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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Triethyllead (TEL) is a CNS neurotoxin producing bizarre neurobehavioral changes. The principal objective of this study was to determine if TEL-induced defects in energy metabolism were responsible for the inhibition of synaptosomal Na+-dependent high-affinity uptake of gamma-aminobutyric acid (GABA). A dose-dependent inhibition of GABA uptake (ID50 = 10 microM TEL) was found during 30-s incubations. Uptake of glutamate was more resistant to the inhibitory effects of TEL. A TEL-induced Cl(-)-dependent synaptosomal deficit of ATP was observed. Such deficit in high-energy phosphate was time-dependent and did not occur in the absence of Cl- or as early as 30 s. Inhibition of GABA uptake, on the other hand, was a Cl(-)-independent phenomenon and was observed at as early as 30 s. TEL was not competitive with Na+ or GABA itself, as the effects of TEL were not overcome with high [Na+] or [GABA]. These results indicate that the locus of TEL inhibition of GABA uptake is not a Cl(-)-dependent event and does not involve a perturbed transmembrane electrochemical gradient, due to either an observed mitochondrial defect or an inhibition of Na+, K+-ATPase directly.
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PMID:Selective inhibition of synaptosomal gamma-aminobutyric acid uptake by triethyllead: role of energy transduction and chloride ion. 288 Sep 29

Uptake of Cl- by plasma membrane vesicles from the rat brain was stimulated by ATP at 37 degrees C, but not by beta, gamma-methylene ATP or at 0 degrees C. The addition of Triton X-100 or sucrose to the incubation medium diminished the ATP-stimulated Cl- uptake, suggesting that Cl- was transported across the membranes into the intravesicular space. This ATP-stimulated Cl- uptake was not affected by 1 mM ouabain. 1 microM oligomycin, 0.1 mM gamma-aminobutyric acid or 0.1 mM picrotoxin. Thus, non-mitochondrial ATP-driven Cl- transport through a system other than Na, K-ATPase or Cl- channels occurs in neuronal plasma membrane vesicles.
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PMID:ATP-dependent Cl- uptake by plasma membrane vesicles from the rat brain. 296 37

In synaptosomal membranes from rat cerebellum, additive responses to adenylate cyclase activity are observed between the beta adrenergic receptors present on the Purkinje cells and the adenosine A-1 receptors or gamma-aminobutyric acid B (GABAB) receptors, which are both associated with the granule cells. In contrast, nonadditive responses are found with the activation of the adenosine A-1 and the GABAB receptors. Because both receptors are mainly associated with the same cell type, the nonadditive response indicates an interaction between the adenosine A-1, GABAB receptors and the adenylate cyclase. The present study suggests that the nonadditivity results from a limited number of adenylate cyclase catalytic units, which both receptor systems share. This conclusion was derived indirectly by showing that 1) a GABAB agonist did not affect the adenosine A-1 recognition site; 2) both receptors additively activated the high-affinity guanosine 5'-triphosphatase, which is believed to reflect the activation of the inhibitory guanine nucleotide unit; and 3) the nonadditivity was still observed after stimulation of adenylate cyclase activity with forskolin.
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PMID:Co-localized adenosine A1 and gamma-aminobutyric acid B (GABAB) receptors of cerebellum may share a common adenylate cyclase catalytic unit. 298 20

Preincubation of rat brain synaptosomes with xanthine and xanthine oxidase (X/XO) in Ca2+-free Krebs buffer resulted in a 27% inhibition of synaptosomal gamma-aminobutyric acid (GABA) uptake. Addition of 1.5 mM CaCl2 increased the inhibition with X/XO to 46%, and inhibition was essentially complete when the calcium ionophore A23187 also was included. In other studies, preincubation of purified rat brain mitochondria with the combination of X/XO and 4 microM CaCl2 produced a significant (38%) decrease in state 3 respiration with glutamate/malate as substrate that was not seen with either X/XO or Ca2+ alone. Similar results were obtained using cultured mouse spinal cord neurons in which incubation with X/XO/ADP/FeCl2 and A23187 produced membrane damage as assessed by a 32% reduction of neuronal Na+, K+-ATPase activity. Neither X/XO/ADP/FeCl2 nor A23187 alone caused detectable inhibition. These results demonstrate the synergistic damaging effect of free radicals and Ca2+ on membrane function. In addition, they suggest that free radical-induced peroxidation of membrane lipid, occurring focally during complete or nearly complete ischemia in vivo, could result in intense cellular perturbation when coupled with increased intracellular Ca2+.
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PMID:Calcium enhances in vitro free radical-induced damage to brain synaptosomes, mitochondria, and cultured spinal cord neurons. 299 23

Triethyllead (TEL), the active metabolite of tetraethyllead, was shown previously to inhibit selectively high-affinity Na+-dependent uptake of gamma-aminobutyric acid (GABA) into cerebrocortical synaptosomes. Such inhibition was not related to the Na+ gradient, Na+,K+-ATPase activity, [Cl-], or energy charge. We report here that TEL inhibits GABA binding to the presynaptic transporter involved in Na+-dependent uptake. Scatchard plot analysis of Na+-dependent [3H]GABA binding to a highly purified synaptic plasma membrane preparation revealed that 25 microM TEL reduced the Bmax by 44%, leaving the KD unchanged. This binding was reversible and predominantly involved membrane uptake sites, as characterized by pharmacological specificity to GABA ligands. Approximately 85% of specific GABA binding was considered membrane uptake site binding, as indicated by sensitivity to nipecotic acid and diaminobutyric acid, with relative insensitivity to muscimol, bicuculline methiodide, baclofen, and beta-alanine. With respect to previous data, these finding suggest that TEL inhibits Na+-sensitive high-affinity GABA uptake by interfering with GABA binding to its presynaptic transporter.
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PMID:Triethyllead inhibits gamma-aminobutyric acid binding to uptake sites in synaptosomal membranes. 303 27

