Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.3.1 (Mg2+-ATPase)
 1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plasma membranes were isolated from rat liver mainly under isotonic conditions. As marker enzymes for the plasma membrane, 5'-nucleotidase and (Na+ + K+)-ATPase were used. The yield of plasma membrane was 0.6-0.9 mg protein per g wet weight of liver. The recovery of 5'-nucleotidase and (Na+ +K+)-ATPase activity was 18 and 48% of the total activity of the whole-liver homogenate, respectively. Judged from the activity of glucose-6-phosphatase and succinate dehydrogenase in the plasma membrane, and from the electron microscopic observation of it, the contamination by microsomes and mitochondria was very low. A further homogenization of the plasma membrane yielded two fractions, the light and heavy fractions, in a discontinuous sucrose gradient centrifugation. The light fraction showed higher specific activities of 5'-nucleotidase, alkaline phosphatase, (Na+ +K+)-ATPase and Mg2+-ATPase, whereas the heavy one showed a higher specific activity of adenylate cyclase. Ligation of the bile duct for 48 h decreased the specific activities of (Na2+ +K+)-ATPase and Mg2+-ATPase in the light fraction, whereas it had no significant influence on the activities of these enzymes in the heavy fraction. The specific activity of alkaline phosphate was elevated in both fractions by the obstruction of the bile flow. Electron microscopy on sections of the plasma membrane subfractions showed that the light fraction consisted of vesicles of various sizes and that the heavy fractions contained membrane sheets and paired membrane strips connected by junctional complexes, as well as vesicles. The origin of these two fractions is discussed and it is suggested that the light fraction was derived from the bile front of the liver cell surface and the heavy one contained the blood front and the lateral surface of it.
 ...
PMID:Subfractionation of rat liver plasma membrane. Uneven distribution of plasma membrane-bound enzymes on the liver cell surface. 17 48

Nuclei, nuclear membranes and rough endoplasmic reticulum (rER) were isolated from onion root tips and stems. Structural preservation and purity of the fractions was determined by electron microscopic and biochemical methods. Gross compositional data (protein, phospholipid, nonpolar lipids, sterols, RNA, DNA), phospholipid and fatty acid patterns, enzyme activities (ATPases, ADPase, IDPase, glucose-6-phosphatase, 5'-nucleotidase, acid phosphatase, and NADH- and NADPH-cytochrome C reductases), and cytochrome contents were determined. A stable, high salt-resistant attachment of some DNA with the nuclear membrane was observed as well as the association of some RNA with high salt-treated nuclear and rER membranes. The phospholipid pattern was identical for both nuclear and rER membranes and showed a predominance of lecithin (about 60%) and phosphatidyl ethanolamine (20-24%). Special care was necessary to minimize lipid degradation by phospholipases during isolations. Nonpolar lipids, mostly sterols and triglycerides, accounted for 35-45% of the membrane lipids. Sterol contents were relatively high in both membrane fractions (molar ratios of sterols to phospholipids ranged from 0.12 to 0.43). Sitosterol accounted for about 80% of the total sterols. Palmitic, oleic, and linoleic acids were the most prevalent acids in membrane-bound lipids as well as in storage lipids and occurred in similar proportions in phospholipids, triglycerides and free fatty acids of the membrane. About 80% of the fatty acids in membrane phospholipids and triglycerides were unsaturated. A cytochrome of the b5 type was characterized in these membranes, but P-450-like cytochromes could not be detected. Both NADH and NADPH-cytochrome c reductases were found in nuclear and rER membranes and appeared to be enriched in rER membranes. Among the phosphatases, Mg2+-ATPase and, to lesser extents, ADPase, IDPase and acid phosphatase activities occurred in the fractions, but significant amounts of monovalent ion-stimulated ATPase, 5'-nucleotidase and glucose-6-phosphatase activities did not. The results obtained emphasize that the close biochemical similarities noted between rER and nuclear membranes of animal cells extend to these fractions from plant cells.
 ...
PMID:Characterization of nuclear membranes and endoplasmic reticulum isolated from plant tissue. 17 22

