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)

The functions of the chromaffin vesicles are reflected in their molecular organization. They contain large amounts of water-soluble proteins and ATP, which act in concert with catecholamines to form a stable storage pool. The vesicles contain an ATP-driven catecholamine transport system that enables the vesicles to take up dopamine, the precursor to NE, and to recover amines that leak out of the granules. The transport system appears to be coupled to the ATPase activity of the vesicle membranes and to include an amine carrier. The enzyme DBH is present as a soluble protein within the vesicle and as a component of the membrane. However, substrates can be acted upon only after they have been transported into the vesicle. During secretion the vesicle membrane fuses with the plasma membrane, but little is known about how this occurs.
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PMID:Functional organization of adrenal chromaffin vesicles. 115 35

The distribution of intraneuronal constituents involved in norepinephrine (NE) storage, uptake, and release were used to estimate changes in NE secretion from the cat ovary after ovulation induced with eCG plus hCG. The content of NE and ATP, which are principally stored in small noradrenergic vesicles (isolated at a density of 1.041 g/ml in Percoll gradient), decreased after ovulation. However, the activity of dopamine beta-hydroxylase, which is principally associated with large noradrenergic vesicles (isolated at a density of 1.033 g/ml in Percoll gradient), was only slightly decreased. Mg(2+)-dependent ATPase, located in both large and small storage vesicles, decreased only in the small storage vesicles, suggesting that preferential secretion from small noradrenergic vesicles occurred. The hormonal treatment also affected the functional capacity of the vesicles, as evidenced by the decrease in uptake and storage capacity as well as the decrease in the stimulated release of 3H-NE observed after ovulation. The aforementioned changes are characteristically seen after a sympathetic discharge; thus they strongly support the notion that ovarian sympathetic activity increases during the ovulatory process, resulting in the postovulatory decrease in both the size and functional capacity of the intraneuronal compartment where NE is stored.
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PMID:Release of norepinephrine from the cat ovary: changes after ovulation. 183 Oct 51

The reactions of cytochrome b561 with other redox-active components of the adrenal chromaffin granule were examined using optical difference spectroscopy. It was shown that there is no direct electron transfer between the cytochrome and dopamine beta-hydroxylase, but that in the presence of ascorbate, turnover of dopamine beta-hydroxylase causes an oxidation of the cytochrome, which is partially reversed by the action of the mitochondrial NADH:A-. oxidoreductase. Thus, these three proteins may be functionally coupled via ascorbate. A quantitative study of the relationship between the redox state of the cytochrome and the ascorbate radical concentration measured by EPR showed that ascorbate reduces the cytochrome in a one-electron transfer reaction. Generation of a proton electrochemical gradient across the granule membrane causes only a small (20 mV) increase in the cytochrome midpoint potential suggesting the cytochrome is not a proton pump. The data are consistent with a model in which cytochrome b561, by reacting with ascorbate or ascorbate free radical on either side of the granule membrane, could couple the ascorbate-consuming reaction of the dopamine beta-hydroxylase inside the chromaffin granule to the ascorbate-regenerating reaction of the NADH:A-. oxidoreductase on the outer mitochondrial membrane. The H+-ATPase of the granule membrane could both drive the flow of electrons in the direction from cytosol to granule and replenish protons consumed by the turnover of dopamine beta-hydroxylase inside the granule.
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PMID:Functional coupling between enzymes of the chromaffin granule membrane. 301 4

Among 30 patients with ventricular arrhythmia resistant to conventional antiarrhythmic therapy, 33% showed normalization of heart rhythm after single i.v. injection of Craviten at a dose of 6 mg. In all patients, sensitive and resistant to this dose of Craviten, serum dopamine beta-hydroxylase activity was initially twice as high as that in healthy controls. After Craviten administration, enzyme activity normalized in the sensitive persons only, parallelly with rhythm normalization. In this group of patients the initially increased erythrocyte membrane ATPase activities (total and ouabain-insensitive) also normalized.
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PMID:Antiarrhythmic efficiency of Craviten and changes in the activities of serum dopamine beta-hydroxylase and erythrocyte membrane ATPases. 302 6

