Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Semliki Forest virus inhibits phosphatidylethanolamine biosynthesis in baby hamster kidney-21 cells 6 h after infection. Viral infection reduced the incorporation of [1,2-14C]-ethanolamine into intact cells by approximately 50%. A similar reduction in the activity of the ethanolaminephosphotransferase (EC 2.7.8.1) was also observed. The apparent Km for CDPethanolamine was 60 muM for the microsomal enzymes from infected or mock-infected cells. In addition, exogenous diglyceride only stimulated by 1.5-fold the ethanolaminephosphotransferase from virus- or mock-infected cells, whereas the same diglyceride preparations stimulated the cholinephosphotransferase (EC 2.7.8.2) from baby hamster kidney cells by sixfold. Generation of endogenous diglyceride by pretreatment of the microsomes with phospholipase C (EC 3.1.4.3) stimulated the activity of the cholinephosphotransferase but not the ethanolaminephosphotranferase. Semliki Forest virus does not inhibit all microsomal enzymes, since the activities of NADH- K3Fe(CN)6 reductase and NADH dehydrogenase (EC 1.6.99.3) were not affected. The ethanolaminephosphotransferase from virus- and mock-infected cells showed similar profiles of activity as a function of temperature; this result and other studies suggest that that membranous environment of the ethanolaminephosphotransferase was not significantly modified by the virus.
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PMID:Inhibition of phosphatidylethanolamine biosynthesis in baby hamster kidney-21 cells infected with Semliki Forest virus. 17 Oct 43

The phospholipid depletion of rat liver mitochondria, induced by acetoneextraction or by digestion with phospholipase A2 or phospholipase C, greatly inhibited the activity of NADH-cytochrome c reductase (rotenone-insensitive). A great decrease of the reductase activity also occurred in isolated outer mitochondrial membranes after incubation with phospholipase A2. The enzyme activity was almost completely restored by the addition of a mixture of mitochondrial phospholipids to either lipid-deficient mitochondria, or lipid-deficient outer membranes. The individual phospholipids present in the outer mitochondrial membrane induced little or no stimulation of the reductase activity. Egg phosphatidylcholine was the most active phospholipid, but dipalmitoyl phosphatidylcholine was almost ineffective. The lipid depletion of mitochondria resulted in the disappearance of the non-linear Arrhenius plot which characterized the native reductase activity. A non-linear plot almost identical to that of the native enzyme was shown by the enzyme reconstituted with mitochondrial phospholipids. Triton X-100, Tween 80 or sodium deoxycholate induced only a small activation of NADH-cytochrome c reductase (rotenone-insensitive) in lipid-deficient mitochondria. The addition of cholesterol to extracted mitochondrial phospholipids at a 1 : 1 molar ratio inhibited the reactivation of NADH-cytochrome c reductase (rotenone-insensitive) but not the binding of phospholipids to lipid-deficient mitochondria or lipid-deficient outer membranes. These results show that NADH-cytochrome c reductase (rotenone-insensitive) of the outer mitochondrial membrane requires phospholipids for its activity. A mixture of phospholipids accomplishes this requirement better than individual phospholipids or detergents. It also seems that the membrane fluidity may influence the reductase activity.
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PMID:The role of lipid-protein interactions in NADH-cytochrome c reductase (rotenone-insensitive) of rat liver mitochondria. 21 8

Heavy beef heart mitochondria depleted of phospholipids by treatment with phospholipase C followed by removal of the by products by lipase treatment or sonication in pentane were analyzed by electron microscopy, chemical analysis and assays of enzymatic activities. The results indicate that diglycerides are present after phospholipase C treatment and are inhibitors of NADH-cytochrome c reductase. After removal of diglycerides with lipase treatment, a phospholipid requirement for NADH-cytochrome c reductase could be demonstrated.
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PMID:Phospholipase C treatment of mitochondria. 92 60

