Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate physicochemical properties of the small intestinal basolateral cell surface during postnatal development, membranes were isolated from suckling (14-17 days) and weanling-mature (35-49 days) rabbit jejunal and ileal enterocytes at 30- to 40-fold purification (based on Na+-K+-ATPase specific activity) and with limited contamination from coisolated cellular elements. Membrane lipid analysis demonstrated age-dependent reductions and proximal to distal increases in total lipid (per milligram protein). Postnatal increases in membrane total cholesterol of jejunum (suckling vs. mature, 0.18 vs. 0.26 mumol/mg protein; P less than 0.01) and ileum (0.18 vs. 0.31 mumol/mg protein; P less than 0.01) resulted in markedly higher cholesterol-to-phospholipid molar ratios (jejunum, 0.43 vs. 0.73; ileum, 0.43 vs. 0.72 mumol/mg protein; P less than 0.01). Membranes from mature animals had higher relative sphingomeylin and phosphatidylcholine content and, in both age groups, fatty acyl saturation was increased in ileum compared with jejunum. By utilization of the fluorophores 1,6-diphenyl-1,3,5-hexatriene and DL-12-(9-anthroyl)stearic acid, the fluidity of basolateral membranes and liposomes prepared from extracted membrane lipid decreased markedly in mature rabbits. Arrhenius plots demonstrated higher apparent thermotropic transition temperatures of mature membrane lipid. These data therefore demonstrate significant changes in small intestinal basolateral membrane lipid composition and fluidity that occur during the weaning period. Possible relationships to ontogenesis of membrane protein function are discussed.
...
PMID:Ontogeny of basolateral membrane lipid composition and fluidity in small intestine. 275 Sep 4

The effects of ethinyl estradiol, a synthetic estrogen with cholestatic properties and a propensity to alter hepatocyte and ileal brush-border membrane fluidity, on lipid structure and Na+-K+-ATPase activity of rabbit small intestinal basolateral membranes were determined. Utilizing the fluorophores 1,6-diphenyl-1,3,5-hexatriene and DL-12-(9-anthroyl)stearic acid, increases in fluorescence anisotropy, the reciprocal of fluidity, were found in basolateral membranes and in membrane lipid liposomes isolated from ileum. Fluidity alterations were accompanied by a marked decrease in bilayer phospholipids (0.37 vs. 0.48 mumol/mg protein; P less than 0.01) and an increase in both the cholesterol-to-phospholipid molar ratio (0.85 vs 0.61; P less than 0.02) and membrane saturated fatty acid content. Estrogen-mediated physicochemical changes were associated with a significant reduction in ileal basolateral membrane Na+-K+-ATPase specific activity (100.0 vs. 185.8 nmol Pi.min-1.mg protein-1; P less than 0.02). Control values both for fluorescence anisotropy and for Na+-K+-ATPase specific activity were restored after in vitro membrane fluidization with benzyl alcohol. The data therefore indicate that ethinyl estradiol effects on basolateral membrane lipid dynamics are confined to the ileum and are associated with inhibition of Na+-K+-ATPase activity. These structural and functional changes appear to be related, in part, to specific modifications in the availability of phospholipid after estrogen treatment.
...
PMID:Estrogen modulates ileal basolateral membrane lipid dynamics and Na+-K+-ATPase activity. 283 62

Rat colonic basolateral membranes were incubated with S-adenosyl-L-[methyl-3H]methionine (0.3 mM) at 37 degrees C for 2 h at pH 9.0. This resulted in an increase in the specific activity of Na+ + K+-ATPase by 60%. Kinetic parameter analysis revealed a 2-fold increase in the Vmax. of this enzymatic activity, whereas the Km for ATP was unchanged. The methylation inhibitor S-adenosyl-L-homocysteine (2 mM) significantly reduced these S-adenosyl-L-methionine-stimulated increases in specific activity and the Vmax. of Na+ + K+-ATPase. S-Adenosyl-L-methionine treatment of basolateral membranes was also found to significantly increase the fluidity of these preparations, as assessed by steady-state fluorescence polarization techniques using the fluorophore 1,6-diphenyl-1,3,5-hexatriene; S-adenosyl-L-homocysteine (2 mM) again markedly reduced this S-adenosyl-L-methionine-induced increase in fluidity. While transmethylation reactions involving phospholipids, non-polar lipids and proteins were all found to exist in rat colonic basolateral membranes, based on a number of observations, the results of the present studies suggest that transmethylation of membrane phospholipids, but not membrane non-polar lipids or proteins, influenced the fluidity of basolateral membranes which, in turn, modified Na+ + K+-ATPase activity in these membranes.
...
PMID:S-adenosyl-L-methionine modulates Na+ + K+-ATPase activity in rat colonic basolateral membranes. 283 60