The maximum yield for the production of L-681,110 by Streptomyces sp. MA-5038 (ATCC 31587) was observed after 5 days' incubation at 28 degrees C and pH about 8.3. L-681,110 was isolated from the fermentation broth by acetone extraction of the mycelia, absorption to Amberlite XAD-2 resin and two separations by thin-layer chromatography. The structure of L-681,110 was found to consist of a sixteen-membered lactone with a new type of substitution. The inhibition of ATPase, activity against Caenorhabditis elegans and stimulation of gamma-aminobutyric acid release indicate that L-681,110 possesses some characteristics of both oligomycin and avermectin. L-681,110 was also active against tapeworm and ticks in an in vivo assay.
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PMID:Discovery, production and purification of the Na+, K+ activated ATPase inhibitor, L-681,110 from the fermentation broth of Streptomyces sp. MA-5038. 609 16

Arachidonic acid, a major polyunsaturated fatty acid of membrane phospholipids in the CNS, reduced the high-affinity uptake of glutamate and gamma-aminobutyric acid (GABA) in both rat brain cortical slices and synaptosomes. alpha-Aminoisobutyric acid uptake was not affected. Intrasynaptosomal sodium was increased concomitant with decreased (Na+ + K+)-ATPase activity in synaptosomal membranes. The reduction of GABA uptake in synaptosomes could be partially reversed by alpha-tocopherol. The inhibition of membrane-bound (Na+ + K+)-ATPase by arachidonic acid was not due to a simple detergent-like action on membranes, since sodium dodecyl sulfate stimulated the sodium pump activity in synaptosomes. These data indicate that arachidonic acid selectively modifies membrane stability and integrity associated with reductions of GABA and glutamate uptake and of (Na+ + K+)-ATPase activity.
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PMID:Reductions of gamma-aminobutyric acid and glutamate uptake and (Na+ + K+)-ATPase activity in brain slices and synaptosomes by arachidonic acid. 613 Jan 23

Synaptosomes isolated from guinea pig cerebral cortex accumulate L-carnitine from the medium in an active process, dependent on the sodium gradient across the plasma membrane and on (Na+ + K+)-ATPase activity. L-Carnitine uptake is inhibited by oxidative phosphorylation uncouplers and by ouabain, a known inhibitor of (Na+ + K+)-ATPase. In addition, the omission of Na+ or its replacement by Li+ inhibited the transport, which was also competitively inhibited by gamma-aminobutyrate. The kinetics of carnitine uptake show that the overall process would consist of two components: a passive diffusion and a carrier-mediated transport which is saturated at 1-2 mM carnitine concentration.
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PMID:Studies on the transport of carnitine in the brain using synaptosomes isolated from guinea-pig cerebral cortex. 631 Dec 66

Pinealocytes, endocrine cells that synthesize and secrete melatonin, possess a large number of synaptic-like microvesicles (MVs) containing synaptophysin. By monitoring cross-reactivity with anti-synaptophysin antibody, the MVs were highly purified from bovine pineal glands. The purified MVs were morphologically similar to but distinct from neuronal synaptic vesicles by their lack of synapsin I. Immunological study indicated that the MVs contained vacuolar H(+)-ATPase, synaptotagmin and synaptobrevin 2 (VAMP2). The MVs accumulated L-glutamate at the expense of ATP hydrolysis by vacuolar H(+)-ATPase. No uptakes of melatonin, serotonin, noradrenaline, gamma-aminobutyrate or acetylcholine were observed. These results indicated that the MVs are organelles for storage of L-glutamate in pinealocytes and suggested a possibility that pinealocytes transmit glutamate signals by MVs-mediated exocytosis.
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PMID:Microvesicles isolated from bovine pineal gland specifically accumulate L-glutamate. 760 13

Histochemical study indicated that the posterior pituitary possesses numerous microvesicles (MVs) containing synaptophysin, a marker protein specific for brain synaptic vesicles (Navone, F., Di Gioia, G., Jahn, R., Browning, M., Greengard, P., and De Camilli, P. (1989) J. Cell Biol. 109, 3425-2433). By monitoring cross-reactivity with anti-synaptophysin antibody, the MVs were highly purified from bovine posterior pituitaries by a combination of differential and sucrose density gradient centrifugations. The purified MVs had an average diameter of about 60 nm and were associated with synaptophysin as revealed by immunoelectron microscopy. The vesicles contained ATPase activity partially sensitive to bafilomycin A1 and to vanadate. The membrane fraction immunoisolated with anti-synaptophysin antibody also exhibited similar ATPase activity. The two ATPases could be purified separately; the vandate-sensitive enzyme was identified as a 115-kDa polypeptide immunochemically similar to chromaffin granule P-ATPase (forming phosphoenzyme intermediate), and the bafilomycin A1-sensitive ATPase showed essentially the same properties as those of vacuolar type H(+)-ATPases. Upon addition of ATP, the MVs formed an electrochemical gradient of protons and took up norepinephrine in a reserpine-sensitive manner, indicating the presence of secondary monoamine transporter coupled with vacuolar type H(+)-ATPase. No uptake of L-glutamate, gamma-aminobutyrate, glycine, or acetylcholine was observed. The identification of MVs as organelles responsible for storage of monoamines is important for understanding the physiological function of the posterior pituitary.
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PMID:Microvesicles isolated from bovine posterior pituitary accumulate norepinephrine. 774 79


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