Previous studies have shown that vertebrate rod outer segments (ROS) have a light activated phospholipase C which hydrolyzes phosphatidylinositol-4,5-bisphosphonate (PIP2). Three different experimental approaches have been used to test the hypothesis that the phosphatidylinositol (PI) biosynthetic cycle is present in ROS and that PIP2 can be regenerated from DG independent of rod inner segments. In the first study, enzyme activities of the PI cycle were assayed simultaneously in the presence of CTP, myo-inositol and [gamma-32P]ATP using endogenous lipids as substrates. Under these conditions, broken (leaky) ROS prepared by continuous sucrose gradient centrifugation showed PI, PIP and DG kinase activities similar to those found in intact ROS and non-ROS membranes, whereas PI synthetase activity was much lower in the leaky ROS than in the other two fractions. The relative distribution of PI synthetase specific activity in the three membrane preparations was similar to that of the microsomal enzyme marker cytochrome c reductase. ROS prepared by discontinuous sucrose gradient centrifugation showed only 2-3% of whole homogenate PI synthetase or phosphatidyl: cytidyl transferase activities, and the distribution of activities was the same as for microsomal and mitochondrial marker enzymes. In the second study, whole retinas were incubated with myo-[2-3H]inositol or [2-3H]glycerol in vitro, and the time course of incorporation of radioactivity into PI and other phospholipids was determined for ROS and three other retinal fractions. Over a 10-hr period, the rate of incorporation of myo-[2-3H]inositol or [2-3H]glycerol into PI in ROS was lowest among the various retinal fractions. In the third study, chemical analysis of the molecular species composition of PI, DG and phosphatidic acid (PA) from ROS shows that PA is substantially different from PI and DG, the latter two being quite similar. These results are consistent with a precursor-product relationship between PI and DG, but not with the conversion of DG to PA or of PA to PI. Taken together, these three studies indicate that ROS do not have PI synthetase or phosphatidyl: cytidyl transferase activities, but do have DG, PI and PIP kinase activities. Thus, the PI in ROS lost through rapid turnover must be replaced with molecules derived from de novo synthesis in the inner segment of the photoreceptor cell.
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PMID:Phosphoinositide metabolism in frog rod outer segments. 216 31

Alkaline phosphatase was released from protoplasts of the yeast Saccharomyces cerevisiae without cell lysis not only by phosphatidylinositol (PI)-specific phospholipase C but also by phosphatidylcholine (PC)-hydrolyzing phospholipase C. Activities of mitochondrial enzymes such as succinate dehydrogenase, antimycin-sensitive NADH-cytochrome c reductase, and oligomycin-sensitive ATPase were decreased by the action of PC-hydrolyzing phospholipase C. Hydrolysis of microsomal PC or PI did not cause any decrease in the activities of NADPH-cytochrome c reductase and antimycin-insensitive NADPH-cytochrome c reductase. In the requirement of phospholipids, the properties of yeast mitochondrial enzymes were very close to those of mammalian mitochondrial enzymes, whereas those of yeast microsomal enzymes were completely different from those of mammalian microsomal enzymes.
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PMID:Effects of phospholipases C on membrane-bound enzymes of yeast. 296 99

The effect of tetrahydro-1 H-1,4 (5H)-dipropanol bis(3,4,5-trimethoxybenzoate)hydrochloride monohydrate (dilazep, Comelian) on puromycin-induced rat renal damage was investigated. In vivo study: Rats were divided into 3 groups, the control group; untreated, the puromycin group; puromycin (150 mg/kg) was injected intraperitoneally once, the dilazep + puromycin group; puromycin (150 mg/kg) was injected 1 h after intraperitoneal dilazep injection (2 mg/kg), and dilazep (2 mg/kg) was injected every 12 h until the end of the experiment. In each group, 84 h after puromycin injection, kidneys were isolated and renal mitochondria were prepared. The endogenous phospholipase activity in kidney homogenate was determined by high performance liquid chromatography. The activities of three segments (NADH-cytochrome c reductase, succinate-cytochrome c reductase and cytochrome c oxidase) of the electron-transport chain in mitochondria were measured enzymatically. In the puromycin group, phospholipase activity was increased and activities of all of three segments of the electron-transport chain were decreased. In the dilazep + puromycin group, premedication with dilazep prevented activation of phospholipase and maintained mitochondrial electron-transport activity. In vitro study: Mitochondria prepared from intact rat kidney were incubated with phospholipase C. Activities of the mitochondrial electron-transport chain were deteriorated by phospholipase C. These results indicated that activation of endogenous phospholipase, which digests membrane phospholipids, essential components in maintaining mitochondrial electron-transport activity, is responsible for the puromycin-induced renal damage. Premedication with dilazep prevented the damage by inhibition of the activation of phospholipase.
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PMID:The effect of dilazep on puromycin-induced rat renal mitochondrial dysfunction. 304 17

Interrelationships between the catalytic behavior of glucose-6-phosphatase and the structure of rat-liver microsomal membranes were investigated. 2. Rabbit anti-microsomal serum completely inhibited glucose-6-phosphate hydrolysis in detergent-modified microsomes but showed no inhibitory effect on the enzyme activity of intact or mechanically disrupted vesicles. 2. Controlled proteolysis of intact microsomes using carboxypeptidase A and/or aminopeptidase M largely denatured enzymes situated on the outer surface of the microsomal vesicles such as monodehydroascorbate reductase and cytochrome c reductase. However, it did not affect the glucose-6-phosphatase activity at all, which remained in a latent state within the membrane. 3. Temperature studies on glucose-6-phosphatase have revealed that only the enzyme activity of intact microsomes exhibited a nonlinear Arrhenius plot, whereas detergent-modified microsomes showed a linear temperature response. 4. Treatment of microsomes with phospholipase C and toluene-2,4-diisocyanate resulted in an apparent loss of about 65% and 85% of the original glucose-6-phosphatase activity and was closely correlated with hydrolysis and chemical modification of phosphatidylethanolamine, respectively. These apparent inactivations could be reversed by addition of Triton X-114 alone without any phospholipid supplementation. These observations indicate that glucose-6-phosphatase is buried within the microsomal membrane, not exposed on either side. They also suggest that phospholipids are involved in the glucose-6-phosphate transport mechanism.
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PMID:Investigations on the possible involvement of phospholipids in the glucose-6-phosphate transport system of rat-liver microsomal glucose-6-phosphatase. 624 79