An alteration in the enzymatic properties of the erythrocyte membrane acetylcholinesterase (AchE) and Na+,K+-ATPase has been described in experimental diabetes mellitus. We studied erythrocyte membrane fluidity and AchE and Na+,K+-ATPase activities in 15 insulin-dependent diabetic patients and 11 normal subjects. Fluidity was assessed by fluorescence polarization, using 1,6-diphenyl-1,3,5-hexatriene as a probe, and AchE and Na+,K+-ATPase activities were measured enzymatically. We found a significant increase in the enzymatic activity of AchE and a change in its enzymatic properties in diabetic patients compared with those in normal subjects. AchE activity correlated inversely with membrane fluorescence polarization, which was decreased in the diabetic patients, indicating an increase in membrane fluidity. Na+,K+-ATPase activity was reduced in the diabetic patients and correlated positively with the fluorescence polarization values. We hypothesize that the abnormal dynamic properties of the erythrocyte membrane may play a major role in determining the described change in enzymatic activity.
...
PMID:Abnormal membrane fluidity and acetylcholinesterase activity in erythrocytes from insulin-dependent diabetic patients. 284 52

Myometrial plasma membrane (MPM) preparations from rats treated with oestradiol were obtained by discontinuous sucrose-gradient centrifugation. The preparations contained calcium-stimulated and magnesium-dependent ATPase (Ca2+/Mg2+-ATPase). A dramatic decrease in the activity of Ca2+/Mg2+-ATPase was observed when preparations were treated with 0.025-10 mumol prostaglandins E2 and F2 alpha (PGE2 and PGF2 alpha)/l. In contrast, there was a marked increase in MPM-bound 5'-nucleotidase activity at low concentrations (up to 2 mumol/l) of PGE2 and PGF2 alpha; higher concentrations (up to 10 mumol/l), however, led to a progressive inhibition of enzyme activity. Association (specific and non-specific binding) of PGE2 and PGF2 alpha with MPM at pH 7 was found to require Ca2+ (half-maximal concentration approximately 0.7 mmol/l). Changes in the allosteric properties of MPM-bound 5'-nucleotidase by concanavalin A (as reflected by changes in the Hill coefficient) indicated a fluidization of the membrane induced by PGE2 and PGF2 alpha. The steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene-labelled MPM decreased in PGE2- and PGF2 alpha-treated MPM from 1.24 +/- 0.04 (S.D.) to 0.66 +/- 0.01 and 0.74 +/- 0.01 respectively, which is consistent with a general increase in membrane fluidity. It is suggested that PGE2 and PGF2 alpha promote changes in the physical properties of MPM which may be relevant to the induction of uterine contractions by enzymatic regulation of intracellular calcium concentrations.
...
PMID:Effect of prostaglandins E2 and F2 alpha on membrane calcium binding, Ca2+/Mg2+-ATPase activity and membrane fluidity in rat myometrial plasma membranes. 294 78

A steady-state fluorescence polarization technique, using the membrane probe 1,6-diphenyl-1,3,5-hexatriene (DPH), showed that separately detectable transitions occurred in the regions of 17, 26 and 36 degrees C in isolated preparations of ram sperm plasma membrane. An independent technique based on the temperature-related behaviour of calcium- and magnesium-activated ATPase detected a single phase transition in the region of 24 degrees C. Modulation of ATPase by neighbouring lipid composition was inferred from findings that phospholipase A2 caused significant stimulation of the enzyme. Cholesterol-rich liposomes caused an upward shift of the phase-transition temperature from 24 degrees C to 30 degrees C, but the reasons for this are unclear. It is considered that these phase transitions may have profound effects on sperm survival and physiology, both during normal fertilization processes and in response to cryostorage.
...
PMID:Thermotropic phase transitions in the plasma membrane of ram spermatozoa. 294 73

