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)

Cytochemical localization of Concanavalin A binding sites in protoplasts of Candida tropicalis, investigated with glycosylated-ferritin and electron microscopy, showed that the lectin was specifically bound to the external protoplast surface. Thus, the plasma membranes have been labelled with 125I-Concanavalin A and followed through the isolation procedure. Relative distribution of 125I-radioactivity and azide-insensitive ATPase activity in the obtained fractions, suggested that this enzyme was an equivocal plasma membrane marker. Despite the presence of internal Concanavalin A binding sites, Concanavalin A could be used unambiguously as an exogenous plasma membrane marker of intact protoplasts.
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PMID:An investigation into the feasibility of using azide-insensitive ATPase and ConA as yeast plasma membrane markers. 612 37

Plasma membranes of vertebrate lens fiber cells contain large numbers of gap junctions that may provide pathways for metabolic cooperation. Characterization of fiber cell gap junctions is thus necessary to understand this function. In this study, plasma membrane fractions were isolated from bovine lens according to established techniques, but without urea, detergents, or proteolytic enzymes. Electron microscopy indicated that isolated plasma membranes with gap junctions form double-membrane vesicles, and gap junctions comprised approximately 35% of the total membrane area in the crude fraction. These vesicles were impermeable to cationized ferritin, suggesting that they were sealed, and may be useful for permeability studies. Treatment of the crude fraction with 2.5% beta-mercaptoethanol or dithiothreitol caused reversible separation of junctional membranes, suggesting that disulfide bonds may be important in maintaining gap junction structure. Fractions with varying proportions of gap junctions were isolated using linear sucrose density gradient centrifugation. The proportional area of gap junction membrane versus total membrane in the various fractions ranged from 10% to at least 51%. The following plasma membrane enzymes were assayed in all fractions: Mg++-ATPase, Ca++-ATPase, alkaline phosphatase, phosphodiesterase, 5'-nucleotidase, and Na+, K+-ATPase. There was no correlation between enzyme activity and gap junction enrichment. This suggests that these enzymes are not associated with fiber cell gap junctions.
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PMID:Biochemical and structural characterization of membrane fractions from bovine lens. 613 51

A new primary fixative, ethyldimethylaminopropyl carbodi-imide-glutaraldehyde-Tris, has been combined with the use of saponin for membrane permeabilization to yield a procedure which preserves ultrastructural morphology, yet retains a cytoplasmic matrix permeable to globulin molecules. This allows pre-embedding localization of intracellular protein antigens in cultured cells by fluorescence or electron microscopy. A further combination of these methods with the 'ferritin bridge' techniqe has allowed discrete localization which is quantifiable. Together, these methods yield an overall technique which provides high quality ultrastructural morphological preservation and precise antigen localization. Examples of the localization of alpha 2-macroglobulin, actin, SV40 T-antigen, tubulin and p60src are demonstrated. Extension of these methods from cultured cells to intact tissue should be possible without major changes.
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PMID:Electron microscopic immunocytochemical localization of intracellular antigens in cultured cells: the EGS and ferritin bridge procedures. 616 Jan 23

Yeast plasma membranes have been isolated from homogenized yeast cells, identified as pure plasma membrane vesicles which were used as antigens. By crossed immunoelectrophoresis with anti-membrane immunoglobulins, 17 discrete antigens have been detected in Triton X-100 extracts from plasma membranes. Three different immunoabsorption experiments were performed with : a) isolated membranes exposing the cytoplasmic surfaces (PS) and the external surfaces (ES), b) yeast protoplasts exposing only antigenic determinants on the ES, c) lysed protoplasts which had been saturated on the ES with antibodies prior to lysis. These absorption experiments demonstrated that seven of the antigens are expressed on the ES while eight immunogens expose antigenic determinants on the PS. Four of the principal immunoprecipitates are not affected by absorption with surface antigens whereas two of the antigens indicate transmembrane characteristics. Of these 17 immunoprecipitates four were shown by zymograms to possess enzymatic activities: ATPase (EC 3.6.1.3) and NADH-dehydrogenase (EC 1.8.99.3) (three separate components). Three of these enzymes are expressed on the PS, and one NADH-dehydrogenase exposes determinants on the ES of the protoplasts. The presence of antigens on the PS of the plasma membrane could also be demonstrated on micrographs by the indirect ferritin-antibody labeling technique followed by freeze-etching and shadowing of the membranes.
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PMID:Immunochemical analysis of the plasma membrane from baker's yeast Saccharomyces cerevisiae. 616 18

