共查询到20条相似文献,搜索用时 15 毫秒
1.
《The International journal of biochemistry》1993,25(8):1183-1187
- 1.1. Synaptic plasma membrane vesicles (SPMV) from rat brain synthesized ceramide-phosphoethanolamine (SpE), an analogue of sphingomyelin (SpC) from phosphatidylethanolamine (PE) and ceramide.
- 2.2. This reaction was catalyzed by PE: ceramide-phosphotransferase.
- 3.3. The presence of PC did not modify the SpE synthesis and PI and PS at twice PE concentration seemed to be activators; only PG was an inhibitor at all concentrations.
- 4.4. Some cations (Mg2+, Mn2+) were without effect, while Ca2+ increased transferase activity, so was interesting to study.
- 5.5. Transferase was compared with sialidase (external enzyme).
- 6.6. Kinetics other than those already performed by us were undertaken in order to confirm its location.
2.
《Comparative biochemistry and physiology. A, Comparative physiology》1989,92(2):263-266
- 1.1. Carp red cells were treated with drugs that affect the cell membranes. The water content of the cells and the accumulation of cAMP in the cells were measured in normoxia and in hypoxia using non-stimulated and adrenergically stimulated cells.
- 2.2. WGA, DIDS + CCCP and A23187 increased the water content of nonstimulated normoxic cells.
- 3.3. In hypoxia ouabain and DIDS + CCCP increased the water content but cytochalasin B, NPM, DIDS, CCCP and A23187 + CA2+ abolished the hypoxia-induced swelling.
- 4.4. Any membrane perturbation induced some cAMP formation, Sophora and Anquilla lectins being most potent.
- 5.5. Also in adrenergically stimulated cells, membrane perturbation generally increased cAMP formation.
- 6.6. However, cAMP accumulation diminished in cells treated with cytochalasin B, CCCP and DIDS + CCCP.
- 7.7. The adrenergic swelling of carp red cells was reduced in normoxia by DIDS. NPM and CCCP increased the adrenergic swelling in normoxia to hypoxic level.
- 8.8. In hypoxia WGA and Anquilla lectin decreased the swelling.
3.
《The International journal of biochemistry》1976,7(12):633-634
- 1.1. Plasma membranes have been isolated from frog (Rana esculenta) liver.
- 2.2. The average yield was 0.194 mg protein/g wet liver.
- 3.3. The activities of plasma membrane-bound enzymes (Na+-K+-ATPase and 5'-nucleotidase as well as of (Mg2+)-ATPase have been determined in the liver homogenate and in isolated plasma membranes.
- 4.4. (Na+-K+-ATPase, 5'-nucleotidase and (Mg2+)-ATPase activities of frog liver are compared with the same enzymatic activities observed in rat liver.
4.
《The International journal of biochemistry》1993,25(11):1593-1599
- 1.1. The cytoplasmic glucocorticoid receptor of rat liver cells is in part recovered in the plasma membrane fraction.
- 2.2. After in vivo administration of [3H]dexamethasone, 0.35% of the radioactivity recovered is bound on plasma membranes.
- 3.3. Dexamethasone also binds in vitro specifically to plasma membranes. Expressed as fmol/mg protein, binding of dexamethasone to plasma membranes is comparable to binding to the soluble cytoplasmic fraction (cytosol).
- 4.4. Using polyclonal antibody to the glucocorticoid receptor and the indirect immunofluorescence technic, an intense decoration of the plasma membranes is observed, denoting a high concentration of glucocorticoid receptor on plasma membranes.
- 5.5. The localization of the receptor on plasma membranes could be of potential importance for its interaction with agents (mitogens, growth factors) initially acting on the cell membrane, regulating subsequent cell proliferation and growth at the level of the cell nucleus.
5.
《The International journal of biochemistry》1994,26(3):403-414
- 1.1. Rat liver microsomal membranes were studied for the presence of protein kinases. Microsomal proteins solubilized with Triton X-100 were analyzed by means of ion exchange chromatography.
- 2.2. Protein kinase activity was detected in the column fractions using specific assays for cAMP-dependent protein kinase, cGMP-dependent protein kinase, protein kinase C, Ca2+/calmodulin-dependent protein kinase and casein kinases.