Ascorbic acid and Mg-ATP were found to regulate norepinephrine biosynthesis in intact secretory vesicles synergistically and specifically, using the model system of isolated bovine chromaffin granules. Dopamine uptake into chromaffin granules was shown to be unrelated to the presence of Mg-ATP and ascorbic acid at external dopamine concentrations of 7.5 and 10 mM. Under these conditions of dopamine uptake, norepinephrine biosynthesis was enhanced 5-6-fold by Mg-ATP and ascorbic acid compared to control experiments with dopamine only. Furthermore, norepinephrine formation was enhanced approximately 3-fold by ascorbic acid and Mg-ATP together compared to norepinephrine formation in granules incubated with either substance alone. The action of Mg-ATP and ascorbic acid together was synergistic and independent of dopamine content of chromaffin granules as well as of dopamine uptake. The apparent Km of norepinephrine formation for external ascorbic acid was 376 microM and for external Mg-ATP was 132 microM, consistent with the larger amounts of cytosolic ascorbic acid and ATP that are available to chromaffin granules. Other physiologic reducing agents were not able to increase norepinephrine biosynthesis in the presence or absence of Mg-ATP. In addition, maximum enhancement of norepinephrine biosynthesis occurred only with the nucleotide ATP and the cation magnesium. The mechanism of the effect of ascorbic acid and Mg-ATP on norepinephrine biosynthesis was investigated and appeared to be independent of a positive membrane potential. The effect was also not mediated by direct action of ADP, ATP, or magnesium on the activity of soluble or particulate dopamine beta-monooxygenase. These data indicate that Mg-ATP and ascorbic acid specifically and synergistically co-regulate dopamine beta-monooxygenase activity in intact chromaffin granules, independent of substrate uptake. Although the mechanism is not known, the data are consistent with the possibility that the chromaffin granule ATPase mediates these effects.
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PMID:Ascorbic acid and Mg-ATP co-regulate dopamine beta-monooxygenase activity in intact chromaffin granules. 314 26

1. Metabolic and ionic requirements for the intra-axonal transport of dopamine beta-hydroxylase (DBH) were investigated in the cat hypogastric nerve-inferior mesenteric ganglion preparation in vitro by monitoring the enzyme accumulation above a crush, 2-2.5 cm distal to the ganglion.2. DBH accumulation in the proximal segment immediately above the crush increased linearly up to 6 h, during incubation in normal Krebs solution at 37 degrees C. The rate of transport of the enzyme was about 4 mm/h.3. Removal of the ganglion, electrical stimulation or reserpine pretreatment (1-6 days before the experiment) did not modify the rate of DBH accumulation.4. Anoxia and glucose deprivation, singly, did not affect accumulation of DBH; however, the combined treatment of anoxia plus glucose deprivation, or dinitrophenol plus glucose deprivation, very markedly interfered with accumulation.5. Removal of sodium or potassium from Krebs solution markedly inhibited the transport of DBH. Preincubation of the nerve in a high-calcium Krebs solution at 4 degrees C, and then reincubation at 37 degrees C, prevented the enzyme accumulation.6. N-ethylmaleimide, ouabain and oligomycin markedly inhibited the transport of DBH.7. The results suggest that transport of DBH, and therefore of noradrenaline storage vesicles, within the hypogastic nerve is dependent on metabolic energy derived from either glycolysis or oxidative phosphorylation. It is also suggested that the sodium-potassium-activated ATPase may play an important role in the intra-axonal transport of storage vesicles.
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PMID:Metabolic and ionic requirements for the axoplasmic transport of dopamine beta-hydroxylase. 414 Feb 29

