Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bacteriophage lambda is assembled from preformed viral capsids (proheads), tails, and genomes that are excised from a concatemeric DNA precursor. The enzyme responsible for insertion of the genome into the precapsid is known as terminase. This enzyme possesses site-specific endonuclease, ATPase, and DNA strand separation ("helicase") catalytic activities, which work in concert to excise and package a single viral genome during phage assembly. We have previously characterized the endonuclease [Tomka, M. A., & Catalano, C. E. (1993) J. Biol. Chem. 268, 3056-3065] and ATPase [Tomka, M. A., & Catalano, C. E. (1993) Biochemistry 32, 11992-11997] catalytic activities of lambda terminase and present here similar studies on the strand separation activity of the enzyme. Strand separation requires terminase, divalent metal, and adenosine nucleotides with a hydrolyzable beta,gamma-phosphate bond. Two apparent binding sites for ATP-mediated strand separation were identified, one of which appears to be distinct from the high- and low-affinity sites previously observed for ATP hydrolysis [Hwang, Y., Catalano, C. E., & Feiss, M. (1995) Biochemistry 35, 2796-2803]. Salt stimulates the reaction at low concentrations but is strongly inhibitory at elevated concentrations, presumably due to impaired DNA binding. The above results are identical with either a complex DNA mixture (a nicked, annealed DNA duplex in the presence of excess nonspecific DNA) or a purified DNA substrate; however, a kinetic analysis of the reaction revealed that the observed rate was approximately 5-fold greater with the purified DNA substrate. Moreover, while Escherichia coli integration host factor (IHF) stimulates terminase-mediated strand separation with both substrates, the observed stimulation is more pronounced with the complex DNA mixture (10-fold rate increase) than the purified DNA substrate (5-fold rate increase). Our data are consistent with a model where IHF binding to the terminase assembly site forms a binary protein.DNA complex readily distinguishable from bulk DNA. The implications of these results to the process of DNA packaging in bacteriophage lambda are discussed.
 ...
PMID:Kinetic characterization of the strand separation ("helicase") activity of the DNA packaging enzyme from bacteriophage lambda. 927 94

Sodium chloride transport across isolated cecum mucosa was investigated in normal rats and rats with adaptive cecum growth induced by dietary polyethylene glycol (PEG). The normal cecum absorbed Cl in excess of Na with a small short-circuit current (ISC). Dietary adaptation led to large equivalent increments of Na and Cl net absorption without adequate ISC change. Inhibitor studies (mucosal amiloride 10(-3) and 10(-4) M; mucosal 4, 4-diisothiocyanatostilbene-2,2-disulfonic acid 5 x 10(-5) M; serosal furosemide 10(-3) M; serosal ouabain 10(-3) M) suggested that normal cecal NaCl absorption involves electroneutral Na/H and Cl/HCO3 exchange at the apical and Na-K-ATPase-mediated exit across the basolateral cell membrane. Dietary adaptation stimulates the loosely coupled antiports and possibly activates a small serosally located NaCl cotransport. Comparative histology showed flattening of all tissue layers and widening of crypts in PEG animals. Crypt widening may facilitate ion access to underutilized transport sites and, at least in part, explain the increased absorption of the enlarged cecum.
 ...
PMID:Sodium chloride transport of normal and dietary enlarged rat cecum in vitro. 981 93

Silver seabream (Sparus sarba) held in seawater (33 per thousand) or acclimated to a hypoosmotic environment of 6 per thousand were given intraperitoneal injections of saline (0.8% NaCl), recombinant bream growth hormone (rbGH, 1 microg/g), or ovine prolactin (oPRL, 6microg/g) for 7 consecutive days. Serum Na+ levels were unaffected by hypoosmotic acclimation and rbGH and oPRL treatment. Treatment of seawater fish with oPRL resulted in hyperchloremia. In 6 per thousand, saline-treated fish exhibited elevated branchial chloride cell (CC) numbers and exposure indices, all of which were markedly reduced by oPRL. CC numbers and morphometrics were unaffected by oPRL in seawater fish. In contrast, rbGH treatment of seawater fish resulted in elevated CC numbers, apical area, and fractional area and, in 6 per thousand fish, elevated CC fractional area and exposure numbers. Branchial Na+-K+-ATPase activity reduced in saline-treated fish adapted to 6% but was unaffected by rbGH regardless of salinity. oPRL reduced activity in both seawater and 6 per thousand-adapted fish. Neither hypoosmotic adaptation nor oPRL had any effect on renal Na+-K+-ATPase activity whereas rbGH reduced activity in both 33 and 6 per thousand. Saline-treated fish adapted to 6 per thousand exhibited reduced Na+-K+-ATPase activity in most regions of the intestine. Treatment with rbGH did not change intestinal Na+-K+-ATPase activity of seawater fish but elevated activity in the anterior regions (esophagus and stomach) of 6 per thousand-adapted fish. Treatment with oPRL elevated Na+-K+-ATPase activity throughout the gastrointestinal tract of seawater fish and in the anterior reaches of 6 per thousand-adapted fish. The data indicated that the as yet uncharacterized osmoregulatory roles of PRL and GH in seabream may warrant further attention as the present study connoted differing responses to that of other teleosts studied.
 ...
PMID:Effects of prolactin and growth hormone on strategies of hypoosmotic adaptation in a marine teleost, Sparus sarba. 988 39