- 3.3. Fractions with protein kinase activity were further analyzed by SDS-polyacrylamide gel electrophoresis.
- 4.4. The results indicate that cAMP-dependent protein kinase type I and II, casein kinases I and II, protein kinase C proenzymes I and II and Ca2+ /calmodulin kinase II are associated with the membranes of endoplasmic reticulum (ER).
6.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1983,74(1):107-111
- 1.1. Plasma membranes were isolated from caudal flank skeletal musculature of rainbow trout by discontinuous sucrose gradient centrifugation.
- 2.2. Na+−K+-ATPase was enriched 8-fold and 5′-nucleotidase activities 4-fold in a fraction isolated at the 8–25% sucrose interface.
- 3.3. A cholesterol: phospholipid ratio of 0.37 in the plasma membrane fraction was 85% greater than that observed in adjacent subcellular fractions.
- 4.4. Electron microscopy provided morphological confirmation of enrichment and integrity of skeletal muscle plasma membranes at the 8–25% sucrose interface.
7.
《Comparative biochemistry and physiology. A, Comparative physiology》1984,77(3):487-491
- 1.1. Longitudinally split or completely regenerated branch tips from Leplogorgia virgulata show no differences in calcium uptake between control and ouabain treatments. This indicates that there is no ouabain sensitive Na+, K+-ATPase involved in calcium uptake.
- 2.2. The tissue fractions of both regenerated and split branch tips show, at certain times, higher calcium uptake than control fractions. In the spicule fractions of these tips calcium uptake decreases in vandate treated specimens.
- 3.3. Pulse-chase experiments show an initial rapid release of calcium from the tips into surrounding seawater.
- 4.4. The results may suggest the presence of outwardly directed calcium pumps on the basal/lateral and apical plasma membranes of the epithelial cells. Outwardly directed calcium pumps may also be envisaged on the cell membranes of scleroblasts. In addition, pumps may move calcium into specific organelles of the scleroblasts en route to the spicule forming vacuoles.
- 5.5. These pumps are likely to be Ca2+-ATPase.
8.
《The International journal of biochemistry》1993,25(5):641-652
- 1.1. A subcellular fractionation procedure for bovine adrenal glands was designed with the aim to study the biochemical properties of Ca2+ stores in chromaffin cells.
- 2.2. The thapsigargin-sensitive compartment of Ca2+ stores was found to be highly enriched in a light microsomal fraction (LMF) on a 15–30% linear sucrose gradient, and was found to be essentially devoid of contamination by plasma, mitochondrial or secretory granule membranes.
- 3.3. A Ca2+-pumping ATPase was identified in this LMF as a 97 kDa protein forming an acid-stable, Ca2+-dependent, thapsigargin-sensitive phosphorylated intermediate upon incubation with [γ-32P]ATP, suggesting this protein to represent a SERCA-3 isoform of Ca2+ ATPases.
- 4.4. A major 162 kDa protein, previously demonstrated in the isolated chromaffin cells, was enriched in the LMF, distributing on sucrose gradients in parallel with the thapsigargin-sensitive Ca2+ uptake.
- 5.5. LMF appears to represent a part of the thapsigargin-sensitive Ca2+ store of chromaffin cells, and should be useful for further studies of the store properties at the subcellular and molecular level.
9.
- 1.1. Lipid concentrations and lecithin:cholesterol acyltransferase (LCAT) activity in the plasma Tropidurus torquatos were remarkably variable.
- 2.2. Both lipid levels and LCAT activity were highest for lizards collected during the early rainy season (March–April) than during other seasons, and were higher for females than for males.
- 3.3. Plasma lipid levels and LCAT activity were significantly and inversely correlated with body weight (age) of male lizards, this being associated with an apparent change to an herbivorous diet in older males.
- 4.4. During prolonged fasting, plasma lipid levels and lecithin:cholesterol acyltransfer (LCAT) and hepatic phospholipids were markedly reduced.
- 5.5. LCAT activity in plasma of fasted and non-fated lizards was significantly correlated with the molar proportion of PC to UC, suggesting that the apparent low LCAT in plasma of fasted lizards is partly due to depletion of PC in the lipoprotein substrates.
10.