Specific effects of various catecholamines as well as functional dependence of mitochondrial enzymes activity on catecholamine metabolism were studied. Dopamine activated cytochrome c oxidase in heart mitochondria and decreased this enzymatic activity in liver tissue. Noradrenaline and adrenaline activated cytochrome c oxidase in liver, brain and kidney tissues. The effect of dopamine on cytochrome c oxidase was prevented by activation of dopamine beta-hydroxylase. Increased activity of monoamine oxidase caused accumulation of catecholamine metabolites, which inhibited the succinate dehydrogenase activity in liver tissue and the cytochrome c oxidase activity in brain, kidney and liver tissues. In the catecholamine regulation of succinate dehydrogenase and ATPase activities in all the tissues studied as well as of cytochrome c oxidase activity in heart tissue the quinoid oxidation products were apparently involved.
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PMID:[Catecholamine metabolism and mitochondrial enzyme activity]. 612 94

"Light" noradrenaline storage vesicles from nerve endings have been isolated by differential centrifugation and differential gradient centrifugation. They have been further purified by isopycnic sucrose/D2O centrifugation. By using these centrifugation techniques, we obtained an isopycnic gradient fraction in which noradrenaline was enriched about 41 times versus a total homogenate. This factor could be raised to 61 by using seminal ducts of castrated rats. Comparison of the distribution patterns in sucrose/D2O isopycnic gradients indicated that light noradrenaline vesicles of nerve endings contain Mg2+-stimulated ATPase and ATP, but that only a minor part of the dopamine beta-hydroxylase can be associated with these vesicles.
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PMID:An improved method for the purification of "light" noradrenaline vesicles from rat vas deferens: some biochemical characteristics. 613 52

Prostaglandins E1 and E2 are specifically bound by particulate fractions from bovine adrenal medulla. The subcellular localization of these binding sites has been investigated by comparing their distribution in subcellular fractions obtained by differential and gradient centrifugation to those of marker enzymes for various organelles. Prostaglandin E2 binding sites were purified about 16-fold with respect to the homogenate in a fraction which was highly enriched in plasma membranes on the basis of the activities of the marker enzymes acetylcholinesterase and calcium-dependent ATPase, which were both purified by about 12-fold in this fraction. The plasma membrane fraction contained relatively low activities of marker enzymes for mitochondria (monoamine oxidase), lysosomes (acid phosphatase), endoplasmic reticulum (glucose-6-phosphatase), Golgi (galactosyl transferase) and chromaffin granule membranes (dopamine beta-hydroxylase). The only other fractions enriched in prostaglandin E2 binding sites were those for the endoplasmic reticulum and the Golgi, in which the binding sites were purified about 4-fold and 7-fold, respectively. This is probably due mainly to contamination with plasma membranes, since calcium-dependent ATPase and acetylcholinesterase were each purified to a similar extent in these two fractions. These data suggest that the high-affinity prostaglandin E2 binding sites of the adrenal medulla are localized primarily on the plasma membranes of the medullary cells.
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PMID:Subcellular localization of prostaglandin E2 binding sites in bovine adrenal medulla. 614 8

The proteins of highly purified chromaffin-granule membranes were separated by one- or two-dimensional electrophoresis, then transferred to nitrocellulose sheets; glycosylation was investigated by binding of several different radioiodinated lectins. Over 20 different glycosylated components were identified; comparison with mitochondrial and microsomal fractions suggested that most of the major glycoproteins are genuine components of the chromaffin granule membrane, rather than contaminants originating in other organelles. Two-dimensional electrophoresis revealed heterogeneity within several of the glycoproteins, and this is ascribed to differences in the state of glycosylation, on the basis of shifts in electrophoretic mobility produced by treatment with neuraminidase. Neuraminidase treatment of chromaffin granule membranes also enhances the binding of many lectins. The identities of the lectin-binding bands are discussed: neither cytochrome b561 nor the F1-like ATPase appears to be glycosylated. Chromogranin A, although a glycoprotein, does not bind any of the lectins tested, but a number of concanavalin-A binding proteins, as well as dopamine beta-hydroxylase, are present in the chromaffin granule lysate.
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PMID:Glycoproteins of the chromaffin granule membrane: separation by two-dimensional electrophoresis and identification by lectin binding. 638 46


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