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:3.4.16.2 (PCP)
3,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To understand the mechanism of the action of ATP on the in vitro transport of the rapidly-labeled RNA from isolated nuclei, the fate of ATP during the incubation as well as the effect of ATP, its analogues and other ribonucleoside triphosphates on the transport was examined and the following results were obtained. (1) More than 97% of added ATP remained acid soluble. No polyadenylation of the rapidly-labeled RNA in the released fraction by added ATP occurred although new polyadenylate segments smaller than 10 S were synthesized. (2) The addition of an ATP-generating system to the reaction mixture restored the initial rate of the release of the rapidly-labeled RNA from isolated nuclei. (3) Among the ribonucleoside triphosphates tested, ATP was most effective in stimulating the release. GTP was about 2/3 as effective as ATP. UTP showed some effect, but CTP showed no effect. EDTA was also non-effective. (4) When no ATP-generating system was added to the reaction mixture, AMP failed to mimic the effect of ATP. However, the combination of AMP and pyrophosphate could take the place of ATP. (5) Both AMP-CPP and AMP-PCP, the ATP analogues, showed the equal degree of their effect on the release, regardless of the position of the methylene bond. From these results, the principal role of ATP in the in vitro transport systems seemed to be its interaction with isolated nuclei to dissociate a structure which retains the rapidly-labeled RNA in the nucleus.
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PMID:The role of ATP in the transport of rapidly-labeled RNA from isolated nuclei of rat liver in vitro. 10 29

ATP promoted biphasic effects on both basal and fMLP-stimulated arachidonic acid (AA) release in neutrophil-like HL60 cells: stimulation in the micromolar range (EC50 = 3.2 +/- 0.9 microM) and inhibition at higher concentrations (EC50 = 90 +/- 11 microM). ATP also inhibited UTP- and platelet activating factor-stimulated AA release. Only stimulatory effects of ATP on basal or fMLP-stimulated phospholipase C were observed. The inhibitory effect of ATP on AA release was not due to reacylation of released AA, chelation of extracellular Ca2+, cell permeabilization, or changes in the rise of [Ca2+]i induced by agonist. The inhibition was rapid, being detected within 5-15 s. The inhibitory effect of ATP on fMLP-stimulated AA release could be desensitized by pretreatment of the cells with 2 mM ATP, but not 20 microM ATP, the concentration that resulted in maximal release of AA and inositol phosphates. The inhibition by ATP was neither dependent on generation of adenosine by ATP hydrolysis nor the result of direct interaction of ATP with P1 purinergic receptors. Among other nucleotides tested (CTP, GTP, ITP, TTP, XTP, adenosine 5'-(beta,gamma-methylene)triphosphate (AMP-PCP), adenyl-5'-yl imidodiphosphate (AMP-P(NH)P), ADP, adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S), and UTP), only UTP and ATP gamma S displayed biphasic effects with potencies and efficacies almost identical to those of ATP. The other nucleotides only exhibited stimulatory effects (EC50 = 60-300 microM). The results are consistent with a model of dual regulation of AA release by two distinct subtypes of P2U receptors in HL60 cells.
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PMID:Dual regulation of arachidonic acid release by P2U purinergic receptors in dibutyryl cyclic AMP-differentiated HL60 cells. 131 16

Uptake of the catecholamines (CA), dopamine (DA) and norepinephrine (NE) into synaptosomes prepared from rat and bovine brains was potentiated by ATP (from 0.1 to 5.0 mM) in a dose-dependent manner. Other nucleotides, particularly the nonhydrolyzable ATP analogs beta,gamma-imidoadenosine-5'-triphosphate (AMP-PNP) and beta,gamma-methyladenosine-5'-triphosphate (AMP-PCP) also potentiated [3H]DA and [3H]NE uptake. Several endogenous 5'-nucleotide triphosphates (e.g. GTP, UTP and CTP) potentiated [3H]CA uptake, but were less effective than ATP. Among the ATP metabolites, only ADP potentiated uptake whereas AMP and adenosine did not. [3H]Dopamine uptake measured in Krebs bicarbonate buffer had a Km of 2.1 microM and a Vmax of 163.9 pmol/mg prot./min. In presence of ATP, [3H]DA uptake had much higher affinity (Km = 0.56 microM) and larger capacity (Vmax = 333 pmol/mg prot./min) than uptake in absence of added ATP. Furthermore, [3H]DA uptake in presence of ATP had faster rate of uptake, and was independent of temperature while in absence of added ATP it was temperature-dependent. This ATP-dependent [3H]DA uptake was retained by synaptosomal ghosts that were obtained after lysing the striatal synaptosomes and removing their contents of synaptic vesicles and mitochondria. It is proposed that, in addition to the carrier-mediated (neuronal) uptake of CA, there is neuronal uptake that is regulated by ATP and inhibited by cocaine, which may be more relevant for terminating the synaptic action of CA because of its faster rate of uptake and larger capacity.
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PMID:ATP-regulated neuronal catecholamine uptake: a new mechanism. 240 89