Our previous mutational analysis of Legionella pneumophila demonstrated a role for type II protein (Lsp) secretion and iron acquisition in intracellular infection and virulence. In gram-negative bacteria, the twin-arginine translocation (Tat) pathway is involved in secretion of proteins, including components of respiratory complexes, across the inner membrane to the periplasm. To assess the significance of Tat for L. pneumophila, tatB mutants were characterized. The mutants exhibited normal growth in standard media but grew slowly under low-iron conditions. They were also impaired in the Nadi assay, indicating that the function of cytochrome c oxidase is influenced by tatB. Consistent with this observation, a subunit of the cytochrome c reductase was shown to be a Tat substrate. Supernatants of the tatB mutants showed a 30% reduction in phospholipase C activity while maintaining normal levels of other Lsp secreted activities. When tested for infection of U937 macrophages, the tatB mutants showed a 10-fold reduction in growth. Double mutants lacking tatB and Lsp secretion were even more defective, suggesting tatB has an intracellular role that is independent of Lsp. tatB mutants were also impaired 20-fold in Hartmannella vermiformis amoebae cultured in the presence of an iron chelator. All mutant phenotypes were complemented by reintroduction of an intact tatB. Thus, L. pneumophila tatB plays a role in the formation of a respiratory complex, growth under low-iron conditions, the secretion of a phospholipase C activity, and intracellular infection.
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PMID:The Legionella pneumophila tatB gene facilitates secretion of phospholipase C, growth under iron-limiting conditions, and intracellular infection. 1578 43

Microsomal membranes from potato tubers were treated with a phospholipase C extracted from Bacillus cereus. A positive correlation could be observed between the hydrolysis of membranous phospholipids and the decrease of the NADH-cytochrome c reductase activity. Addition of total lipid or phospholipid micelles to phospholipase C-treated microsomes partially restored the NADH-cytochrome c reductase activity, thus proving the lipid-dependence of this enzyme.
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PMID:Regulation by Lipids of Plant Microsomal Enzymes: II. LIPID DEPENDENCE OF THE NADH-CYTOCHROME c REDUCTASE OF POTATO TUBERS. 1666 41

Gradually increasing atmospheric CO2 partial pressure (pCO2) has caused an imbalance in carbonate chemistry and resulted in decreased seawater pH in marine ecosystems, termed seawater acidification. Anthropogenic seawater acidification is postulated to affect the physiology of many marine calcifying organisms. To understand the possible effects of seawater acidification on the proteomic responses of a marine crustacean brine shrimp (Artemia sinica) three groups of cysts were hatched and further raised in seawater at different pH levels (8.2 as control and 7.8 and 7.6 as acidification stress levels according to the predicted levels at the end of this century and next century, respectively) for 1, 7 and 14 days followed by examination of the protein expression changes via two-dimensional gel electrophoresis. Searches of protein databases revealed that 67 differential protein spots were altered due to lower pH level (7.6 and 7.8) stress in comparison to control groups (pH 8.2) by mass spectrometry. Generally, these differentially expressed proteins included the following: 1) metabolic process-related proteins involved in glycolysis and glucogenesis, nucleotide/amino acid/fatty acid metabolism, protein biosynthesis, DNA replication and apoptosis; 2) stress response-related proteins, such as peroxiredoxin, thioredoxin peroxidase, 70-kDa heat shock protein, Na/K ATPase, and ubiquinol-cytochrome c reductase; 3) immune defence-related proteins, such as prophenoloxidase and ferritin; 4) cytoskeletal-related proteins, such as myosin light chain, TCP1 subunit 2, tropomyosin and tubulin alpha chain; and 5) signal transduction-related proteins, such as phospholipase C-like protein, 14-3-3 zeta, translationally controlled tumour protein and RNA binding motif protein. Taken together, these data support the idea that CO2-driven seawater acidification may affect protein expression in the crustacean A. sinica and possibly also in other species that feed on brine shrimp in the ecosystem, particularly marine food webs.
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PMID:Differential protein expression using proteomics from a crustacean brine shrimp (Artemia sinica) under CO2-driven seawater acidification. 2772 59


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