《Comparative biochemistry and physiology. A, Comparative physiology》1993,104(2):227-232
- 1.1. The activity of brush border enzymes (alkaline phosphatase, maltase, sucrase, trehalase, leucine amino peptidase) was higher in purified membranes prepared with calcium. The contamination of these membranes with basolateral membranes was also lower (1.27 for Na-K-ATPase activity ratio).
- 2.2. The extraction of brush border lipids was carried out according to Folch adapted method. Two dimensional thin layer chromatography was used to separate the phospholipidic fractions. Fatty acids of phospholipids were analysed using gas chromatography after acid transmethylation (column SP 2330).
- 3.3. Phospholipids are composed of phosphatidylcholine (PC: 33%), phosphatidylethanolamine (PE: 30%), sphingomyeline (SM: 21%), phosphatidylserine (PS: 14%) and phosphatidylinositol (PI: 2%). 4. PC, PE and PS are characterized by high levels of unsaturated fatty acids (monounsaturated MUFA: 21.5% and polyunsaturated PUFA: 34.9%). The most abundant PUFA belong to the (n-3) family [18:3 (n-3), 20:5 (n-3) and 22:6 (n-3)].
- 4.5. Fatty acids from sphingomyelin of purified membranes have low proportions of PUFA (13.5%) but higher proportions of MUFA (39.5%).
- 5.6. No specific differences were found between calcium and magnesium prepared membranes.
- 6.7. The low content in LPC and the absence of LPE confirmed the absence of major structural lipids transformation during the membrane purification with calcium or magnesium.
- 7.8. Glycine transport was measured during 10 sec at different temperatures using the rapid filtration technique. Glycine transport was higher with Na+ than with K+. In the presence of Na+, this transport increases with temperature.
- 8.9. Arrhenius curves were mono phasic without obvious breakpoint and indicated no phase transition in the lipid bilayer.
- 9.10. A significant Na+ dependent glycine transport has been characterized at low temperatures (0°C) which suggests a possible role of membrane polyunsaturated fatty acids in the control of glycine transport.
11.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1991,98(2):237-242
- 1.1. The incorporation of 32P into the contractile proteins of the anterior byssus retractor muscle of Mytilus edilus L. was analyzed during the different stages of a contraction-catch-relaxatin cycle.
- 2.2. The experiments were performed with saponin-skinned fibers preincubated with γ-32P-ATP.
- 3.3. The total amount of 32P incorporated into the fiber proteins was anlyzed by measuring the label of TCA-insoluble protein in a scintillation counter.
- 4.4. The dose incorporated was about twice as high during Ca2+ induced contraction and serotonin induced accelerated relaxation as during test and catch.
- 5.5. The molecular mass of the phosphorylated proteins was analyzed by autoradiography of the proteins separated by SDS-PAGE.
- 6.6. Up to 26 protein spots of different molecular masses were labelled, including such well characterized protein spe+cies as myosin heavy and light chains, paramyosin and tropomyosin.
12.
《Comparative biochemistry and physiology. A, Comparative physiology》1991,98(4):823-832
- 1.1. In crayfish, light stimulation of the retinular cells induces a depolarizing receptor potential.
- 2.2. Experiments were designed to determine the role of Na+ and Ca2+ on receptor potential during dark And light states.
- 3.3. Depolarization depends on Na+ and Ca2+ availability to the retinular cell.
- 4.4. Repolarization velocity and response duration depend on extracellular Ca2+ availability.
- 5.5. Light adaptation increases receptor potential dependence on calcium and sodium ions.
- 6.6. We analyse these results with respect to other invertebrate photoreceptors.
13.
《The International journal of biochemistry》1981,13(8):959-962
- 1.1. In establishing a protocol for the use of a phospholipid (PL) 2 exchange protein (PLEP) preparation to incorporate fluorescent lipids into membrane fragments, the potential for the PLEP preparation to alter membrane composition was investigated.
- 2.2. Cholesterol was removed from erythrocyte ghosts and PL content was increased after incubation of the membranes with phosphatidylcholine (PC) vesicles and a nonspecific bovine liver PLEP preparation.
- 3.3. The elevated PL/cholesterol ratio of the ghosts decreased fluorescence polarization of diphenylhexatriene (DPH), indicating an increased average membrane fluidity.