Micromolar concentrations of copper (Cu2+) and cysteine induce rapid efflux of calcium from sarcoplasmic reticulum (SR) vesicles. This effect appears to be due to a Cu2+-catalyzed oxidation of the added cysteine to a critical sulfhydryl group on the release protein from sarcoplasmic reticulum (J. L. Trimm, G. Salama, and J. J. Abramson (1986) J. Biol. Chem. 261, 16092-16098). The data presented here indicate that adenine nucleotides synergistically stimulate copper/cysteine (oxidation)-induced calcium efflux from SR vesicles. The order of effectiveness in stimulating calcium efflux is ATP greater than AMP-PCP greater than cAMP greater than AMP greater than adenine approximately NAD approximately NADH. Non-adenine-containing nucleotides such as GTP, CTP, UTP, and ITP and the high energy phosphate compound, acetyl phosphate, were ineffective in stimulating oxidation-induced calcium efflux. The relative effectiveness of various adenine nucleotides in stimulating calcium-induced calcium efflux and oxidation-induced calcium efflux are identical, suggesting that a common mode of action is involved when calcium release is triggered by either method. The stimulatory effect of the adenine nucleotides on oxidation-induced efflux is independent of external magnesium concentration and independent of the magnesium gradient across the SR membrane.
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PMID:Adenine nucleotides stimulate oxidation-induced calcium efflux from sarcoplasmic reticulum vesicles. 245 34

1. The whole-cell voltage-clamp technique was used to study the effects of extracellular ATP on smooth muscle cells isolated from the rat vas deferens. 2. ATP (1-200 microM) elicited an inward-rectifying current that was rapid in onset (less than or equal to 100 ms), reached a peak value that depended on [ATP], and desensitized in the continued presence of ATP (half-time approximately 2 s). 3. Cells recovered from desensitization when incubated in the absence of ATP (resensitization half-time approximately 2 min). 4. A comparison was made of the ability of ATP and several of its structural analogues to stimulate inward current at a negative holding potential. ATP was by far the most effective compound among the series ATP, ADP, AMP, adenosine, GTP, UTP and ITP. ADP elicited a current that was 20-25% as large as that produced by ATP, while the other compounds were ineffective at a concentration which produced a maximal ATP response. 5. AMP-CPP (alpha, beta-methylene ATP), AMP-PCP (beta, gamma-methylene ATP), and AMP-PNP (beta, gamma-imido ATP), which are relatively resistant to hydrolysis, were similarly compared to ATP. While none of these analogues elicited a current resembling the ATP-induced current, AMP-CPP and AMP-PNP each produced a small, relatively sustained inward current; AMP-PCP had little or no effect. 6. The ATP-sensitive conductance is cation selective, but does not appear to discriminate strongly between Na+, K+ and Mg2+. 7. Analysis of the fluctuations which accompany the ATP-induced current suggests that ATP controls a population of channels with a unitary current greater than 0.5 pA at -130 mV. 8. The ATP-evoked current discussed in this report may be responsible for the depolarizing effect of ATP previously described in multicellular preparations of the vas deferens.
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PMID:An ATP-sensitive conductance in single smooth muscle cells from the rat vas deferens. 245 75

1. Adult female Culex pipiens and Culiseta inornata have purinergic receptors that respond to extracellular ADP and related compounds. Stimulation of these receptors caused ingestion of artificial diets. Addition of bicarbonate to the saline solvent enhanced the phagostimulatory effect. Saline-bicarbonate was as effective a solvent as blood plasma for Cx. pipiens, and was used in the dose-effect determinations. Ranking of the potencies was: ADP greater than AMP-PNP greater than ATP = AMP greater than AMP-PCP much greater than 2'dAMP greater than 2'dADP greater than 2'dATP. At 1 mM concentration, ITP, GTP, CTP, UTP, c-AMP, 2'AMP, 3'AMP, DPG, or GSH + glucose caused fewer than 50% of the insects to gorge, as did 2'3'dd-ATP, A tetra P, and AMP-CPP at 100 microM. 2. The potency ranking for Cu. inornata was: ADP greater than AMP-PNP greater than ATP greater than AMP-PCP much greater than AMP much greater than AMP-S. The concentrations required to produce the ED50 response (inducing 50% of the test insects to gorge) were much higher than those required for Cx. pipiens; however, saline, not saline-bicarbonate, was used as the solvent. With the exception of the very low potency of AMP for Cu. inornata, the ADP potency index values for the other chemicals tested on both species are similar.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Purinergic reception by culicine mosquitoes. 290 19

When the effects of varying concentrations of ATP on the dissociation rate of the ouabain-enzyme complex were studied, the dissociation rate constant increased with increasing ATP concentrations up to 1 mM, and then decreased with further rise in ATP; indicating that ATP binds to two distinct sites on the complex. ADP and AMP-PNP had similar biphasic effects. GTP, CTP, UTP, and AMP-PCP reduced the dissociation rate. AMP and Pi had no effects. Increase in dissociation rate caused by 0.5 mM ATP was not abolished by saturating CTP, indicating the binding of CTP to only one of the two ATP sites. The data suggest the existence of separate catalytic and regulatory sites, with different affinities and nucleotide specificities.
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PMID:Coexistence of two ATP sites on the ouabain-complexed (Na+ + K+)-ATPase. 300 82

