). 50- to 100-mu diameter polystyrene macrobeads did not influence cell function in any of these experiments. Aminotriazole, 5 x 10(-3) (M), a peroxidase inhibitor, blocked the stimulatory effect of microbead-induced phagocytosis on phospholipogenesis only. These studies indicate that in isolated thyroid cells the phagocytotic process, per se, may alter activity of the membrane-bound adenyl cyclase enzyme. The resultant increase in cyclic 3',5'-adenosine monophosphate may be a triggering mechanism for (some) subsequent metabolic changes occuring during phagocytosis. Since these changes mimic those induced by thyrotropin, it is suggested that a variety of thyrotropin effects on thyroid may be secondary to stimulation of colloid resorption and hormone secretion.
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PMID:Stimulatory effects of induced phagocytosis on the function of isolated thyroid cells. 434 55

Incubation of rat extraorbital lacrimal gland slices with the beta-agonist isoproterenol caused peroxidase secretion but no K+ release. The peroxidase secretion was inhibited by propranolol. Addition of dibutyryl cyclic AMP or adenosine 3'5'-cyclic phosphorothioate to lacrimal slices produced peroxidase secretion at a higher rate than that obtained with optimal concentration of isoproterenol. Methyl isobutylxanthine is also a strong stimulator of peroxidase secretion. Peroxidase activity was determined by a modified sensitive guaiacol method. Membrane fraction of lacrimal cells was shown to contain an isoproterenol-stimulated adenylate cyclase activity. It is therefore suggested that there is a beta-adrenergic receptor in the rat lacrimal gland and that its stimulation causes activation of an adenylate cyclase which leads to peroxidase secretion.
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PMID:beta-Adrenergic receptors stimulated peroxidase secretion from rat lacrimal gland. 616 88

The arachidonate inhibition of the adenylate-cyclase system of cultured pig thyroid cells was not mediated by cyclooxygenase, lipoxygenase or peroxidase metabolites. Indeed ETYA, an inhibitor of cyclooxygenase and lipoxygenase, and methimazole, an inhibitor of peroxidase and iodination were without effect on the arachidonate inhibition. Moreover the effect of arachidonate was amplified by a combination with ETYA. In 32P incorporation experiments we observed a modification of the labelling of individual phospholipids of cultured pig thyroid cells resulting in a decrease into phosphatidylinositol (PI) and an increase into phosphatidate (PA) of arachidonate and ETYA-treated cells. These results may be explained by an inhibition of CDP-diacylglycerol: inositol transferase and conversely a stimulation of PI specific phospholipase C yielding a decrease in PI and an increase in PA, which inhibits in turn adenylate cyclase activity possibly by Ca2+ translocation.
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PMID:Effects of eicosatetraynoic acid (ETYA) on cultured pig thyroid cells. Relationships between the inhibition of the phosphatidate-phosphatidyl inositol cycle, the iodination and the cyclic AMP responsiveness to thyrotropin. 618 61

Regulation of cellular content of the endogenous opioid peptides Met5-enkephalin and Leu5-enkephalin was investigated in neuroblastoma X glioma hybrid cells NG108-15 grown in both serum-supplemented and serum-free defined media. Untreated cells and cells induced to differentiate were stained using anti-Met5-enkephalin and anti-Leu5-enkephalin with the peroxidase-antiperoxidase immunocytochemical technique at the light microscopic level. In untreated NG108-15 cells grown in serum-supplemented medium, intense enkephalin-like immunoreactivity was localized in cell bodies and short processes of a select population of cells. The volume fraction of stained untreated cells remained constant throughout the time period investigated. When cells were induced to differentiate with N6,O2'-dibutyryl adenosine 3':5'-cyclic monophosphate (dBcAMP) or 8-bromo cyclic adenosine monophosphate (1.0 mM) treatment for 5 days, staining was found throughout the cytoplasm of perikarya and the extensive processes which were expressed, and the volume fraction of stained cells increased over 2-fold. Receptor-mediated stimulation of adenylate cyclase by prostaglandin E1 (10 microM) for 5 days produced results similar to those with dBcAMP. Pure cultures of differentiated cells with intense staining were obtained by further treatment of cultures, grown in the presence or absence of dBcAMP, with arabinosylcytosine (araC). Untreated, dBcAMP-treated and araC-treated NG108-15 cells grown in defined medium expressed staining patterns and volume fractions of stained cells similar to those grown in serum-supplemented medium; sodium butyrate (1.0 mM), however, increased the volume fraction of stained cells grown in defined medium over 3-fold, whereas it had little effect on staining of cells grown with serum. The presence of both Met5- and Leu5-enkephalin-like activities in NG108-15 cells was confirmed in acid extracts of cells by radioreceptor assay after separation by reverse phase high pressure liquid chromatography. Induction of differentiation in NG108-15 cells by dBcAMP treatment increased the cellular concentration of both enkephalins to over 2 times the levels found in untreated cells. The biochemical analysis for Met5-enkephalin- and Leu5-enkephalin-like activity compared well with the immunocytochemical data indicating that the enkephalin content is correlated with the state of differentiation of NG108-15 cells.
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PMID:Induction of differentiation increases Met5-enkephalin and Leu5-enkephalin content in NG108-15 hybrid cells: an immunocytochemical and biochemical analysis. 619 53