The plant V-type H+-ATPase (V-ATPase) does not only serve basic housekeeping functions but is also involved in stress-induced NaCl sequestration during salinity stress. To address the question whether the same isoforms conferring housekeeping functions are equally involved in the response to high salinity, we have isolated cDNA clones for subunits A and c, as representing the peripheral V1 complex and the membrane-integral V0 complex, respectively, from the halotolerant sugar beet (Beta vulgaris L., diploid variety). RNA blot analysis with gene-specific probes revealed a coordinate expression of the cloned subunit A and c isoforms during plant development and in response to high salinity. Also, in rapidly dividing suspension-cultured cells with 10-fold increased transcript amounts as compared to young leaf tissue, the ratio of transcripts for both genes was similar to the ratio found for transcripts in leaves of different age. We have then isolated partial genomic clones (BVA/70 for Beta V-ATPase 70 kDa subunit; BVA/16-1 for Beta V-ATPase 16 kDa subunit), including the promoter regions. Transcription start mapping revealed long 5'-UTR leader sequences (230 and 172 bases, respectively) for both genes. Both promoters contain putative G-box motifs in similar distance to the TATA boxes. For a quantitative comparison of relative promoter strength, the BVA/70 and BVA/16-1 promoters linked to the luciferase reporter gene (LUC) were delivered to sugar beet suspension-cultured cells by particle bombardment. The BVA/16-1 promoter showed a 1.7-fold higher activity as compared with the BVA/70 promoter. Salt treatment induced an increase of BVA/70 (+70%) and BVA/16-1 (+57%) promoter activities, concomitant with increased transcript amounts. The following sequences have been deposited at the EMBL database X98767: Beta vulgaris V-ATPase subunit A, cDNA clone; X98851, B. vulgaris V-ATPase subunit c isoform 1, cDNA clone; Y11038, B. vulgaris V-ATPase subunit A, partial genomic clone; Y11037, B. vulgaris V-ATPase subunit c isoform 1, partial genomic clone.
 ...
PMID:cDNA and genomic cloning of sugar beet V-type H+-ATPase subunit A and c isoforms: evidence for coordinate expression during plant development and coordinate induction in response to high salinity. 1009 75

The aim of this study is to evaluate the role of non-selective endothelin blockade (TAK-044) in ischemic myocardial injury. Forty anesthetized rats were separated into four groups: 1) TAK-I group, after preinjection of TAK-044 (3 mg/kg), LAD was ligated for 60 min and reperfused for 60 min; 2) Saline (SAL)-I group, LAD ligation and reperfusion without TAK-044; 3) TAK-C group, sham operated TAK group; 4) SAL-C group, sham-operated SAL group. Myocardium from each group was separated and analyzed by biochemical and ultrastructural procedures. Reperfusion arrhythmia (VT) was observed in 88% of the SAL-I group, in contrast to only 36% of the TAK-I group. At the end of reperfusion, hemodynamics indicated no significant differences between these two groups. The Ca(++)-ATPase activity of sarcoplasmic reticulum (SR) was 3.9 mumoles Pi/mg protein/h (39% of SAL-C group) in the SAL-I group, while that in the TAK-I group was significantly higher at 6.1 (54%). The ratio of infarct/risk area was 58% in the SAL-I group and 36% in the TAK-I group. In the ultrastructural observations, irreversibly injured cells of the ischemic portion were reduced significantly from 35% (SAL-I group) to 14% (TAK-I group). Thus, our results indicated that endothelin blockade reduced ischemic cellular injury. The mechanism of this reduction was speculated to be a resistance to ischemic injury in the subcellular levels of the myocardium conferred by a reduction of vascular constriction and improvement of imbalance in the energy supply and demand.
 ...
PMID:Effect of non-selective endothelin blockade, TAK-044, on the ischemic cellular injury of rat heart. 1032 57