The binding and cross-linking of the ATP photoaffinity analogue 8-azidoadenosine 5'-triphosphate (azido-ATP) with recA protein have been investigated, and through cross-linking inhibition studies, the binding of other nucleotide cofactors to recA protein has also been studied. The azido-ATP molecule was shown to be a good ATP analogue with regard to recA protein binding and enzymatic function by three criteria: first, the cross-linking follows a simple hyperbolic binding curve with a Kd of 4 microM and a cross-linking efficiency ranging from 10% to 70% depending on conditions; second, ATP, dATP, and adenosine 5'-O-(3-thiotriphosphate) (ATP-gamma-S) specifically inhibit the cross-linking of azido-ATP to recA protein; third, azido-ATP is a substrate for recA protein ATPase activity. Quantitative analysis of the cross-linking inhibition studies using a variety of nucleotide cofactors as competitors has shown that the binding affinity of adenine-containing nucleotides for recA protein decreases in the following order: ATP-gamma-S greater than dATP greater than ATP greater than adenylyl beta,gamma-imidodiphosphate (AMP-PNP) much greater than adenylyl beta,gamma-methylenediphosphate (AMP-PCP) approximately adenine. Similar competition studies also showed that nearly all of the other nucleotide triphosphates also bind to recA protein, with the affinity decreasing in the following order: UTP greater than GTP approximately equal to dCTP greater than dGTP greater than CTP. In addition, studies performed in the presence of single-stranded DNA demonstrated that the affinity of ATP, dATP, ATP-gamma-S, and AMP-PNP for recA protein is significantly increased. These results are discussed in terms of the reciprocal effects that nucleotide cofactors have on the modulation of recA protein--single-stranded DNA binding affinity and vice versa. In addition, it is demonstrated that nucleotide and DNA binding are necessary though not sufficient conditions for ATPase activity. The significance of this result in terms of the possible requirement of critically sized clusters of 15 or more recA protein molecules contiguously bound to DNA for ATPase activity is discussed.
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PMID:Interaction of recA protein with a photoaffinity analogue of ATP, 8-azido-ATP: determination of nucleotide cofactor binding parameters and of the relationship between ATP binding and ATP hydrolysis. 353 81

Poliovirus replicase- and host factor-catalyzed copying of 3'-terminal polyadenylic acid [poly(A)] of poliovirion RNA was studied. Host factor-stimulated synthesis of polyuridylic acid [poly(U)] by the replicase required ATP in addition to UTP. ATP was not required for the oligouridylic acid-primed copying of 3'-terminal poly(A) of virion RNA. GTP, CTP, and AMP-PCP (5'-adenylyl beta-gamma methylenediphosphate, an ATP analog) could not replace ATP in host factor-stimulated synthesis of poly(U). Antibodies to poliovirus genome-linked protein (VPg) specifically precipitated in vitro-synthesized poly(U) from a host factor-stimulated reaction. The poly(U) synthesized in a host factor-stimulated reaction was shown to be attached to VPg precursor polypeptide(s) via a tyrosine-phosphate bond as found in poliovirion VPg-RNA.
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PMID:ATP is required for initiation of poliovirus RNA synthesis in vitro: demonstration of tyrosine-phosphate linkage between in vitro-synthesized RNA and genome-linked protein. 632 50

Evidence in this and other reports from this laboratory suggest that adrenergic nerves in rat heart ventricle slices incubated in a Na+-deprived (choline+) medium containing Ca++ (Ch+--Ca++), transport (by a cocaine-sensitive mechanism) 3H-norepinephrine outwardly from synaptic vesicles attached or fused to the plasma membrane. The 3H-amine secretion was not inhibited by probenecid, an anion transport inhibitor which may prevent exocytosis. The 3H-amine release was rapidly inhibited by exogenous nucleotides ATP, UTP, and GTP greater than ADP greater than AMP greater than the nucleoside adenosine. Magnesium++ tended to increase and reserpine to decrease the effect of ATP. Neither increasing the [Ca++] nor [Mg++] (to compete with Ca++ for ATP) decreased the effect of 3 mM ATP. After secretion began, lowering the Ca++ concentration by ommission, or by the inclusion of either a low concentration of EDTA or the Ca++-binding, but non-energy-conserving synthetic analogs of ATP: AMP--PCP and AMP--PNP, gradually lowered the rates of secretion. By comparison, the rapid effects of the energy-conserving nucleotides suggested that their effects were at least partially independent of chelation, and were energy dependent. ATP, unlike cocaine, did not inhibit the uptake of NE in a Krebs HCO3 medium. Inhibition of (Na+ + K+)-ATPase by ouabain neither inhibited the release by Ch+--Ca++, nor antagonizes the release inhibiting effect of ATP. Hence, ATP did not increase apparent retention of NE by stimulating the uptake of released NE. The ATP-inhibited secretion was not increased by theophylline.
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PMID:The effect of exogenous adenosinetriphosphate on the choline-calcium stimulated release of 3H-norepinephrine in rat heart ventricle slices. 668 77


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