1. Binding of liposomal-[14C]-cholesterol into dog brain synaptosomal plasma membranes (SPM) follows a sigmoid path (Hill coefficient h = 1.96 +/- 0.12). 2. Ca2+-stimulated ATPase activity increased (approx. 95%) at a concentration range (0.1-0.4 mM) of liposomal cholesterol and testosterone (up to 10 microM). While progesterone up to 10 microM decreased the enzyme activity (approx. 70%) in dog and rabbit brain SPM. 3. Fluorescence anisotropy, [(r0/r)-1]-1, of 1,6-diphenyl-1,3,5-hexatriene (DPH) was 1.04 +/- 0.04 in rabbit brain SPM and 1.72 +/- 0.09 in dog brain SPM. 4. Lipid phase separations at 23.5 +/- 1.2 degrees C in dog brain SPM and at 17.2 +/- 0.9 degrees C in rabbit brain SPM were observed. In dog brain SPM it increased to 33.4 +/- 1.8 degrees C, while in rabbit brain SPM was abolished after treatment with liposomal cholesterol. 5. The allosteric inhibition of Ca2+-stimulated ATPase by Na+ ions showed a Hill coefficient h = 1.72 +/- 0.15 and h = 1.48 +/- 0.08 for dog and rabbit brain SPM respectively, which increased to h = 2.83 +/- 0.55 and h = 2.34 +/- 0.35 after treatment with liposomal cholesterol.
...
PMID:Structure activity relationship of cholesterol and steroid hormones with respect to their effects on the Ca2+-stimulated ATPase and lipid fluidity of synaptosomal plasma membranes from dog and rabbit brain. 296 32

The binding of [14C]cortisol into dog brain synaptosomal plasma membranes (SPM) follows an exponential path described by the general formula y = a.ebx. The specific activity of the SPM-bound (Na+ + K+)-stimulated ATPase was linearly increased at different concentrations of cortisol. Changes in the allosteric properties of (Na+ + K+)-stimulated ATPase by fluoride (F-) (i.e. changes of Hill coefficients) indicate that cortisol increases the membrane fluidity. The fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene-labeled SPM decreased in cortisol treated SPM compared to untreated (control) SPM, which is consistent with a general increase in membrane fluidity. This increase of fluidity by cortisol may play a role in the physiological effects of this hormone in the brain.
...
PMID:Cortisol effect on (Na+ + K+)-stimulated ATPase activity and on bilayer fluidity of dog brain synaptosomal plasma membranes. 300 15

The effect of cholesterol on the activity of sarcoplasmic reticulum Ca-ATPase, reconstituted in proteoliposomes containing soybean phosphatidylethanolamine (PE), egg phosphatidylcholine (PC), and cholesterol, was examined. The protein incorporation efficiency increased with PE content but appeared to be independent of cholesterol content. At low cholesterol, PE stimulated calcium uptake. The coupling efficiency of the proteoliposomes increased with an increase in cholesterol content at each PC/(PC + PE) ratio and was more pronounced for those proteoliposomes containing high PE. Dynamic fluorescence measurements of the incorporated lipophilic probe, diphenyl-1,3,5-hexatriene, revealed a decrease in the motion and an increase in the order of the phospholipid fatty acyl chains in proteoliposomes with high cholesterol content. A complementary observation was made using electron spin resonance of the spin label, 2,2-dimethyl-5-dodecyl-5-methyloxazolidine N-oxide. Freeze-fracture electron microscopy studies on proteoliposomes containing 0.20 molar ratio of PC/(PC + PE) and cholesterol revealed predominantly vesicular structures with occasional bilayer defects at high cholesterol content. It is postulated that the cholesterol-induced enhancement of the Ca-transport function of the Ca-ATPase is related to the hydration-related bilayer-destabilizing characteristic of the cholesterol molecule as revealed by 31P NMR.
...
PMID:The role of cholesterol in the activity of reconstituted Ca-ATPase vesicles containing unsaturated phosphatidylethanolamine. 300 90

[14C]Estradiol, [14C]estrone, [14C]progesterone and [3H]prostaglandins (PGs) E2 and F2 alpha, when incubated with myometrial plasma membranes (MPM) at a concentration of 1 X 10(-6) M for 1 h at 37 degrees C, bind into MPM at pmolar concentrations. Unlabeled steroids inhibited [3H]PGE2 and [3H]PGF2 alpha binding to MPM in a dose-dependent manner. Membrane-bound and free steroids or PGs were found to be essentially unchanged under the present incubation conditions. Ca2+ ions up to 10 mM increased steroid binding into MPM. Molecular interactions between steroids and MPM were assessed by measuring the steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), and by estimating the changes in the allosteric properties of MPM-bound (Na+ + K+)ATPase by fluoride (F-). Steroids appear to increase the MPM fluidity, evaluated through changes in the Hill coefficient for MPM-bound (Na+ + K+)ATPase by F- and by the fluorescence polarization method. Binding of sex steroids to MPM increased the membrane fluidity and decreased the binding of the uterus stimulatory PGs by membrane receptors. These studies provide a basis for postulating that a 'non-genomic' mechanism of sex steroids induces reduction of uterine contractions.
...
PMID:Sex steroid and prostaglandin interactions upon the purified rat myometrial plasma membranes. 301 59


<< Previous 1 2 3 4 5 6 7 8 9 Next >>

---