Female rats were injected subcutaneously with ethionine, and enzymic activities of liver membranes (Na+-k+-stimulated ATPase, Mg2+-stimulated ATPase, glucose-6-phosphatase, NADPH: cytochrome c oxido-reductase and NAD-nucleosidase) examined at proper intervals, during the intraperitoneal treatment of an egg phospholipid preparation (EPL). It is shown that EPL is unable to overcome the enzymic changes due to severe ethionine treatment, but is able to facilitate the recovery times after drug withdrawal for all the enzymic activities, except for NAD-nucleosidase. At lower dosage of the drug, the ethionine treatment is able to prevent the observed change of the glucose-6-phosphatase activity but not that of the Mg2+-ATPase. It is suggested that the EPL treatment may modify the chemical composition ahd/or architecture of liver membranes, altered by the ethionine injection, thus acting, at least partially, on the enzymic changes.
 ...
PMID:The effect of egg phospholipid administration upon liver enzymic activities during ethionine treatment. 18 Dec 70

By means of a preparation technique based on the discontinuous sucrose density gradient, subcellular fractions were isolated from guinea pig intestinal smooth muscle cells. A fraction which distributed to a 33% sucrose layer showed relatively high activities of 5'-nucleotidase, Na+ . K+-ATPase and ouabain sensitive Na+ . K+-ATPase. The fraction had a low NaN3 sensitive Mg2+-ATPase activity. On the other hand, the high activity of glucose-6-phosphatase showed a broad distribution. Though the sucrose density gradient proceeded over a series of the fine layers, cross-contamination of microsome into the 33% sucrose fraction was not reduced. To reduce microsomal cross-contamination, another procedure was employed. The homogenization time of 77000 xg sediment to be layered on the top of the sucrose density gradients was prolonged. This procedure did not change the distribution of K+ activated p-nitrophenylphosphatase, K+ activated ouabain sensitive p-nitrophenylphosphatase and ouabain sensitive Na+ . K+-ATPase activities. The peak of NADH cytochrome c reductase activity was shifted to a 38% sucrose fraction from a 33% sucrose fraction and the activity of this marker enzyme in the 33% sucrose fraction decreased to 60% of that of the prior procedure.
 ...
PMID:[Examination of plasma membrane-enriched fraction from guinea pig intestinal smooth muscle by means of some marker enzymes (author's transl)]. 23 74

Human blood platelets are capable of removing Ca2+ from the cytoplasm by means of an active, ATP-dependent and cyclic AMP-stimulated transport system. Calcium-accumulating vesicles are obtained by sonicating platelets. On density gradient centrifugation, this activity is found in the heavier of two membrane fractions. Concentrated in this fraction are also the Ca2+-stimulated Mg2+-ATPase and glucose-6-phosphatase, believed to be a marker for internal membrane systems. When the isolated vesicles are loaded with Ca2+, a third band separates from the two vesicular fractions in the density gradient. This band C contains virtually all the Ca2+-accumulating activity. Evidence that this activity is due to an active uptake and not to surface binding or adsorption is presented. Whereas electron microscopy does not reveal striking differences between active and inactive fractions, differences in protein composition are revealed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Furthermore, this band contains an enzyme system which converts arachidonic acid to malondialdehyde and therefore this fraction must be the site of prostaglandin synthesis. Membranes prepared by loading platelets with glycerol, followed by osmotic lysis are unable to accumulate calcium. In sodium dodecyl sulphate-polyacrylamide gel electrophoresis such membranes show significant differences in their protein pattern as compared to the actively Ca2+-accumulating vesicular membranes of band C. All preparations with Ca2+-accumulating activity also contain markers for plasma membranes and the question whether this activity is due exclusively to an intracellular structural element equivalent to the sarcoplasmic reticulum of muscle or whether an "extrusion pump" expelling Ca2+ to the outside of the cell is also involved, cannot yet be ;nswered.
 ...
PMID:Further characterization of calcium-accumulating vesicles from human blood platelets. 69 5

Administration of lindane at a dose of 20 mg/kg body weight/day for 15 days to male rats brought about marked growth retardation. Succinic dehydrogenase, Mg2+-ATPase and glucose-6-phosphatase activities were inhibited in different fractions of liver tissues. Mg2+-ATPase, alkaline phosphatase and NADH-dehydrogenase activities were also inhibited in the liver plasma membranes of the lindane treated animals. Stimulation of 5'-nucleotidase activity in liver plasma membrane was observed under lindane intoxication. Supplementation of L-ascorbic acid by separate oral administration to the lindane intoxicated rats neutralized the growth retardation and maintained almost normal values of all the enzymes studied.
 ...
PMID:Protective effect of L-ascorbic acid in lindane intoxicated rats. 618 53