Two different procedures were employed for the isolation of sarcolemma from the rat heart and the membranes were studied with respect to the presence of cell surface material as well as their functional characteristics. Both hypotonic shock-LiBr treatment method (fraction HL) and sucrose density gradient method (fraction S) yielded membranes enriched 8 to 13 fold with respect to Na+-K+ ATPase and adenylate cyclase activities in comparison to heart homogenate. Cell surface material was demonstrated on the outer surface of the vesicles only in fraction HL with cationic dyes, lanthanum and ferritin, applied either to the isolated fractions or perfused in the heart through coronaries. Fraction HL also had high sialic acid content. ATP independent Ca2+ binding in fraction HL was about 6 times more than that in fraction S which had little sialic acid and showed no cell surface staining with cationic dyes. On the other hand, ATP-dependent Ca2+ binding and Ca2+-stimulated Mg2+ dependent ATPase activities in fraction S were 4 to 6 times higher than those in fraction HL. Epinephrine stimulated adenylate cyclase in fractions HL and S by 24 and 3% whereas ouabain was found to inhibit Na+-K+ ATPase in these fractions by 80 and 10% respectively. A mild treatment of the membranes with deoxycholate to eliminate the semipermeable characteristics or effects of sidedness of the vesicles resulted in an almost complete ouabain inhibition of Na+-K+ ATPase in both fractions. These data suggest that presence of cell surface material as well as membrane sidedness has an important role in in vitro expression of functional characteristics of sarcolemma. It is emphasized that sarcolemmal preparations containing cell surface material will provide information more realistic to the native conditions in situ.
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PMID:Differences in sarcolemmal preparations: cell surface material and membrane sidedness. 619 85

During the last week of gestation of the fetal rat, the epithelium of the colon is rapidly remodeled. At 16 days a primitive stratified epithelium surrounds a small central lumen. Over the next 3 days, the main lumen extends narrow clefts down to the basal cell layer and small secondary lumina appear within the stratified epithelium between these clefts. At 19 and 20 days, secondary lumina enlarge but remain discrete; an infusion of cationic ferritin into the main lumen does not enter secondary lumina. During the 2 days prior to birth (21-22), the secondary lumina join the main lumen as superficial cells are sloughed, and the epithelium becomes simple columnar. Freeze-fracture replicas indicate that luminal and nonluminal membrane domains of epithelial cell plasma membranes are separated by continuous tight junctions throughout the conversion process. Cytochemical analysis of tissue slices from 16- to 22-day fetal colon demonstrated the appearance and segregation of two phosphatases on apical and basolateral membrane domains during epithelial conversion. Cysteine-sensitive pH 9.0 (alkaline) phosphatase activity was first detected along the luminal membranes of cells bordering both primary and secondary lumina at 18 days gestation and increased to a maximum at 20-21 days; weaker activity was present on basolateral membranes. Phosphatase activity at pH 8.0 also appeared at 18 days and increased thereafter, but was localized primarily on nonluminal membranes. At pH 8.0, reaction product appeared on both inner and outer sides of the membrane, and was only partially abolished by omission of K+ or addition of ouabain; thus the reaction may be only partially due to K+-dependent ATPase activity. Biochemical analysis of the cytochemical media confirmed the appearance of phosphatase activities at 18 days. Thus, plasma membrane phosphatase activities appear while the epithelium is still stratified, but are segregated to luminal and nonluminal membrane domains at the onset of activity. Segregation is maintained throughout the process of conversion of a simple columnar epithelium.
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PMID:Epithelial differentiation in the fetal rat colon. I. Plasma membrane phosphatase activities. 630 78

The ultrastructural localization of the Ca2+ + Mg2+-dependent ATPase of sarcoplasmic reticulum in rat gracilis muscle was determined by indirect immunoferritin labeling of ultrathin frozen sections. Simultaneous visualization of ferritin particles and of adsorption-stained cellular membranes showed that the Ca2+ + Mg2+-ATPase was concentrated in the longitudinal sarcoplasmic reticulum and in the nonjunctional regions of the terminal cisternae membrane but was virtually absent from mitochondria, plasma membranes, transverse tubules, and junctional sarcoplasmic reticulum. Ferritin particles were found preponderantly on the cytoplasmic surface of the membrane, in agreement with published data showing an asymmetry of the Ca2+ + Mg2+-ATPase within the sarcoplasmic reticulum membrane. Comparison of the density of ferritin particles in fast and slow myofibers suggested that the density of the Ca2+ + Mg2+-ATPase in the sarcoplasmic reticulum membrane in a fast myofiber is approximately two times higher than in a slow myofiber.
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PMID:Ultrastructural localization of the Ca2+ + Mg2+-dependent ATPase of sarcoplasmic reticulum in rat skeletal muscle by immunoferritin labeling of ultrathin frozen sections. 646 Jul 75