To characterize the role of cyclic nucleotides in secretion of enzymes by the lacrimal gland, pieces of rat exorbital glands were perfused with (1) 8-bromoadenosine-3',5'-cyclic monophosphate (8 Br cyclic AMP), (2) 8-bromoguanosine-3',5'-cyclic monophosphate (8 Br cyclic GMP), (3) forskolin, a stimulator of adenylate cyclase activity, (4) 3-isobutyl-1-methylxanthine (IBMX), an inhibitor of phosphodiesterase activity, or (5) carbachol, a cholinergic agonist. As a measure of enzyme secretion, timed collections of the perifusate effluent were analysed for peroxidase, an enzyme secreted by the lacrimal gland. Control peroxidase secretion was 0.3-0.9 (u./min per milligram protein). Peroxidase secretion was stimulated by 8 Br cyclic AMP (1 mM), but not by 8 Br cyclic GMP (1 mM). A 2-fold increase was detected. Peroxidase secretion was also stimulated by forskolin (60 microM), IBMX (1 mM), and the cholinergic agonist carbachol, which all stimulated peroxidase secretion 2-or 3-fold. The effect of maximally effective concentrations of IBMX (1 mM) and carbachol (0.1 mM) on secretion was additive. Finally, Ca2+ depletion in the presence of EGTA (1 mM) inhibited both IBMX-and carbachol-induced secretion by 45% and 60% respectively. We conclude that cyclic AMP, but not cyclic GMP, can stimulate lacrimal gland enzyme secretion. Cyclic AMP appears to utilize a pathway separate from but convergent with cholinergic agonists.
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PMID:Cyclic nucleotide-dependent enzyme secretion in the rat lacrimal gland. 620 48

A variety of proteins and tissue preparations (rabbit erythrocyte lysate, catalase, peroxidase, creatine phosphokinase, and lima bean trypsin inhibitor) contain protein activator(s) of the extracellular adenylate cyclase of intact Bordetella pertussis organisms. Stimulation of adenylate cyclase activity of up to 1000-fold over basal activity can be obtained. Activation of the adenylate cyclase is due to the presence of calmodulin in these protein preparations. The criteria to establish this were: Ca2+ dependence of the activation, inhibition by trifluoperazine, heat stability of the activator, chromatographic behavior like authentic calmodulin, and stimulation of cyclic nucleotide phosphodiesterase by the activators. The great sensitivity of the B.pertussis adenylate cyclase assay makes this and ideal system for the detection of trace amounts of calmodulin, in the presence of large amounts of other proteins.
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PMID:Spurious protein activators of Bordetella pertussis adenylate cyclase. 626 34

A plasma membrane-enriched vesicle fraction has been prepared from Trypanosoma brucei by sonication and differential centrifugation on sucrose gradients. This fraction is enriched 5-fold in the plasma membrane marker enzymes adenyl cyclase (EC 4.6.1.1) and ouabain-inhibitable, (Na+ +K+)-dependent adenosine triphosphatase (EC 3.6.1.3). It is also enriched up to 14-fold in iodinated surface proteins, and up to 4-fold in (3H-mannose-labeled glycoproteins, of which the major variable surface coat glycoprotein is the main constituent. Proteins of the plasma membrane fraction and other subcellular fractions have been identified by electrophoretic analysis in sodium dodecyl sulfate-polyacrylamide gradient slab gels. Several high molecular weight surface glycopeptides have been selectively investigated and partially characterized by a combination of metabolic labeling with [3H]mannose, lactoperoxidase-catalyzed surface iodination, and affinity chromatography on Con A-Sepharose. In addition to the major variable surface coat glycoprotein (estimated Mr = 58000), there are several minor surface glycopeptides (Mr = 76000, 86000 and 92000-100000) which are apparent extrinsic membrane components, and two surface glycopeptides (Mr = 42000 and 130000) which are intrinsic membrane components.
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PMID:Identification and partial characterization of plasma membrane polypeptides of Trypanosoma brucei. 628 66