A procedure is described for the preparation of a membrane fraction enriched in basal-lateral plasma membranes from gastric mucosa. Gastric glands isolated from rabbit were employed as starting material, greatly reducing contamination from non-glandular cell types. The distribution of cellular components during the fractionation procedure was monitored with specific marker enzymes. (Na+ + K+)-ATPase, ouabain-sensitive K+-stimulated p-nitrophenyl-phosphatase and histamine-stimulated adenylate cyclase were used as markers for basal-lateral membranes. These three markers were similarly distributed during both differential and equilibrium density gradient centrifugation. The enriched membrane fraction contained more than 30% of the total initial activities of the three basal-lateral membrane markers which were purified better than 11-fold with respect to protein. (Na+ + K+)-ATPase activity was resolved from the activities of acid phosphatase, pepsin, Mg2+-ATPase, cytochrome c oxidase, NADPH-cytochrome c reductase, glucose-6-phosphatase, (K+ + H+)-ATPase, DNA and RNA.
 ...
PMID:An enriched preparation of basal-lateral plasma membranes from gastric glandular cells. 626 84

Although there is some evidence that extrachoroidal sites for the production of cerebrospinal fluid (CSF) are important, the choroid plexuses in the ventricles contribute the major part of CSF formation. The exact mechanism for CSF production is not fully understood. In order to study this mechanism from the enzyme histochemical standpoint, the previously reported studies are reviewed, in addition to the authors' own electron microscopic enzyme histochemical observations on this tissue. The ultrastructure and enzyme biochemistry of choroid plexus epithelial cells are considered, together with the histochemistry of the following enzymes: alkaline and acid phosphatase, Mg2+-ATPase, Na+, K+-ATPase, glucose-6-phosphatase, thiamine pyrophosphatase, adenylate cyclase, carbonic anhydrase, oxidoreductase, esterase, several hydrolases, and other enzymes. Finally, CSF formation and active transport in the choroid plexus epithelial cells are discussed, mainly in terms of the results of our enzyme cytochemical observations on Na+, K+-ATPase and carbonic anhydrase in this tissue.
 ...
PMID:The enzyme histochemistry of the choroid plexus. 683 Nov 99

Chronic dieldrin administration to rats (5 mg/kg/day) produced pathological changes in liver and kidney tissues. Dieldrin treated rats showed high levels of liver ascorbic acid and increased activities of inorganic pyrophosphatase in brain and glucose-6-phosphatase in liver. The activities of Mg2+-ATPase in liver and acetylcholinesterase in brain were decreased under toxic doses of dieldrin. L-Ascorbic acid supplements in treated animals could partially prevent the pathological alterations, as observed histologically in liver and kidney tissues. Administration of this vitamin could also prevent alterations in some enzyme activities produced by toxic dieldrin doses.
 ...
PMID:Effects of L-ascorbic acid supplementation on dieldrin toxicity in rats. 714 87

The influence of extraneous supplementation of L-ascorbic acid in chronic chlordane toxicity has been studied in rats. Oral administration of chlordane brings about a marked growth retardative effect, stimulates vitamin C synthesis in the system, elevates the vitamin C status of the liver and kidney tissues and also the urinary excretion. It inhibits the activities of acid and alkaline phosphatases, SDH and Mg2+-ATPase of both hepatic and renal tissues. The activities of serum and mitochondrial GOT, serum alkaline phosphatase, and glucose-6-phosphatase of both hepatic and renal tissues are markedly stimulated. The normal histological patterns of both liver and kidney tissues are grossly altered under chlordane toxicity condition. There occurs marked increase in the hepatic lipid composition. Supplementation of L-ascorbic acid in high doses to the chlordane treated rats can effectively counteract some of these alterations in respect of enzyme activities, morphological characteristics and of hepatic lipid composition.
 ...
PMID:Studies on the protective effects of L-ascorbic acid in chronic chlordane toxicity. 731 25


1 2 Next >>