- 4.4. The increased PL/cholesterol ratio and reduced DPH fluorescence polarization were prevented by including cholesterol in the PC vesicles during the initial incubation of ghosts with PLEP preparation and lipid.
- 5.5. In addition, the PC content of ghost membranes was elevated after incubation with PLEP preparation and either PC or mixed PC-cholesterol vesicles.
14.
《The International journal of biochemistry》1978,9(4):253-262
- 1.1. Plasma membranes were obtained from hamster (Mesocricetus auratus Wateth.) and chicken (Callus gallus L.). Skeletal muscle was isolated by muscle homogenization, protein extraction by inorganic salt solutions (0.4 M LiBr and 0.6 M KCl) and differential centrifugation. After purification on a discontinuous sucrose gradient, several fractions were obtained. The upper fraction (20% sucrose, w/w) yielded in the form of vesicles by electron microscope examination.
- 2.2. (Na+ + K+ )-ATPase and 5'-nucleotidase as plasma membrane markers were found to be concentrated in the upper fraction. Practically no succinate dehydrogenase activity was detected.
- 3.3. By means of polyacrylamide gel electrophoresis it was possible to separate 7–8 protein bands the molecular weights of which range from 26,000 to 200,000 daltons; and 4 bands for glycoproteins.
- 4.4. The ratio lipid: protein and the molar ratio cholesterol :phospholipid were found to be 0.93–0.94 and 0.25–0.38, respectively.
- 5.5. Glucose, mannose, galactose and fucose, hexosamines and sialic acids were determined in these preparations of membranes.
15.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1991,98(4):753-758
- 1.1. In the plasma membrane of mussel gill cells an ouabain insensitive, Ca2+-activated ATPase activity is present. The ATPase has high Ca2+ affinity (Kma = 0.3 μM).
- 2.2. The optimum assay conditions to evaluate the enzymatic activity of the Ca2+-stimulated ATPase at 19°C are: 120–300 mM KCl ionic strength, pH 7.0 and 2 mM ATP. As for mammalian enzymes, the Ca2+ ATPase activity is stimulated by DTT (0.5–1 mM) and it is inhibited by low concentrations of vanadate (10–50 μM) and -SH inhibitors such as PCMB and PCMBS (10 μM); the enzyme appears to be calmodulin insensitive.
- 3.3. Electrophoretic analyses of plasma membrane proteins demonstrate that: (a) Ca2+ at n-μM concentrations is necessary to activate ATP hydrolysis with consequent formation of the enzyme-phosphate complex; (b) the steady state concentration of the phosphorylated intermediate is increased in the presence of La3+; (c) the mol. wt of Ca2+ ATPase is about 140 kDa.
- 4.4. Low Ca2+ concentrations (n-μM) are sufficient to stimulate the ATP-dependent Ca2+ uptake by plasma membrane inside-out vesicles.
- 5.5. The results indicate that the Ca2+ pump present in the gill plasma membranes could be responsible for Ca2+ extrusion and therefore involved in maintaining the cytosolic Ca2+ concentration within physiological levels.
16.
- 1.1. Rainbow trout were acclimated to salt water (1.5, 2.0 or 3.0%, which means 40, 60 or 85% concentrated sea-water) and the electrolyte, glucose and cortisol concentrations of the plasma as well as the extra- and intracellular muscle space, the muscle electrolyte concentrations and the ATPase activity were analysed.
- 2.2. Plasma osmolality, Na+, Ca2+ and Mg2+ concentrations of the plasma had a maximum at 24 hr after the start of acclimation when acclimated to 3.0% salt water. Plasma osmolality, Na+ and Mg2+ concentrations were significantly higher during the whole acclimation time when exposed to 3.0% salt water.
- 3.3. Variations and regulations of ECS and ICS were clearly demonstrated. The intracellular electrolyte concentrations were also maximal at 24 hr.
- 4.4. The plasma glucose level was just slightly elevated, but the cortisol level clearly indicated a stress response at 24 hr.
- 5.5. The activity of gill Na-K-ATPase increased during the acclimation time.
- 6.6. The regulatory processes in trout during acclimation to salt water are compared with those occurring in tilapia and carp.
17.