Iodinated native bovine parathyroid hormone (bPTH(1-84)) was separated from uniodinated hormone by reversed-phase liquid chromatography techniques after lactoperoxidase labeling. Analysis of iodinated residues after enzymatic digestion indicated that the major labeled product was largely monoiodinated on the sole tyrosine residue. This material retained full bioactivity in an in vitro renal adenylate cyclase assay. Binding of 125I-bPTH(1-84) to rabbit renal membranes at 4 degrees C was proportional to membrane protein concentration and was saturable and dissociable. Radioligand binding was inhibited by concentrations of unlabeled bPTH(1-84) required to stimulate adenylate cyclase in the same membrane preparation but was not inhibited by non-PTH peptides other than adrenocorticotropin at high concentrations (greater than 10 microM). Synthetic NH2-terminal analogues of bPTH(1-84) all elicited approximately equivalent inhibition of radioligand binding which was, however, less potent than unlabeled bPTH(1-84), suggesting a role for the carboxyl region of the molecule in the interaction of bPTH(1-84) with its receptor. Activity of the NH2-terminal agonists was similar to bPTH(1-84) in stimulating adenylate cyclase. Although substitution in sequence position one, of serine in human PTH(1-34) for alanine in bPTH(1-34), reduced activity in the adenylate cyclase assay, inhibition of 125I-bPTH(1-84) binding by both peptides and by an analogue of bPTH(3-34) was equivalent, consistent with a minimal contribution of the first 2 residues for receptor binding of the NH2-terminal region of PTH. The results illustrate the utility of the radiolabeled preparation of native bPTH we have developed and emphasize the importance of probing the PTH receptor with an intact hormone to maximize information concerning the mechanism of PTH action.
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PMID:Characterization of the rabbit renal receptor for native parathyroid hormone employing a radioligand purified by reversed-phase liquid chromatography. 629 18

The human HL-60 myeloid leukaemia cell line developed, during maturational changes induced by dimethyl sulphoxide, an enhanced capacity for phorbol myristate acetate- stimulated oxidative activity and acquired a cytochrome b. Titration of the absorbance at 559 nm at potentials of-190 to -370 mV indicated that this cytochrome had a very low potential, differentiating it from mitochondrial and endoplasmic reticulum cytochromes and identifying it as the cytochrome b(-245) that has been recently found in other phagocytic cells. Subcellular fractionation studies of mature HL-60 cells showed that cytochrome b had a dual distribution within the cell. The lighter peak of activity was associated with the plasma membrane markers, adenylate cyclase and receptors for the N- formal-L-methionyl-L-leucyl-L-phenylalanine (f-Met-Leu-Phe) peptide. The denser components localized with the mitochondria but were distinct from mitochondrial cytochromes because whereas the activity of cytochrome c oxidase fell during HL-60 cell maturation, that of this cytochrome b was markedly increased. Concentrations of myeloperoxidase were unrelated to activity of the oxidase system and decreased as the cell matured. The increase in the concentrations of cytochrome b with cellular maturation parallelled the increase in the stimulated nonmitochondrial respiratory activity of these cells. The turnover of the hexose monophosphate shunt of immature cells was increased by the oxidising agents, methylene blue and tert-butylhydroperoxide, indicating that these immature cells have stimulated nonmitochondrial respiratory activity by maturing HL-60 cells is associated with, and is probably dependent upon, the acquisition by these cells of the cytochrome b(-245) oxidase system.
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PMID:Development of cytochrome b and an active oxidase system in association with maturation of a human promyelocytic (HL-60) cell line. 629 56

In the present study, the expression of beta-adrenergic receptors, the activity of the enzyme adenylate cyclase (AC), and the intracellular concentration of cyclic adenosine 3',5'-monophosphate (cAMP) were investigated in HL-60 cells before and after their differentiation to monocytic or more mature granulocytic cells. Treatment of the HL-60 promyelocytes with 12-O-tetradecanoylphorbol 13-acetate or human interleukin 2 resulted in the appearance of cells with monocytic characteristics (morphology, non-specific esterase, adherence, reaction with a monocyte-specific monoclonal antibody). Induction with retinoic acid resulted in differentiation to cells with typical features of mature granulocytes (morphology, peroxidase, nitro-blue tetrazolium reduction). During maturation to monocytes, the density of beta-adrenergic receptors decreased, whereas it remained constant during maturation to granulocytes. In comparison with normal circulating monocytes or polymorphonuclear granulocytes, expression of beta-adrenergic receptors on the surface of the differentiated HL-60 cells was low. Activation of AC by the hormones isoproterenol, prostaglandin E1, and histamine generally decreased with HL-60 maturation and enzyme activities were markedly below those measured in normal peripheral leukocytes. In the induced monocytic HL-60 cells, the weak effectiveness of isoproterenol was due to the loss of beta-adrenergic receptors. In the induced granulocytic HL-60 cells, the reduced hormonal AC activation could be explained by the impaired coupling between hormone receptors and catalytic enzyme unit. The concentration of intracellular cAMP after differentiation of HL-60 cells reflected the increase in basal AC activity and the decrease in hormone stimulation of the enzyme. Our data indicate that HL-60 cells induced to differentiate possess some monocyte- and granulocyte-like properties, but do not meet several important functional criteria of their new cell identities.
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PMID:[In vitro differentiation of leukaemic promyelocytes (HL-60): effect on beta-adrenergic receptors and adenylate cyclase activity]. 631 Aug 99


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