Studies have been carried out to examine in vitro drug transport in plasma membrane vesicles isolated from HL60/ADR cells that overexpress MRP. The results demonstrate that glutathione (GSH) enhances transport of daunomycin. A greater increase in transport activity occurs when the reaction is carried out in the presence of both GSH and sodium chloride. Sodium chloride alone has no effect on daunomycin transport. It has also been observed that GSH in the presence of sodium chloride induces a major increase in the transport level of LTC4. Thus far, no metal ion other than sodium chloride has been found to be active in the drug transport system. Kinetic analysis reveals that GSH in the presence of sodium chloride greatly reduces Km and increases Vmax, for daunomycin. Additional studies show that ATPase activity in isolated plasma membrane from HL60/ADR cells is greatly enhanced in the presence of both GSH and sodium chloride. These results suggest the possibility that GSH and sodium chloride stimulate MRP-mediated transport as a result of increased ATPase activity.
 ...
PMID:Multidrug resistance-associated protein (MRP) mediated transport of daunomycin and leukotriene C4 (LTC4) in isolated plasma membrane vesicles. 1065 18

The effect of cromakalim, an opener of ATP-sensitive potassium (KATP) channel, on precontracted aortic rings from control and salt-loaded rats was studied in Sprague-Dawley rats. Salt-loading experiments involved the induction of hypertension by 6-week feeding of 80 g sodium chloride (NaCl) per kilogram (kg) diet while the control diet had 3 g NaCl per kg diet. Blood pressure and heart rate were determined by cannulation of a femoral artery under urethane/alpha-chloralose anaesthesia. Isolated aortic rings were mounted in tissue baths for isometric tension measurement. The sodium-potassium adenosine triphosphatase (Na-K ATPase) pump activity was measured by potassium (K+)-induced relaxation (with or without ouabain) following precontraction with 10(-7) M noradrenaline. The KATP channel was studied by measuring the relaxation response to cromakalim, precontracted with either 10(-7) M noradrenaline or 60 mM potassium chloride (KCl). The Na-K ATPase pump appeared to be inhibited during salt loading. ATPase inactivation was found to be ouabain sensitive but did not seem to affect subsequent K(+)-induced contraction. Cromakalim produced relaxation of noradrenaline-precontracted rings from the control rats; rings from salt-loaded rats showed significantly less relaxation than control (p < 0.05) under similar conditions. During K(+)-induced precontraction, cromakalim produced a weak biphasic response in the control rings--an initial relaxation and then a reversal. Cromakalim produced further contraction of K(+)-induced precontraction in the salt-loaded group. The results suggest that ATP-sensitive potassium channels and Na-K ATPase pumps on the vascular smooth muscle membrane may be deactivated in the development of hypertension during salt loading.
 ...
PMID:Salt-induced hypertension in rats alters the response of isolated aortic rings to cromakalim. 1139 81

A genetic variant of the gene for the alpha(1)-isoform of Na(+)-K(+)-ATPase (Atp1a1) was suggested to be involved in the pathogenesis of salt hypertension in Dahl rats through altered Na(+):K(+) coupling ratio. We studied Na(+)-K(+) pump activity in erythrocytes of Dahl salt-sensitive (SS/Jr) rats in relation to plasma lipids and blood pressure (BP) and the linkage of polymorphic microsatellite marker D2Arb18 (located within intron 1 and exon 2 of Atp1a1 gene) with various phenotypes in 130 SS/Jr x SR/Jr F(2) rats. Salt-hypertensive SS/Jr rats had higher erythrocyte Na(+) content, enhanced ouabain-sensitive (OS) Na(+) and Rb(+) transport, and higher Na(+):Rb(+) coupling ratio of the Na(+)-K(+) pump. BP of F(2) hybrids correlated with erythrocyte Na(+) content, OS Na(+) extrusion, and OS Na(+):Rb(+) coupling ratio, but not with OS Rb(+) uptake. In F(2) hybrids there was a significant association indicating suggestive linkage (P < 0.005, LOD score 2.5) of an intragenic marker D2Arb18 with pulse pressure but not with mean arterial pressure or any parameter of Na(+)-K(+) pump activity (including its Na(+):Rb(+) coupling ratio). In contrast, plasma cholesterol, which was elevated in salt-hypertensive Dahl rats and which correlated with BP in F(2) hybrids, was also positively associated with OS Na(+) extrusion. The abnormal Na(+):K(+) stoichiometry of the Na(+)-K(+) pump is a consequence of elevated erythrocyte Na(+) content and suppressed OS Rb(+):K(+) exchange. In conclusion, abnormal cholesterol metabolism but not the Atp1a1 gene locus might represent an important factor for both high BP and altered Na(+)-K(+) pump function in salt-hypertensive Dahl rats.
 ...
PMID:Altered Na+-K+ pump activity and plasma lipids in salt-hypertensive Dahl rats: relationship to Atp1a1 gene. 1145 25