《Comparative biochemistry and physiology. A, Comparative physiology》1992,101(2):259-267
- 1.1. Changes in glomerular nitration rate (GFR), urine and blood properties and plasma catecholamines of carp were investigated during and following hypoxia.
- 2.2. GFR and urine flow decreased with increased urinary concentrations of bio-components, except protein, in the course of hypoxia.
- 3.3. Decreases in blood pH, and increases in haematocrit value and plasma K+, Ca2+, Mg2+, inorganic phosphate (Pi), ammonia, lactic acid and catecholamines (CAs) were observed as hypoxia progressed.
- 4.4. Increased GFR and urine flow, and higher values for urinary components, except protein, compared with those of the control were found in the initial post-stress stage.
- 5.5. The possible significance of increased plasma CAs in relation to changes in renal function in hypoxic carp is discussed.
18.
《The International journal of biochemistry》1994,26(9):1103-1109
- 1.1. Adenylylation, a posttranslational modification of proteins, was investigated in saponin-permeabilized acinar cells of the rat parotid gland.
- 2.2. When cells were incubated with [2,8-3H]ATP, several proteins, including a 26 kDa protein in the particulate fraction, were labeled.
- 3.3. Upon incubation of cells with [α-32P]ATP in the presence of cAMP and 3-isobutyl-lmethylxanthine, 32P-labeling of the 26 kDa protein was observed.
- 4.4. After treatment with snake venom phosphodiesterase, [32P]AMP was released from the 26kDa protein. Such release was not observed when cells were labeled with [γ-32P]ATP.
- 5.5. The 32P-labeling pattern of proteins with [α-32P]ATP was clearly different from that with [adenylate-32P]NAD+.
- 6.6. The results suggest that the 26 kDa protein is one of the adenylylation substrates in rat parotid acinar cells.
19.
《Comparative biochemistry and physiology. A, Comparative physiology》1990,95(1):171-175
- 1.1. Freshwater nonanadromous rainbow trout, Salmo gairdneri, were injected three times a week with either saline, 10μg cortisol/g, 1.0μg thyroxine/g or 10μg cortisol/g + 1.0μg thyroxine/g during a period of 28 days (12 injections). A separate group was derived as a subgroup from the thyroxine group on day 14 and received Cortisol + thyroxine from day 14 until day 28 (six injections).
- 2.2. Gill chloride cell number and Na+/K+-ATPase activity increased by cortisol treatment, the changes being significant on days 7 and 14, respectively.
- 3.3. Thyroxine treatment did not affect gill Na+/K+-ATPase activity or chloride cell number directly. Neither did it modify the stimulatory effect of cortisol on these parameters.
- 4.4. Muscle water decreased in cortisol-treated fish and increased in thyroxine-treated fish, while no changes were observed in the combined hormone groups.
- 5.5. No changes were observed in plasma chloride in any group during the experiment.
- 6.6. The results demonstrate a putative role of cortisol in stimulating hypo-osmoregulatory mechanisms and suggest that thyroxine is without a direct or a supportive effect for cortisol action.
20.
《The International journal of biochemistry》1994,26(7):905-911
- 1.1. Parotid plasma membrane nonpump low-affinity Ca2+-ATPase, which possesses high-affinity (Ca2+ + Mg2+ )-ATPase activity, was characterized.
- 2.2. Purified Ca2+-ATPase hydrolyzed the nucleoside triphosphates, GTP, ITP, CTP, UTP, TTP (67–93% of ATP) and nucleoside diphosphates, ADP. GDP, IDP, CDP, TDP (12–40% of ATP) but not AMP and p-NPP.
- 3.3. The maximum activities of Ca2+- and (Ca2+ +Mg2+ )-ATPases were obtained in the presence of 1 mM and 0.13 μ M Ca2+, respectively.
- 4.4. The Km values for Ca2+ in Ca2+- and (Ca2++ Mg2+ )-ATPases were 0.2 mM and 22 nM. respectively.
- 5.5. The activities of both Ca2+- and (Ca2+ + Mg2+ )-ATPases were found in the right-side-out-vesicles obtained from the plasma membrane-rich fraction.
- 6.6. These features suggest that Ca2+-ATPase is an ecto-Ca2+-dependent nucleoside triphosphatase.