Electron microscopy cytochemistry has been used to study the cytoplasmic location of liposomes and lipid vesicles following specific antibody-dependent phagocytosis. The vesicle compositions were 94-99 mol% 'fluid' lipid (egg phosphatidylcholine or dimyristoylphosphatidylcholine at 37 degrees C or 'solid' lipid (dipalmitoylphosphatidylcholine at 37 degrees C). In some cases, 4 mol% phosphatidylserine was included in the vesicle membrane so as to vary the surface charge density. These vesicles undergo specific antibody-dependent phagocytosis by RAW264 macrophages when the lipid membranes contain 1-2 mol% dinitrophenyl lipid hapten in the presence of rabbit anti-dinitrophenyl IgG antibody. Internalized lipid vesicles can be visualized with the electron microscope when ferritin is trapped in the internal aqueous compartments prior to internalization. The lipid vesicles were demonstrated to be internal to the macrophage plasma membranes by selectively staining the plasma membranes with Ruthenium red. The cytoplasmic location of vesicles and liposomes was studied by electron microscopic staining for activities of the following enzymes: (1) acid phosphatase; (2) inorganic trimetaphosphatase; (3) adenosine triphosphatase; and (4) glucose-6-phosphatase. The first two enzymatic activities were found in association with ferritin-containing vesicles after antibody-dependent phagocytosis, showing the formation of vesicle-containing phagolysosomes. Adenosine triphosphatase and glucose-6-phosphatase were primary not associated with the vesicles, suggesting a minimal association of vesicles with plasma membrane, Golgi, endoplasmic reticulum and perinuclear cisternae. Phagosome-lysosome fusion did not appear to depend on the type of target lipid vesicle or liposome, on the 'fluidity' of the target membrane, or the presence of phosphatidylserine in the target membrane.
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PMID:Cytochemical study of liposome and lipid vesicle phagocytosis. 668 37

The examination of septic children has revealed characteristics of iron and red cell metabolism: deep and persistent hypotransferrinemia, normo- or hypersideremia, normal ferritin levels. Red cells of septic children contain low concentrations of ATPase, histidine, lipoproteins, there is compensatory enhancement of 2,3-DPG, G-6-PD SH-group activity. In terminal sepsis the activity of the above parameters drastically falls entailing hemolysis, anemia and severe hypoxia.
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PMID:[The metabolic activity of the erythrocytes and the characteristics of ferrokinetics in children with sepsis]. 802 Jul 13

We studied the effect of chronic exposure (6 weeks and 6 months) of mice to drinking (tap) water containing 1.76% (0.06 M) aluminum lactate on some cytochemical properties of the blood-brain barrier (BBB). The plasmalemma-bound enzymatic activities of alkaline phosphatase (AP) and Ca(2+)-activated adenosine triphosphatase (Ca(2+)-ATPase) were studied at the ultrastructural level. Anionic sites were localized with cationized ferritin in a pre-embedding procedure and with cationic colloidal gold in a post-embedding procedure applied to brain samples embedded in Lowicryl K4M. Intravenously injected Evans blue and horseradish peroxidase (HRP) were used for evaluation of the functional state of the BBB. The results indicate that chronic exposure to aluminum does not noticeably affect barrier function of the endothelium of cerebral cortex blood microvessels. Focal leakage of larger than capillary microvessels (presumably arterioles and venules) was observed only in a few areas, such as the basal ganglia and amygdaloid nuclei. The localization of both enzymatic activities (AP and Ca(2+)-ATPase) in microvessels remained essentially unchanged. The localization of anionic sites was also unchanged except on the luminal surface of the endothelium of a few blood microvessels located in areas of the brain where leakage of the injected HRP was noted. In these vessels the injected HRP was often attached to the luminal surface of the endothelial cells, suggesting its increased stickiness. These data, compared with our previous observations on brain microvascular endothelial cells growing in vitro, indicate that cytotoxicity of aluminum is evidently less pronounced in the living organism, presumably due to action of detoxicating and regulatory mechanisms.
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PMID:Ultracytochemical studies of the effects of aluminum on the blood-brain barrier of mice. 828 66


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