The effects of an intravenous injection of Interleukin-12 (IL-12) after endotoxin administration and without endotoxin administration on diaphragm muscle were studied using Wistar rats. Three treatment groups, namely a control (Saline+endotoxin) group, an IL-12+endotoxin group and an IL-12 only group were studied. E. coli endotoxin (30 mg/kg) was injected intraperitoneally 5 min after Saline or IL-12 (0.25 microg) injection. In the control group, the force-frequency curves, twitch tension (TT) and slope during contraction time (TT/CT) were significantly lower at 4 h than those at 0 h due to endotoxin (P<0.001, P<0.01 and P<0.01, respectively), and NO production was increased at 4 h as shown by NADPH diaphorase staining. In the IL-12+endotoxin group, the decrement of the force-frequency curves, TT and TT/CT induced by endotoxin at 4 h were significantly prevented compared with those of the control group (P<0.001, P<0.05 and P<0.05, respectively), and NO production was blocked at 4 h. In the IL-12 only group, the force-frequency curves were decreased in the range of high frequency and IL-12 resulted in NO production. Furthermore, the positive muscle fibers detected by NADPH diaphorase staining were classified as type I and IIa muscle fibers by ATPase staining in the control and IL-12 only groups. It is concluded that IL-12 prevents the deterioration of diaphragm muscle contraction induced by endotoxin by reducing NO production in type I and IIa muscle fibers. These results suggest that IL-12 and endotoxin may interfere with each other.
 ...
PMID:Interleukin-12 prevents diaphragm muscle deterioration in a septic animal model. 1169 2

Programmed cell death (PCD) is a fundamental cellular process conserved in metazoans, plants and yeast. Evidence is presented that salt induces PCD in yeast and plants because of an ionic, rather than osmotic, etiology. In yeast, NaCl inhibited growth and caused a time-dependent reduction in viability that was preceded by DNA fragmentation. NaCl also induced the cytological hallmarks of lysigenous-type PCD, including nuclear fragmentation, vacuolation and lysis. The human anti-apoptotic protein Bcl-2 increased salt tolerance of wild-type yeast strain and calcineurin-deficient yeast mutant (cnb1Delta) that is defective for ion homeostasis, but had no effect on the NaCl or sorbitol sensitivity of the osmotic hypersensitive hog1Delta mutant -- results that further link PCD in the response to the ion disequilibrium under salt stress. Bcl-2 suppression of cnb1Delta salt sensitivity was ENA1 (P-type ATPase gene)-dependent, due in part to transcriptional activation. Salt-induced PCD (TUNEL staining and DNA laddering) in primary roots of both Arabidopsis thaliana wild type (Col-1 gl1) and sos1 (salt overly sensitive) mutant seedlings correlated positively with treatment lethality. Wild-type plants survived salt stress levels that were lethal to sos1 plants because secondary roots were produced from the shoot/root transition zone. PCD-mediated elimination of the primary root in response to salt shock appears to be an adaptive mechanism that facilitates the production of roots more able to cope with a saline environment. Both salt-sensitive mutants of yeast (cnb1Delta) and Arabidopsis (sos1) exhibit substantially more profound PCD symptoms, indicating that salt-induced PCD is mediated by ion disequilibrium.
 ...
PMID:Salt causes ion disequilibrium-induced programmed cell death in yeast and plants. 1187 77


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>